gb_dfss_v2_trwpres[1]

Green Belt Training Material

DFSSDesign for Six Sigma

© TRW Automotive Inc. 20052

Goals of the DFSS Module• The goals of this module are to understand:

– Purpose and key concepts of Design for Six Sigma (DFSS)

– Relationship with other activities & processes:– E.g. GDPIM, existing practices in design and the business

– Continuing relevance of DMAIC in Design:– DMAIC methodology & tools– When to use the “IDOV” methodology

– Key tools

– TRW plans for DFSS deployment.


Why DFSS?

• DFSS has a different emphasis: – It addresses getting it right first

time (and every time the design is implemented thereafter).

•Remember that DMAIC is an improvement methodology.•DMAIC is applied where the product (or service, or process) exists and when there is substantial opportunity for improvement – i.e. it was not right first time (and/or that circumstances have changed).


DFSS at TRW Automotive is:• It is three concepts, to be taken together:

– First, it is a set of principles• It’s about getting the design right - for product or

process.

– Second, a methodology to implement these principles• Identify, Design, Optimize, Validate - (IDOV)

– Third, the structured use of appropriate tools to support the principles, such as:

• Quality Function Deployment (QFD)• Design Scorecards• Robust Design


DFSS Concept #1: A Set of Principles

• Do not design what the customer does not want

• Do not design what you cannot make

• The design must work every time

• The “design” can be the design of a product, process, or The “design” can be the design of a product, process, or service.service.

• In this module “Product” is used to imply all of these.In this module “Product” is used to imply all of these.


The Vision of DFSS

Reactive Design Quality

Predictive Design Quality DFSS

From• Evolving design requirements• Extensive design rework • Product performance

assessed by “build and test”• Performance and producibility

problems fixed after product in use

• Functionally serial product development

• Quality “tested in”

To• Disciplined CTQ flowdown• Controlled design parameters• Product performance modeled

and simulated • Designed for robust performance

and producibility

• Functionally integrated product development

• Quality “designed in”

Note: Where you see ‘product’ you can read manufacturing or transactional process


DFSS Concept #2: Methodology - “I”• Identify and Define the customer and the business needs•Analogous to the DMAIC “Define” & “Measure” phases -

– There’s a strong emphasis on “Identifying” the customer needs

• Focus on designing what the customer does want.– Identify and make a good fit of the business needs, as

well.• Manufacturability (* see notes) and cost are critical from the

start.– Benchmarking also occurs – measuring and analyzing

strengths and weaknesses of other product.• Competitors, other industries, and TRW’s

own product and processes are all potential and useful benchmarks.

• However the new design is likely to end up quite different from the benchmark.


DFSS Concept #2: Methodology - “D”• Design and Develop the product– There is no direct equivalent within DMAIC– What matters in the Design needs to be

identified‡ – performance, “build” process, etc.– It involves the creation of multiple concepts

to best meet the needs and requirements which were identified• The “manufacturing” process is designed and developed at

the same time as the product is designed– Then the selection & evaluation of the best concept is carried

out• Simulation or other concept analysis may be necessary• Ideas from more than one concept can be combined• Evaluation criteria such as cost are a major part of this

selection– An initial estimate of product (or process) performance &

“manufacturing”capability is then predicted


DFSS Concept #2: Methodology - “O”• Optimize the design– Start by implementing the “Best” concept from the Design phase

(or possibly a couple of alternatives):– How can it be made better?

• How does it perform against expectations?• How can the Manufacturability* be improved?• Can the cost be reduced (for example, are component tolerances too tight)?• What effect does the real environment have on the product -

is it robust ‡?


DFSS Concept #2: Methodology - “V”• Validate the design– Move towards product launch -– Validate representative parts

• Does it meet customer and businessexpectations?

– Validate the roll-out of the product• Is the manufacturing* process stable over

time?• Are the key performance criteria controlled

in advance of completion of product manufacture?

– What is useful for the future?• How can the experience from this product

be used to benefit the next design?


What can IDOV be applied to?•The IDOV methodology is “scaleable” and applicable to many designs – anything from large to very small:

– It can be used for design of a complex system– It can be applied to design of a single component– All services and processes can have IDOV applied to

their design.

•Transactional business processes:

Products:

Manufacturing processes:


The Fit of DFSS to Other Activities•GDPIM is TRW Automotive’s product introduction methodology, with standard deliverables (checklists, tollgate reviews and so on).

– GDPIM is “What” needs to be delivered during the design of new automotive systems and modules.

– DFSS complements GDPIM by helping to answer “How” to provide a good design

•DFSS builds upon good design practice

•DFSS does not replace:– Research & Development– Good Engineering practice– Commercialization


So, Why is DMAIC Still Necessary?

• Six Sigma fundamentals are acquired through DMAIC• Essential statistics, variation, accurate collection and use of data, etc.

• DMAIC remains the optimum methodology of improvement for any reasonably complex problem because:

• The problem is effectively defined - with scope, benefit and timescales• A baseline is established and any improvement is assessed objectively• The problem is analyzed before improvements are implemented,

reducing repetitive “best guess” attempts• The control phase focusses on sustaining the improvement• And you will now be aware of more !

• The training introduces appropriate tools (e.g. D.O.E. & Reliability analysis)

• They are introduced within DMAIC & taken further in DFSS


Which Methodology To Use:• Classic 6σ (DMAIC)Classic 6σ (DMAIC)

– An Improvement Methodology– Appropriate for the majority of 6σ

projects– Appropriate for design

improvements (potentially lower risk than a new design)

– Perform pilot build and implement change during the Improve phase

– Appropriate only if focus will be on 1 or 2 CTQ’s

• DFSS (IDOV)DFSS (IDOV)– Methodology for creation from

new (or “start again”)– Less appropriate if a baseline

already exists– Perform pilot build and

implement design during the Validate phase

– Appropriate if a balance needs to be established between many CTQ’s

Define

Measure

Analyze

Improve

Control


Which Methodology To Use:

Existing Process, product

or service ?

Meet clientrequirements ?

Process Management

No

Business need to improve?

IDOV

IncrementalImprovementsufficient ?

No

No

Yes

Yes

Yes

Improvement Approach

Step 4Is solution a new

process,Product or service ?

Step 1- DefineStep 2- MeasureStep 3- Analyse

Step 5- Control

No

DMAIC

Yes

Yes

Less appropriate if a baseline already exists: If a baseline already exists, it is an improvement project – DFSS is more suitable for new or ‘start again’ projects, in which case benchmarks (comparisons with competitor, other areas or businesses) are relevant, but are not a representative baseline.

Some terminology:The whole thing (DFSS, IDOV, DMAIC, Classic) is called “Six Sigma”Classic Six Sigma is the description of the activity which will follow the DMAIC methodology, which the Green Belts have just been taught.Design for Six Sigma is the description of theactivity which will follow the IDOV methodology, and is the subject of this module.Of the five terms, only DMAIC and DFSS are used in the same way, industry-wideBut “Classic Six Sigma” and IDOV are commonly used in the industryThe overarching term “Six Sigma” and the specific “Classic Six Sigma” are sometimes confounded with each other.

No


DFSS Concept #3: Structured Use of Appropriate Tools• Project Management • Benchmarking – performance & process• Multi-Generation-Product-Plan (MGPP) • Quality Function Deployment (QFD) • Design Scorecards• Modeling & Simulation• Theory of Inventive Problem Solving (TRIZ)• Pugh matrix• Cost/Benefit Analysis • Failure Mode and Effects Analysis (FMEA)• Design for Manufacture / Assembly• Design of Experiments• Taguchi Robust Engineering Techniques• Statistical Analysis of Tolerances – Flowdown & Flowup• Reliability Testing and Analysis (e.g. HALT, Weibull)


Quality Function Deployment - QFD 1

Correlation

Technical Evaluation(from benchmark information)

Importance

CompetitiveComparison

(From benchmark & VOC)

Target(from benchmark &internal information)

Importance

CustomerRequirements

(from VOC)

Measures(From benchmark & VOC)

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Level Design Characteristic Units Data Type Target USL LSL Mean Std Dev ST/LT Cp/Pp Cpk/Ppk DPMU Sigma

Score Target Sigma

Product Flow rate l/sec variable 50 60 40 53 3 ST 1.11 0.778 9800 2.34 4

Sub-Assy Output Bore Diameter

mm variable 8 10 7 8.1 0.2 ST 2.5 1.833 0 5.51 6

Design Requirements Our Performance

Design Scorecard Format

The solution assumes data is normally distributed Current Sigma

Metric

How centered

is it ?

How variable is the critical parameter ?

Expected Defect Rate

List of Critical to Quality Requirements for the

product, subassemblies & components

Information that must be entered using current

performance data for the critical parameter

Performance expected of the critical parameter

These are the ‘Performance Indicators’ and show how well the critical requirements are being met. (Values automatically generated

by the spreadsheet.)


The Key Role of Statistics

•The ability to predict the quality of a system from its components is at the heart of the DFSS process and the basis of scorecards.•The sigma level is a meaningful measure of this prediction•Statistics underlie the prediction and control of variation•Product Reliability prediction is an essential measure of launch performance•Statistical tolerancing may provide benefits - versus ‘worst case’ tolerance stacks.•And many other analyses …

– Do you remember the Vision?Do you remember the Vision?


Quality Prediction: Sigma Flow-up

σ part1, σ part2, ...

Sigma (σ) system

Design Scorecards - Tool for:• Predicting product quality during design• Allocating resources to meet design requirements• Flowup from Manufacturing Capability

Design parameters are statistical, with mean values and

variabilities

Platform

Control Brake System

Automobile

Engine Chassis Fascia

Subsystems

Assemblies

Parts

Probability of failure to meet a system CTQ is due to design parameter variation at lower levels of the system hierarchy

and … can be predicted during the design process via the transfer functions (σ flow-up)


Robust Design: Taguchi Method

Initial Design

M

yStep-1Reduce Variability

M

y Step-2Adjust Slope

M

y

Ideal Functiony = M

M

y Reality

M

y

y0

Variability due to noises

•Model the Ideal input/output function of the design:

•Optimize in two steps– variation first, then adjust

performance:

•Continue with Tolerance Design

Example:

m= pedal force

Y= braking force at wheels.


DFSS Deployment• Initial focus is in the 3 major Engineering groups• The training is for specific project teams – i.e. “pull” training•Internal classes provide– An introduction to DFSS and the theory of IDOV– An understanding of IDOV and the related process tools– Specific tool training (currently under development)

• ‘OV’ is by an external consultancy during 2003• Tool training provided ‘just in time’ against a scheduled calendar• Courses are provided for specific tools, e.g:– QFD training – Taguchi Robustness Engineering Techniques


Method ToolsPrinciples

DFSS is …..

In Summary, DFSS ….• DFSS is three things:

• A set of 3 principles• A methodology (IDOV)• The timely use of

appropriate tools• It can be used in the design of

products, manufacturing processes, and services such as transactional processes.

• DFSS does NOT replace GDPIM but strengthens it• The IDOV methodology is scaleable and can be applied

at many levels• Typically used when:

• There is no existing product/process/service OR• Incremental improvement is not sufficient.

gb_dfss_v2_trwpres[1]

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