Optimization of Multiple Quality Characteristics Using Desirability Function Advanced Tools of Quality Engineering

The desirability approach The method finds operating conditions X that provide the "most desirable" response values Xi - Quality characteristics Yi(x) - Response values for Xi di(Yi) - Desirability of response Yi(Xi) D – Overall desirability achieved

The desirability approach Nominal-the-best (NTB)

The desirability approach Smaller-the-better (STB)

The desirability approach Larger-the-better (LTB)

The desirability approach

Example The controllable factors : X1 - Hydrated silica level X2 - Silane coupling agent level X3 - sulfur level. The responses to be optimized : Y1 - PICO Abrasion index (120 < Y1 )LTB Y % modulus (1000 < Y2 ) LTB Y3 - Elongation at break (400 < Y3<600)NTB Y4 - Hardness (60 < Y4 < 75) NTB