Do you know for a fact that all 5 factors have a significant effect on the process?
If not, start with a fractional factorial of the 5 factors at 2 levels. Keep the resolution of the design at IV or greater to identify main effects and 2-way interactions. This is called a screening design. It is used to reduce the number of factors to those that are significant.
Once the number of factors has been reduced, the next step is to run the modeling and optimization experiment. The best approach is to run a response surface design on the remaining factors.
Another possibility depending on your process is EVOP (Evolutionary Optimization of Process). This involves making small incremental changes and tweaking the process along the path of steepest ascent.
Once the number of factors has been reduced, the next step is to run the modeling and optimization experiment. The best approach is to run a response surface design on the remaining factors.
General Linear Model: Flow Coat Th versus Spin Level, Spray Level, ...
Factor Type Levels Values
Spin Level fixed 3 4, 9, 14
Spray Level fixed 3 3, 6, 10
Dwell Level fixed 3 10, 17, 24
Analysis of Variance for Flow Coat Thickness, using Adjusted SS for Tests
Source DF Seq SS Adj SS Adj MS F P
Spin Level 2 88.653 88.653 44.327 19.52 0.000
Spray Level 2 0.038 0.038 0.019 0.01 0.992
Dwell Level 2 13.887 13.887 6.944 3.06 0.075
Spin Level*Spray Level 4 20.147 20.147 5.037 2.22 0.113
Error 16 36.330 36.330 2.271
Total 26 159.055
S = 1.50686 R-Sq = 77.16% R-Sq(adj) = 62.88%
Unusual Observations for Flow Coat Thickness
Flow Coat
Obs Thickness Fit SE Fit Residual St Resid
1 4.7800 8.3307 0.9618 -3.5507 -3.06 R
24 12.1000 9.7274 0.9618 2.3726 2.05 R
R denotes an observation with a large standardized residual.
Response Surface Regression: Flow Coat Th versus Spin Level, Spray Level, ...
The analysis was done using uncoded units.
Estimated Regression Coefficients for Flow Coat Thickness
Term Coef SE Coef T P
Constant 20.9833 3.09852 6.772 0.000
Spin Level -2.2437 0.51575 -4.350 0.000
Spray Level -0.4193 0.24278 -1.727 0.100
Dwell Level -0.2919 0.12180 -2.397 0.026
Spin Level*Spin Level 0.0674 0.02440 2.760 0.012
Spin Level*Spray Level 0.0473 0.02457 1.925 0.069
Spin Level*Dwell Level 0.0196 0.01232 1.588 0.128
S = 1.49431 PRESS = 79.3696
R-Sq = 71.92% R-Sq(pred) = 50.10% R-Sq(adj) = 63.50%
Analysis of Variance for Flow Coat Thickness
Source DF Seq SS Adj SS Adj MS F P
Regression 6 114.396 114.396 19.0660 8.54 0.000
Linear 3 83.475 44.818 14.9394 6.69 0.003
Spin Level 1 71.640 42.259 42.2591 18.93 0.000
Spray Level 1 0.009 6.662 6.6617 2.98 0.100
Dwell Level 1 11.826 12.828 12.8277 5.74 0.026
Square 1 17.013 17.013 17.0129 7.62 0.012
Spin Level*Spin Level 1 17.013 17.013 17.0129 7.62 0.012
Interaction 2 13.908 13.908 6.9539 3.11 0.066
Spin Level*Spray Level 1 8.277 8.277 8.2770 3.71 0.069
Spin Level*Dwell Level 1 5.631 5.631 5.6307 2.52 0.128
Residual Error 20 44.659 44.659 2.2330
Total 26 159.055
Unusual Observations for Flow Coat Thickness
Flow Coat
Obs StdOrder Thickness Fit SE Fit Residual St Resid
1 1 4.780 7.268 0.915 -2.488 -2.11 R
24 24 12.100 8.764 0.726 3.336 2.55 R
R denotes an observation with a large standardized residual.