Application of the Taguchi method for consistent polymer melt production in injection moulding

The consistency of polymer melt production in the injection-moulding proces s has been studied using a Taguchi design-of-experiment method for acryloni trile butadiene styrene (ABS) and high-density polyethylene. Systematic exp erimentation with injection-moulding machine settings helped to establish b oth qualitative and quantitative process understanding in attempting to con trol the melt quality, assessed here by the shot weight variability. Optimu m machine settings were determined which gave the lowest variations in the shot weight. In the case of ABS, uncontrollable influences (noise factors; here the injection stroke and moisture content) were incorporated in the st udy in such a way that the optimum levels recommended by the analysis make the process (i.e, shot weight) insensitive to variations caused by the nois e factors. The set melt temperature and screw-back pressure were observed t o be the most influential control factors affecting the shot weight variabi lity for both polymers.