Six Sigma Green Belt Part 7 - Institute of Industrial and ... · Six Sigma Green Belt Part 7 ......

Six Sigma Green Belt

Part 7

Root Cause Analysis

7-1 © 2013 Institute of Industrial Engineers

Cost and Value

In the economic battle of competition between organizations producing similar products or services cost is the ultimate measure.

Green Belts must be cost conscious and value oriented to perform in the best interests of the organization.


Cost

The cost of anything is the sum of the labor, raw materials, and overhead used to produce it. The minimum cost required to accomplish the functions desired is necessary cost; any cost above this is unnecessary.


Variable Costs

• Variable cost is directly associated with the production of a product:

Direct labor

Direct materials

$0.00

$200.00

$400.00

$600.00

$800.00

$1,000.00

$1,200.00

$1,400.00

0 50 100 150 200

Units Produced

Co

st


Fixed Costs

Fixed cost is not affected by a change in level of production.

$0.00

$50.00

$100.00

$150.00

$200.00

$250.00

0 50 100 150

Units Produced

To

tal C

ost


Total Costs

$0.00

$200.00

$400.00

$600.00

$800.00

$1,000.00

$1,200.00

$1,400.00

$1,600.00

0 50 100 150

Units Produced

To

tal C

ost


Revenue

Income received from each unit sold.

$0.00

$200.00

$400.00

$600.00

$800.00

$1,000.00

$1,200.00

$1,400.00

$1,600.00

$1,800.00

0 50 100 150

Units Sold

Re

ve

nu

e


Break Even

Point at which total costs equals total revenue.

$0.00

$200.00

$400.00

$600.00

$800.00

$1,000.00

$1,200.00

$1,400.00

$1,600.00

$1,800.00

0 50 100 150

Units

Breakeven

Point

Surplus

Loss


Practice

• Our organization currently provides 100,000 units per year. Using the present method our annual costs are:

• Engineering: $2,000

• Tooling: $12,000

• Installation: $4,000

• The variable cost is $3 per unit.

Fixed Costs


Practice Continued

• A six sigma green belt has suggested a modification based on DMAIIC. This is designed to replace the current process. The costs are as follows:

• Engineering: $25,000

• Special Equipment: $35,000

• Training: $5,000

• Re-layout: $10,000

• The Variable cost per unit using this method is $2.05 per unit.

Fixed Costs


Practice Question

a. Which is the better alternative under current conditions?

b. Determine the break over point between the two alternatives.

c. What assumptions are we making?

d. How much more do we make at the same production/sales level (if anything) with the improved method?


Root Cause Analysis

All organizations have problems that plague their operations, reduce profits, and create customer dissatisfaction. We called many of these special causes of variation. Most organizations try to fix these problems quickly without ever finding what caused them in the first place, making the problems reappear. Root cause analysis is the process of finding and eliminating the cause, which would prevent the problem from returning. Only when the root cause is identified and eliminated can the problem be solved.


Process Definition

A process is a set of conditions or set of causes which work together to produce a given result. It includes: Inputs, Outputs, Transformations, and Feedback.

A process is any work that meets the four criteria: it is recurrent; it affects some aspect of organizational capability; it can be accomplished differently so as to make contribution to customer or/and profit; it involves co-ordination.

SIPOC Model

Suppliers

Customers

Inputs Outputs Process


SIPOC

A method to assist in developing the flow on a process map is SIPOC

Suppliers: Who supplies the inputs to do the job?

Inputs: What are the products/services that your suppliers give you?

Process/Sequence: What are the steps to convert the inputs to outputs?

Outputs (products or services): What products or services are produced?

Customers: Who receives your products and services? What do they need? What are their requirements?


Flowcharts

• A flowchart is a graphical representation of a process

• The first step in many process improvement projects is to create a flowchart


Flow Charts

• Map of the process showing elements such as

– Operations

– Decisions

– Delays

– Storages

– Handling

– Information

Flow


Process Analysis Using Flow Chart

Questions to ask:

a. Why

b. When

c. Where

d. Who

e. How

f. Why

???


Swim Lane Flow Chart

Value

Stream Map

7-18 © 2013 IIE and Aft Systems, Inc.

University Travel Process Employee

Desires to

Travel

Verifies with

Dept. Head

Employee

Completes

Request to

Travel Form

Process

EndsDept. Head

Approval

Dean

Approval

VP ApprovalPresident

Approval

Process

Ends

Business Office

Encumbers

Funds

Employee

Travels

Process

Ends

Process

Ends

Process

Ends

No

No

No

No

No

Yes

Yes

Yes

YesYes


Check Sheets

• Check sheets are used to record data.

• They are simple to use. They are:

– Visual

– Easy to Interpret

– Organize Data Collection

• Check sheets are designed, structured formats for recording process data in a manner that can reveal underlying patterns


Check Sheets

• Check Sheets are data gathering tools that can be used in forming histograms and Pareto charts

• Check sheets are a form used to record the frequency of occurrence of certain product or service characteristics

• Check sheets can be either tabular or schematic


Standard Check Sheet Design

This check sheet helps to gather data on quality problems actually experienced

Characteristic Performance Measurement Tally Total

(What Could Go Wrong) Standard Frequency


Sample Check Sheet Apparel Manufacturing

Potential Problem Observed Defective Frequency

Inside out 210 13 0.062

Machine broken 21 0 0.000

No operator 21 0 0.000

No raw material 21 0 0.000

No thread 21 0 0.000

Side seam mismatch 168 32 0.190

Thread color 336 44 0.131

Torn material 168 21 0.125

Upside down 210 10 0.048

Wrong needle 168 1 0.006


Sample Check Sheet Incoming Calls

Date:

Time Tally Total

9:00-10:00

10:00-11:00

11:00-12:00

12:00-1:00

1:00-2:00

2:00-3:00

3:00-4:00

4:00-5:00


Sample Check Sheet


Pareto Analysis

0

10

20

30

40

50

60

H B G A I D F E C

Problem

• Pareto Analysis reflects the frequency or impact of problems. The actual analysis can appear either as a table or as a bar chart

• It is a guide to selecting opportunities and prioritizing


Pareto Principle

• Derives from the 80-20 Rule: 80% of the problems are due to 20% of the causes

• Identify problems to study

• Identify most likely causes

• Point out significant frequencies or costs

• Based upon Juran’s work

» Significant Few and the Trivial Many


Cause-Effect Diagram

• Tool for organizing team’s knowledge about a process – in effect it is organized or structured brainstorming

• Graphical picture of what is known about the process

• Communication tool

• Named after Dr. Ishikawa


Ishikawa Diagram

The cause and effect diagram assists in reaching a common understanding of the problem and exposes the potential drivers of the problem


Typical Categories for Branches

Manufacturing

– Methods

– Materials

– Equipment

– People

– Environment

Service

– Procedures

– Processes

– Policies

– People


Sample Cause Effect Diagram

METHODS MACHINE Operator

Mat'l ID Training Tension Information

Placement Set Up

Specs Wrong Clearance Calibration

Missing Pattern Tools

None Cutting Tools

Fixtures Volume Capacity

Cutting Direction Maintenance

Over use

Speed

Dull Knife Standards

Incentives

Maintenance Wrong Size

Cut

Parts

Space Time Available Stress

Light Storage Schedule Schedule

Environ. Substitute Standards Attitudes

Temperature Wages

Finish Specs Motivation

Humidity

Strength Composition Discipline

Static Electricity Loose Trainers

Spread Incorrect

Shrinkage Tight Training

None

ENVIRONMENT MATERIALS PEOPLE Cost


Scatter Diagram

• Graph of one sample variable versus another

• May show cause and effect relationships

• May show strong correlation with a cause and effect relationship

0

5

10

15

20

25

1 3 5 7 9 11 13 15 17 19

X Values

Y V

alu

es

•A correlation of +1 indicates a

perfect positive relationship

•A correlation of –1 indicates a

perfect negative relationship

•A correlation of 0 means no

significant relationship


Using a Scatter Diagram

• Vary over normal operating range

• Extrapolate with care – don’t go beyond the limits of the observed data

• Stratify or sort by classification, such as shift, to find interactions

• Beware of happenstance or hidden variable data in which there may appear to be a strong correlation but no valid reason for it


FMEA Definition

A procedure by which each potential failure mode in a system is analyzed to determine the results of effects thereof on the system and to classify each potential failure mode according to its severity, the likelihood of it occurring, and the ability of the system to prevent it from occurring.


Background

The failure mode and effects analysis (FMEA) is the most widely used analysis procedure in practice at the initial stages of system development.

The FMEA is usually performed during the conceptual

and initial design phases of the system in order to assure that all possible failure modes have been considered and that proper provisions have been made to eliminate all the potential failures.


History of FMEA

• Created by the aerospace industry in the 1960s.

• Ford began using FMEA in 1972.

• Incorporated by the “Big Three” in 1988.

• Automotive Industry Action Group and American Society for Quality Control copyright standards in 1993.


FMEA Flow Chart

Define each step in Flow

List function

Brainstorm potential failure

modes

Describe effects of the failures

Determine severity of

failures

Determine probability of

failure

Determine detection rate of failure (control)

Assign RPN

Take action to improve

Tracking Form

Process FMEA

Part/Process Suppliers Affected: Prepared by:

Name:

Manufacturing Model Year: FMEA Date:

Reponsibility:

Other Areas: Release Date: Key ProductionDate:

Process Purpose Potential Potential Severity Class Potential Occur Current Detect RPN Recom Respon Actions

Failure Effects Cause Controls Actions

Mode


Additional RCA Tools and Techniques


TRIZ - Inventive

Problem Solving

The theory of inventive problem solving is based upon extensive research

into real inventions. The research focused on the most significant of those

inventions - where the solution to the problem was not entirely obvious

and required no trade-offs. The results of which revealed that inventors

worldwide sub-consciously applied a common technique - TRIZ brings

together these techniques and combines them with very practical

methods.

Scientific approach to new

solutions to engineering

problems.

Brainstorming

(Osborne)

This is a classic tool recognised by many, but it is not that successful at

generating new ideas. As a method it is not efficient at generating new

ideas - Life is just too short! Limited to smaller groups - can create

problems with group dynamics.

Generating new

associations.

Brainstorming -

Catalogue

Techniques

Participants Use pictorial matter (Catalogues, photos, etc.) as triggers.

More structure than the classic - slightly more efficient as well.

Competitive analysis, new

features.

Card / Post-it

Systems

Participants Use slips to write ideas down - requires little management

intervention or leadership skills - It can be used successfully on large

groups. A variation of this technique is 'pass it on' where participants pass

on a single card adding ideas to the list.

Idea generation for large

groups

Brain writing -

Trigger / Cascade

Similar to classic brainstorming - without the disadvantages. More efficient

at generating new ideas. Participants use post-it pads to provide triggers

for discussion.

Ideal for new teams.

Knowledge Trees Structured brainstorming and reference technique for generation of new

products. Highly effective when used by cross functional teams. Can be

applied to virtually all aspects in the product design phase. The method

was developed by IPM and is used on a regular basis.

Generating specifications.

Sharing product knowledge

and general understanding.

Parametric

Analysis

Parameter based analysis - Quantitative, Qualitative, Categorical. An

existing (or competitor) product is used as a benchmark with particular

attention being paid to specific parameters. It is then indicated how these

parameters would have to be different to enhance satisfaction.

Developing an existing

product or product portfolio.

Semantic

Processes -

Random

Matching

Random word-to-word to trigger new associations General purpose tool

Semantic

Processes - Idea

Search Matrix

Checklists of questions to trigger new thoughts and ideas General purpose tool


Excursion

Technique

Using words and situations to lead away from the problem and

reality. Switching back when a new idea or association is seen.

Often closes on one idea

General purpose tool

Problem

Abstraction -

Why?Why?....

Problem Abstraction or Semantic Processes (redefinition)

attempts to reduce problems to their most basic level - problem

goals and boundaries are then set. The procedure then follows a

series of Why? questions followed by a subsequent Alternative?

Good Team exercise.

Developing existing

portfolio. Identifying

market opportunities for

new products.

Ideas Book Simple technique but can reap good results - Ideas are entered

into a dedicated book from anyone who wishes (and at any time) -

a relaxed approach to new ideas and suggestions. Can fall quickly

into disrepute if not part of an evaluations procedure.

Good when no time limit

is present. Ongoing

suggestions.

Orthographic

Analysis

Orthographic analysis is a way of arranging several attributes of a

problem in a graphical representation of corresponding

dimensions. A general purpose version of orthographic analysis

takes a product and represents its Material, Manufacturing

Processes and its Market along three orthographic axes.

Portfolio enhancement.

Specific solutions to

known market

requirements.

SCAMPER -

Stretch Matrix

Substitute, Combine, Adapt, Magnify ( or Minify), Put to other

uses, Eliminate, Re-arrange (or Reverse) - Together they make

up a checklist of possible product modifications.

Product improvements

and enhancements.

Analogies A particular form of thinking or reasoning in which the properties

of one object are thought of in terms of a second object which is

different but does have elements in common with the former.

Ideas may come from nature or other similar products.

New product features.

Evaluation -

PIPS

Phases of Integrated Problem Solving - Is a numerical scoring tool

that divides the problem (or opportunity) and processes into

individual stages and evaluates individually.

Products and Processes

Clichés and

Proverbs

A technique to jog the mind out of conventional thinking (out of a

rut). Armed with a list of common Clichés and Proverbs ask how

each one may apply or be applied to the subject or problem.

General Use


QFD : Quality

Function

Deployment

Quality Function Deployment is a customer oriented approach to

product development and innovation. It is a powerful tool for use

by product managers and development teams. The methodology

takes the design team through the concept, creation and

realization phases of a new product with absolute focus. QFD also

defines what the end user is really looking for in the way of

features and benefits.

Structured Product

Specifications. Taking

the 'Voice of the

Customer' through all

relevant areas of the

Company.

Delphi

Technique

The Delphi Technique pulls ideas from participants by means of a

highly structured series of questionnaires gradually honing into

problems or opportunities. Participants are chosen for their

knowledge in their particular field. This technique is good for

groups of participants who do not normally meet. The success or

failure of this technique is only as good as the chosen

participants.

Problem solving,

Product definition.

Brainstorming -

Catalogue

Techniques

Participants Use pictorial matter (Catalogues, photos, etc.) as

triggers. More structure than the classic - slightly more efficient as

well.

Competitive analysis,

new features.

Card / Post-it

Systems

Participants Use slips to write ideas down - requires little

management intervention or leadership skills - It can be used

successfully on large groups. A variation of this technique is 'pass

it on' where participants pass on a single card adding ideas to the

list.

Idea generation for large

groups

Market Needs

Research

Market Needs Research is a technique for finding out what the

Customer requires (and needs) from a product. It determines

whether Users perceive a need which is not currently satisfied by

existing products. Similar to elements of the QFD process it is

essential to have direct access to the end user and to understand

user requirements. The process defines subsequent questions

that need to be handled by traditional research methods

(Quantitative and or Qualitative).

New product

specifications


Opportunity

Specification

A concise specification document describing the market need for a

proposed new product. It is a good tool for screening new ideas (products)

against the companys' capabilities. It describes the business opportunity of

the proposed product in terms of core benefits. It also justifies the business

opportunity in terms of commercial viability.

Concise business

justification, market

opportunities, product

identification

Knowledge Trees Structured brainstorming and reference technique for generation of new

products. Highly effective when used by cross functional teams. Can be

applied to virtually all aspects in the product design phase. The method

was developed by IPM and is used on a regular basis.

Generating specifications.

Sharing product knowledge

and general understanding.

Visual Mapping Series of matrices position product features and attributes in a visual way -

Simple but powerful technique to share new product features with a multi

disciplinary team

Product definition - Aids in

the communication between

Development, Marketing,

Industrial design.

Product Function

Analysis or

(FAST)

Function Analysis Systematic Technique is a method of systematically

analysing the functions performed by a product. Once again intimate

knowledge of the customers needs and wants with regards to product

features and functions. A function tree answers the questions of How and

Why functions are required.

Good for analysing both

new and existing products,

the results of which being

used in methodologies like

QFD, VAVE, FMEA etc.

FMEA Failure Mode Effect Analysis - Highlights the problem areas (safety related)

of a design - Severity and Probability analysis.

Screening for potential

problems (safety or

reliability related) with new

products.

VAVE Value Analysis Value Engineered - Primarily an engineering /

manufacturing tool to optimise design features in the most cost effective

way

Optimised cost effective

design prior to manufacture.


The 6s Process

ID Customer Expectations

Process Flow Analysis

Root Cause Analysis

(Cause & Effect, Pareto)

Key Process Identified Data Collection Strategy

•Histogram

•Scatter Diagram

•Run Chart

•Control Chart

Baseline Measures

Propose Improvement Plan

Implement Plan

Collect & Analyze Data

Compare with Previous Results

Document & Standardize

Monitor

Causes Identified?

No

Objectives Met?

YES

No

YES

Define Measure and Analyze Improve, Implement

and Control


Six

Sigm

a G

ree

n B

elt

An

alys

is P

roce

ss

Determine what to

measure, how to

measure, and

sampling scheme.

Measure

Construct

Histogram Finish

Improve the

Process

no

Is it the expected

shape?

Is the data time

dependent?

Draw Control

Chart(s) Capable?

In Control?

Identify Special

Cause(s) Evaluate Capability

Significant Change?

Identify Special

Cause(s)

Address Special

Causes

Address Special

Causes Significant?

yes yes

yes

yes

yes

no

no

no

yes

no

no


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