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Why/When is Taguchi Method Appropriate?

Why/When is Taguchi Method Appropriate?. A new tip Every Friday. Friday, 8 th June 2001. Tip #8. Taguchi Method Finds best settings to optimize TWO quality characteristics Simultaneously (next 7 slides). Friday, 8 th June 2001.

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Why/When is Taguchi Method Appropriate?

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  1. Why/When is Taguchi Method Appropriate? A new tip Every Friday Friday, 8th June 2001

  2. Tip #8 Taguchi Method Finds best settings to optimizeTWO quality characteristics Simultaneously(next 7 slides) Friday, 8th June 2001

  3. Taguchi Method :Finds best settings to optimize TWO quality characteristics Simultaneously • A process has “several” quality characteristics • Desirable Qualities e.g. Larger-the-Better (strength, throughput etc) or Nominal-the-Best (specified dimensions, uniformity) • Undesirable properties e.g. Smaller-the-better (defects, resources - material/time, cost) • Objective of Taguchi Method is to determine the best settings of Control Factors such that • Desirable qualities are enhanced .and. • Undesirable properties are minimized/eliminated • Process becomes ROBUST i.e. insensitive toNoIsE

  4. Taguchi Method :Finds best settings to optimize TWO quality characteristics Simultaneously • Taguchi Method is most effective when there is at least one quality characteristic that is sensitive to variations or NoIsE • Desirable Qualities e.g. “Nominal-the-Best” type are sensitive to NoIsE S/N Ratio  = 10 Log10 ( mean2/ Variance ) • Undesirable properties e.g. “Smaller-the-better ” type are also sensitive to NoIsE S/N Ratio  = – 10 Log10 ( 1/n  Yi2 )  – 10 Log10 (Variance) . . . if ideal value = zero

  5. Taguchi Method :Finds best settings to optimize TWO quality characteristics Simultaneously • Let us use the “quality Loss” function for quality characteristics • Desirable Qualities e.g. “Nominal-the-Best” Quality Loss, Qa = (Variance / mean2 ) = ( 2 /2 ) e.g. “Larger-the-Better” Quality Loss, Qa = [ 1/n  (1/Yi2 ) ] • Undesirable properties e.g. “Smaller-the-better ” Quality Loss, Qa = [ 1/n  Yi2]

  6. Taguchi Method :Finds best settings to optimize TWO quality characteristics Simultaneously • We can “minimize” the “Total quality Loss” function for TWO or more quality characteristics • Total Quality Loss, Qa,total = Qa,1 + Qa,2 + . . . • To obtain SN Ratio, take the Log-form of the “Total quality Loss” function SN Ratio = -10 Log [Qa,total ] = -10 Log [ Qa,1 + Qa,2 + Qa,3 + . . .]

  7. Taguchi Method :Finds best settings to optimize TWO quality characteristics Simultaneously • We can “add” the “quality Loss” functions for TWO quality characteristics, as given below • Desirable Qualities e.g. TWO quality characteristics of “Nominal-the-Best” type Combined Quality Loss, Qa = ( 12 /12 ) + ( 22/ 22 ) • Desirable Qualities e.g. TWO quality characteristics of “Larger-the-Better” type Combined Quality Loss, Qa = [1/m (1/Y1j )2] + [1/n (1/Y2j )2] • Undesirable properties e.g.TWOquality characteristics of “smaller-the-better” type Combined Quality Loss, Qa = [1/m (Y1j )2] + [1/n (Y2j )2]

  8. Taguchi Method :Finds best settings to optimize TWO quality characteristics Simultaneously • Example : Computer Benchmarking • Time required for obtaining the time and date  T1 • Time required for opening and closing a file  T2 • Desired quality characteristics : time T1 andT2 both  “smaller-the-better” • Total Quality Loss, Qa,total= [1/m (T1j )2] + [1/n (T2j )2] • To obtain SN Ratio, take the Log-form of the “Total quality Loss” • SN Ratio = -10 Log [ {1/m (T1j )2} + {1/n (T2j )2} ]

  9. Taguchi Method :Finds best settings to optimize TWO quality characteristics Simultaneously • Example : Telecom Connectivity • Calls connected per hour on X’Mas day  C1 • Calls connected per hour on Monday morning  C2 • Desired quality characteristics : calls C1andC2 both  “Larger-the-Better” • Total Quality Loss, Qa,total= [1/m (1/C1j )2] + [1/n (1/C2j )2] • To obtain SN Ratio, take the Log-form of the “Total quality Loss” • SN Ratio = -10 Log [ {1/m (1/C1j )2} + {1/n (1/C2j )2} ] Friday, 8th June 2001

  10. 7. Taguchi Method When to select a ‘Larger’ OA to perform “Factorial Experiments” Taguchi MethodUsing Orthogonal Arrays for Generating Balanced Combinations of NoIsE Factors 5. Taguchi MethodSignal-to-Noise Ratio for Quality Characteristicsapproaching IDEAL value Friday, 1st June 2001 Friday, 25th May 2001 Friday, 18th May 2001 Earlier Tips Links below Tips 4,3,2,1 

  11. 4. Taguchi Methodimproves " quality “ at all the life stages atthe design stage itself 3. Taguchi MethodAppropriate forConcurrent Engineering 2. Taguchi Methodcan studyInteraction between Noise Factors and Control Factors 1. Taguchi’sSignal-to-Noise Ratiosare inLog form Friday, 11th May 2001 Friday, 4th May 2001 Friday, 27th April 2001 Friday, 6th April 2001 Earlier Tips Links below

  12. Taguchi Method 1st Priority : Variance Reduction2nd Priority : Factor Effects 15.“inner” L9 array with “outer” L4 and L9 NoIsE arrays Taguchi Method “inner” L18 array with “outer” L4 and L9 NoIsE arrays Taguchi Method Why/When is TaguchiMethod not Appropriate? Friday, 3rd Aug 2001 Friday, 27th July 2001 Friday, 20th July 2001 Friday, 13th July 2001 More Tips Links below Tips 12, 11, 10 

  13. Taguchi Method “inner” L8 array with “outer” L4 and L9 NoIsE arrays Taguchi Method Useful at ALL Life-stages of a Process or Product Taguchi Method Performs Process “centering” or “fine tuning” Friday, 6th July 2001 Friday, 29th June 2001 Friday, 22nd June 2001 More Tips Links below Tips 9, 8, 7 

  14. Taguchi Method Identifies the “right”NoIsEfactor(s) for Tolerance Design Taguchi Method Finds best settings to optimizeTWO quality characteristics Simultaneously 7. Taguchi Method When to select a ‘Larger’ OA to perform “Factorial Experiments” Friday, 15th June 2001 Friday, 8th June 2001 Friday, 1st June 2001 More Tips Links below Tips 6, 5, 4 

  15. Taguchi MethodUsing Orthogonal Arrays for Generating Balanced Combinations of NoIsE Factors Taguchi MethodSignal-to-Noise Ratio for Quality Characteristicsapproaching IDEAL value 4. Taguchi Methodimproves " quality “ at all the life stages atthe design stage itself Friday, 25th May 2001 Friday, 18th May 2001 Friday, 11th May 2001 More Tips Links below Tips 3, 2, 1 

  16. 3. Taguchi MethodAppropriate forConcurrent Engineering 2. Taguchi Methodcan studyInteraction between Noise Factors and Control Factors 1. Taguchi’sSignal-to-Noise Ratiosare inLog form Friday, 4th May 2001 Friday, 27th April 2001 Friday, 6th April 2001 More Tips Links below

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