Investigations and Optimization of Injection Molding Process of PVC Sole Investigations and Optimization of Injection Molding Process of PVC Sole

Abstract

This paper reports on an investigation and optimization of the injection molding process of PVC sole. It is aimed to provide optimum injection molding process of PVC sole thereby reduce product defects, particularly in Kangaroo shoe factory. To investigate the root cause of defects in the process and setting optimal values of responsible parameters. To achieve the above objective, three month data on defects were collected, characterized and quantified using questioner. The hybrid results of Pareto chart and Failure mode and effect analysis technique was used to investigate the frequency of defects and their effects for reasonable selections. Root cause analysis followed by 5-Why was used to identify the root causes of those defects to come up with responsible parameters. So, that the analysis had done between process, process and parameters, parameter and parameter, parameter and defects, and among defects logically and using principles. The overflow and underweight (incomplete) became targeted defects and melt temperature, injection speed, injection pressure and packing pressure were determined as the influencing parameters. The Taguchi method is used to design of experiment and optimize the process. The experimental investigation was conducted under varying input influential process parameters and optimization to reduce the most frequently occurring and chronic effects on the quality of PVC sole. The study reveals that the optimum values of melt temperature, injection speed, injection pressure and packing pressure were determined as, 160 oC, 10 cm/s, 0.4 bar and 0.4 bar, respectively. The level of significance of each parameter was determined by the help of analysis of variance, so that packing pressure contributes 65%, melt temperature 14.62 % and injection speed 14.68% while injection pressure is statistically not significant. Finally, the study recommended Kangaroo shoe factory to realize that the current of trial setting values is not effective and has forwarded optimal setting for influential parameters which is better than the existing operation condition.