On the use of three level orthogonal arrays in robust parameter design

Robust parameter design, originally proposed by Taguchi [System of Experimental Design, vols. 1 and 2, UNIPUB, New York, 1987], is an off-line production technique for reducing variation and improving product's quality by using the product arrays. However, the use of the product arrays results in an exorbitant number of runs. To overcome the drawbacks of the product array several scientists proposed the use of combined arrays, where the control and noise factors are combined in a single array. In this paper, we propose some three level orthogonal arrays that can be used as combined arrays.