Managing Quality Integrating the Supply Chain S. Thomas Foster - Download as PowerPoint

Document Sample

```					Lecture 11 -
Six-Sigma Management
and Tools
6Σ Organization, DMAIC, Taguchi
Method, Robust Design, Design of
Experiments, Design for Six
Sigma, Reasons for 6Σ Failure

Rev. 10/24/11   SJSU Bus. 142 - David Bentley   1
Topics
 What is Six-Sigma?
 Organizing Six-Sigma

 DMAIC overview

 DMAIC phases

 The Taguchi method

 Design for Six-Sigma

 Using Six-Sigma from a contingency

perspective
11/13/07   SJSU Bus. 142 - David Bentley   2
Six Sigma Evolution
   Started as a simple quality metric at
Motorola in 1986 (Bill Smith)
   Concept migrated to Allied Signal
    (acquired Honeywell and took its name)
   Picked up by General Electric
 Commitment by CEO Jack Welch in 1995
    Grown to be an integrated strategy for
attaining extremely high levels of quality

Rev. 04/15/09   SJSU Bus. 142 - David Bentley   3
What is Six-Sigma?
    Sigma () is a Greek letter used to
designate a standard deviation (SD) in
statistics
    Six refers to the number of SD’s from the
specialized limit to the mean.
    Six sigma is a fairly recent umbrella
approach to achieve quality

Rev. 10/29/08   SJSU Bus. 142 - David Bentley   4
Percent Not Meeting
Specifications
   +1Σ        =   32%
   +2Σ        =   4.5%
   +3Σ        =   0.3%
   +6Σ        =   0.00034%

11/13/07            SJSU Bus. 142 - David Bentley   5
Six-Sigma Levels
Sigma Level   Long-term ppm* defects
1                     691,462
2                     308,538
3                     66,807
4                      6,210
5                       233
6                       3.4

11/13/07            SJSU Bus. 142 - David Bentley   6
Statistics - DPU
   Defect
   Six Sigma: “any mistake or error passed on to
the customer” ???
   General view: any variation from specifications
   DPU (defects per unit)
   Number of defects per unit of work
   Ex: 3 lost bags ÷ 8,000 customers
= .000375
Rev. 11/10/08   SJSU Bus. 142 - David Bentley     7
Statistics – dpmo (defects per
million opportunities)
   Process may have more than one
opportunity for error (e.g., airline baggage)
   dpmo = (DPU × 1,000,000) ÷
opportunities for error
   Ex: (.000375)(1,000,000) ÷ 1.6 =
234.375
or (3 lost bags × 1,000,000) ÷ (8,000
customers × 1.6 average bags)
= 234.375
Rev. 04/27/09   SJSU Bus. 142 - David Bentley   8
Statistics – dpmo                    (cont’d)

   May extend the concept to include higher
level processes
    E.g., may consider all opportunities for errors
for a flight (from ticketing to baggage claim)

11/13/07         SJSU Bus. 142 - David Bentley     9
Statistics - Off-Centering
   Represents a shift in the process mean
   Impossible to always keep the process
mean the same (this WOULD be perfection)
   Does NOT represent a change in
specifications
   Control of shift within ± 1.5 σ of the target
mean keeps defects to a maximum of 3.4
per million

11/13/07       SJSU Bus. 142 - David Bentley   10
Statistics - Off-Centering (cont’d)
Source: Evans & Lindsay, The Management and Control of Quality, Southwestern, 2005

11/13/07                                     SJSU Bus. 142 - David Bentley          11
k-Sigma Quality Levels
   Number of defects per million opportunities
   For a specified off-centering and
   a desired quality level

Rev. 11/03/08      SJSU Bus. 142 - David Bentley   12
k-Sigma Quality Levels
Source: Evans & Lindsay, The Management and Control of Quality, Southwestern, 2005

11/13/07                                    SJSU Bus. 142 - David Bentley            13
Six Sigma and Other
Techniques

Six-Sigma is … designed to handle
the most difficult quality problems.
% Quality Problems Techniques
90%          Basic tools of Quality
< 10%             Six-Sigma
< 1%              Outside specialists

11/13/07            SJSU Bus. 142 - David Bentley   14
Organizing Six Sigma

11/13/07   SJSU Bus. 142 - David Bentley   15
Key Players
   Champion. Work with black belts to
identify possible projects
   Master Black Belts. Work with and train
new black belts
   Black Belts. Committed full time to
completing cost-reduction projects
   Green Belts. Trained in basic quality
tools

11/13/07     SJSU Bus. 142 - David Bentley   16
Distribution of Six Sigma
Trained Employees
In a company with 100 employees there
might be:
 One black belt
 Sixty green belts
 Some companies have yellow belts, employees
familiar with improvement processes

11/13/07       SJSU Bus. 142 - David Bentley   17
Six Sigma Tools

DMAIC, Taguchi Method, Design
for Six Sigma

11/13/07            SJSU Bus. 142 - David Bentley   18
DMAIC

11/13/07   SJSU Bus. 142 - David Bentley   19
DMAIC
DMAIC Overview

   Stands for the six phases:
 Define
 Measure

 Analyze

 Improve

 Control

11/13/07         SJSU Bus. 142 - David Bentley       20
DMAIC
Define – (1)
    Four Sub-Phases:
1.     Develop the business case
2.     Project evaluation
3.     Pareto analysis
4.     Project definition

11/13/07             SJSU Bus. 142 - David Bentley       21
DMAIC
Define – (2)

   Developing the Business Case:
1.   Identify a group of possible projects
2.   Writing the business case
3.   Stratifying the business case into problem
statement and objective statement

11/13/07           SJSU Bus. 142 - David Bentley       22
DMAIC
Define – (3)

    RUMBA is a device used to check the
efficacy of the business case
1.    Realistic
2.    Understandable
3.    Measurable
4.    Believable
5.    Actionable

Rev. 11/03/08     SJSU Bus. 142 - David Bentley       23
DMAIC
Measure – (1)

     Two major steps:
1.   Selecting process outcomes
2.   Verifying measurements

Rev. 11/15/07       SJSU Bus. 142 - David Bentley       24
DMAIC
Measure – (2)
   Selecting process outcomes (step 1)
    Tools Used:
   Process map (flowchart)
   XY matrix (like QFD)
   FMEA (Failure Modes and Effects Analysis)
(aka DFMEA)
   Gauge R&R (Repeatability and Reproducibility)
   Capability Assessment (cp or cpk)

Rev. 10/29/08         SJSU Bus. 142 - David Bentley       25
DMAIC
Measure – (3)
      Verifying measurements (step 2)
    Tools Used:
   Gauges, calipers and other tools.
   Management System Analysis (MSA) is used
to determine if measurements are consistent

11/13/07              SJSU Bus. 142 - David Bentley       26
DMAIC
Measure – (4)
    Gauge R&R
     Most commonly used MSA
     Determine the accuracy and precision

11/13/07             SJSU Bus. 142 - David Bentley       27
DMAIC
Repeatability & Reproducibility

11/13/07   SJSU Bus. 142 - David Bentley       28
Measurement System                                    DMAIC
Evaluation
   Variation can be due to:
    Process variation
    Measurement system error
   Random
   Systematic (bias)
    A combination of the two

02/26/06              SJSU Bus. 142 - David Bentley       29
DMAIC
Metrology - 1
   Definition: The Science of Measurement
   Accuracy
    How close an observation is to a standard
   Precision
    How close random individual
measurements are to each other

02/26/06        SJSU Bus. 142 - David Bentley       30
DMAIC
Metrology - 2
   Repeatability
    Instrument variation
    Variation in measurements using same
instrument and same individual
   Reproducibility
    Operator variation
    Variation in measurements using same
instrument and different individual
02/26/06        SJSU Bus. 142 - David Bentley       31
DMAIC
R&R Studies
   Select m operators and n parts
   Calibrate the measuring instrument
   Randomly measure each part by each
operator for r trials
   Compute key statistics to quantify
repeatability and reproducibility

02/26/06     SJSU Bus. 142 - David Bentley       32
DMAIC

02/25/06   SJSU Bus. 142 - David Bentley       33
DMAIC
R&R Evaluation
   Repeatability and/or reproducibility error as
a percent of the tolerance
    Acceptable: < 10%
    Unacceptable: > 30%
    Questionable: 10-30%
   Decision based on criticality of the quality
characteristic being measured and cost factors

Rev. 11/27/06         SJSU Bus. 142 - David Bentley       34
DMAIC
Calibration
   Compare 2 instruments or systems
   1 with known relationship to national
standards
   1 with unknown relationship to national
standards

02/26/06          SJSU Bus. 142 - David Bentley       35
DMAIC
Analyze – (1)
   Three major steps:
1.   Define your performance objectives (X’s)
2.   Identify independent variables
3.   Analyze sources of variability

11/13/07          SJSU Bus. 142 - David Bentley       36
DMAIC
Analyze – (2)
   Define your performance objectives (X’s)
(step 1)

11/13/07      SJSU Bus. 142 - David Bentley       37
DMAIC
Analyze –       (3)

   Identify the independent variables where
data will be gathered (step 2)
   Process maps (flowcharts), XY matrices,
brainstorming, and FMEA’s are the tools used

11/13/07          SJSU Bus. 142 - David Bentley       38
DMAIC
Analyze –        (4)

   Analyze sources of variability (step 3)
   Use visual and statistical tools to better
understand the relationships between
dependent and independent variables

11/13/07           SJSU Bus. 142 - David Bentley       39
DMAIC
Improve
     Off-line experimentation
    Analysis of variance (ANOVA)
    Determines whether independent
variable affect variation in dependent
variables
    Taguchi method or approach

Rev. 11/03/08            SJSU Bus. 142 - David Bentley       40
DMAIC
Control Phase

     Manage the improved processes
using control charts… covered in:
    Variables
    Attributes

Rev. 10/29/08      SJSU Bus. 142 - David Bentley       41
The Taguchi Method

11/13/07   SJSU Bus. 142 - David Bentley   42
The Taguchi Method provides:
1.   A basis for determining the functional
relationship between controllable factors
2.   A method for adjusting a mean of a process
by optimizing controllable variables.
3.   A procedure for examining the relationship
between random noise … and product or
service variability

Rev. 04/28/08   SJSU Bus. 142 - David Bentley   43
Design of Experiments (DOE)
   Robust design – designed so that
products are inherently defect free
   Concept Design – considers process
design and technology choices
   Parameter Design – selection of
control factors and optimal levels
   Tolerance Design – specification limits

Rev. 11/03/08   SJSU Bus. 142 - David Bentley   44
The Taguchi Process
1.     Problem identification
2.     Brainstorming session
3.     Experimental design
4.     Experimentation
5.     Analysis
6.     Confirming experiment

11/13/07     SJSU Bus. 142 - David Bentley   45
Taguchi Quality Loss Function
   Traditional view: anything within
specification limits is OK, with no loss
   Taguchi
   Any variation from the target mean represents
a potential loss
   The greater the distance from the target mean
the greater the potential loss

04/28/08          SJSU Bus. 142 - David Bentley   46
Design for Six Sigma

DFSS

11/13/07   SJSU Bus. 142 - David Bentley   47
Design for Six-Sigma (DFSS)
    Used in designing new products with
high performance, instead of DMAIC
1. DMADV (see next slide)
2. IDOV (see 2 slides ahead)

    Focuses on final engineering design
optimization
    Relates to new processes and products

Rev. 11/03/08   SJSU Bus. 142 - David Bentley   48
1.     Design
2.     Measure
3.     Analyze
4.     Design
5.     Verify

11/13/07             SJSU Bus. 142 - David Bentley   49
IDOV
1.     Identify
2.     Design
3.     Optimize
4.     Verify

11/13/07              SJSU Bus. 142 - David Bentley   50
Reasons for Six Sigma Failure

11/13/07   SJSU Bus. 142 - David Bentley   51
Reasons for Six-Sigma Failure
- (1)
1.     Lack of leadership by champions
2.     Misunderstood roles and responsibility
3.     Lack of appropriate culture for
improvement

11/13/07       SJSU Bus. 142 - David Bentley   52
Reasons for Six-Sigma Failure
- (2)
4.     Resistance to change and the Six-Sigma
structure
5.     Faulty strategies for deployment
6.     Lack of data

11/13/07      SJSU Bus. 142 - David Bentley   53
Summary
    The process for Six-Sigma is define,
measure, analyze, improve and control
    Keys to Six-Sigma success are skilled
management, leadership and long-
term commitment

11/13/07      SJSU Bus. 142 - David Bentley   54

```
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
 views: 143 posted: 7/27/2012 language: English pages: 54
How are you planning on using Docstoc?