Laura Delgado Díaz 1
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EFFICIENCY AND EFFECTIVENESS ANALYSIS OF THE INVENTORY SYSTEM IN A TESTING FACILITY BY APPLYING LEAN AND SIX SIGMA TOOLS
TRABAJO FIN DE MÁSTER PARA LA
OBTENCIÓN DEL TÍTULO DE MÁSTER
EN INGENIERÍA INDUSTRIAL
SEPTIEMBRE 2019
Laura Delgado Díaz
DIRECTOR DEL TRABAJO FIN DE MASTER:
Pablo Segovia Velasco
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 3
RESUMEN Este Trabajo de Fin de Máster ha sido desarrollado con el objetivo de analizar la
eficiencia y efectividad de un laboratorio de pruebas de una empresa de componentes
mecánicos, mediante la aplicación de metodologías Lean y Six Sigma. El foco se pondrá en
su sistema de gestión de inventario, el cual se encarga de la manipulación y seguimiento de los
prototipos empleados en las pruebas.
La empresa estudiada se encarga del diseño, fabricación y mejora de distintos
componentes mecánicos para la industria de la automoción. Debido a que la naturaleza y detalle
de dichos componentes no es relevante para el presente proyecto, no será detallado. El nombre
de la empresa tampoco se mencionará por motivos de confidencialidad.
Es una compañía mediana que posee una estructura jerarquizada, dividida en distintos
departamentos. Entre ellos, caben destacar el departamento de Mecánica y el Laboratorio de
Pruebas, los cuales deben trabajar de manera coordinada en las etapas de diseño y mejora para
validar los productos creados en la empresa. Para ello se empLean prototipos y distintos bancos
de ensayo capaces de realizar pruebas mecánicas de distinta naturaleza.
El laboratorio de pruebas está dividido a su vez en el laboratorio técnico y el
laboratorio operacional, los cuales se encargan del mantenimiento de los bancos de ensayo y de
la planificación de las distintas pruebas, respectivamente. Es también tarea del laboratorio
operacional, y, en particular, de los coordinadores de pruebas, el asegurar que los prototipos se
encuentran localizados y disponibles y que las distintas pruebas mecánicas pueden realizarse.
Los coordinadores de pruebas supervisan a su vez las distintas operaciones de los prototipos y
del laboratorio, y aseguran la disponibilidad de personal y material para realizar los procesos.
En la Figura 1 se puede observar la estructura de dicho laboratorio.
Figura 1 - Estructura del laboratorio de pruebas
Laboratorio de pruebas
Laboratorio técnico
Desarrollo de bancos de
ensayo
Ingenieros de montaje
Ingenieros de hardware y
software
Soporte y procesos
Laboratorio operacional
Coordinadores de pruebas
Operaciones de prototipos
Montaje de prototipos
Operaciones del laboratorio
Ingenieros de pruebas
Mecánicos
RESUMEN
4 Escuela Técnica Superior de Ingenieros Industriales (UPM)
En la empresa se realizan diferentes procesos, desde la oferta y negociación hasta la
obtención del producto final y su posterior venta. Para el presente trabajo, los más relevantes
serán los procesos relacionados con el laboratorio de pruebas, los cuales son Montaje, Prueba
y Validación. El montaje y desmontaje de prototipos se realiza en el departamento de
Operaciones, y su relevancia reside en asegurar que dichos componentes cumplen los
requerimientos de montaje antes de una prueba, o en detectar fallos mecánicos tras haber sido
probados. Las pruebas mecánicas se desarrollan en los bancos de ensayo, y los resultados de
las mismas se envían al departamento de Desarrollo para su posterior validación.
Por lo tanto, los pasos a seguir para realizar una prueba son los siguientes, tal y como se
muestra en la Figura 2: el ingeniero de desarrollo solicita la realización de una prueba y envía
la orden al laboratorio. A continuación, el coordinador de pruebas se encarga de planificar dicha
prueba y asegurar la disponibilidad de los recursos necesarios para la misma. Dichos recursos
son el requerimiento de la prueba, el personal, el banco de ensayos, el montaje, la secuencia de
la prueba y el prototipo. Una vez todos esos elementos están disponibles, el ingeniero de
pruebas realiza la prueba y comparte sus resultados con el ingeniero de desarrollo.
Figura 2 - Pasos a seguir a la hora de realizar una prueba
El laboratorio de pruebas posee 16 bancos de ensayo diferentes, con al menos un
ingeniero de pruebas encargado de cada banco. Debido al elevado coste e importancia de los
bancos, es un objetivo clave de la empresa el maximizar su utilización. Además de los bancos
de ensayo, el laboratorio de pruebas posee un área de montaje y desmontaje de los prototipos y
tres áreas destinadas a su almacenaje.
Una vez analizada la empresa y el laboratorio de pruebas, es posible detectar el
principal problema que se intentará resolver en esta tesis. Durante los últimos años, la empresa
se ha visto envuelta en un proceso de rápida expansión y crecimiento que ha causado que el
funcionamiento de algunos procesos en el laboratorio no sea el óptimo. Se han detectado
diversas ocasiones en las que los bancos de ensayos no pueden realizar alguna prueba y uno de
los principales motivos es la ausencia de prototipo.
Pese a que hay diferentes áreas de almacenaje, su función no está siempre clara y se dan
situaciones en las que los prototipos son almacenados de forma incorrecta. Esta falta de
transparencia y trazabilidad dificulta el hecho de localizarlos antes o después de haber realizado
una prueba, causando esperas y tareas adicionales a los empleados encargados de encontrarlos.
Crear una orden (INGENIERO DE DESARROLLO)
Planificar la orden (COORDINADOR
DE PRUEBAS)
Preparar la prueba (COORDINADOR DE
PRUEBAS)
Realizar la prueba (INGENIERO DE
PRUEBAS)
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
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Por tanto, el objetivo de este proyecto consiste en analizar cómo la aplicación de
metodologías Lean y Six Sigma puede resultar beneficiosa para mejorar el rendimiento del
laboratorio de pruebas, así como incrementar la trazabilidad y localización de los prototipos.
Con esto se pretende llegar a un mejor entendimiento acerca de cómo un control ineficiente del
inventario puede afectar a los procesos en el laboratorio y sus consecuencias económicas.
Más específicamente, los objetivos del trabajo consisten en la definición y análisis de
los distintos procesos del Laboratorio e identificación de sus desperdicios y sus causas. Así
mismo, se tienen que estudiar las posibles formas de mitigar el efecto de los desperdicios
detectados mediante la aplicación de herramientas Lean. Adicionalmente, se deben ofrecer
propuestas basadas en dicha metodología, definiendo los pasos necesarios para su
implementación y realizando un estudio económico de viabilidad. Finalmente, dichos pasos
deben llevarse a cabo siguiendo Six Sigma.
Antes de comenzar con el desarrollo de la solución, es necesario definir algunos
conceptos claves para este proyecto, tales como el control de inventario, los sistemas de
inventario, las metodologías Lean y Six Sigma y sus herramientas más relevantes.
Desarrollar un adecuado control de inventario es una tarea clave para cualquier
empresa. El mantener la cantidad adecuada de elementos almacenados, en el lugar adecuado y
en el momento adecuado, juega un papel crucial a la hora de satisfacer la demanda y disminuir
costes. Los costes de inventario son los asociados con los costes de pedido, los costes de
almacenaje y los costes de falta de stock.
Para controlar el inventario de forma adecuada, se utilizan los sistemas de inventario.
Dichos sistemas se encargan de contabilizar y organizar el inventario, así como de mejorar su
trazabilidad y registrar los movimientos de cada uno de sus elementos.
La metodología Lean surgió en los años 30 cuando la empresa Toyota creó el Sistema
de Producción de Toyota (TPS), mejorando las ideas de integración de procesos de Henry Ford.
Dicho sistema, que se ha convertido en el ejemplo Lean mundial, se basa en la mejora continua
y optimización de procesos mediante la eliminación de actividades que no aportan valor.
Asimismo, con la eliminación de dichas actividades, denominadas desperdicios o mudas, se
logra un aumento de la calidad y una notable disminución de costes.
Lean se considera una filosofía de trabajo, compuesta de un conjunto de técnicas que, a
la hora de ser implantadas, suponen tanto un alto nivel de compromiso por parte de la dirección
de la compañía, como un profundo cambio cultural en su organización. Los distintos posibles
desperdicios que pueden localizarse en cualquier empresa, según Lean, son los mostrados en
la Figura 3.
RESUMEN
6 Escuela Técnica Superior de Ingenieros Industriales (UPM)
Figura 3 - 7 posibles desperdicios o mudas
Para eliminar dichos desperdicios, se puede utilizar un elevado número de
herramientas Lean, las cuales se pueden implantar de forma independiente o conjunta. Las
más relevantes para este trabajo son:
• VSM: en inglés, Value Stream Mapping o mapas de flujo de valor, se utilizan
para ver y representar las distintas etapas de un proceso, con el objetivo de
detectar fallos y oportunidades de mejora.
• Análisis de causa y efecto: se utilizan para relacionar los distintos desperdicios
con sus posibles causas. Uno de los más comunes es el diagrama de Ishikawa o
de espina de pez.
• PDCA: en inglés, hace referencia a Plan, Do, Control, Act, y es una herramienta
basada en la aplicación de cuatro etapas para la mejora continua de procesos,
productos y servicios.
• Flujo continuo: el objetivo de esta herramienta es el diseño de procesos cuyas
etapas se suceden de manera continua, minimizando las esperas y eliminando
los defectos.
• Estandarización de procesos: elaboración de instrucciones que ilustren el
mejor método para realizar las tareas de manera adecuada.
• 5S: busca la eficiencia de las personas en su área de trabajo, mediante la
búsqueda del orden, limpieza y organización. Consta de 5 etapas, originalmente
en japonés, que marcan las pautas para lograr dicha organización: Sort
(clasificación), Seiton (organización), Seiso (limpieza), Seiketsu
(estandarización) y Shitsuke (disciplina).
• Kaizen: busca el incremento de la productividad y la búsqueda de la mejor
continua, mediante la estandarización del trabajo y la documentación de las
mejores prácticas.
Sobreproducción
Fabricación de productos innecesarios.
Esperas
Tiempos que algunos procesos deben
permanecer inactivos debido al proceso
anterior.
Transporte
Innecesario movimiento de
materiales.
Movimiento
Innecesario movimiento de los
trabajadores.
Reprocesos
Realización de más procesos de los
requeridos para obtener el producto solicitado
por el cliente.
Inventario
Exceso de productos que sobrepasa las necesidades de la
empresa.
Defectos
Productos que necesitan arreglos o reparaciones, o que
tienen que ser descartados.
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
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• Kanban: el objetivo de esta herramienta es la mejora de la trazabilidad,
colaboración y accesibilidad de la información mediante tablas Kanban capaces
de representar el estado de las tareas en tiempo real.
Pese a que la filosofía Lean surgió originalmente con el objetivo de optimizar procesos
de producción, es también aplicable al resto de procesos en las empresas. Los beneficios de
incluir el pensamiento Lean en control de inventarios son, entre otros, la disminución de niveles
de inventario, el incremento de los estándares en materiales y procesos, la mejora de
colaboraciones y una reducción general en costes.
Six Sigma se define como una metodología cuyo objetivo es mejorar la calidad a través
de la identificación y eliminación de las causes de defectos. Se originó inicialmente en Motorola
y posteriormente desarrollada en GE en 1990. Para lograr Six Sigma estadísticamente, un
proceso no debe producir más de 3.4 defectos por millón de oportunidades, considerando
defecto como todo aquello que no cumple con los requerimientos del cliente y oportunidad, la
posibilidad de que se dé un defecto.
Una de las herramientas más usadas y relevantes de la metodología Six Sigma es
DMAIC. Sus siglas en inglés (Define, Measure, Analysis, Improve y Control) se refieren a 5
fases interconectadas que se usan para definir y mejorar procesos existentes. Esta metodología
ha sido la empleada a lo largo del trabajo en la discusión y obtención de los resultados.
La primera parte de la obtención de los resultados y su discusión consiste en un
análisis de la estructura. Se corresponde con las primeras etapas de Definición y Medición
(Define y Measure) de la metodología DMAIC, y consiste en la creación de un mapa de flujo
de valor de los distintos procesos realizados al probar un prototipo, para detectar posibles
retrasos y cuellos de botella.
Para crear el mapa, ha sido necesario recabar información de los empleados del
laboratorio en contacto con los prototipos: los coordinadores de pruebas, los trabajadores del
departamento de montaje, los ingenieros de pruebas y los mecánicos del laboratorio, encargados
de montar y desmontar los prototipos en los bancos de ensayo. Pese a que los coordinadores de
pruebas, encargados de asegurar que todos los elementos necesarios para las pruebas estén
listos, son los responsables de los prototipos, son múltiples las ocasiones en las que los
mecánicos deben buscar los componentes ellos mismos. Los técnicos de montaje pueden
compartir su visión relativa al tratamiento de los prototipos en el departamento de montaje, y
los ingenieros de pruebas pueden ofrecer información de primera mano sobre las pruebas que
se realizan, cómo se reciben y se entregan los prototipos antes y después de las pruebas, y cómo
registran su estado.
RESUMEN
8 Escuela Técnica Superior de Ingenieros Industriales (UPM)
Una vez obtenida dicha información, el proceso de creación del mapa se divide en 5
etapas: decidir su alcance, definir los procesos, indicar los flujos de información, recabar la
información crítica y añadirla junto con los tiempos al mapa. Con ello, se obtienen dos mapas,
uno de situación ideal y otro real, cuya comparación permite detectar las ineficiencias del
laboratorio de pruebas relacionadas con el control de los prototipos. Se observa que dichas
ineficiencias están relacionadas con el incremento de las esperas entre procesos, las cuales están
vinculadas con los tiempos de búsqueda de los prototipos. Se ha detectado un escenario en el
que las dificultades para localizar prototipos son más comunes, y es el caso de prototipos que
tienen que ser probados por segunda o tercera vez y no se guardó un registro adecuado de su
última localización tras la anterior prueba. Al día, se ha observado que se dedica al menos una
hora en buscar algún prototipo.
Tras obtener el flujo de mapa de valor, y, como parte de la etapa de Análisis (Analysis)
de DMAIC, se pasa a la identificación de los desperdicios o mudas existentes en el laboratorio.
Se observa que, debido a las esperas entre procesos, la trazabilidad insuficiente de los prototipos
y la repetición de procesos innecesarios, los desperdicios más significativos son las Esperas, el
Movimiento y los Reprocesos. El principal problema causado por estas mudas es el retraso del
tiempo de inicio de alguna prueba, lo que conlleva la inutilización del banco de ensayo,
causando importantes impactos económicos y, en el peor de los casos, ocasionando retrasos en
el envío de los resultados al cliente.
Los desperdicios detectados están relacionados con dos problemas en particular: las
dificultades al encontrar un prototipo y la repetición innecesaria de procesos. Para entender
mejor las causas de dichos problemas, se lleva a cabo un análisis de causa y efecto mediante
dos diagramas de Ishikawa.
Entre las causas más comunes de no hallar un prototipo se encuentran la falta de
estandarización e información relativa a la localización de los prototipos, los descuidos y
olvidos de los empleados, la comunicación deficiente y la falta de un sistema de inventario
adecuado que registre los movimientos de los prototipos.
En cuanto a la repetición de procesos, se observan causas similares, también
relacionadas con la ausencia de estándares y de un sistema de registro de las acciones de los
prototipos y los problemas de comunicación entre empleados.
Una vez detectados los desperdicios y analizados las causas de sus problemas
relacionados, se inicia la etapa de Mejora (Improve) de DMAIC, en la cual se ofrecen soluciones
para mitigar el efecto de dichas mudas.
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Se ha detectado que, debido a la trazabilidad deficiente de los prototipos, las esperas son
frecuentes entre procesos del laboratorio, ocasionando retrasos e incumplimiento de los tiempos
de entrega. Para disminuir dichas esperas, se ofrecen tres acciones posibles: mejorar la
sincronización entre procesos, mejorar la fiabilidad de los procesos y reducir las faltas de
tiempo mediante un incremento de la eficiencia. Para ello, se propone la utilización de dos
herramientas Lean: flujo continuo y estandarización de procesos.
Debido a que las pruebas no se solicitan ni se realizan a una frecuencia constante, lograr
el flujo continuo en el laboratorio no es tarea fácil. Sin embargo, hay una serie de prácticas que
pueden emplearse para favorecer el flujo continuo. Entre ellas, destaca un aumento de la
consistencia al realizar las pruebas, ya que no debería ser posible empezar una nueva prueba
hasta que el prototipo de la prueba anterior esté colocado en su sitio y sus resultados hayan sido
propiamente registrados. Asimismo, todos los empleados deberían ser conscientes de la
importancia de mantener la organización de los prototipos. Con ello, se lograría incrementar la
frecuencia y calidad del envío de resultados al cliente, y disminuir las esperas.
La estandarización de procesos se puede lograr aplicando la herramienta Kaizen de
mejora continua. Esta herramienta utiliza cuatro etapas, denominadas DAMI: Define, Achieve,
Maintain y Improve. Primero se define un estándar con un objetivo a conseguir y se asegura
que dicho estándar es comprendido por los empleados del laboratorio. Una vez logrado dicho
estándar, debe ser posible mantenerlo. Finalmente, se pasa a la etapa de mejora de dicho
estándar y se vuelve a la primera etapa de nuevo. Mediante la definición de estándares
relacionados con el número de prototipos perdidos o fuera de sitio, se puede lograr la
disminución de los tiempos de espera en el laboratorio.
Para reducir el movimiento innecesario de los empleados en el laboratorio, se ofrecen
dos soluciones, las cuales son la disminución de tiempo de viaje entre procesos (por ejemplo,
entre tomar el prototipo y llevarlo al banco de ensayo en el que se requiere), y la eliminación
de acciones innecesarias (recorrer el laboratorio de arriba a abajo con el objetivo de encontrar
un prototipo).
Una herramienta Lean muy útil para reducir este desperdicio es 5S, la cual está
directamente relacionada con la mejora de la eficiencia de los trabajadores y el aumento del
orden en el laboratorio. Las 5S se deben aplicar en el siguiente orden: primero debe hacerse una
lista con todos los prototipos del laboratorio para detectar cuáles son realmente necesarios y
cuáles se pueden descartar (Sort), a continuación, deben ordenarse y colocarse en posiciones
de fácil acceso, para reducir esperas (Seiton). El siguiente paso es mantener limpio el área de
trabajo, para así facilitar la identificación de problemas (Seiso), y posteriormente incluir
MUDA 1
MUDA 2
RESUMEN
10 Escuela Técnica Superior de Ingenieros Industriales (UPM)
estándares para mantener los prototipos en posición y el laboratorio en orden (Seiketsu).
Finalmente, el último paso consiste en implementar disciplinas y hábitos para mantener las
mejoras y los estándares a largo plazo (Shitsuke).
Algunas de las soluciones para eliminar los reprocesos son la aclaración de los
estándares y expectativas de los clientes con anticipación, la confirmación de que todos los
procesos que se realizan son necesarios para lograr dichas expectativas y el uso apropiado de
procesos. Aunque éste es el desperdicio que sucede con menos frecuencia en el laboratorio, la
repetición de pruebas en un prototipo de manera innecesaria puede conllevar daños mecánicos
que lo hagan invalido para futuras pruebas. Para prevenir y eliminar este desperdicio puede
utilizarse la herramienta Lean Kaizen tal y como se sugiere para la Muda 1.
Mediante la combinación de herramientas Lean y Six Sigma, se pueden ofrecer
soluciones adicionales con el fin de eliminar los desperdicios detectados y mejorar la
trazabilidiad y organización de los prototipos. Dichas soluciones consisten en la Integración de
Sistemas y la Automatización Parcial del laboratorio, y están basadas en la filosofía Kaizen de
búsqueda de la mejora continua.
La integración de sistemas es una propuesta que consiste en la centralización de la
información proveniente de las distintas herramientas de planificación y seguimiento utilizadas
en el laboratorio. Su objetivo es mejorar la calidad de la información, incrementar la visibilidad
y productividad, disminuir esperas y aumentar la capacidad de reacción en caso de ineficiencias.
Todo ello, mediante la combinación de herramientas Lean, tales como flujo continuo y Kanban.
Como previamente se ha mencionado, esta propuesta unifica la información de tres
herramientas: el Diario de seguimiento de prototipos, en el que los ingenieros de pruebas deben
registrar los movimientos diarios del banco de ensayo, así como el prototipo que se utiliza; el
Plan global de pruebas, en el que los coordinadores de pruebas planifican los futuros tests; y,
las Peticiones de montaje, mediante el cual se pueden solicitar acciones de montaje o
desmontaje de los prototipos. La unión de dichas herramientas en un único sistema de Estado
de prototipos, equivalente a un sistema de inventario, permite obtener una imagen global de los
procesos del laboratorio, así como llevar un mejor seguimiento de las pruebas y los prototipos.
El elemento más importante de dicho sistema es la Matriz de estado de los prototipos.
Dicha matriz representa el estado de los prototipos a lo largo del tiempo, a fin de detectar
tendencias y corregir errores. Se define como estado físico de un prototipo la comparación entre
su localización actual y su localización requerida. Hay cuatro posibilidades diferentes de
estados: “En posición”, “Realizando una prueba”, “Posición errónea” y “Desconocido”. El
MUDA 3
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Laura Delgado Díaz 11
funcionamiento de la matriz es muy similar a una tabla Kanban, ya que permite organizar el
trabajo desde un nivel organizativo y acceder al estado de los prototipos en cualquier momento.
La información de dicha matriz se debe registrar en un conjunto de bases de datos, entre
las que destacan la base de datos de Prototipos, la de Lugares de almacenamiento, la de
Distribuidores y la de Usuarios. Las bases de datos deben estar interconectadas y se tienen que
actualizar cada vez que se registre algún cambio en el sistema. Entre los posibles cambios
destacan: cambio en el estado de un prototipo, registro de un nuevo prototipo, realización de
una prueba en un prototipo, movimientos… La utilización de bases de datos para visualizar la
información en una tabla Kanban, favorece la metodología de flujo continuo y mejora continua.
Con la automatización parcial del laboratorio se busca la disminución del error
humano y la mejora de la trazabilidad. Se apuesta por el uso de etiquetas y lectores de radio
frecuencia RFID para identificar tanto los prototipos como los distintos lugares de almacenaje.
Esta propuesta complementa a la integración de sistemas ya que ofrece información actualizada
sobre la localización de los prototipos y promueve el flujo continuo.
Para llevar a cabo la propuesta, primero es necesario aplicar la metodología 5S para
identificar los distintos prototipos, clasificarlos y asignarles lugar de almacenaje. Asimismo, se
requiere de una reestructuración y redefinición de los posibles almacenes en el laboratorio de
pruebas. Una vez realizados dichos pasos, se asignan etiquetas RFID a cada uno de los
prototipos y se colocan lectores en la entrada de los posibles almacenes y bancos de ensayo. De
esta manera, quedaría registrado cada movimiento realizado por los prototipos, siendo posible
actualizar la base de datos con su último estado.
Una vez definida la etapa de Mejora de DMAIC, se finaliza con la etapa de Control, en
la que se definen indicadores para asegurar el mantenimiento de las soluciones propuestas.
Dichos indicadores se denominan KPI o Key Performance Indicators, y se dividen en
“Indicadores rezagados” e “Indicadores líderes”, en función de si la información que analizan
es histórica o actual, respectivamente. Para la presente tesis se han utilizado datos sobre el
estado de 25 prototipos en el período comprendido entre el 27 de octubre de 2018 y el 31 de
mayo de 2019.
Los Indicadores rezagados arrojan información muy valiosa a la hora de detectar
tendencias históricas y saber cómo el control de inventario de los prototipos ha funcionado a lo
largo del tiempo. Los Indicadores líderes, por el contrario, analizan los últimos resultados
registrados en el sistema para obtener su funcionamiento actual. Entre la información de mayor
valor que pueden proporcionar se encuentra el porcentaje de prototipos en localizaciones
erróneas o desconocida. Se observa que, para el 31 de mayo, un 36% de los prototipos de la
muestra seleccionada se encuentran en una posición errónea, y del 16% se desconoce su
posición. Para asegurar la trazabilidad y control de los prototipos, debería ser objetivo común
del laboratorio el minimizar dichos porcentajes.
RESUMEN
12 Escuela Técnica Superior de Ingenieros Industriales (UPM)
Una vez definidas las propuestas, se sugieren pasos a seguir para su implementación, la
cual se podría llevar a cabo en un tiempo estimado de 68 días, y se analiza su viabilidad
económica. Comparando los costes estimados de la implementación y mantenimiento del
sistema de Estado de prototipos con los costes actuales incurridos, se observa que podría
lograrse una significante reducción de costes desde el año siguiente a su implantación. Dicha
reducción de costes iría incrementando con los años, pudiendo lograr un ahorro estimado de
133.827 € en el quinto año.
Tras finalizar la etapa de resultados y discusión, se estudian los diferentes impactos que
el proyecto podría causar en sociedad. Dichos impactos son principalmente legales (licencias
de los programas utilizados), profesionales (mejora del rendimiento de los trabajadores,
incremento de la calidad de la comunicación, etc.) y económicos (las propuestas solucionadas
podrían suponer ahorros significativos para la empresa).
Se concluye que, pese a las limitaciones existentes, se ha logrado satisfactoriamente el
objetivo de este proyecto: el análisis de la aplicación de metodologías Lean y Six Sigma para
mejorar los procesos en un laboratorio de pruebas y eliminar sus desperdicios. Se ha justificado
también cómo un control ineficiente del inventario puede afectar a los procesos en el laboratorio
y qué consecuencias económicas acarrea. El desarrollo de la solución se ha llevado a cabo
siguiendo la metodología DMAIC de Six Sigma.
Como opciones de mejora futuras, algunas de las sugeridas son el llevar a cabo la
implementación de las sugerencias propuestas, realizar la difusión del pensamiento Lean a lo
largo de la empresa, la creación de una interfaz de usuario e incorporación de más
funcionalidades en el sistema de Estado de prototipos, etc.
Por último, se realiza un estudio de la planificación temporal del proyecto y un estudio
económico del mismo. El proyecto se ha llevado a cabo en un intervalo de 11 meses, y se han
empleado un total de 377 horas en su realización. Económicamente, teniendo en cuenta la mano
de obra y el equipamiento, supondría unos costes totales de 13.631,32 €
To my professor Pablo, for his interest in the project since the very beginning, it would
not have been possible without your patience, guidance and help
To my abuelo and my yayo, who have always loved me and support me, and who I
miss every day…, I just hope to make you feel proud
To the rest of my family, for all your encouragement and love, even from the distance,
I have never really felt far away from home. Specially to my cousin Sofía, for being brave
enough to join me in this new crazy chapter and for all the laughs, cries and unconditional
support
To my friends, to the ones they have been always there and to the new ones with whom
I am sharing these new adventures
And finally, to my colleagues, for their help, guidance, patience and good energy,
I can feel really lucky to work with you
Thank you so much
Laura Delgado Díaz
September 2019 - Ghent, Belgium
ABSTRACT
Lean and Six Sigma methodologies were introduced in the 40’s and the 80’s,
respectively. Since then, the number of companies that have implemented their tools in order
to enhance their efficiency and quality has not cease to grow. Both are defined as Continuous
Improvement methods that pursue operational excellence and customer satisfaction.
The purpose of this Master thesis has been to analyse the performance and efficiency of
a testing lab in a company specialized in mechanical components for the automotive industry.
By using concepts from Lean and Six Sigma, there have been spotted the different challenges
faced by the facilities and have been offered different suggestions to improve their processes.
To properly comprehend those processes, a combination of observations and interviews
has formed the main source of information throughout the project. A theoretical framework
constituted by the prevailing theory on Lean and Six Sigma has been linked and merged with
those observations.
After acknowledging that one of the highest-value processes is the management and
tracking of the testing prototypes, a discussion has been started from that point. There have
been approached the wastes by using tools such as VSM or Root-cause analysis. Subsequently,
the provided recommendations are in the form of standardized processes, 5S or Kaizen.
Moreover, there have been suggested two additional innovative solutions whose aim is to
improve planning, schedule and tracking, through continuous flow, Kanban tools and PDCA
approaches. The whole discussion has been carried out adopting the Six Sigma DMAIC
method.
Furthermore, there have been successfully detected the existing bottleneck processes,
identified their influence, and provided recommendations to mitigate their effect.
Keywords: Lean, Six Sigma, wastes, Inventory Control, Inventory Systems, testing lab,
mechanical prototypes
Unesco nomenclature:
• 3310.99 Industrial Technology
• 1207.08 Inventory
• 1207.10 Network flow
• 1207.13 Scheduling
• 3310.03 Industrial processes
• 5311.07 Operations research
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 19
TABLE OF CONTENTS
1. INTRODUCTION ................................................................................................ 23
1.1. Background ..................................................................................................... 23
1.1.1. Structure of the company .......................................................................... 23
1.1.2. Processes in the company ......................................................................... 26
1.1.3. Testing facilities ....................................................................................... 28
1.2. Problem description ........................................................................................ 31
1.3. Purpose ........................................................................................................... 31
1.4. Structure of the Thesis .................................................................................... 31
2. OBJECTIVES ...................................................................................................... 33
2.1. General objectives .......................................................................................... 33
2.2. Specific objectives .......................................................................................... 34
3. STATE OF THE ART ......................................................................................... 35
3.1. Inventory Control ........................................................................................... 35
3.2. Introduction to Inventory Systems ................................................................. 36
3.3. Lean thinking .................................................................................................. 37
3.3.1. Seven wastes ............................................................................................. 38
3.3.2. Lean tools ................................................................................................. 39
3.3.2.1. Value Stream Mapping ....................................................................... 39
3.3.2.2. Root cause analysis ............................................................................. 39
3.3.2.3. PDCA approach .................................................................................. 39
3.3.2.4. Continuous flow .................................................................................. 39
3.3.2.5. Standardized work .............................................................................. 39
3.3.2.6. 5S ........................................................................................................ 40
3.3.2.7. Kaizen ................................................................................................. 40
3.3.2.8. Kanban ................................................................................................ 40
3.3.3. Lean applied to inventory control ............................................................. 41
3.4. Six Sigma ........................................................................................................ 41
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20 Escuela Técnica Superior de Ingenieros Industriales (UPM)
3.4.1. DMAIC ..................................................................................................... 42
4. METHODOLOGY .............................................................................................. 43
4.1. Initial study ..................................................................................................... 43
4.2. Project preparation .......................................................................................... 44
5. RESULTS AND DISCUSSION .......................................................................... 45
5.1. Structure analysis ............................................................................................ 45
5.1.1. VSM.......................................................................................................... 45
5.1.2. Muda (waste) identification ...................................................................... 52
5.1.3. Root cause analysis ................................................................................... 54
5.2. Design of the solution ..................................................................................... 57
5.2.1. PDCA approach ........................................................................................ 57
5.2.2. Waste 1: waiting ....................................................................................... 58
5.2.2.1. Continuous flow .................................................................................. 58
5.2.2.2. Standardized work .............................................................................. 59
5.2.3. Waste 2: motion ........................................................................................ 59
5.2.3.1. 5S ........................................................................................................ 59
5.2.4. Waste 3: over processing .......................................................................... 60
5.2.4.1. Kaizen ................................................................................................. 61
5.2.5. Additional solutions .................................................................................. 61
5.2.5.1. System Integration .............................................................................. 61
5.2.5.2. Partial automatization and tracking .................................................... 70
5.2.5.3. KPIs .................................................................................................... 79
5.2.5.4. Steps for their implementation ............................................................ 86
5.2.5.5. Economic feasibility ........................................................................... 88
5.3. Legal, professional and economic impacts ..................................................... 92
6. CONCLUSIONS .................................................................................................. 93
6.1. General conclusions ........................................................................................ 93
6.2. Specific conclusions ....................................................................................... 94
6.3. Limitations ...................................................................................................... 96
7. FUTURE WORK ................................................................................................. 97
8. TEMPORAL PLANNING AND PROJECT BUDGET ................................... 99
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 21
8.1. Temporal Planning ......................................................................................... 99
8.2. Work Breakdown Structure .......................................................................... 102
8.3. Project Budget .............................................................................................. 103
9. REFERENCES ................................................................................................... 105
10. ABBREVIATIONS AND ACRONYMS ...................................................... 109
List of figures ............................................................................................................ 111
List of tables .............................................................................................................. 113
APPENDIX 1: RFID tags and readers ................................................................... 115
APPENDIX 2: Estimated parameters for the Economic Feasibility Study ........ 117
APPENDIX 3: Interview guide ............................................................................... 119
TABLE OF CONTENTS
22 Escuela Técnica Superior de Ingenieros Industriales (UPM)
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 23
Chapter 1.
INTRODUCTION
1. INTRODUCTION
The purpose of this first chapter is to give a general view of the framework of this Master
thesis, as well as the problems expected to be solved and the objectives that want to be achieved.
There will be also included an overview of all the different chapters and parts in which this
thesis is divided.
1.1. Background
The main function of any testing facility is to accomplish quality and performance
checks of products, in order to give feedback to its clients. Since it provides qualitative and
quantitative output about their performance, it is a key part of any manufacturing company,
especially in design and validation stages. Therefore, it is critical to optimize the effectiveness
and efficiency of its processes.
This chapter’s goal is to contribute to a global understanding about how the company
works, its structure, which are its processes and a final focus on the Testing facilities.
1.1.1. Structure of the company
The studied company is a mechanical company specialized in the design, manufacture
and testing of different assemblies and components for the high-performance automotive
industry. It is a medium size company with ~1500 employees, founded in the 70s that serves a
global client base thanks to its operations based in North America and Europe. For the present
project, the characteristics of those types of car components are not relevant and therefore they
will not be detailed. For confidentiality reasons, the name of the company will not be mentioned
either.
The structure of the company is a hierarchical organization, whose employees are
ranked in different levels within the company, each level being above another one. To ease the
control of the different processes, each level is led by a person who is responsible of several
workers. This structure is followed in all the departments of the company, clearly defining the
role of every employee and their relationship with the rest of the employees. It is a centralized
INTRODUCTION
24 Escuela Técnica Superior de Ingenieros Industriales (UPM)
structure, which means that higher management is often responsible for taking the most
important decisions.
To have a more precise idea, in Figure 1 it is possible to see an overview of the
company’s organization, and its different main departments.
Figure 1 - Structure of the company
As a head of the company there is the manager director, who makes sure all the
departments are aligned and functioning properly. He is responsible for the daily operations of
the company and is also expected to keep the company solvent, as well as to promote its
innovation and expansion within the industry. Below the director, it is possible to find some
key departments such as Mechanics, the department of Controls and the Testing Lab.
The Mechanics department oversees the design and production of the different
products from the company, and is divided in three sub departments: Development, Systems
and CAD. Development is responsible for defining the products and their characteristics, and
ensure it follows the client requirements –design wise-. The Systems department has to make
sure the different subsystems of the product work, and how to achieve that; in the CAD
department they are responsible of the mechanical design of the components of the product, as
well as of the theoretical materials, strengths, resistance and mechanical tests of them.
In the Controls department they are focused on the performance of the whole system
and how every part of the product interacts with the rest. Furthermore, it is also a core task of
the department to prepare the software in the system to be as autonomous and intelligent as
possible.
For the scope of this master thesis, the most important department would be the Testing
Lab. In this department there are performed mechanical tests to validate the quality and
functionality of the product, so it is one of the most critical departments of the company. The
Manager Director
Mechanics
Development Systems CAD
Controls Testing Lab
Operational Lab
Technical Lab
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Laura Delgado Díaz 25
Mechanics department and, in particular, the Development department, is the direct responsible
of requesting and detailing the tests that have to be performed. The Testing Lab is divided in
the Technical Lab, responsible of the instrumentation and controls; and the Operational Lab.
Figure 2 - Structure of the Testing Lab
The test lab is organizationally structured as shown in the Figure 2. As mentioned, it has
two main subdivisions: the Technical Lab and the Operational Lab. The Technical Lab must
maintain the test benches and the necessary equipment to perform the tests, whereas the
Operational Lab acts more directly on the product itself, making sure that test runs and validates
the quality of the product.
As previously mentioned, the Technical Lab oversees the maintenance of the Test
benches, it must ensure their quality and availability. The different tests are run in the test
benches, so it is critical to keep them in the optimal conditions, making sure they work
according to the specifications. Since the company runs high performance mechanical tests for
the automotive industry, it is always primordial to keep the safety in the Lab.
As a part of this department, there is the Test Bench Development department and
Support and Processes department. The Test Development Department has two types of
engineers: Test Setup Engineers and Hardware and Software Engineers. The first ones must
make sure the setup is correct before starting any test, which means, the Test Bench is in good
conditions and is successfully equipped with all the required sensors and elements specified in
the Test. The second group of engineers, Hardware and Software engineers, provide the
Testing Lab
Technical Lab
Test Bench Development
Test Setup Engineers
Hard. & Soft. Engineers
Support & processes
Operational Lab
Tests coordination
Prototype Operations
Prototype Assembly
Lab Operations
Test BenchesLab
Mechanics
INTRODUCTION
26 Escuela Técnica Superior de Ingenieros Industriales (UPM)
necessary tools such as required electronic devices or programming modules to make sure the
test can be programmed, and the CPU is communicated with the test bench. The Support and
Processes Department manages the different test benches and makes sure the specifications
related with quality and security issues are fulfilled.
The Operational Lab is responsible of managing the different products that are going
to be tested and planning the different tests. The head of the department is closely in contact
with the tests coordinators, whose main function is to plan the different tests, ensuring not only
the availability of the products that are going to be tested, but also the readiness of the sequence,
the test request, the test bench and the staff. Inside the Operational Lab, there are also two sub-
departments: Prototype Operations Department and Lab Operations Department. In Prototype
Operations they are mainly responsible of the assembly and disassembly of all the different
parts and products, evaluating them by visual inspection and reporting the results to the Test
Coordinators. Lab Operations Department is divided in the Test Benches and the Lab
Mechanics. The Test Benches are the physical location where the tests are done and they are
direct responsibility of the Test Engineers, whereas the Test Mechanics are the staff responsible
of mounting the different products to test, as well as to ensure the mechanical status of the
Benches.
1.1.2. Processes in the company
The different stages before selling any product, from the product concept to
manufacturing, are the ones shown in the Figure 3:
Figure 3 - Processes in the company
Offer and negotiation
Definition of the product
Final design, development and research
CAD
CAMTesting of the
prototypeProduction Assembly
Testing ValidationDevelopment
of the product
Final product and selling
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Laura Delgado Díaz 27
1. Offer and negotiation: there is a meeting between the company and the client where
the client determines his requirements and specifications regarding the product. If both
sides come to an agreement, the project is signed.
2. Definition of the product: the second step is to define in detail all the parts of the
product, according to the client’s specifications. That means, define not only which
elements are going to be in the product, but also which departments should be involved
in the process. There are some aspects that need to be consider such as:
a. The reliability of the product.
b.What would be the manufacturing costs, keeping in mind the price
agreed with the client to leave room for profit.
c. The complexity of the manufacture, considering all the components that
conform the product.
d.Determination of the materials that are going to be needed for
production.
3. Final design, development and research: include all the needed materials and
dimensions of the product, editing the design as much as necessary. All vital details
should be included.
4. Computer-aided design: also known as CAD, in this step the goal is to develop a
computer model of the final design, by using 3D rendering software. By doing so, it is
possible to detect and reveal any potential issues that were not obvious during the
product design stage.
5. Computer-aided manufacturing: simulate the manufacturing process of the different
components and products, using computer simulation software.
6. Testing of the prototype: in this step the main goal is to check the behaviour of the
prototype, making sure it works as expected, and, if any issue is detected, schedule the
necessary amendments on the design that should be done to correct it.
7. Production: once the prototype has passed the tests and there are no more issues to
solve, the next step is to proceed with the manufacturing of the product. Some of the
decisions that should be taken at this stage are the materials that are needed, the batch
number and the manufacturer. For the studied company, the manufacturing process is
done internally for the majority of the components of the product.
8. Assembly: the scope of this step is to gather all the different manufactured parts and
build the final product.
9. Testing: once the product has been manufactured and assembled it is time to do rigorous
tests to validate it. Those tests will be requested by the Development department, as
mentioned before, and they will take place in the Testing Lab.
10. Validation: the Test Engineers have to send the results of the tests to the Development
department, who is the responsible of the validation of those tests. If the validation
process is not successful, it might be necessary to redesign some parts of the product
and to develop specific tests to investigate the root causes of the issues.
INTRODUCTION
28 Escuela Técnica Superior de Ingenieros Industriales (UPM)
11. Development of the product: once the validation process is completed, the product can
start to be manufactured.
12. Final product and selling: the clients –mainly automotive brands- receive the product
after the manufacturing, which will be ready for them to include it in their vehicles and
try their behaviour and performance.
This project will be focused on the analysis of the Testing stages, mainly, but also
indirectly in the Assembly and Validation stages.
1.1.3. Testing facilities
The tests in the testing lab are processed following the structure shown in Figure 4:
Figure 4 - Tests requesting process
1. Create an order: first an order from Engineering (development department) is
created, requesting for a test to be performed, to check the behaviour for
validation a specific mechanical component. The order is detailed in a document
called Test Request, where is stated the Unit where the test should be performed,
the tools and sensors to use, the different steps to follow while testing and the
results that are expected.
2. Plan the order: afterwards, the order is sent to the Test Lab Coordinators, whose
task is now to plan the test, when and where it has to be performed, which tools
are needed, and who would be the responsible people (Test Engineers, Test
Bench Engineers, Test Mechanics) involved in the test. The test coordinator
must plan the test starting day, the end day, as well as the tests that must be
performed before and after. To plan those starting and ending date he asks for
input from the Test Engineer. The goal would be to keep the test bench as less
idle as possible.
3. Prepare the test: as mentioned before, it is also duty of the Test Lab Coordinator
to make sure that the planned dates are reached. In the Figure 5 it is possible to
see a schematic overview of all the different elements that need to be aligned
and ready before starting every test. Therefore, before the test starting date, the
Create order (ENGINEERING)
Plan the order (LAB COORD)
Prepare the test (LAB COORD)
Test (LAB ENGINEER)
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Laura Delgado Díaz 29
Test Bench Coordinator has to make sure the sequence is ready (Test engineers),
the test bench will be ready (Test Bench Engineers), the tools and prototype to
test will be ready (Engineering and Test Mechanics), as well as the necessary
staff to monitor and make sure the test runs.
Figure 5 - Test readiness requirements
4. Test: the test engineer would be responsible of preparing and starting the test,
supervising its performance and keeping the requestors informed about the
results. Once the test has been done (it can end up as FAILED or SUCCEEDED),
the tested prototype is taken out of the Test bench and the Test Bench Engineers
and Test Mechanics should make sure the bench is ready for the following
planned test.
The physical place in the company where the tests are performed is called the Test Lab.
This place is divided in different regions by functionality: Test Benches, Assembly zones, and
Storage areas.
In total, 16 test benches are allocated in the Test Lab. At least one test engineer is
responsible of every test bench. These benches develop different mechanic tests, and it is key
for the company to minimize their idle time as much as possible. The idle time (and therefore
the delays) from the benches can come from different causes, as explained before: test sequence
not ready, test bench or test request not ready, prototype to test not ready, setup not ready and
lack of staff. The warehouse of the Test Lab should be ready to avoid the lack of the materials
needed for the Setup and ensure the readiness of the prototypes, and it should make sure all the
elements are localized and ready to use before starting any test.
The Assembly zones are the physical areas where the different mechanical components
and parts are mounted or disassembled. They are directly linked with the Test benches and the
warehouse, since the parts need to be ready before the tests start, and there should be also room
TEST READY
Test Request
Staff
Setup
Prototype
Test Sequence
INTRODUCTION
30 Escuela Técnica Superior de Ingenieros Industriales (UPM)
for disassembly in case it is required after a test is done, or the test fails. To sum up, in Assembly
there are two processes: assembly and disassembly of the parts, which are explained further in
detail:
• Assembly: it is a process required every time a test is going to be performed and
every time a component has been disassembled and needs to be mounted again
to carry on with testing or shipment.
• Disassembly: this process might be required when a test finishes and it is
specified by the requesters to analyse it internally, or when a test fails, and it is
necessary to check the interior of the component in order to analyse the root
causes better.
In Figure 6 it is possible to see a schematic view of the Test Lab, divided in the
different areas. The areas in blue (TU) represent the different Test cells or Test Units, the area
in orange (AW) is the Assembly workshop and the areas in green (WH) represent the different
storage locations. Currently, WH1 is used to temporary store items such as some prototypes
that have arrived. WH2 is used for obsolete prototypes that are not really needed and WH3 has
space for some critical prototypes that must be stored there for a while. The yellow areas
represent the working area of the Test Engineers controlling the different tests and the white
area is currently a free space. The grey areas represent space dedicated to other departments.
The whole area of the facilities is around 6000m2 and its perimeter is approximately 300 meters.
The longest distance (in diagonal), is 114 meters. Therefore, it takes less than 5 min to walk
from any point to any other point within the facilities.
Figure 6 - 2D map of the Testing Facilities
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Laura Delgado Díaz 31
1.2. Problem description
Due to the fast grow of the company, and its rapid increase of human and materials
resources, the performance of the Testing facilities is often not optimal. The main goal of the
facilities is to minimize the idle time of the test benches, due to their high costs. However, there
are several situations where the test bench cannot run a test and one of the most common causes
is the lack of testing prototype.
Although there are several storage areas, their function is not often clear and there are
misunderstandings and errors made when storing a prototype before or after a test. That lack of
transparency and poor tracking of the items lead to many situations where the employees
struggle to find the prototypes to test.
1.3. Purpose
The purpose of this project is to analyse the benefits of applying Lean thinking and Six
Sigma principles in the Testing facilities. Therefore, the goal is to increase the knowledge about
those methodologies and apply their tools to study, characterize and try to improve the
performance of the Test Lab, by mainly focusing on the prototypes’ management. This will
lead to a better understanding of how a poor control of the inventory can affect the different
processes in the Testing facilities and its economic consequences.
1.4. Structure of the Thesis
Chapter 2 presents the general and specific objectives pursued by the Thesis.
Chapter 3 provides an overview about the state of the art, mainly related with Inventory
Control, Lean methodologies and Six Sigma.
Chapter 4 states the methodology that has been followed in order to successfully
accomplish the objectives of this thesis.
Chapter 5 shows the obtained results, analyses and provides a detailed discussion about
them.
Chapter 6 describes the major findings as conclusions.
Chapter 7 suggests future work that could overcome the limitations of this thesis.
Chapter 8 presents the planning over time as well as the budget that would have to be
spent when performing this type of project.
The last two chapters, 9 and 10, state the References, Abbreviations and Acronyms used
in the project. Finally, there are also collected the list of tables and figures; as well as three
appendixes.
INTRODUCTION
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Chapter 2.
OBJECTIVES
2. OBJECTIVES
The objectives throughout this thesis can be classified in two categories, general
objectives, which provides a global overview of what needs to be achieved, and specific
objectives, more focused on providing a more detailed description of all the steps that need to
be followed in order to accomplish the general objectives.
2.1. General objectives
The main aim of this project is to deeply analyse the different processes that occurs in
the Test Lab and detect how the management of the testing components affects its performance.
Once done that, and based on a proper theoretical background, it is possible to suggest different
solutions that will improve the normal functioning of the activities in the facilities and its
control of inventory.
It will be necessary to properly identify the wastes that occur and use Lean tools to
propose ways of reducing or eliminating them. The whole identification and search of the
solution will be carried out by following the DMAIC methodology from Six Sigma (Define,
Measure, Analyse, Improve and Control).
OBJECTIVES
34 Escuela Técnica Superior de Ingenieros Industriales (UPM)
2.2. Specific objectives
To make sure the general objectives are achieved, it is necessary to define the specific
objectives, which will be related with the different stages of the Project:
1. Define, measure and analyse the current processes in the Testing facilities by using
Lean tools.
2. Identify the different wastes related with the prototypes and existing in the facilities
and carry on a root cause analysis.
3. Study the solution to mitigate the effect of each one of the wastes, by applying
different and specific Lean tools.
4. Propose alternative solutions based on Lean and Six Sigma methods.
5. Define and describe those proposals and its needed elements.
6. Define the necessary steps to successfully implement both proposals.
7. Analyse the economic feasibility of the proposals.
8. To perform all the previous stages, follow the Six Sigma methodology to identify
and search for the solution.
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Chapter 3.
STATE OF THE ART
3. STATE OF THE ART
The objective of this chapter is to provide a basic background about Inventory Control
and its importance for the companies, an overview of Inventory Systems, as well as Lean
thinking and its applications in warehousing. Finally, it will be explained the main
characteristics of Six Sigma and how is it beneficial for companies.
3.1. Inventory Control
For any company, one of the most important logistic drivers in its Supply Chain is the
Inventory. The challenge of having the right number of elements stored in the right place, in
the right moment, is key to face the customer demands and decrease the costs of the company.
Inventory Control can be considered as essential to improve service and reduce costs, and it
determines how good a company manages its working capital to maintain a consistent and
adequate cash flow [1].
There are three different types of inventory costs, which are the following:
o Ordering costs: cost of purchasing a new item for the company.
o Holding costs: cost of money tied up in inventory, such as the cost of
capital or the opportunity cost of the money [2]. Moreover, it also considers:
▪ Cost of the physical space occupied by the inventory including
rent, depreciation, utility costs, insurance, taxes, etc.
▪ Cost of handling the items.
▪ Cost of deterioration and obsolescence.
o Shortage costs: costs of running out of inventory in stock [3]. These costs
include:
▪ Loss of time and delays
▪ Costs of pilferage, obsolescence and shrinkage
▪ Costs of misuse of the workforce
▪ Loss of potential sales
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Through a proper Inventory Control, the main objective is to minimize the costs related
with holding too much unnecessary inventory and shortage of items (not enough stock to meet
the demand). Therefore, it is critical for any company to calculate the right number of products
while coping with the uncertainty of the Supply Chain. As shown in the Figure 7, the holding
costs and the ordering costs are key to obtain the optimal amount of products (Q*) that need to
be purchased to minimize the total costs.
Figure 7 - Optimum batch size in Inventory Control
3.2. Introduction to Inventory Systems
As mentioned, it is a crucial challenge for every company to find the optimal and most
suitable system to manage its inventory. Inventory management is responsible of the inventory
system of a company, which is an element of the supply chain and it refers more specifically
to processes such as storing, ordering and using a company’s inventory. It is also included the
management of raw materials, components and finished products [4].
Inventory systems also ease the process of organizing and managing multiple items in
several locations. Although there are multiple types of inventory system, which can vary in
their individual design, feature set and operations, they all share some basic capabilities [5], as
shown in the Figure 8.
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Figure 8 - Basic characteristics of inventory systems
Therefore, for most companies, implementing a proper Inventory System is a key
activity that has a huge impact in its daily operations and financial statements.
3.3. Lean thinking
The core idea of Lean thinking is to gradually work on eliminating waste from the
company’s processes [6]. Every activity that does not add any value from the client’s
perspective is considered as a muda or waste. A Lean organization understands the customer
value and focus its efforts and processes to continuously increase it.
In 1913, Henry Ford came up with a solution to integrate his entire production process.
In the 1930s, and based on Ford’s idea, in Toyota they invented the Toyota Production
System, which became the leading Lean exemplar in the world.
This system mainly moved the focus of the manufacturing engineer from individual
machines and their utilization, to the flow of the product through the total process. Toyota stated
that it would be possible to decrease the costs, increase the variety and quality, as well as to
obtain very rapid throughput times to respond to changing customer desires by [7]:
• Properly sizing the machines for the actual volume needed.
• Implementing self-monitoring machines to ensure quality.
•The system must always be aware of all the items stored in the company. It should not only provide a total count of inventories, but also data related with the amount of inventory allocated in a specific location
Count
•It is common that most items do not stay in a single location. In order to obtain a precise inventory count, an inventory system must be able to track the movement from one location to another.
Track
•Keeping a proper record of the transactions associated with inventory management is key for companies to avoid financial issues and inaccurate inventory numbers.
Record
•Inventory systems are able to manage the inventory’s characteristics such as how much inventory to order, order cycle, supplier information, production costs, product lead time, lot-size availability, product units of measurement, among others.
Manage
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• Aligning the machines up in process sequence.
• Pioneering quick setups so each machine could make small volumes of many
part numbers.
• Having each process step notify the previous step of its current needs for
materials.
This could also help to make the information management much simpler and more
accurate. Toyota turned into the largest automaker in the world, considering the overall sales,
which made it stand as the strongest proof of the power of Lean enterprise.
Since Lean thinking is unstoppably being spread across the world, its tools have been
adapted beyond manufacturing, to distribution and logistics, services, retail, healthcare,
construction, maintenance, and even government.
3.3.1. Seven wastes
As previously explained, the main idea of Lean is to eliminate everything and anything
which is not adding value for the customer. There are identified 7 main areas of waste, that are
typically known as the 7 deadly wastes [8]:
• Overproduction: manufacturing a product before it is needed, which leads to
extra inventory and an increase of storage costs.
• Waiting: time that some of the processes must be on hold for the previous
transaction.
• Transport: avoidable movement of raw materials, finished goods or work-in-
progress.
• Motion: unnecessary movement of people.
• Over-processing: do more processing that is needed to produce what is required
by the customer.
• Inventory: quantities of different products (such as raw materials, work in
process or finished goods), that exceed the needs of the company.
• Defects: deficiencies in products that need some rework, or they are scrap.
A highly relevant form of waste that is not included in seven wastes is the unused
human potential. This waste causes the loss of many opportunities, as, for instance, the lack
of motivation, the lack of creativity and the lack of ideas. To avoid and eliminate this eighth
waste, it is normally advisable to develop strong coaching skills for managers that can end up
being very effective in strengthening employee contributions.
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3.3.2. Lean tools
There is an extensive collection of Lean tools, which can eliminate the different wastes
and improve the company operations. The most relevant Lean tools for this project will be
explained in this chapter.
3.3.2.1.Value Stream Mapping
A Value Stream Mapping o VSM is a tool used to visually plot the flow of different
processes. Shows the current and expected state of steps highlighting opportunities for
improvement. This Lean tool can expose the waste in the current processes and offer a roadmap
for development through the future state. [6]
3.3.2.2.Root cause analysis
Ishikawa diagrams: This technique, published by Kaoru Ishikawa in 1990 [9], clearly
plots the root causes of the problem. Moreover, it is also a useful tool for uncovering bottlenecks
in a process and identifying why a process is not working. [10]
3.3.2.3.PDCA approach
PDCA, also known as the ‘Deming Wheel’, is a four-stage Lean tool for continually
improving processes, products or services. It was developed by Dr William Edwards Deming
in the 1950s., and it provides a simple and effective way of solving problems and managing
change. [11]
PDCA stands for Plan, Do, Check and Act, which are four steps that should be followed
in order the get the highest quality results in our solutions.
3.3.2.4.Continuous flow
The objective of this tool is to design processes whose flow is continuous and the
number of buffers between steps have been minimized or eliminated. [12] By implementing
continuous flow, it is possible to eliminate many forms of waste, such as inventory, waiting,
time and transport.
3.3.2.5.Standardized work
The goal of this Lean tool is to use standardized work instructions to ensure the use of
a consistent method and consistent times for each step of production. [13] Standardized work
is also defined as the basis of operations to make sure the products are made in the easiest,
safest and most effective way based on the current technologies and formulas. [14]
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40 Escuela Técnica Superior de Ingenieros Industriales (UPM)
3.3.2.6.5S
5S is a strategy based on the CANDO1 system developed by Henry Ford at the beginning
of the 20th century [15]. 5S stands for the Japanese words used to describe the steps of a
workplace organization process: Seiri (sort), Seiton (Set in order), Seiso (Shine), Seiketsu
(Standardize) and Shitsuke (Sustain). Those steps need to be taken in the mentioned order, as
shown in the Figure 9.
Figure 9 - 5S steps
3.3.2.7.Kaizen
The name of this philosophy comes from a Japanese term meaning “change for the
better” or “continuous improvement”. It should be necessary to document the current best
practice to define the standardized work that will form the baseline for continuous
improvement. Once that standard has been improved, a new standard will become the baseline
for further improvements, and so on, [16] following the PDCA cycle.
3.3.2.8.Kanban
Kanban is a Lean tool which stands for improving the traceability, collaboration and
accessibility of information. It represents work items on a Kanban board, that allows team
members to check the state of every piece of work at any time. Those boards can either be
1CANDO system: C=cleaning up, A=arranging, N=neatness, D=discipline and O=ongoing improvement
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physical or digital and their task is to ensure the team’s work is visualized, their workflow is
standardized, and all issues or dependencies can be immediately identified and resolved. [17]
3.3.3. Lean applied to inventory control
When it comes to inventory control it is also possible to apply Lean techniques, since
they help companies to reduce costs, improve flexibility and have more time to spotlight the
customers’ needs. For instance, by applying Lean tools to control the inventory, it is possible
to obtain some benefits such as:
• Decrease of storage units and inventory levels
• Increase of the standards in materials and processes
• Improvement of collaborations
• Overall reduction in costs
Therefore, Lean supply chain and inventory management enable companies to improve
efficiency and increase profits. [18]
3.4. Six Sigma
Six Sigma is defined as an improved method whose goal is to maximize quality through
the identification and elimination of sources of defects. It was initially originated in Motorola
and further developed by GE in the 1990s. In order to statistically achieve Six Sigma, a process
shall not produce more than 3.4 defects per million opportunities, as represented in the Figure
10. A Six Sigma defect can be defined as anything that is not aligned with the customer
specifications, and an opportunity is considered as the total number of chances for a defect [19].
Figure 10 - Six Sigma distribution
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3.4.1. DMAIC
DMAIC, which stands for Define, Measure, Analysis, Improve and Control, is an
essential part of a company’s Six Sigma programme, and it is mainly used to assess and improve
existing processes. The actions that define its name are linked with five interconnected phases,
which will be explained further in detail [20]:
1. Define: the first step consists on identifying and selecting the right project, as well
as selecting its boundaries and goals.
2. Measure: gather data to determine the “current state” of the project. That data is
referred to key process characteristics, the scope of parameters and their
performances.
3. Analyse: interpret the data to identify key causes and process determinants. If the
result is not what expected, its design can be modified and restart in the “Measure”
stage.
4. Improve: change the process by addressing and eliminating the root causes, in order
to optimize its performance.
5. Control: implement procedures to ensure the gains are sustained.
In Figure 11 there are schematically represented the stages of the DMAIC methodology [21].
Figure 11 - DMAIC Methodology
Define
Measure
Analyse
Design acceptance?
Improve
Control
Redesign
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Chapter 4.
METHODOLOGY
4. METHODOLOGY
The general methodology that has been followed to obtain the results of this thesis is the
Six Sigma DMAIC method. This methodology, which includes definition of measurement,
improvement and control, provides a structure framework for solving business issues by
following an effective process execution. [22]
In this chapter it will be detailed how it was the initial study and the preparation that it
was necessary to carry out the project.
4.1. Initial study
The idea for this Master Thesis got born while working as a test engineer in a mechanical
lab. It was noticed that some processes were not working properly and there was some
misunderstandings and problems in the testing facilities due to the control of the assets in the
inventory. That seemed challenging so the decision of analysing the prototypes’ warehouse and
the different processes related with it, in order to give some ideas to try to improve its
performance was taken. By merely observation, analysis of the historical data, and different
interviews with responsible people inside the company, all combined with personal experience
and effects observed while performing the different tests, it was possible to come to a more
precise idea about how the warehouse was working. In the APPENDIX 3: Interview guide,
there are exposed the different questions that were asked during the interviews.
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44 Escuela Técnica Superior de Ingenieros Industriales (UPM)
4.2. Project preparation
The preparation for the project was divided in two stages. The first stage consisted on
getting familiar with all the technical knowledge that it was required for the project. During that
stage, it was necessary to investigate about Supply Chain Management and its logistical and
cross-functional drivers, Lean thinking and Six Sigma, Warehouse Management Systems and
latest and modern inventory issues and solutions, such as automatization or system integration.
The second stage was mainly focused on the gathering of information about the Testing
facilities. It was analysed in detail how the Testing facilities were working, the elements that
they were being stored in the different storage locations, how was the division of
responsibilities, the main complaints from the employees and issues they were facing, as well
as the details about the physical distribution of the facilities. To obtain a more detailed
understanding of how the management of the prototypes was being handled, it was selected one
test bench as a reference and deeply analysed all its activities during a 10-month interval. Once
done that, it was possible to apply all the theoretical knowledge in the real-life example.
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Chapter 5.
RESULTS AND DISCUSSION
5. RESULTS AND DISCUSSION
The aim of this chapter is to describe the different phases followed to obtain the results.
Those are the structure analysis, the design of the solution and the legal, professional and
economic impacts caused by the project.
5.1. Structure analysis
The scope of this chapter will be to analyse the structure of the testing facilities by
applying Lean thinking and tools such as VSM or root cause analysis. By doing so, it will be
possible to properly identify the existing wastes in that specific department in the company.
Once that has been achieved, the objective of the following chapter: “Design of the solution”,
will be to find solutions to minimize those wastes.
5.1.1. VSM
Value Stream Maps are particularly valuable for representing the flow of production and
highlighting opportunities for improvement. By creating a VSM that represents the processes
of the testing facilities the objective is to easily detect which are the bottlenecks and where do
they occur. A VSM can be as complex as wanted, so therefore is especially important to
determine beforehand which are the process adding the highest value. In this case, it has been
analysed all the process followed when testing a prototype, in order to look for possible delays
or restrains. Since the testing process is similar in every test bench, the results obtained can be
extrapolated to every single prototype tested in the company.
To carry out the mapping [23], it has been used first-hand information coming from
representatives of different departments. Since they have a realistic perspective on how things
are done, it is possible to obtain an objective status of the system and the different processes,
and spot real problems on it. Considering that the objective of this project is to detect how the
inventory control of the prototypes is affecting the testing processes, it was necessary to gather
information from representatives of departments in contact with the prototypes and in charge
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of their tracking. For that reason, it was key to have the perspective of Test coordinators,
Prototype Technicians, Test Engineers and Lab Mechanics. In the Figure 12 is shown the
Testing Lab structure, highlighting the departments of the mentioned representatives. The
representatives in Test coordination, the Test coordinators, could offer information related with
all the stages that the prototypes go through since their entrance in the company till they are
stored or sent to the client. The representatives in Prototype Assembly, the Prototype
Technicians, could offer their vision related with the handling and treatment of the prototypes
in assembly. The representatives in the Test Benches, the Test Engineers, provided first-hand
vision of the different tests that are carried in their Test Bench, how the prototypes are received
and delivered after testing, and how their test status is logged. The Lab Mechanics could also
offer output about the difficulties they encounter to find prototypes. Once that information was
gathered, was possible to start mapping.
Figure 12 - Prototype stakeholders in the Testing Facilities
The process of creating the VSM using the gathered information has been carried out
following different stages. In the Figure 13 is possible to see the final VSM obtained.
1. Decide how far to go
Firstly, it was necessary to indicate a start and end point, to show where the internal
processes begin and ends. The start point is stated at the pickup of the prototypes,
not only from external suppliers but also from internal ones, for the cases where re-
testing of prototypes is carried out.
Testing Lab
Technical Lab
Test Bench Development
Test Setup Engineers
Hard. & Soft. Engineers
Support & processes
Operational Lab
Tests coordination
Prototype Operations
Prototype Assembly
Lab Operations
Test Benches Lab Mechanics
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The end point is determined as the delivery or storage of the prototype and the
sharing of the information with the customer, a Test requestor from Development
department.
2. Define the processes
Secondly, there has been determined all the different processes that the prototype
goes through to get from the start to the end point and they add value along the way.
Those processes are:
1) Functionality check 1: once the prototype has been delivered from the
supplier, it must go through a process to check if it has the necessary
functionality requirements to be tested. This process is typically carried out
in a Test Bench specialized in End of Line (EoL) testing.
2) Testing: if the prototype successfully passes the Functionality check, it is
handed from the EoL bench to the test bench where the required test needs
to be performed. The information related with that test must be provided by
the Engineering department in advance.
3) Functionality check 2: once the test has been done, it is typically requested
to carry out a second functionality check to confirm the results and prove the
prototype is still passing the functionality requirements.
4) Disassembly: afterwards, it is common to realize some physical checks of
the prototype in the Assembly department, to add as information to the Test
results.
5) Storage: finally, the last stage is to properly store the prototype. Depending
on the result of the test and the type of prototype, as well as the future
planning for that prototype, there must be designed some specialized areas
for its storage.
3. Indicate the Information Flows
The Information Flows are represented in the top part of the VSM. The Engineering
Department (the customer), needs to communicate the Testing Lab which test want
to perform, and Testing Control needs to align when, where, how and with which
prototype that test can be performed. If it is a prototype that needs to be provided by
an external supplier, the Testing department needs to contact him and align the date
and way of the delivery. However, if it is a prototype that has been already tested
and it is already allocated in the testing facilities, they need to have it localized and
align the date and way of the delivery as well to the test engineer.
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Considering the testing process is not a process following a Continuous flow, the
frequency of those Information Flows is variable, depending on the requirements of
the Engineering department.
4. Gather the critical data
Once all the basic structure has been determined it was necessary to specify some
critical data for each process. For this case, the relevant information to gather was
the location of the processes, the number of shifts done and the total time of
availability per day. As well, it was also important to include the transfer time and
the cycle times. Since they are flexible processes, depending on the request, the
determined cycle times are an average of the real ones. For the testing process, since
it can take from less than 10 mins to months and it is not possible to shorten or
optimize it, the cycle time has not been considered. The transfer time before and
after testing processes considers the mounting and dismounting time of the prototype
by a Mechanic in the Test Bench, as well as the receiving time. That receiving time
is defined as the amount of time that it takes to find the prototype in the facilities,
take it from that location and move it to the new one. Since the facilities have a
relatively small size, the biggest distance that a prototype needs to be manually
moved should not take more than 10 minutes (600 seconds).
5. Add data and timelines to the Map
Finally, all those times and data are added to the map. As a result, it is seen that the
total Lead times when testing a prototype is 24.600 seconds and the total processing
time higher than 20.400 seconds. This means, on average a prototype should spend
at least a total of 45.000 seconds (12,5 hours) since it arrives in the facilities till it is
stored or delivered. On average, as well, for short tests, the lead times and the
processing times are very similar. However, the longer the test is, the longer the
processing time takes, and the bigger is the difference with the lead times.
To sum up, following those steps has made it possible to create the Ideal Value Stream
Mapping, where all the processes work as planned and there are no downtimes. However, the
current Real Value Stream Mapping of the company differs from the ideal situation. Once the
Ideal situation was created, it was simple to modify it to see where the process is having
inefficiencies, focusing exclusively on the inventory management of the prototypes. On the
Figure 14, it is shown the final Real VSM, having the differences with the Ideal VSM marked
in red.
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Figure 13 - Ideal VSM
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Figure 14 - Real VSM
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Once both VSM have been compared, and just by focusing on the inefficiencies created
by the Inventory control of the prototypes, it is possible to see that they are related with an
increase of the receiving time. The receiving time is defined as the sum of the following:
𝑅𝑒𝑐𝑒𝑖𝑣𝑖𝑛𝑔 𝑡𝑖𝑚𝑒 (𝑠)
= 𝑇𝑖𝑚𝑒 𝑠𝑒𝑎𝑟𝑐ℎ𝑖𝑛𝑔 𝑓𝑜𝑟 𝑡ℎ𝑒 𝑝𝑟𝑜𝑡𝑜𝑦𝑝𝑒
+ 𝑇𝑖𝑚𝑒 𝑚𝑜𝑣𝑖𝑛𝑔 𝑡ℎ𝑒 𝑝𝑟𝑜𝑡𝑜𝑦𝑝𝑒 𝑓𝑟𝑜𝑚 𝑙𝑜𝑐𝑎𝑡𝑖𝑜𝑛 𝐴 𝑡𝑜 𝐵
It has already been explained that the time to move the prototypes is rarely significant
due to the small distances in the facilities. However, the issues start to appear when the time
searching for a prototype is higher than it should be. Optimally, it should not take more than a
couple of minutes to find the latest location of a prototype in the facilities, whilst in real life it
has been experienced that is rather often to spend more than 3 hours in that process. Taking
more time than the necessary on that process can have important consequences, from small
delays in the starting time of a test on its scheduled day, to more relevant postponements. It can
cause tests to be postponed days or even weeks in some occasions, the idleness of the test
benches and, in the worst cases, delays in the delivery of the results of critical tests to the client.
In the real VSM it has been reflected as an example a critical situation where the process
of finding the prototype was taking more than 3 hours for every stage in between processes.
That would mean that the total lead times would increase to 75.600 seconds, which represents
a 307% increase compared with the ideal scenario. However, these difficulties when finding a
prototype do not occur with the same frequency for all the receiving times. They are mainly
detected in the delivery before the first Process, especially if the Supplier is internal and the
prototype had been already been tested and was already allocated inside the testing facilities.
In those situations, the responsible of finding the prototype, the Test Coordinator, or, in some
cases, the Lab Mechanic, is not able to find its physical location, or the prototype has been
misplaced and is not standing in its assigned location.
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5.1.2. Muda (waste) identification
A Value Stream Map is especially useful when it comes to waste identification.
According to Lean Thinking, as it has been already explained in the Chapter 3, there are seven
wastes that can be eating up the profits of an organization. To analyse which ones are the ones
affecting the testing processes, it would be necessary to study each one of them keeping the
VSM in mind.
WASTES Influence Level
Over-
production
As previously defined, overproduction is described as the
manufacture of a product before it is needed, which leads to extra
inventory and an increase of storage costs. Since the testing facility
is providing a service and not focused on production, this waste does
not occur.
-
Waiting
This waste happens when some of the processes must be on
hold for a previous transaction. As it has been detected in the current
VSM, this occurs specially when a test is not able to start because
the prototype is not ready or in the wrong position.
Transport
Since the facilities have a small size, the movement or
materials, prototypes or tools does not require a significant amount
of time (typically the longest transportation transaction takes no
more than 10 minutes to be done). Therefore, this is not a waste that
is detected during the analysis.
-
Motion
The insufficient tracking of the prototypes leads to the need
of working hours to search for them. This mainly affects the
responsible workers in the testing facilities. When these situations
occur, they need to go to the different locations where the prototype
might be and check if it is there. It can be concluded that this
unnecessary movement of people is a waste which affects the
facilities.
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Over
processing
In the testing facilities there are situations where some
processes are repeated for different reasons. As an example,
sometimes when a prototype arrives in the company is driven
through a quality test that had already been made in the supplier
facilities. This leads to an increase of the lead times, which causes,
as a result, an increment of the waiting time and, in some cases, even
to the postponement of tests.
Inventory
This waste is detected when quantities of different products
(such as raw materials, work in process or finished goods), exceed
the needs of the company. This is especially problematic when the
company has very tight space limitations, since it will increase the
storage costs. Due to the enough storing space in the facilities and
the moderate amount of testing prototypes, this waste does not have
enough influence. The inventory levels can just become an issue for
the tested prototypes that have to be stored in the Validation
Warehouse for long term.
Defects
The main goal of the whole testing Laboratory is to detect
defects on the prototypes. During the testing process there are no
defects being made but detected. Since it is also not focused on a
production process, this waste is not affecting the company.
-
Table 1 - Seven wastes of the testing facilities
To sum up, after analysing the wastes in the facilities in Table 1, there have been
detected three mayor ones: waiting, motion and, with lower impact but still representative,
over processing. The biggest problem these wastes can cause is the postponement of the
starting time of a test, which leads to the idleness of that test bench and delays in sending the
requested information to the customer.
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5.1.3. Root cause analysis
The wastes studied previously occur due to two mayor problems of the testing facilities:
• Difficulties when finding a prototype (poor tracking of the prototypes)
• Repetition of processes such as quality processes
In order to obtain a better understanding of the reasons why these issues occur is
necessary to use the Lean tool Root-Cause analysis. It has been decided to use the Fishbone
Diagram or Ishikawa Diagram to do so.
For the first problem, poor tracking of prototypes, there have been detected 7 different
factors: Process, Information, Methodology, Supplier, Man or mind power, Management and
Physical evidences. In the diagram shown in the Figure 15 is possible to see in detail the
underlying causes related with the mentioned factors. By analysing the diagram, it is possible
to investigate the most likely causes further and detect which ones are contributing to the
problem.
Therefore, from the information shown in the diagram, it is easy to detect correlations
between some of the causes. For instance, the employee’s mistakes can be easily linked with
the fact that there is poor access to the information related with the prototypes status, as well as
there is a lack of a uniform system with standard information about their position. That poorness
in the information system is related with the lack of coordination mechanisms or location
procedures from the management department, since they focus their efforts on improving other
processes which they considered had higher importance.
When it comes to supplier mistakes, since the company cannot control external
processes, it is hard to find a solution for that. However, it has been experienced that those
mistakes do not occur often.
For the second problem, the repetition of processes, there have been distinguished 5
different factors, as shown in detail in the Figure 16. These factors are: Method, Information as
part of the Materials used, Man or Mind power, Management department and Physical
evidences.
The causes that occur with the highest frequency are the ones related with the
Information system and the communication issues. As observed for the problem previously
analysed, ‘difficulties when finding a prototype’, it is also common that the information related
with the status and history of tests a prototype has done is not centralized in a common system.
There is also a lack of standard procedures to log that information properly.
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Figure 15 - Tracking of prototypes: Fishbone Diagram
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56 Escuela Técnica Superior de Ingenieros Industriales (UPM)
Figure 16 - Over processing: Fishbone diagram
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Laura Delgado Díaz 57
5.2. Design of the solution
Once the different wastes have been identified and studied, the scope of this section is
to evaluate different solutions to eliminate or minimize their influence. As explained in the
previous section, the identified wastes are Waiting, Motion and Over processing. Those
wastes cause delays, misuse of the work force and have important economic impacts which will
be analysed further in detail.
As complementary solutions there will be two additional suggestions, based on the
combination of Lean and Six Sigma tools: the Integration of the internal systems in the Testing
Facilities and a Partial automatization and improvement of the prototype’s tracking. For optimal
results, those two solutions should be used simultaneously. A detailed definition and
explanation of both will be done in the last point of this chapter.
5.2.1. PDCA approach
Before evaluating the different wastes and their possible solutions in detail, it is
necessary to mention that any improvement should be implemented following the PDCA
methodology, schematically shown on the Figure 17.
Figure 17 - PDCA approach
PLANUnderstand and
identify the problems
DO
Gather data and test potential
solutions
CHECK
Analyze the results
ACT
Implement the solution
RESULTS AND DISCUSSION
58 Escuela Técnica Superior de Ingenieros Industriales (UPM)
5.2.2. Waste 1: waiting
Due to the poor tracking of the prototypes, as previously explained, it is often to perceive
waiting times along the process. If those waiting times are spread across the chain, that can
affect the delivery date of results to the customer, which can have critical consequences with
the clients and the signed projects.
Therefore, it is key to reduce as much as possible this waste. In order to do so, there are
three actions or objectives to pursue [24]:
• Improve the synchronization between the processes
• Increase the reliability of processes
• Reduce downtime by improving the efficiency.
As Lean Tools to decrease waiting are particularly useful: Continuous Flow and
Standardized Work. Let’s try to consider both more exhaustively and recommend ways to
implement them in the organization.
5.2.2.1. Continuous flow
As schematically shown in the Figure 18, continuous flow allows to move a single
prototype through every step of the Testing process instead of grouping different prototypes
into batches. Simply, once you start working on a product, you should keep focused on it until
it is ready to be delivered to the customer. [12]
To be more precise, to achieve Continuous Flow in the testing facilities, it would be
necessary to improve the consistency when testing. It should not be possible to start a new test
if the prototype from previous test is still on the Test Bench and its test results has not been
properly logged and sent yet. This would allow to provide value to the customers with a higher
frequency and to decrease the time they spend on hold to receive their order. For the studied
case, that value would be the Information with the Test Results and the customers, the Test
Requestors, from the Development department.
Figure 18 - Working in batches VS Continuous Flow
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 59
5.2.2.2. Standardized work
In the testing facilities, standardized work can be achieved by using the business
philosophy Kaizen.
For instance, to define the best practice in the facilities and decrease the waiting waste,
a possible standard could be to try to achieve a daily percentage of missing and misplaced
prototypes less than 5%. It would be necessary to involve all the workers in contact with the
prototypes and make sure the standard is understood and pursued by all of them. Once that
standard is achieved, it would be necessary to be able to properly maintain it. Afterwards the
last step would be to pursue the improvement of that standard, which could be to achieve less
than 1% of daily prototypes, for example.
It can be concluded that the thinking process for Kaizen, in order to achieve
standardization, consists of 4 steps: Define, Achieve, Maintain and Improve (DAMI) [25].
5.2.3. Waste 2: motion
It has previously defined motion as the unnecessary movement of people. To get rid of
this waste, it is often to take two different actions [24]:
• Decrease travel time between stages or process stations
• Remove excessive or unnecessary machine movements or actions
In the testing facilities, unnecessary motion occurs mainly when a Test coordinator
needs to go through the different storage locations in order to find a prototype. A possible action
to take could be to assign an official area near the Test Benches where to allocate the prototypes
that are scheduled to be tested, and therefore decreasing the travel time between the pickup of
the prototype and its setup on the Test Bench. Moreover, if the prototypes have a better-defined
position in the facilities, it would be possible to remove excessive and unnecessary actions,
since it would decrease the time looking for them, and as a result to mitigate the motion.
There is a Lean tool which is typically applied to improve the physical organization of
a company and workplace efficiency, the Japanese methodology 5S.
5.2.3.1. 5S
Although the organization follows with highly accuracy the 5S methodology, there is
still room for improvement when it comes to the prototypes’ storage. To improve its storage, it
should be necessary to dedicate some workforce to apply the mentioned steps in the following
way:
1. Sort: make a list with all the prototypes stored in the different locations of the
facilities, distinguish between necessary and unnecessary ones, in order to get rid of
what is not needed. This would help to increase the free space in the facilities and to
obtain a better understanding of the status of the items that are currently being stored.
RESULTS AND DISCUSSION
60 Escuela Técnica Superior de Ingenieros Industriales (UPM)
2. Set in order: by following the practice of orderly storage, it would be possible to
efficiently pick up the right item, decreasing waste and lead times, and with easy
access for everyone. It should be necessary to assign a place for all the prototypes
and to keep all of them in their place. This step will be more detailly explained in
5.2.5.2.1.
3. Shine: try to create a clean workplace without dirt, dust or garbage, in order to
identify problems such as leaks, spills, excess, damage… more easily. Since this is
a step already followed in the company, it should be enough to keep the efforts on
maintain the workspace clean as it is.
4. Standardize: this step is based on the setting up of standards for a neat and clean
workplace. To make abnormalities more visible to management, it should be needed
to send alarms through tools such as Kanban boards, for instance. Thanks to that, it
would easier and more automatic to detect when a prototype is not in its assigned
position, or to trigger an alarm some days before the start date of a test if the testing
prototype has not arrived or been found yet.
5. Sustain: finally, the last step is to implement habits and behaviours in order to
maintain the stablished standards over the long term. To do so, it should be necessary
to spread the 5S mentality through all the levels of the company and ensure leader
commitment to establish and maintain responsibilities.
5.2.4. Waste 3: over processing
It has been stated that over processing is the performance of more processing than it is
needed to meet the customer’s requirements. In order to eliminate its influence, some tips could
be the following [24]:
• Clarify customers' standards and expectations ahead of time
• Only perform processes that are necessary to meet these expectations and
standards
• Use appropriate processes (avoid overly complex machinery or processes if
possible)
Since the unnecessary repetitions of processes does not occur with high frequency, it is
not a critical waste. However, to prevent it to happen it should be necessary to improve the
communication throughout departments, and to make sure than even the lower areas know the
client requirements and expectations. Through a system like the one that will be explained in
5.2.5.1, it would be possible to log and check easily the process that have already been done to
a prototype. Having that information clear, it would be rarer to repeat processes unnecessarily.
To decrease over processing, it is typically used the Lean Tool Kaizen.
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Laura Delgado Díaz 61
5.2.4.1. Kaizen
On production companies, it is common to use the Takt Time term (time required for
producing one unit) in order to reduce over production. However, since the Testing facilities
are not focused on production, over processing can be reduced just by properly defining the
work sequence and instigating the use of SOP (Standard Operating Procedures). This would be
defined as the exact sequence of steps taken to complete the work. Therefore, the over
processing waste, as well as the waiting times, will be solved when standardizing the different
operations.
5.2.5. Additional solutions
As mentioned, based on the combination of Lean and Six Sigma tools, there will be
suggested two additional solutions to mitigate the wastes. Those solutions are named as the
Integration of Systems and the Partial Automatization of the facilities, and they are based on
Kaizen philosophy of continuous improvement. In the following two sections they will be
explained further in detail.
5.2.5.1.System Integration
This proposal is based on the centralization of the information from the different
management tools used currently in the facilities to plan tests and log the testing information of
the prototypes. That information would be stored in different databases and displayed in a
Matrix that would work as a Kanban board, pursuing Continuous flow. The goal is to improve
the quality of the information, as well as to achieve higher responsiveness, lower transportation
costs, higher product availability and lower safety inventory.
Through Systems Integration, not only it is possible to complement Lean principles, but
also to encourage the employees to pursue continues improvement in the company, as well as
to minimize or eliminate the waste. [26] It helps to analyse business processes more easily and
to improve employee productivity.
When it comes to Inventory Systems, some of the existing benefits of the System
Integration are the optimization of inventory to meet product availability, the improve of the
inventory visibility and the state of the inventory accuracy.
The different management tools whose information would be centralized are the
following ones:
• Prototype Logged Diary: it is a tool filled in everyday by every Test Engineer.
It is a system used by management to check the performance of the test benches
in the Testing Lab. It has information related with the Test Bench they are
operating, the prototype they are testing and the test which is being performed.
Furthermore, it is also used as a diary to log when a Test Bench is being repaired,
when it is not being used, etc.
RESULTS AND DISCUSSION
62 Escuela Técnica Superior de Ingenieros Industriales (UPM)
• Testing Global Plan: it is a tool which can only be modified by management
and it is used to plan all the incoming tests. The information is divided by Test
Bench and it contains, among other data, the requested starting date of every
future test, as well as the prototype that will be tested. It also saves the estimated
duration of every test.
• Assembly Workshop requests: this system is mainly used by the Test
Engineers and the workers in Assembly to indicate when an assembly or
disassembly work needs to be done to a specific prototype.
In order to integrate their information, it would be necessary to develop an additional
system, that could be named as ‘Prototype status system’. It would work as an Inventory System
and it would use their data as schematically shown in the Figure 19.
Figure 19 - Integration of systems
5.2.5.1.1. System description and definition
The whole goal of the system would be to create the Prototype Status Matrix, whose
general definition is shown in the Figure 20. This Matrix could show the daily status of a
number N of prototypes through a number T of days. Thanks to that information, it would be
possible to obtain valuable quantitative outputs related with how the Inventory management of
the prototypes is working.
Prototype Logged Diary
•Past data by test bench
•Tests performed by every prototype
Testing Global Plan
•Future data by test bench
•Tests that will be performed by every prototype
Assembly Workshop requests
•Current and future requests of assembly/disassembly of prototypes
Prototype status system
• Past and current data by prototype
• Information related with tests performed
• Historical status for every prototype
• Requested location
• System data bases
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 63
Figure 20 - Prototype Status Matrix
In order to obtain a better understanding about how Prototype Status Matrix works, it
would be necessary to describe more in detail its structure:
• S ꞓ MN x T: Status of the prototype n at the timeframe t
S is a NxT matrix whose components represent the status of a prototype
in a portion of time. For instance, the element s12 would represent the status of
the prototype 1 in the timeframe 2.
• n = 0, 1, …N: Prototype n, being N total number of prototypes
• t = 0, 1, …T: Timeframe t, being T total number of timeframes
• k ꞓ (1, 4): coding for the status of the proto
To classify the physical status of the prototypes there have been created
4 different categories, as shown in the Figure 21. Those categories are: In
position, Testing, Wrong position and Unknown Position; and are assigned to
every prototype by comparing its requested location in a period t and its
current location in that period. Through this system, it is easy to identify the
number of prototypes that need to be reallocated or found, and to trigger alarms
in that case.
Figure 21 - Status codes for the prototypes
RESULTS AND DISCUSSION
64 Escuela Técnica Superior de Ingenieros Industriales (UPM)
• SkSNn: Sum of all the timeframes at which the prototype n had the status k
• TotalSNn: Total of timeframes with logged status for the prototype n
• PercSkSNn: Percentage that the prototype n was at the status k during its
timeframe
• SkDatet: Sum of all the prototypes that had the status k at the timeframe t
• TotalDate
t: Total of prototypes with logged status at the time t
• PercSkDate
t: Percentage of prototypes with status k at the time t
In the Figure 22, it is possible to see an example of the Prototype Status Matrix, using
daily data from 25 prototypes during the month of May, in a Test Bench in particular. As it is
possible to see in the image, there have been tested 4 different prototypes during that month in
that Test Bench. In total, the Bench has only been idle two days, during the first weekend of the
month, which means a 93,54% of utilization.
∀ 𝑠𝑛𝑡 = 𝑘, 𝑆𝑘𝑆𝑁𝑛 = ∑ 𝑠𝑛𝑡
𝑡=𝑇
𝑡=0
𝑇𝑜𝑡𝑎𝑙𝑆𝑁𝑛 = ∑ 𝑆𝑘𝑆𝑁𝑛
𝑘=4
𝑘=1
𝑃𝑒𝑟𝑐𝑆𝑘𝑆𝑁𝑛 =𝑆𝑘𝑆𝑁𝑛
𝑇𝑜𝑡𝑎𝑙𝑆𝑁𝑛
∀ 𝑠𝑛𝑡 = 𝑘, 𝑆𝑘𝐷𝑎𝑡𝑒𝑡 = ∑ 𝑠𝑛𝑡
𝑛=𝑁
𝑛=0
𝑇𝑜𝑡𝑎𝑙𝐷𝑎𝑡𝑒𝑡 = ∑ 𝑆𝑘𝐷𝑎𝑡𝑒𝑡
𝑘=4
𝑘=1
𝑃𝑒𝑟𝑐𝑆𝑘𝐷𝑎𝑡𝑒𝑡 =𝑆𝑘𝐷𝑎𝑡𝑒
𝑡𝑇𝑜𝑡𝑎𝑙𝐷𝑎𝑡𝑒
𝑡
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 65
Figure 22 - Example of a Prototype Status Matrix
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RESULTS AND DISCUSSION
66 Escuela Técnica Superior de Ingenieros Industriales (UPM)
This prototype status matrix should be automatically filled in in a daily basis, by
checking the information of each prototype and comparing it with their requested status, to keep
an accurate track and record of its movements. From a Lean point of view, this matrix would
work as a Kanban board since it would help to manage the work at an organizational level and
access to the state of every prototype at any time.
The information of the Prototype Status Matrix should be stored in a Data Base and it
should be accessible and reachable by the workers in the Lab. That database would be named
as Prototypes Database and it should be aligned with three other databases, as shown in the
Figure 23. These databases would provide information of the different storage locations, the
users and the suppliers, as they will be explained further below.
Figure 23 - Databases of the system
When designing the databases, it was considered that they should store as much
information about the prototypes as possible, to enhance Continuous Flow. Following the
principles of Inventory Systems, the databases should be able to help the system to properly
count, track, record and manage the information of the prototypes and the storage locations.
The Prototypes Database is shown on the Table 2, and it should store information
related with different aspects of each prototype:
• Identification and qualitative information: ID, Serial Number, weight,
dimensions, image, description, category, testing type.
• Record information: tests done, historical data.
• Tracking information: RFID tag id, current location, requested location.
• Management information: registration date, status, last modification date,
responsible coordinator, supplier.
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 67
DATABASE DATA DESCRIPTION
PROTOTYPES
PROTOTYPE_ID INT(10000) Prototype Identifier given by the system (AUTO_INCREMENT attribute should be added)
PROTOTYPE_SN VARCHAR(200) Serial Number of the Prototype (for example, '524')
RFID_ID INT(10000) Id of the RFID tag placed on the prototype
CATEGORY VARCHAR(200) Category to which the prototype is linked, normally referring to a system or subsystem
TESTING_TYPE VARCHAR(200) Type of the prototype: Debug, Validation or Teardown
WEIGHT INT(1000) Weight of the prototype in g
DIMENSIONS INT(1000) Dimensions of the prototype in cm
PROTOTYPE_IMAGE VARCHAR(200) Jpeg or png file of a picture of the prototype
PROTOTYPE_DESCRIPTION VARCHAR(1000) Optional description of the prototype
REGISTRATION_DATE DATETIME() Date when the prototype was registered in the system
TESTS_DONE VARCHAR[][] Matrix containing information of the tests done for that prototype
HISTORICAL_DATA INT[]
Array of integers containing the historical daily status information of the prototype since it was registered in the system
CURRENT_LOCATION_ID INT(1000) Last location of the prototype registered by the system
REQUESTED_LOCATION_ID INT(1000) Requested location of the prototype
STATUS VARCHAR(100) Current physical status of the prototype: In position, testing, wrong position, unknown
LAST_MOD_DATE DATETIME() Date of the last modification done to the status of the prototype
COORD_RESPONSIBLE_ID INT(1000) Name of the Test Coordinator who is directly responsible of the prototype
PROTOTYPE_SUPPLIER_ID INT(1000) Name of the supplier in charge of an specific SKU
Table 2 - Prototypes Database
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68 Escuela Técnica Superior de Ingenieros Industriales (UPM)
The database of the storage locations is described in the Table 3 and should store
information related with the different storage locations, such as their identificatory and code,
their type, their capacity, description… Since it is linked with the prototypes database, it would
be possible to access information such as the number of prototypes stored in a specific location,
their storage availability, etc.
DATABASE DATA DESCRIPTION
STORAGE
LOCATIONS
STORAGE_ID INT(1000)
Location Identifier
(AUTO_INCREMENT attribute
should be added)
STORAGE_CODE VARCHAR(200)
Storage code used by the Users to
Identify the locations and place the
elements in position, or search for
the elements
RFID_READER_ID INT(10000)
ID of the Walkthrough RFID tags
reader placed at the entrance of
the storage location
USE_TYPE VARCHAR(30) Picking, reserve, storage…
STORAGE_DESCRIPTION VARCHAR(1000) Optional description of the storage
location
LOCATION_CAPACITY INT(1000) Capacity of the storage location in
square meters
WAREHOUSE_IMAGE VARCHAR(200) Jpeg or png file of a picture of the
storage location
Table 3 - Storage Locations Database
The Users and Suppliers databases are detailed in the Table 4 and 5, respectively. The
Users database should store information related with the employees in the Testing Facilities,
such as their personal details, the code of their personal RFID badge and their position in the
company. This database should be linked with the Test Coordinator defined in the Prototypes
Database for each prototype.
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DATABASE DATA DESCRIPTION
USERS
USER_ID INT(1000) User Identifier (AUTO_INCREMENT attribute should be added)
USER_NAME VARCHAR(200) First name and last name of the user
USER_RFID_ID INT(10000) Id of the personal RFID badge of that user
USER_POSITION VARCHAR(30) Position within the firm: Test lab technician, Test engineer, Team Management…
USER_TFN VARCHAR(20) User's telephone number
USER_EMAIL VARCHAR(250) User's mail address
USER_IMAGE VARCHAR(200) Jpeg or png file of a picture of the user
Table 4 - Users Database
The suppliers’ database is key management-wise, and it should store information related
with the different suppliers, such as their name, company, contact information… This database
should be linked with the prototypes database.
DATABASE DATA DESCRIPTION
SUPPLIERS
SUPPLIER_ID INT(1000) Supplier Identifier (AUTO_INCREMENT attribute should be added)
SUPPLIER_NAME VARCHAR(100) First name and last name of the supplier
SUPPLIER_COMPANY VARCHAR(200) Company for which the supplier is working
SUPPLIER_TFN VARCHAR(20) Supplier's telephone number
SUPPLIER_EMAIL VARCHAR(250) Supplier's mail address
SUPPLIER_IMAGE VARCHAR(200) Jpeg or png file of a picture of the supplier/logo of his company
Table 5 - Suppliers Database
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70 Escuela Técnica Superior de Ingenieros Industriales (UPM)
5.2.5.2.Partial automatization and tracking
In order to effectively implement an Inventory System, one of the most recommended
solutions is to invest in automatization. Through this proposal the goal is to try to eliminate
the risk of human error and increase product visibility. The main applied Lean tools are
continuous flow and 5S.
To increase the traceability of the prototypes and visibility in the Testing Lab through
automatization, it is key to analyse which activities are currently done manually and not
providing any added value. For instance, as it has been stated, there is a huge investment of
time in the search of the prototypes, as well as the recording of their testing results, and they
are not very well-defined procedures. If it would be possible to know at any time the latest
location and status of a prototype, without the need of manually logging that information in the
database, that would solve that issue and reduce the motion, waiting and processing wastes.
In order to do so, it should be necessary to increase the automatization in the Testing
Lab. There should be implemented Radio-frequency identification (RFID) tags in the
prototypes, as well as RFID readers in the doors, to know always when a certain prototype is
entering or exiting a certain area. Also, to decrease the risk of human error, the entrance to some
of the locations should be restricted just for people with the proper permissions. To do so, it
would be necessary to add RFID readers at their entrance, as well as to install electromagnetic
door locks and provide the workers personal RFID badges.
This proposal is needed in combination with the Integration of Systems, since it provides
to the Prototype Status System the Current Location of each one of the prototypes, and
completes the information related with the tests performed, as shown in the Figure 24.
Figure 24 - Combination of proposals
Prototype Logged Diary
•Past data by test bench
•Tests performed by every prototype
Testing Global Plan
•Future data by test bench
•Tests that will be performed by every prototype
Assembly Workshop requests
•Current and future requests of assembly/disassembly of prototypes
Partial automatization and tracking proposal
•Current location of the prototypes
Prototype status system
•Past and current data by prototype
•Information related with tests performed
•Historical status for every prototype
•Requested location
•System data bases
•Current location
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5.2.5.2.1. Improvement of the storage locations
This proposal is only effective with a proper classification and distribution of the storage
locations. To redistribute the storage accuracy, it would be necessary to classify the different
prototypes according to various categories, in the Prototype Status System. Those categories
would be the following:
• Debugging prototypes: the main function of these prototypes is to be used to
try the programmed sequences in the Test Benches and find and resolve defects
or problems, before mounting the final prototype to test. These prototypes are
normally tested more than one time and should be storage in a location nearby
the test benches, to increase accessibility.
• Validation prototypes: these prototypes are highly important for the company
since they are used to validate and approve different quality or functionality
standards of the products. They perform the tests once they have been debugged
and they are typically tested only one time. After the test has been done, they are
stored for one year.
• Teardown prototypes: these types of prototypes are similar to the validation
ones, but once they have performed the test it is not necessary to store them, and
they can be discarded.
Therefore, in the Testing facilities, the storage places should be defined to be able to
keep all the different prototypes in place and classified. Since in the current situation there are
not clearly defined positions, those should be created. Depending on the different types of
prototypes and if they have been tested already or not, there should be the different locations
shown in the Figure 25. Those locations should be used by the Prototypes Status System, based
on the Information from the Testing Global Plan, to determine the current Requested Location
for each prototype and store it in the data base.
Figure 25 - Prototypes default locations depending on type of prototypes
Test OK Test NOK
Debugging Test Unit Test Unit Test Unit -
Validation"To test"
warehouseTest Unit
Validation warehouse as
"PASSED"
Validation warehouse
as "FAILED"
Teardown"To test"
warehouseTest Unit
Before testing TestingType of
prototype
After Testing
Teardown warehouse
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72 Escuela Técnica Superior de Ingenieros Industriales (UPM)
Accordingly, by looking at the table, the warehouse should be divided in 6 distinct
locations, which must be perfectly defined and easily differentiated one from the other:
• Testing units: inside the testing units there should only be the debugging
prototypes. For those prototypes which are tested in different test benches, there
should be a debugging warehouse close by to those test units and easily
accessible for the mechanics who are responsible for mounting and dismounting
the products.
• “To test” warehouse: it should have a destined location for the validation
prototypes and another one for the teardown ones. There could be an area at the
entrance of every Test Bench where to allocate the next prototype to test by the
Test Coordinator, and therefore make it easier and more accessible for the
Mechanics to know which prototype to mount.
• Validation warehouse: once the validation prototypes have been tested, they
should be stored in the validation warehouse. It would be necessary to assign an
available space for those prototypes which have had a successful outcome from
the test (PASSED), and another one for the ones which have FAILED.
• Teardown warehouse: it should be a small location to store the teardown
prototypes temporarily before they are shipped out from the company. These
prototypes should not occupy an area with big movement of people and there
should be stablished time intervals to review which prototypes need to get out
of the company and the prototype database need to be updated when that occurs.
• Assembly workhouse: when they need to be assembled or disassembled, the
prototypes will be stored in the assembly workhouse. There should be a clear
delimited space for the prototypes that needs work from assembly, and for those
ones which have been already assembled again and need to be picked up.
• Received prototypes: this area should be used to temporarily keep all the new
prototypes that arrive to the company. Every time a prototype arrives, it should
be defined its type and created a new entry in the database. The area must be
allocated right at the entrance, where the prototypes enter in the company.
To keep all the prototypes in order and ensure traceability in the testing facilities, they
should be stored in one of the possible locations. It should be everyone’s responsibility to
reallocate a prototype if it is noticed in a wrong location, as well as the Prototype Status System
will send alarms to the Test Coordinators every time a prototype is misplaced, or its information
has been lost. Therefore, it is important to apply the 5S step “Set in order”, properly [27], as
shown in the Table 6.
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SET IN ORDER
RULE
PARTIAL AUTOMATIZATION AND
TRACKING PROPOSAL
Identify an establish a
location for all the
materials needed in the
work and assign fixed
places.
It has already been analysed all the possible storage
locations and determined which prototypes should be
stored in which location, and under what circumstances.
Place heavy products at a
comfortable height to
make it easier to be
picked up.
For the light prototypes that can be lifted by hand, there
are assigned shelves in the different locations. For the
heavier prototypes, they should be placed in the ground,
where it is easy to access to them and pick them up with
a lift or a trolley.
Determine how the things
should be put away and
follow those rules.
It should be responsibility of the Test Coordinators to
warn everybody in contact with the prototypes about its
default locations, and which rules to follow every time a
test is finished, a prototype must be dropped/picked up in
assembly, etc. However, the automatization of the
warehouse, in combination with the Integration of
Systems, would make sure those rules are followed by
sending alarms every time a prototype is misplaced, and
their information do not match.
Table 6 - Set in order step from 5S applied in the Testing facilities
In the Figure 26 is possible to see a proposal of how the Inventory locations in the
Testing Facilities could be allocated. The white space could serve as an extra storage room if
the volume of prototypes increases, and if there is more space needed in the validation
warehouse or the teardown area.
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74 Escuela Técnica Superior de Ingenieros Industriales (UPM)
Figure 26 - Proposal of the Inventory Allocations
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5.2.5.2.2. RFIDs tags and walkthrough readers
Once it has been defined how to improve the storage locations, there is just one last step
to finish the automatization and tracking proposal definition. That step would be to specify
which elements should be added to the testing areas in order to properly track the location of
the prototypes and to improve the transparency and safety of information in the facilities.
Firstly, to track the location of the prototypes it would be necessary to use two key
elements: RFID tags and Walkthrough RFID readers. Radio-Frequency-Identification or RFID
tags are particularly useful to uniquely identify the tagged prototypes, since they use an
electromagnetic field that transmits data from the tag to a reader. Unlike other similar
technologies, such as barcodes, RFID tags do not require that the scanner keeps a line-of-sight
with each code, they only need to be within range of the tag to read it. [28] Walkthrough RFID
readers are scanners which are typically allocated at the entrance of a room and can read any
RFID tag that passes through them. The characteristics of those tags and readers in the testing
facilities are the following:
• RFID tags: there should be physically attached to every prototype as soon as it
enters the company, and they should be able to resist the testing conditions.
Therefore, they should hold temperatures from -40°C to 200°C and should resist
humidity.
• Walkthrough RFID readers: to automatize the process of reading those RFID
tags, and make it faster, there should be allocated one walkthrough RFID reader
at the entrance of every key location in the warehouse. Those locations would
be the mentioned above: Assembly workshop, each one of the Testing Units and
each one of the warehouses.
The information of the RFID tags and the walkthrough readers should be linked with
the Prototype Status System and the Prototypes Database. Every time a new RFID reader is
activated, that should create a new entry of a prototype in the Database, which should be
updated with the location obtained through the Walkthrough readers.
Secondly, to improve the transparency and safety of information in the facilities, and
therefore increase efficiency, it would be necessary to use personal RFID badges and RFID
door readers to enter in some of the locations. Since the Validation warehouse is storing
particularly sensitive information, it should be accessible just by certain employees, such as the
Test Coordinators.
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76 Escuela Técnica Superior de Ingenieros Industriales (UPM)
In the Figure 27 is shown again the map of the facilities with the proposed positions for
the RFID Walkthrough Readers and the RFID door reader. It would be allocated one
Walkthrough reader at the entrance of each one of the Test Units (in case of Test Units with
more than one possible entrance, it should be standardized that every time a mechanic
allocate/take out a prototype from a bench he should cross the entrance with the walkthrough
reader). For the teardown warehouse, the only possible entry should also be the one with the
reader, and the validation warehouse would have at the entrance a RFID door reader.
Every time a prototype crosses a RFID Walkthrough Reader, its current location must
be updated in the database by using the ID of the reader and the previous location registered in
the system. For instance, if the latest location of a prototype was “To Test warehouse” and it
crosses the reader of the cell TU2, the system will update its location to “Test Unit TU2”. When
crossing the reader again to exit the Test Bench, the system should then show “Tested
warehouse”, which shares area with the warehouse “To Test”. By default, the tested prototype
should be kept at the exit of the Test Bench in a specific area till the Test Coordinator picks it
up to move it to its next location.
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Figure 27 - Location of the RFID Readers in the Facilities
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78 Escuela Técnica Superior de Ingenieros Industriales (UPM)
In total, it would be necessary to install 21 readers at the entrances of key locations and
one reader for the personal cards of the employees in the Validation Warehouse (WH3). That
would be enough to properly track the movements of the prototypes in the Testing facilities.
When a prototype is allocated in the white and grey area between the WH1 and the WH3, the
location in the database would be shown as “In transfer zone”.
In the Figure 28 it is shown a conceptual image of how the RFID Walkthrough Readers
should be installed at the entrance of the Testing Units, as well as the new marked areas that
should be added for temporarily storing the prototypes that have been or are going to be tested.
Figure 28 - Changes at the entrances of the Test Units
This combination of RFID readers and tags is extremely flexible and easy to be modified
in case of company growing, sudden need of extra space and reallocation of areas, among
others.
In the APPENDIX 1: RFID tags and readers, it is offered a proposal of particular RFID
elements that could be used, as well as a brief explanation about what led to their choice and
their unitary price.
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5.2.5.3.KPIs
As part of the Control stage from PDCA and DMAIC, it will be necessary to use some
Lean parameters known as KPIs or Key Performance Indicators. They are defined as metrics
which have been designed to track and encourage progress towards critical objectives of the
organization. [13]
There is a wide variety of KPIs, depending on the type of organization, although they
are often divided in two common categories: lagging indicators and leading indicators. [29]
On the one hand, lagging indicators appear after an event has occurred, and they are result-
oriented. They analyse historical data and show a reaction to something that has already
happened in a process. On the other hand, leading indicators give real-time measures of events
happening in the moment. They track right at the process and give predictive factors before an
injury happens.
For the testing facilities, there will be suggested a set of lagging and leading indicators,
using the information obtained through the Prototype Status Matrix and the historical data
gathered.2
5.2.5.3.1.1. Lagging KPIs
The lagging indicators will be obtained, as it is already has been mentioned, using
historical data. More specifically, as shown in the Figure 29, the procurement of the Lagging
KPIs is a process that is done using the historical data from the Prototype Status Matrix. That
information is gathered once when implementing the system, by using the Past data by Test
Bench and prototype that comes from the Prototype Logged Diary and the stored elements in
the different warehouse locations.
From the historical data of the prototypes, it is especially interesting for the testing
facilities, to know how well their inventory control has been working through the time.
2 All the KPIs explained in 0 will be related with just a set of data gathered using daily
information from a sample of 25 prototypes, during the testing period between the 27th of October 2018
and the 31st of May 2019. Therefore, every conclusion made in that chapter, or any result shown will be
only applicable for that sample.
RESULTS AND DISCUSSION
80 Escuela Técnica Superior de Ingenieros Industriales (UPM)
Figure 29 - Procurement process of Lagging KPIs
In the Figure 30 it is possible to see the sampled prototypes and information related with
their location status throughout their lifetime (since they entered the facilities). Some interesting
KPIs that can be extracted from that information are:
• Percentage of prototypes that have been properly stored in the right location
(either ‘In position’ or ‘Testing’) more than 90% of their lifetime = 40%
• Percentage of prototypes that have been stored in a wrong position more than
50% of their lifetime = 36%
• Percentage of prototypes whose position has been unknown more than 20% of
their lifetime = 20%
The task of the testing facility would be to use these parameters as indicators over time
(for example, by checking monthly or weekly) to prove if the performance of the Inventory
tracking is improving. For instance, their goal would be to try to check if the percentage of
prototypes in wrong and unknown position is decreasing, and the percentage of prototypes in
position is increasing.
Figure 30 – Historical results per prototype (%) of the analysed sample
LAGGING KPIs
Prototype Status Matrix (historical data)
Prototype Logged Diary
Past Data by Test Bench
Stored elements in the
different warehouse locations
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In the Figure 31 there are shown the average monthly tendencies in percentage over the
total number of prototypes during the analysed timeframes. When looking at the graph, it is
possible to see that the percentage of testing time has decreased proportionally with the time
since the company has been receiving more prototypes without increasing the number of test
benches. The percentage of prototypes in position has not varied significantly over time (around
~40%), and the prototypes in the wrong position has increased from 25% to 41%. The average
number of prototypes that have been misplaced and whose position is unknown has increased
and decreased in proportion, representing in the last month the 17% of all the prototypes.
Figure 31 – Percentages of monthly historical tendencies of the analysed sample
In the Figure 32 is not only possible to visualize the monthly historical tendencies, but
also how the number of prototypes increases with time, and how they have been managed. It is
possible to see that the number of prototypes in position has been increasing, as well as the ones
in the wrong position. There have been 4 prototypes with an unknown position since January
and on average there are tested less than 2 prototypes per month, for the sample analysed.
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82 Escuela Técnica Superior de Ingenieros Industriales (UPM)
Figure 32 - Monthly historical tendencies of the analysed sample
5.2.5.3.1.2. Leading KPIs
The most valuable information from the Matrix is the latest status of the prototypes.
From that information, it is possible to calculate KPIs such as the percentage of prototypes in
position, the percentage of prototypes testing and the percentage of prototypes whose position
is wrong or unknown. For instance, for the day 31/05/2019, there was a 44% of the prototypes
in position, 4% were being tested, 36% were misplaced and the remaining 16% belonged to
prototypes in an unknown position, as shown in the Figure 33.
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Figure 33 - Prototype status by 31/05/2019 of the analysed sample
Therefore, a proper way of knowing if the Prototype Status System is working is through
those KPIs. The goal would be to achieve the situation shown in the Figure 34, where it has
been possible to reallocate all the misplaced prototypes, and the missing ones have been found
and put in their correct position. The number of prototypes in position would increase in a
109%, for the analysed sample.
Figure 34 - Improvements in the prototypes’ status for the analysed sample
The process of obtaining the status of the prototypes and, therefore, the Leading KPIs,
is shown in the Figure 35. To know the status of a prototype for a certain date, it is necessary
to compare its requested location with its current location.
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84 Escuela Técnica Superior de Ingenieros Industriales (UPM)
Its requested location will be normally given by the information from the Testing
Global Plan, except for those cases when an Assembly Work is required. When there is no
information provided in any of those platforms for a prototype, its requested location should
match with its default location. That location is given by the type of the prototype and the
number of tests done, as it will be further explained in the Figure 25.
Its current location will be obtained as it is explained in 5.2.5.2.2.
Figure 35 - Procurement process of Leading KPIs
One important functionality of the Prototype Status System, related with Kanban boards,
would be the daily check-ups and reminders. To keep the high quality of the system and the
organization, the system would check every day the location of each prototype, it would
compare it with the requested location and would send actions to the Test Coordinators. For the
misplaced prototypes, it would remind them to move them, as well as for the unknown, to
dedicate some workforce to search for them. For instance, in the Table 7 is possible to see the
status for the analysed prototypes, as well as the required actions to take towards them, for the
31st of May 2019.
LEADING KPIs
Prototype Status Matrix (current daily
data)STATUS
Current location
RFID tags information
Previous current location
Requested location
1°. Assembly Workshop
Request
2°. Global Plan
3°. Default location
Prototype type
Number of tests done
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ID
31
/05
/19
STATUS BY 31/05/2019
Necessary actions Required
Location Current Location
1 1 VW#2A.3 VW#2A.3 2 3 VW#3B.5 TB#15 Move! 3 1 TB#15 TB#15
4 1 VW#2C.8 TB#15
5 4 ?? ?? Find! 6 3 VW#5A.11 TB#15 Move! 7 1 TB#15 TB#15
8 4 ?? ?? Find! 9 1 VW#2A.4 VW#2A.4
10 4 ?? ?? Find! 11 1 TB#15 TB#15
12 4 ?? ?? Find! 13 3 VW#6B.1 TB#15 Move! 14 3 VW#2C.3 TB#15 Move! 15 1 VW#1A.10 VW#1A.10
16 3 VW#2D.3 TB#15 Move! 17 3 VW#10A.5 TB#15 Move! 18 1 VW#8A.2 VW#8A.2
19 1 VW#2B.1 VW#2B.1
20 3 VW#2A.4 TB#15 Move! 21 1 VW#1D.5 VW#1D.5
22 1 TB#15 TB#15
23 3 VW#5C.3 TB#15 Move! 24 3 VW#2A.1 TB#15 Move! 25 2 TB#15 TB#15
Table 7 - Prototypes by 31/05/2019: Status and actions to take.
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86 Escuela Técnica Superior de Ingenieros Industriales (UPM)
5.2.5.4.Steps for their implementation
Once both solutions have been properly defined, one of the lasts but most important
steps is to determine the different stages that should be followed to implement them and analyse
the estimated investment of time that should be made.
STAGE DEFINITION ESTIMATED
TIME
1 Analyse the
organization of
the workplace
Obtain the location of all the prototypes currently
stored in the testing facilities, by following 5S ‘sort’
rules. Make a list with their location and their type
(validation, debug or teardown).
2 days
2 Procurement of
the historical
results
Gather all the historical data from the prototypes
that comes from the Prototype Logged Diary, as it
was explained on the Figure 29. Once that
information has been obtained, and with the
prototypes’ location obtained in the Stage 1, it
would be possible to create a Prototype Status
Matrix and afterwards calculate the Lagging KPIs.
Those KPIs would provide an approximate idea
about how the system has been working in the past
and they would be used as first standard to improve
the storing processes in the facilities. Those results
could be logged in Microsoft Excel, using the Figure
22 as a reference.
7 days
3 Obtention of
the status of the
prototypes
Follow the steps explained in the Figure 35 to obtain
the current status of the prototypes and calculate
the Leading KPIs. To automatize this process, it can
be used Visual Basic as programming language, since
it is compatible with Microsoft Excel.
7 days
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4 Improvement of
the storage’s
location
This step should be as described in 5.2.5.2.1.
Following 5S rules, and using the information about
their status, organize the prototypes and assign a
location to all of them. Discard the ones that are no
longer providing added value to the company.
2 days
5 RFID tags and
readers
implementation
Once having determined the new storage locations
and the prototypes have been reorganized, it is
necessary to do the following steps:
• Installation Walkthrough readers and RFID
door readers
• Assignation of RFID tags to every critical
prototype
• Provide a personalized RFID badge to the
employees in the Testing facilities
20 days
6 Creation of the
data bases
Create and define in an open source Data Base
management system, such as PostgreSQL, the four
different databases shown in the Figure 23.
Complete all of them with the information from the
prototypes, the users and the suppliers.
20 days
7 Creation of the
Prototype
Status System
Include some programming and debugging time to
make sure the information of all the systems is
correlated.
10 days
8 Program daily
check-ups
Repeat the Stage 3 in a daily basis (for example, plan
and program daily check-ups at 6am), to obtain the
daily status of the prototypes, update the databases
and the Prototype Status Matrix, and send
reminders to the direct responsible to fix the
location of the misplaced or missing prototypes.
< 5 min
(automatized
process)
Table 8 – Suggested steps for the implementation of the two proposals
To sum up, the implementation of the Prototype Status System and all its features in the
testing facilities would take an estimated time of 68 days. This time could be shortened if some
activities, such as the stage 6 and 7 are started while doing other processes. Afterwards, there
would only be needed less than 5 minutes every day to automatically check the status of all the
prototypes and easily fix any misplacement or issue in the warehouses. The higher the volume
of prototypes in the facilities, the more useful the system will be.
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88 Escuela Técnica Superior de Ingenieros Industriales (UPM)
5.2.5.5. Economic feasibility
The determination of the economic feasibility of the presented endeavour is a key last
step to estimate whether it will be profitable for the company. This study analyses the data and
provides a cost outlook for the business project.
To analyse the economic feasibility of the Prototype Status System, it will be composed
a projected 5-year business plan that will compare the costs of implementing the system with
the costs of not having an integrated inventory system and preserving things as they currently
are. The mentioned business plan is presented in the Figure 36 and it compares the total
estimated expenses of the Prototype System with the costs of the current situation.
In order to be able to accomplish this comparison, it has been necessary to make some
hypothesis. For instance, considering that they are tested yearly an average of 85 prototypes per
test bench, that value could provide an approximated number of prototypes currently in the
facilities. Based on the previous yearly growth of the company, it has been estimated a 10%
growth for the incoming years, which would have an influence in the number of Test Benches
and prototypes. In the APPENDIX 2: Estimated parameters for the Economic Feasibility Study,
there are shown the different parameters that have been used when calculating the costs for the
study.
• Total costs of the Prototype Status System
Economically, the Prototype Status System will only need two main investments. The
first one will consist on an initial payment in the first year for the implementation of the whole
system and its elements in the Testing Facilities. This is mentioned in the business plan as
‘Implementation Investment’, and it gives an estimated cost for all the steps explained in
5.2.5.4. Furthermore, it considers the cost of the necessary hardware (RFID tags and readers)
and the salaries of the employees in charge of its setup, such as programmers for the software
and technicians for the hardware installation. The estimated Implementation Investment of the
system would be 58.482,7 €.
Once the whole system has been successfully implemented and debugged, it will be only
needed to do a brief maintenance and control work every year to ensure its functioning. That
work will mainly consist on the registration of the new prototypes in the system, which has
been estimated to take 15 minutes per prototype (considering the assignation of a new RFID
tag and the creation of a new entry in the Prototypes database). The responsible employees for
that task could be the Test Coordinators, since they oversee the status and traceability of the
prototypes and the tests they perform. The costs of this control and maintenance will increase
as the number of prototypes do, being 5.534 € for the Year 1 and 8.102 € for the Year 5.
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 89
• Total costs of the current situation
To take an economic outlook over the current situation, it is necessary to consider the
inventory costs in the facilities. These costs are shared by every storage location and, as
explained in the Chapter 3, there are split in three different expenses: ordering costs, holding
costs and shortage costs.
The implementation of the Prototype System would improve the traceability of the
prototypes, which is directly linked with a decrease in shortage costs. Since it would not affect
the annual purchases, the ordering costs would not be altered and the difference in holding costs
would be almost insignificant, considering that the rent and depreciation are the same for all
the company storage units and there is currently enough space to store all the prototypes.
However, due to the growing tendency of the company, the holding costs could gain importance
soon and the available space would be a more critical constrain.
Therefore, for the current analysis there have been only studied the most significant
inventory costs, which are the shortage costs.
To measure them, it has been acknowledged that every day there is at least 1 hour spent
on looking for a prototype. That means, every day at least one employee (normally one of the
test mechanics), is spending one-hour time on that task, and there is at least one test bench
whose activities are on hold due to the absence of the testing prototype. This provides the most
common and less aggressive scenario for the analysis.
Accordingly, the total costs of the current situation will be the sum of the total shortage
costs and its related salary costs. On average, every test bench cost 2.500€ a day, that leads to
104,17€ per hour, which repeated 20 times per month, provides the value of the yearly shortage
costs. The salary costs are calculated using the test mechanics’ payroll. This gives a minimum
value of 34.600 € that are yearly spent due to the poor traceability of the prototypes.
RESULTS AND DISCUSSION
90 Escuela Técnica Superior de Ingenieros Industriales (UPM)
Figure 36 – Economic feasibility study
BU
SINESS P
LAN
Year 0Year 1
Year 2Year 3
Year 4Year 5
Nu
mb
er of Test B
ench
es16
1718
1919
20
Nu
mb
er of Pro
totyp
es1357
14251496
15711649
1732
Average am
mo
un
t of n
ew p
roto
types
-68
7175
7982
RFID
tags2,700.03
€ 135.00
€ 141.75
€ 148.84
€ 156.28
€ 164.10
€
Lamin
ate RFID
tags for th
e emp
loyees’ b
adges
32.67€
--
--
-
Walkth
rou
gh R
FID read
ers35,700.00
€ 1,360.00
€ 1,428.00
€ 1,499.40
€ 1,574.37
€ 1,653.09
€
RFID
reader fo
r the em
plo
yees’ bad
ges and
com
pu
ter ho
st4,050.00
€ -
--
--
Program
min
g of th
e softw
are12,000.00
€ -
--
--
Installatio
n o
f the h
ardw
are4,000.00
€ -
--
--
Imp
lemen
tatio
n In
vestmen
t58,482.70
€ 1,495.00
€ 1,569.75
€ 1,648.24
€ 1,730.65
€ 1,817.18
€
Co
ntro
l and
main
ten
ance
-€
1,272.00€
1,335.60€
1,402.38€
1,472.50€
1,546.12€
TOTA
L CO
STS PR
OTO
TYPE SYSTEM
58,482.70€
2,767.00€
2,905.35€
3,050.62€
3,203.15€
3,363.31€
Aggregate
cost
58,482.70€
61,249.70€
64,155.06€
67,205.67€
70,408.82€
73,772.13€
Sho
rtage costs
25,000.00€
25,000.00€
25,000.00€
25,000.00€
25,000.00€
25,000.00€
Salary costs
9,600.00€
9,600.00€
9,600.00€
9,600.00€
9,600.00€
9,600.00€
TOTA
L CO
STS CU
RR
ENT SITU
ATIO
N
34,600.00€
34,600.00€
34,600.00€
34,600.00€
34,600.00€
34,600.00€
Aggregate
cost
34,600.00€
69,200.00€
103,800.00€
138,400.00€
173,000.00€
207,600.00€
DIFFER
ENC
E(23,882.70)
€ 7,950.30
€ 39,644.94
€ 71,194.33
€ 102,591.18
€ 133,827.87
€
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 91
• Costs comparison
Finally, by comparing both alternatives and calculating the difference between them, it
is possible to detect which one will be more beneficial economically for the company. In the
Figure 37 it is shown how their estimated costs evolve over time. Both show an increasing
tendency, being the current situation significatively faster than the prototype system alternative.
Although the costs during the initial year are higher for the Prototype System proposal
due to its implementation (58.482,7 € versus 34.600 € of the current situation), the costs of the
maintenance and control are noticeably lower and could reduce the company’s costs
significantly from the Year 1 onwards. By implementing the Prototype System, it will be
possible to have saved up to 133.827,87 € by the Year 5.
Figure 37 - Costs comparison between the Prototype System and the Current situation
RESULTS AND DISCUSSION
92 Escuela Técnica Superior de Ingenieros Industriales (UPM)
5.3. Legal, professional and economic impacts
This last part of the chapter is focused on the study of the different impacts that this
project might cause in society. Those impacts will be mainly legal, professional and ethical.
Legally, the impacts of this project are related with the licenses of the computer
programs that have been used. There have been needed open-source programs such as
GanttProject or licensed programs such as Adobe or the Office package from Microsoft.
Professionally, the proposed suggestions to improve the processes in the facilities
would offer several benefits. The existence of a system with instant access to the information
would significantly reduce the motion, decrease the tracking time, increase the knowledge and
improve the communication, etc. Moreover, the safety and security of information would
increase, and the employees could improve their performance, by focusing on tasks with higher
added value for the company.
Economically, the solution offered in this project would suppose a relevant saving in
costs if properly implemented in the company. Those savings would be directly related with the
elimination of wastes and optimization of the processes, and therefore with the increase of the
efficiency of the company and its employees.
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 93
Chapter 6.
CONCLUSIONS
6. CONCLUSIONS
Once having finished the results and discussion, it is possible to obtain the conclusions
of this Master Thesis. Those conclusions are divided into general conclusions, specific
conclusions and limitations of the project.
6.1. General conclusions
The main goal of this Master Thesis was to analyse how the application of Lean and Six
Sigma tools could improve the performance of the Testing Facilities in a mechanical company.
In order to do so, it has been carried out a detailed analysis of the activities executed in the
department and the influence that the management of the testing components has in its
performance.
When working in this project it has been possible to acknowledge the importance of
investing in a proper Inventory System, especially in a company where it is so critical to keep
its items accordingly tracked. Moreover, there have been recognized the benefits of applying
Lean and Six Sigma methodologies. It has been discovered that, with the current situation, the
performance in the Lab is far from optimal. There has been detected three wastes that cause
noticeable economic impacts, as well as an inadequate use of the workforce and the inventory.
By implementing the solutions suggested in this Master thesis, related with the enhancement of
the management of the prototypes, that situation could be improved. Besides the economic
benefits, the company could take strategic advantages from performing a better tracking of the
prototypes, as well as the eight waste would be decreased by preventing the employees from
losing time on searching tasks.
From a personal point of view, working on this Master thesis in order to finish the
Master of Engineering in Industrial Technologies has been a challenging but enriching
experience. It has been possible to acquire valuable technical knowledge as well as there have
been improved professional skills such as self-work and management, preparation of reports
and meetings’ performance and arrangement.
CONCLUSSIONS
94 Escuela Técnica Superior de Ingenieros Industriales (UPM)
6.2. Specific conclusions
Once the project has been done, it is possible to realise that all the specific objectives
detailed in the chapter 2.2, has been achieved:
1. It has been defined, measured and analysed the current processes in the Testing
facilities by using Lean tools such as Value Stream Mapping.
2. There have been identified the different wastes related with the prototypes and
existing in the facilities, which are waiting, motion and processing. Also, it has been
carried out a root cause analysis for those wastes.
3. It has been studied the different solutions to mitigate the effect of each one of the
wastes, by applying Lean tools such as PDCA, 5S, Kaizen, Continuous Flow and
Standardized job.
4. There have been proposed alternative solutions based on Lean and Six Sigma
methods, such as system integration and a partial automatization of the facilities. In
the Table 9 is possible to see how each one of the proposals would contribute to the
wastes’ elimination.
Table 9 - Proposals overview and wastes
5. It has been defined and described the Integration of systems proposal and suggest
possible KPIs to analyse its performance.
a. This proposal would be based on virtual aggregation by combining the
information of the existing Information systems to obtain the status of the
prototypes.
b. It has been described the “status of a prototype” as its geographical
information in a specific moment.
Integration of
systems
Partial
automatization
and improvement
of inventory
tracking
Synchronize processes as much as possible ✔
Increase reliability of processes ✔ ✔
Reduce down time by improving efficiency ✔
Decrease travel time between stages or process stations ✔
Remove excessive or unnecessary machine movements/actions ✔ ✔
Clarify customers' standards and expectations ahead of time ✔
Only perform processes necessary to meet these standards and
expectations✔ ✔
Use appropriate processes (avoid overly complex machinery or
processes if possible) ✔
Waiting
Motion
Processing
Proposals
Wastes Solutions
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 95
c. It has been defined the Prototypes Status Matrix, which would provide an
overview of the current situation, working as a virtual Kanban board.
d. To pursue continuous flow, there has been defined 4 databases: prototypes,
storage, users and suppliers, whose information would improve the
performance of the Inventory System.
e. There have been suggested lagging and leading indicators as possible KPIs,
as a Control step of the PDCA and DMAIC approach.
6. It has been defined the Partial automatization and tracking proposal and its
needed elements.
a. This proposal complements the Integration of Systems by providing the
current status of each prototype.
b. It has been carried out an analysis to improve the storage locations based on
the type of prototypes and following 5S rules.
c. There have been suggested RFID readers and Walkthrough readers as
possible elements to improve the tracking of the prototypes and contribute
to continuous flow.
7. There have been defined 8 necessary steps to successfully implement both
proposals.
8. It has been analysed the economic feasibility of the proposals. There have been
perceived the clear economic benefits that its implementation would have in the
Testing facilities.
9. Moreover, it has been followed the DMAIC methodology [30] from Six Sigma to
identify and search for the solution.
a. Define: it has been identified the problem, as well as its boundaries and goals
through the initial studies and observations. It has been detected that the
company’s inventory system is not properly developed in its testing
facilities.
b. Measure: the VSM has been used to obtain a global view and measurements
of the facilities, as well as to determine the “current state” of the project.
c. Analyse: the data has been interpreted to identify key causes and process
determinants through Muda identification and Root cause analysis.
d. Improve: in order to optimize the performance of the processes in the
facilities, there has been suggested several solutions for each waste by using
Lean tools, as well as two additional proposals.
e. Control: there has been defined KPIs to be able to check whether the gains
are sustained.
CONCLUSSIONS
96 Escuela Técnica Superior de Ingenieros Industriales (UPM)
6.3. Limitations
During the project there has been faced some limitations, mainly related with the
restrained access to information. Firstly, it is important to mention the confidentiality aspects
that made the gathering of data a difficult task. It has been only possible to access to a limited
amount of information that has been combined with the observations and feedback from the
interviews.
Secondly, some internal difficulties and the lack of standardization and transparency in
processes made it arduous to access to some of the previous and current data. Some Lean
methods were then not possible to be applicable, such as Spaghetti diagrams.
Finally, the time limitations conditioned the size of the sample taken for the discussion.
However, although a bigger sample could affect the results, the followed procedure in order to
obtain them would be the same.
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 97
Chapter 7.
FUTURE WORK
7. FUTURE WORK
Throughout this thesis there have been found several subjects which could be interesting
for further research and work.
1. Increase the sampling to obtain the real data in the facilities: due to timing
limitations, the project has been done by using a sample of 25 prototypes, during the
testing period between the 27th of October 2018 and the 31st of May 2019. As a
future action, it should be necessary to include the data from all the prototypes
currently stored and used in the facilities.
2. Implementation of the suggested proposals: as a future work, the next step could
be to implement the theoretical suggestions of this thesis in the facilities. The stages
explained in 5.2.5.4 could be used as a reference.
3. Performance tests: in order to check the effectiveness of the proposals, there could
be performed different trial attempts till reaching validation. It could be followed
the PDCA cycle to perform this future work.
4. Resistance to changes: a Lean and Six Sigma application requires the involvement
of the workers and employees. One of the hardest but necessary tasks if the proposals
are implemented, would be to gradually change their mindset. That change should
be gradual and would cover the acceptance of the standards, the learning of the new
procedures and the change of methodologies. Moreover, it would be also an
interesting area of study to explore the enthusiasm and willingness for the employees
to implement Lean throughout the facilities.
5. Programming language: for the current data gathered, Microsoft Excel is enough
to plot and analyse the information logged of the prototypes in the Prototype Status
Matrix. However, for future analysis of the KPIs and once the databases increase
their volume, it would be necessary to use more powerful programming languages
of analysing data, such as Python or Visual Basic, for instance.
6. User interface: for future data visualization and specific searches, it would be
beneficial to invest in a proper user interface for the Prototype Status System. Thus,
it could be possible to show the results in a user-friendly way and ease the
management tasks.
FUTURE WORK
98 Escuela Técnica Superior de Ingenieros Industriales (UPM)
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Laura Delgado Díaz 99
Chapter 8.
TEMPORAL PLANNING AND
PROJECT BUDGET
8. TEMPORAL PLANNING AND PROJECT BUDGET
The main goal of this chapter is to show the temporal planning of the project, its work
breakdown structure and its project budget.
8.1. Temporal Planning
The project started on November 2018, but it was not till February 2019 that it started
to take its final shape. This fact is due to a pair of meetings that occurred internally with one of
the Planning responsible employees in the Testing facilities. After the first meeting, which took
place in November of 2018, it was defined the project scope of the thesis and which researches
to do during the incoming months. However, in February it was planned another meeting to
solve some questions and issues and during that encounter it was agreed to redefine the project
scope. That led to a new change of approach and perspective that entailed a new project
structure.
There are two different stages that split the performance of the project. The first stage,
based on personal preparation and study of the theoretical requirements of the project, lasted
till May of 2019. The stage of the results and discussion of the project occurred between May
and September of 2019. In total, the whole duration of the project has been 11 months, and in
the Figure 38 is possible to see the distribution of worked hours per month.
There have been considered the hours dedicated to the preparation and development of
the solution, as well as the extra hours that were needed to prepare the report. To sum up, there
have been invested 377 hours on this Master thesis.
TEMPORAL PLANNING AND PROJECT BUDGET
100 Escuela Técnica Superior de Ingenieros Industriales (UPM)
Figure 38 - Monthly number of hours worked in the project
In the Figure 39 is shown the Gantt Chart with the temporal planning of the project,
divided by tasks. The chart has been made by using the software “GanttProject”, and it offers a
detailed view of the start and end date of the tasks done, as well as the order that has been
followed to accomplish them.
A representation of the Work Breakdown Structure can be seen in the chapter 8.2, in
the Figure 40, which provides a view of all the stages done in other to perform this project.
They are linked with the tasks represented in the Gantt Chart.
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 101
Figure 39 - Gantt chart of the project
TEMPORAL PLANNING AND PROJECT BUDGET
102 Escuela Técnica Superior de Ingenieros Industriales (UPM)
8.2. Work Breakdown Structure
Figure 40 - Work Breakdown Structure of the project
Mas
ter
Thes
is
PROJECT MANAGEMENT
Planning
Project scope
Redefining project scope
Project Structure
Control and monitoring
Deliverables
Meetings
PREVIOUS STUDIES
State of the art
Inventory Management Systems
Lean Thinking and Six Sigma
Data Gathering
Historical data
Interviews and researches
DEVELOPMENT
Data analysis
Application of theoretical background
Wastes Identification
Application of Lean tools to solve wastes
Definition of proposed solutions
DOCUMENTATION
Report
Review
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 103
8.3. Project Budget
The aim of this chapter is to provide an economic study of this Master thesis. That study
would provide an estimated cost of the project based on two concepts: the workforce and the
computer material.
The workforce was one junior engineer and one senior engineer expert in management
of warehouses and Lean techniques. Estimating an hourly salary of 25 € for the junior engineer
and considering there were needed 461 hours to do the project, his total cost would be 11.525
€. The senior engineer should receive an estimated wage of 100 € per hour. Considering
meetings and reviewing time, he needed to invest 16 hours in the project, what makes a total of
1.600 €. Thus, the total cost of the workforce during the 11 months of the Master thesis would
be 13.125 €.
The computer material considers the hardware and software that was needed for the
project. As hardware, it has been used a Laptop Lenovo IdeaPad 320, whose cost is 699,95 €
[31] and a HP USB Optical Scroll Mouse of 10,99 € [32]. The total cost of the devices is 710,94
€ and, assuming a 5 years amortization, during 11 months of work on the project, the estimated
cost is 130,34 €.
As software, it has been used open-source programs as much as possible, except for
Adobe Photoshop, whose price is 24,19 € per month [33], being the total cost 266,09 €, during
11 months of work. It has been also needed the Microsoft Office package, which costs 9,99 €
per month [34], being 109,89 € for the total project.
In the Table 10 there is a summary of the costs of the project, being 13.631,32 € the total
estimated investment that would be needed to perform this Master thesis.
Table 10 - Total cost of the project considering the requirements for the workforce and material
11,525.00 €
1,600.00 €
130.34 €
Adobe 109.89 €
Office 266.09 €
13,631.32 €TOTAL
Computer material
WorkforceJunior Engineer
Senior Engineer expert
Hardware
Software licenses
TEMPORAL PLANNING AND PROJECT BUDGET
104 Escuela Técnica Superior de Ingenieros Industriales (UPM)
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Laura Delgado Díaz 105
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[
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[
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[
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30] E. CLOWER, Applying DMAIC to Inventory Problems: Fixing an inventory
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enovo%20IdeaPad.
[
32] Dodax,
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promo&awc=8248_1567441454_c61f4bad935fd4b65c547ece9ae9092f.
[
33] Adobe,
https://commerce.adobe.com/checkout/email/?items%5B0%5D%5Bid%5D=30404A88
D89A328584307175B8B27616&items%5B0%5D%5Bq%5D=1&cli=adobe_com&lang
=nl&co=BE&promoid=&sdid=&trackingid=&mv=&rUrl=.
[
34] Office Products,
https://products.office.com/en-us/buy/office.
[
35] UHF 915 MHZ FR4 HIGH TEMPERATURE RFID TAGS,
https://www.rfidinc.com/uhf-915-mhz-fr4-high-temperature-rfid-tags.
[
36] UHF 915 MHZ PVC LAMINATE RFID TAGS,
https://www.rfidinc.com/uhf-915-mhz-pvc-laminate-rfid-tags.
[
37] HopeLand,
https://www.hopelandrfid.com/access-control-rfid-tracking-gate-reader-
cl7226d_p21.html.
[
38] Alibaba.com,
https://www.alibaba.com/product-detail/Card-reader-Distance-5m-Hf-
Gate_60780354192.html?spm=a2700.7724857.normalList.262.1b10636aDHua8B.
[
39] Learn Management, Hierarchical Structure,
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[
40] S. Bragg, Shortage costs, AccountingTools,
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REFERENCES
108 Escuela Técnica Superior de Ingenieros Industriales (UPM)
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 109
10. ABBREVIATIONS AND ACRONYMS
5S Sort, Set in Order, Shine, Standardize, Sustain
DAMI Define, Achieve, Maintain, Improve
DMAIC Define, Measure, Analyse, Improve, Control
EoL End of Line
ETSII Escuela Técnica Superior de Ingenieros Industriales
ID Identificador
KPI Key Performance Indicator
PDCA Plan, Do, Check, Act
RFID Radio-frequency identification
SOP Standard Operating Procedures
UNESCO United Nations Educational, Scientific and Cultural Organization
URL Uniform Resource Locator
VSM Value Stream Mapping
WBS Work breakdown structure
WWW Word Wide Web
LIST OF FIGURES
110 Escuela Técnica Superior de Ingenieros Industriales (UPM)
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 111
List of figures
Figure 1 - Structure of the company ......................................................................................... 24
Figure 2 - Structure of the Testing Lab .................................................................................... 25
Figure 3 - Processes in the company ........................................................................................ 26
Figure 4 - Tests requesting process .......................................................................................... 28
Figure 5 - Test readiness requirements .................................................................................... 29
Figure 6 - 2D map of the Testing Facilities ............................................................................. 30
Figure 7 - Optimum batch size in Inventory Control ............................................................... 36
Figure 8 - Basic characteristics of inventory systems .............................................................. 37
Figure 9 - 5S steps .................................................................................................................... 40
Figure 10 - Six Sigma distribution ........................................................................................... 41
Figure 11 - DMAIC Methodology ............................................................................................ 42
Figure 12 - Prototype stakeholders in the Testing Facilities ................................................... 46
Figure 13 - Ideal VSM .............................................................................................................. 49
Figure 14 - Real VSM ............................................................................................................... 50
Figure 15 - Tracking of prototypes: Fishbone Diagram .......................................................... 55
Figure 16 - Over processing: Fishbone diagram ..................................................................... 56
Figure 17 - PDCA approach .................................................................................................... 57
Figure 18 - Working in batches VS Continuous Flow .............................................................. 58
Figure 19 - Integration of systems ............................................................................................ 62
Figure 20 - Prototype Status Matrix ......................................................................................... 63
Figure 21 - Status codes for the prototypes .............................................................................. 63
Figure 22 - Example of a Prototype Status Matrix ................................................................... 65
Figure 23 - Databases of the system ........................................................................................ 66
Figure 24 - Combination of proposals ..................................................................................... 70
Figure 25 - Prototypes default locations depending on type of prototypes .............................. 71
Figure 26 - Proposal of the Inventory Allocations ................................................................... 74
Figure 27 - Location of the RFID Readers in the Facilities ..................................................... 77
Figure 28 - Changes at the entrances of the Test Units ........................................................... 78
Figure 29 - Procurement process of Lagging KPIs .................................................................. 80
Figure 30 – Historical results per prototype (%) ..................................................................... 80
Figure 31 – Percentages of monthly historical tendencies ...................................................... 81
Figure 32 - Monthly historical tendencies................................................................................ 82
Figure 33 - Prototype status by 31/05/2019 ............................................................................. 83
Figure 34 - Improvements in the prototypes’ status ................................................................. 83
Figure 35 - Procurement process of Leading KPIs .................................................................. 84
Figure 36 – Economic feasibility study .................................................................................... 90
Figure 37 - Costs comparison between the Prototype System and the Current situation ........ 91
Figure 38 - Monthly number of hours worked in the project ................................................. 100
Figure 39 - Gantt chart of the project .................................................................................... 101
Figure 40 - Work Breakdown Structure of the project ........................................................... 102
LIST OF FIGURES
112 Escuela Técnica Superior de Ingenieros Industriales (UPM)
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 113
List of tables
Table 1 - Seven wastes of the testing facilities ......................................................................... 53
Table 2 - Prototypes Database ................................................................................................. 67
Table 3 - Storage Locations Database ..................................................................................... 68
Table 4 - Users Database ......................................................................................................... 69
Table 5 - Suppliers Database ................................................................................................... 69
Table 6 - Set in order step from 5S applied in the Testing facilities......................................... 73
Table 7 - Prototypes by 31/05/2019: Status and actions to take. ............................................. 85
Table 8 – Suggested steps for the implementation of the two proposals .................................. 87
Table 9 - Proposals overview and wastes................................................................................. 94
Table 10 - Total cost of the project considering the requirements for the workforce and material
............................................................................................................................................................. 103
Table 11 - Possible RFID tags and readers ........................................................................... 115
Table 12 - Estimated parameters used in the Economic Feasibility study ............................. 117
Table 13 - Estimated salaries used in the Economic Feasibility Study .................................. 117
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 114
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 115
APPENDIX 1: RFID tags and readers
Image Name Reference Comments
Unitary
price
RFID tags for
the prototypes
UHF 915 MHZ
fr4 high
temperature
RFID tags [26]
Able to hold extreme
temperatures up to
200°C
€ 1.99
Laminate
RFID tags for
the
employees’
badges
UHF 915 MHZ
pvc laminate
RFID tags [27]
Affordable and
frequency within the
range
€ 0.99
Walkthrough
RFID Reader
Access Control
RFID Tracking
Gate Reader
CL7226D [28]
Suitable to read the
RFID tags for the
following reasons:
-Supports 860 to
960MHz UHF RFID
Cards
-Working width up to 3
meters
€ 1700
RFID reader
for the
employees’
badges
Card-reader
Distance 5m Hf
Gate Rfid Long
Range Reader
with Sdk [29]
Suitable cause it can
detect the frequency
range: 902~928MHZ
(FCC)
€ 160
Table 11 - Possible RFID tags and readers
APPENDIX
116 Escuela Técnica Superior de Ingenieros Industriales (UPM)
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 117
APPENDIX 2: Estimated parameters for the Economic
Feasibility Study
Table 12 - Estimated parameters used in the Economic Feasibility study
Table 13 - Estimated salaries used in the Economic Feasibility Study
ESTIMATED PARAMATERS
RFID tags for the prototypes 1.99 €/unit
Laminate RFID tags for the employees’ badges 0.99 €/unit
Total number of employees in the Testing Facilities 33
Walkthrough RFID Reader 1700.00 €/unit
Total number of walkthrough RFID Readers needed in Year 0 21
RFID reader for the employees’ badges and computer host 4050.00 €
Annual growth 10%
Average number of prototypes tested in a test bench per year 85
Average time to register a new prototype in the system 15 min
Average hour cost of a Test Bench 104.17 €/hour
Average number of working days per month 20
ESTIMATED SALARIES (€/hour)
Programmer 100€
Technician 40€
Test Coordinator 75€
APPENDIX
118 Escuela Técnica Superior de Ingenieros Industriales (UPM)
Efficiency and effectiveness analysis of the inventory system in a testing facility by applying Lean and Six Sigma tools
Laura Delgado Díaz 119
APPENDIX 3: Interview guide
Most interactions with the employees in the Testing facilities were through casual
observations and non-interfering queries during the workday. The following questions were
defined as necessary to obtain a more precise idea about the performance of the Lab.
• How is the planning done on a daily basis?
• Who is the people responsible of keeping track of all the prototypes in the lab
nowadays and how are they kept track?
• Is there any existing inventory system for the prototypes in the lab? If so, which
one and how does it work?
• Which type of prototypes are stored?
• How many new prototypes arrive every month/year for testing?
• How often does a prototype get lost? Which are the issues faced when trying to
find it?
• Which the protocol when looking for a prototype?
• Who is working in the lab and has access to the stored mechanical components
(stakeholders)?
• Is there any map of the warehouse and the distinct storage locations? How are
they stored? Is there already a protocol to follow when storing the different
elements? (Stored according to categories, type of products, etc.)
• Label data system: are there different types of labels depending on the elements
that they stored?
• Which are the daily costs of the test benches?