Study and Optimization of Process Parameters in Plastic Injection Moulding
Injection moulding is one of the most popular polymer processing methods due to its high production rate as well as its ability to produce very intricate geometries at very cheaper cost and within few seconds. There are several flaws which occur while producing plastic parts by Injection moulding, like warpage, shrinkage, flash, sink marks etc. Shrinkage is one of the most critical problems which cause dimensional changes in the parts during the moulding process. Shrinkage can be minimized by setting optimal process parameters on injection moulding machine. In this study, determining the optimal process parameter is routinely performed in plastic injection moulding industry as it has a direct and dramatic influence on product quality and costs. Using the trial and error approach to determine the process parameters for injection moulding no longer good enough. Factor that affects the quality of a moulded part can be classified in to four categories: 1) Part design 2) Mould design 3) Machine performance 4) Processing conditions. The part and mould design are assumed as established and fixed. During production, quality characteristics may deviate due to drifting or shifting of processing conditions caused by machine wear, environmental changes or operator fatigue. This study aim to review the research of the practical use of Taguchi method in the optimization of processing parameters for injection moulding. The Taguchi robust parameter design has been widely used over the past decade to solve many signal response process parameter designs. The study on the Taguchi methods with various approaches including signal to noise ratio. Mould analysis based on two level fractional designs. Orthogonal arrays of Taguchi, the signal to noise ratio are utilized to find the optimal levels and the effect of process, parameters are determined by many researches on shrinkage and warpage. Different observations were taken for a material namely Polypropylene (PP). Taguchi method is used to investigate the effects of melting temperature, injection pressure, packing pressure and cooling time on the shrinkage of PP. Taguchi method has two main instruments, which are signal-to-noise (S/N) ratio and orthogonal arrays. S/N ratios were used for determining the optimum combinations of the process conditions for shrinkage. The S/N ratio takes both the average and the variability of the quality characteristics into consideration. The results showed that the minimum shrinkage for PP the melt temperature was the most effective factor for PP followed by injection pressure and packing pressure and cooling time was found to be the least effective factor.
Author Name: Y. P. Tidke, A.V. Dhote and Dr. C.R. Patil