Design of experiments DOE Steps Define problem Define

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Design of experiments (DOE) Steps Define problem Define experimental objectives Select factors that influence

Design of experiments (DOE) Steps Define problem Define experimental objectives Select factors that influence quality Select control & noise factors Select levels for factors Select orthogonal arrays Select interactions Conduct tests Analyze results

Design of experiments (DOE) Breadmaking problem: Level Factor 1 2 1. flour 21/3 cups

Design of experiments (DOE) Breadmaking problem: Level Factor 1 2 1. flour 21/3 cups all-purpose 2. sugar 2 Tsp 21/2 Tsp 3. salt 1 tsp 1/2 4. butter 1 Tsp margarine 5. milk 1 cup homogenized 6. dry yeast 1 tsp brand A 21/3 cups special tsp 1 cup low-fat 1 tsp brand B

Design of experiments (DOE) How many loaves of bread to get "best" set of

Design of experiments (DOE) How many loaves of bread to get "best" set of ingredients? 6 factors, each w/ 2 levels ––> 26 = 64! Taguchi method (Genechi Taguchi) says only a few needed

Design of experiments (DOE) Testing methods Factors and factor levels Trial A B C

Design of experiments (DOE) Testing methods Factors and factor levels Trial A B C D 1. 1 1 2. 2 1 1 1 3. 1 2 1 1 4. 1 1 2 1 5. 1 1 1 2

Design of experiments (DOE) Testing methods Factors and factor levels Trial A B C

Design of experiments (DOE) Testing methods Factors and factor levels Trial A B C 1. 1 1 1 2 2 3. 2 1 2 4. 2 2 1 Better……. . "orthogonal" Standard L 4 orthogonal array

Design of experiments (DOE) Which OA to use? Depends on: # of factors &

Design of experiments (DOE) Which OA to use? Depends on: # of factors & interactions # of levels for each factor Use L 4, L 8(7 factors), L 12(11 factors), L 16(15 factors), …. . OAs - determined by # trials to be run # of levels usually 2 or 3

Design of experiments (DOE) Some factors may interact. Then: Factors and factor levels Trial

Design of experiments (DOE) Some factors may interact. Then: Factors and factor levels Trial A B C(=Ax. B) 1. 1 1 1 2 2 3. 2 1 2 4. 2 2 1