Transcript Why Taguchi Method?

Why/When is Taguchi Method
Appropriate?
Tip #1
Taguchi’s Signal-to-Noise Ratios are in Log form
Friday, 6 April 2001
Earlier Tip
Taguchi’s Signal-to-Noise Ratios are in Log form
Friday, 6 April 2001
Friday, 6-April-2001
Taguchi’s Signal-to-Noise Ratios are in Log form
• very important reason
– Taking “logarithm” improves ‘additivity’. Why?
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Most functions in ‘nature’ follow the power-laws
Y = A exp (-Ea/kT) (EXPONENTIAL)
Y = B Ax . . . . ( a – RAISED – POWER X)
Y = B Xa . . . . ( X – RAISED – POWER a)
– On taking logarithm  these become ‘additive’
• For example  Log10 ( B Xa . exp(-Ea/kT) )
= Log10(B) + a. Log10 (X) + (-Ea/kT) . Log10 (e)
• These are ‘additive’ for variables (Log10 X) and (1/T)
Friday, 6-April-2001
Taguchi’s Signal-to-Noise Ratios are in Log form
• Let us say we are trying reduce ‘defects’ in a process using L9 array
• The prediction will be, say,
– 7 defects +- a few defects
– The prediction error may be high due to errors in individual 9 experiments. Say
it is +- 9
– 7 defects +-9  -2 to 17 defects
???????(-2 is problem)
• Taguchi’s SN-Ratio for smaller-the-better

–  = -10 Log10 ( 1/n
Yi2 )
– Its range is – infinity to +infinity
(-/10)
2
– Extreme values are = +infinity  defects = 0
[average Y = 10
]
–
= - infinity  defects = infinity
– Always predicts defects between allowed range of 0 to infinity
More Tips
16.
Taguchi Method
r n
e
1st Priority : Va ia ce R duction
2nd Priority : Factor Effects
15.
“inner” L9 array with
“outer” L4 and L9 NoIsE arrays
14.
Taguchi Method
“inner” L18 array with
“outer” L4 and L9 NoIsE arrays
13.
Links below
Friday, 3rd Aug 2001
Friday, 27th July 2001
Friday, 20th July 2001
Taguchi Method
Why/When is Taguchi Method not Appropriate?
Friday, 13th July 2001
Tips 12, 11, 10 
More Tips
12. Taguchi Method
Links below
Friday, 6th July 2001
“inner” L8 array with
“outer” L4 and L9 NoIsE arrays
11. Taguchi Method
Friday, 29th June 2001
Useful at ALL Life-stages of a Process or
Product
10. Taguchi Method
Friday, 22nd June 2001
Performs Process “centering” or “fine tuning”
Tips 9, 8, 7 
More Tips
9. Taguchi Method
Links below
Friday, 15th June 2001
Identifies the “right” NoIsE factor(s)
for Tolerance Design
8.
Taguchi Method
Friday, 8th June 2001
Finds best settings to optimize
TWO quality characteristics Simultaneously
7.
Taguchi Method
Friday, 1st June 2001
When to select a ‘Larger’ OA to perform
“Factorial Experiments”
Tips 6, 5, 4 
More Tips
6. Taguchi Method
Links below
Friday, 25th May 2001
Using Orthogonal Arrays for Generating
Balanced Combinations of NoIsE Factors
5.
Taguchi Method
Friday, 18th May 2001
Signal-to-Noise Ratio for Quality
Characteristics
approaching IDEAL value
4. Taguchi Method
Friday, 11th May 2001
improves " quality “ at all the life stages
at the design stage itself
Tips 3, 2, 1 
More Tips
Links below
3. Taguchi Method
Appropriate for Concurrent Engineering
Friday, 4th May 2001
2.
Friday, 27th April 2001
Taguchi Method can study Interaction
between Noise Factors and Control
Factors
1.
Taguchi’s Signal-to-Noise Ratios are in
Log form
Friday, 6th April 2001
end