The drawn cups were sectioned at th

The drawn cups were sectioned at the middle and the thickness was measured at seventeen points at uniform intervals from the centre of the cup to the edge of the flange, as shown in Fig.3.The measured thickness values are shown in Table5. The percent contribution measures proposed by TAGUCHI were used for the interpretation of experimental results[17, 20]. The percent contribution values reflect the relative portion of the total variation observed in an experiment which is attributed to each factor. It is a function of the sums-of-squares, for each factor, indicating its relative power to reduce the response variation. In other words, the percent contribution of a given factor indicates the potential reduction in the total variation that can be achieved, if this factor is controlled precisely[15]. The level average and the percent contribution of each parameter were calculated as described below[21].