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8/4/2019 Chap 5 - MOM
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Manufacturing & OperationsManagement
Topic 5Maintenance Management
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Introduction
o A plant is a place where men, materials,money, equipment, machinery, etc. arebrought together for manufacturingproducts
o Quality of product depends on theperformance of equipment & machinery
o
Breakdown of one equipment mayparalyze the whole system and the lossof production hour may increase thewound
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o All the production facilities are subject todeterioration (temperature rise,vibrations, loosening, seasoning of parts, accumulation of dirt, rusting of parts, etc.) due to their use and
exposure to the environmentalconditionso If unchecked and unattended,
culminates and brings facilities uselesso In this context, maintenance assumes
importance as an engineering function
Introduction Continued
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What is maintenance management ?
o Maintenance management issystematic approachn to planning the maintenance activities,n use of decision making tools to evaluate
& select the best set of alternatives formaintenance, cost & operational control
n
Improving the overall efficiency & effectiveness of the operating system
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Objectives of Maintenance
o To keep all the production facilities in an
optimum working conditiono Ensure specified accuracy to products & time
schedule of delivery to customerso To keep the downtime of the machine at
minimumo To improve productivity of existing machine
tools and to avoid sinking of additional capitalo To keep the factory overheads to minimum
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o To extend the useful life of plant andmachinery, without sacrificing the levelof performance
o Minimization of wear and tear toincrease the longevity of the equipment
o Elimination of unsafe conditions that
cause accidents thereby ensuring safetyof the workmen
o Achievement of all the above objectivesat the least cost to the company
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Costs associated withbreakdowno Down time costo Idle wageso Loss of materialso Cost of repairso Opportunity costo Effect on other machineso
Expediting costo Accident costo Added set up costo Tool breakageo Increase in WIP investment
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o Overtime wages paid to themaintenance
o
Premium paid on the spare partso Reduced life of the equipmento Broken promiseso
Lowered Moraleo Higher spares inventory investmento Cost of standby equipment
Costs Continued
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Economic aspects of maintenance
Cost
Degree of maintenance efforts0
Total Cost
Cost of labour & overhead
Cost of downtime
Total Costs
of Repairs
low high
Cost of quality
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Types of maintenance
o Breakdown maintenance :In this type of maintenance, no care is taken forthe machine, until equipment fails.
Repair is then undertaken.This type of maintenance could be used whenthe equipment failure does not significantlyaffect the operation or production or generate
any significant loss other than repair cost.However, an important aspect is that the failure
of a component from a big machine may beinjurious to the operator. Hence breakdown
maintenance should be avoided.
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Preventive maintenance
o It is a regular maintenance (cleaning,inspection, oiling and re-tightening), design toretain the healthy condition of equipment and
prevent failure through the prevention of deterioration, periodic inspection or equipmentcondition diagnosis, to measure deterioration.
o It is further divided into periodic maintenance
and predictive maintenance. Just like human lifeis extended by preventive medicine, theequipment service life can be prolonged bydoing preventive maintenance.
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Basic activities of thepreventive maintenanceo Preventive inspectiono Planned lubricationo
Cleaning and upkeepo Minor adjustments and repairso Equipment recordso
Spares controlo Condition monitoring
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o Periodic maintenance (Time basedmaintenance - TBM)n Time based maintenance consists of
periodically inspecting, servicing andcleaning equipment and replacing partsto prevent sudden failure and processproblems. E.g. Replacement of coolant oroil every 15 days.
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o Predictive maintenance:This is a method in which the service life of important partis predicted based on inspection or diagnosis, in order touse the parts to the limit of their service life.
Compared to periodic maintenance, predictivemaintenance is condition-based maintenance. It managestrend values, by measuring and analyzing data aboutdeterioration and employs a surveillance system, designedto monitor conditions through an on-line system.
E.g. Replacement of coolant or oil, if there is a change incolor. Change in color indicates the deteriorating conditionof the oil. As this is a condition-based maintenance, the oilor coolant is replaced.
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Corrective maintenance
o It improves equipment and itscomponents so that preventivemaintenance can be carried outreliably.
o Equipment with design weakness mustbe redesigned to improve reliability orimproving maintainability. Thishappens at the equipment user level.
o E.g. Installing a guard, to prevent theburrs falling in the coolant tank
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Maintenance prevention
o This program indicates the design of newequipment.
o Weakness of current machines is sufficiently
studied (on site information leading to failureprevention, easier maintenance and prevents of defects, safety and ease of manufacturing).
o The observations and the study made are
shared with the equipment manufacturer andnecessary changes are made in the design of new machine.
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Planning Maintenance workcycle
Planning
Controlling Scheduling
ExecutingAnalysis
Recording
MaintenancePlanning
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Total Productive Maintenance
o Development of the TPM conceptbegan in 1970s in Japan
o
JIPM (Japan Institute of PlantMaintenance) Award is given to bestTPM implementation
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Concept
o The word TOTAL in TPM has three meaningn Total Effectiveness : Indicates TPM pursuit of
economic efficiency or profitabilityn Total Maintenance System : includes
maintenance prevention (MP) andmaintainability improvement (MI) as well aspreventive maintenance
n
Total Participation of all Employees : includesAutonomous maintenance by operatorsthrough SGA
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Objectives
o The objective of TPM is much wider then justminimizing equipment; the objective is tominimize the life cycle cost i.e., the cost for the
entire lifespan of the equipment.o TPM aims to maximize equipment effectivenesso TPM establishes a thorough system of
preventive maintenance for the entire life spano TPM is implemented by various departments
(Engineering, operations, maintenance)o TPM involves every single employeeo TPM is based on promotion of PM through
motivation management (autonomous SGA)
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o TPM aims forn Zero Defects (ZD)n Zero Accidentsn Zero Breakdowns
n In TPM ZERO is HERO
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Stages in TPM implementation:Step A - PREPARATORY STAGE:o STEP 1 - Announcement by
Management to all about TPM introduction in the organization:
o STEP 2 - Initial education and propaganda for TPM
o STEP 3 - Setting up TPM and
departmental committeeso STEP 4 - Establishing the TPM working
system and target: (benchmarking &
target)
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Stages in TPMimplementation:o STEP B - INTRODUCTION STAGE
n Small get-together with suppliersand customers.
§ STAGE C - IMPLEMENTATIONo STAGE D - INSTITUTIONALISING
STAGEn By now the TPM implementation
activities would have reached maturitystage. Now is the time to apply forvarious award & accolades.
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Direct benefits of TPM
o Increase in productivity and OEE(Overall Equipment Efficiency)
o
Reduction in customer complaints.o Reduction in the manufacturing cost by30%.
o Satisfying the customers needs by 100% (Delivering the right quantity at theright time, in the required quality.)
o Reduced accidents.
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Indirect benefits of TPM o
Higher confidence level among theemployees.o A clean, neat and attractive work place.o Favorable change in the attitude of the
operators.o Achieve goals by working as team.o Horizontal deployment of a new concept
in all areas of the organization.o Sharing knowledge and experience.o The workers get a feeling of owning the
machine.
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The requirements for TPM tosucceed are:
v Commitment from Management - initial drivefrom top downv Commitment from shop floor - Bottom updriven after startv
The necessary resources made availablev Support from Maintenance Departmentsv Everybody to try it.
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CONCLUSION
•
Typically 60% of breakdowns are caused byloose bolts and poor lubrication
• Dirty conditions are a major cause of failureand accelerate wear and deterioration of machinery
•
Product quality, throughput, safety andmorale are all inextricably linked to themachine condition