Robust Design

Question 1

What are the three definitions of Robust design?

Answer 1

1. (Performance) Robust design creates performance characteristics that are very insensitive to variation in manufacturing process and enviro variation
2. (Economic) Robust design is the design of product or process that results in functionally acceptable products within economic tolerance.

’ ensuring satisfactory performance of a car for economically sensible tolerances’

3. (Variation) Robust design improves product quality by reducing by reducing the effect of variation

‘ensuring that a medical device has minimum variation in operation’

Question 2

What is the Taguchi methodology?

Answer 2

mathematical way of quantifying cost as a function of variation. Includes product costs and user costs during operation, manufacturing + quality costs requirements are also included

Question 3

What’s the equation for Taguchi’s method

Answer 3

L(Y) = K(Y-M)^2

L - loss due to y
M - performance target
K - loss parameter (Lc/Do^2)
Lc - average loss to customer
Do - customer tolerance limit

Question 4

What are the key issues with Taguchi’s approach?

Answer 4

1) Loss function not related to any physical relationship between a critical parameter and any quality aspect.
2) does not take into account cost of manufacturing depends on tolerances set
3) hard to determine the coefficient h (cost incurred when defect product is shipped to customer)