TAGUCHI’S QUALITY ENGINEERING & ANALYSIS

Presentation Given By

Vishal Sachdeva

3611758

Submitted ToEr.Rahul SinglaA.P DME

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What were Taguchi’s views about quality??

•Taguchi defines Quality Level of aproduct as the Total Loss incurred bysociety due to failure of a product toperform as desired when it deviatesfrom the delivered target performancelevels.

•This includes costs associated withpoor performance, operating costs(which changes as a product ages) andany added expenses due to harmfulside effects of the product in use

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DThe Loss Function

Considering the Loss Function,

it is quantifiable

Larger is Better:

Smaller is Better:

Nominal is Best:

21( )L y k

y

2( )L y ky

2

( )

:

m is the target of the

process specification

L y k y m

where

02

0

0

0

is cost of repair or replace

a product and must include

loss due to unavailability

during repair

is the functional limit on

y of a product where it would

fail to perform its function

half the

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time

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SConsidering The Cost Of Loss (K)

k in the L(y) equation is found from:

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Nominal Is Best

We can define a processes average loss as:

s is process (product) Standard Deviation

y(with bar) is process (product) mean

2

2L k s y m

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•A0 is $2 (a very low number of this type!) found by

estimating that the loss is 10% of the $20 product cost

when a part is exactly 8.55 or 8.45 units

•Process specification is: 8.5+.05 units

•Historically: ybar = 8.492 and s = 0.016

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•Average Loss:

•If we make 250,000 units a year

•Annual Loss is $64,000

2 2

22 0.016 8.492 8.500

.05

800 .00032 $0.256

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Shift the Mean to nominal

Reduce variation (s = 0.01)

Fix Both!

22800 .016 0 $0.2048

Annual Loss is $51200 about 20% reduction

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22800 .010 .008 $0.1312

Annual Loss is $32800 about 50% reduction

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22800 .010 0 $0.08

Annual Loss is $20000 about 66% reduction

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Benefits To Companies

•Help companies to perform the Quality Fix!

Quality problems are due to Noises in the product or process system

Noise is any undesirable effect that increases variability

•Conduct extensive Problem Analyses

•Employ Inter-disciplinary Teams

•Perform Designed Experimental Analyses

•Evaluate Experiments using ANOVA and Signal-to noise techniques.

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Defining The Taguchi Approach

•The Point Then Is To Produce Processes

Or Products The Are ROBUST AGAINST

NOISES• Don’t spend the money to eliminate all noise,

build designs (product and process) that can

perform as desired – low variability – in the

presence of noise!

Here:

ROBUSTNESS = HIGH QUALITY

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Defining The Taguchi Approach

Noise Factors Cause Functional Variation

They Fall Into Three “Classes”

1. Outer Noise – Environmental Conditions

2. Inner Noise – Lifetime Deterioration

3. Between Product Noise – Piece To Piece Variation

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Defining the Taguchi Approach

•TO RELIABLY MEET OUR DESIGN GOALS

MEANS: DESIGNING QUALITY IN!

•We find that Taguchi considered THREE

LEVELS OF DESIGN:

level 1: SYSTEM DESIGN

level 2: PARAMETER DESIGN

level 3: TOLERANCE DESIGN

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SYSTEM DESIGN

•All About Innovation – New Ideas,

Techniques, Philosophies

•Application Of Science And

Engineering Knowledge

•Includes Selection Of:

Materials

Processes

Tentative Parameter Values

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Parameter Design

•Tests For Levels Of Parameter Values

•Selects "Best Levels" For Operating Parameters to be Least Sensitive to Noises

•Develops Processes Or Products That Are Robust

•A Key Step To Increasing Quality Without Increased Cost

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Tolerance Design

•A "Last Resort" Improvement Step

•Identifies Parameters Having the greatest Influence

On Output Variation

•Tightens Tolerances On These Parameters

•Typically Means Increases In Cost

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Taguchi methods summary

•Taguchi methods (TM) are product or process improvement

techniques that use DOE methods for improvements

•A set of cookbook designs are available – and they can be

modified to build a rich set of studies (beyond what we have

seen in MP labs!)

•TM requires a commitment to complete studies and the

discipline to continue in the face of setbacks (as do all quality

improvement methods!)

Thank You