<![CDATA[ Polypropylene clothes hangers are widely produced by injection moulding, and volume variation is a common concern because it relates to product strength and durability. This study determines the parameter combination predicted to be optimal for hanger volume using the Taguchi design. Four parameters were examined at three levels: heating temperature (200, 250, 300 °C), cooling temperature (10, 15, 20 °C), injection time (10, 14, 18 s), and cooling time (15, 20, 25 s), in an L9(3⁴) orthogonal array with three replications (27 observations). Volume was calculated from product mass using a fixed density, so it is equivalent to a mass measurement. The signal to noise (S/N) ratio was computed from the deviation of volume from a target of 89.63 cm³ using the smaller-the-better criterion, so it measures closeness to the target rather than volume uniformity alone. In the S/N ANOVA (nine S/N values, factor B pooled into error), the contributions were heating temperature 54.33%, injection time 21.67%, and cooling time 10.44%. Only heating temperature was significant at α = 0.10 (p = 0.055); injection time (p = 0.119) and cooling time (p = 0.197) were not. A supplementary analysis of the 27 raw data showed heating temperature, injection time, and cooling time to be significant and cooling temperature not (p = 0.709). The combination of 300 °C, 15 °C, 10 s, and 15 s is a predicted optimum that has not been confirmed experimentally. Agreement between manual and Minitab results shows only computational consistency.]]>
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