STUDY OF PROCESS PARAMETERS FOR INJECTION MOLDED POLYPROPYLENE END CAPS FOR GI PIPES

Polypropylene end caps are used to cover the threaded ends of pipes for avoiding the wear and tear of pipe threaded ends. The aim of the paper is to study process parameters of the injection molding process for producing the end caps. The main process parameters are mold temperature, melt temperature, injection temperature, injection pressure, injection time, packing pressure, packing time and cooling time. Moreover, the aim is also to vary the process parameters to reduce defects such as short shot etc. from pipe end caps during manufacturing. In this work, injection molding parameters for the minimum short shot were determined by the Taguchi method and the analysis of variance (ANOVA) methods. Four parameters viz. injection pressure, mold closing speed, screw speed and barrel temperature is taken into consideration at three different levels. According to the results, barrel temperature has the most and screw speed has the least significant effect on quality characteristic respectively. The prediction made by Taguchi parameter design technique is in good agreement with the confirmation results. Varying process parameters critically influences productivity, quality, and cost of production by reducing defects such as short shot etc.