Thermo-mechanical stability Criteria for Volumetric Shrinkage Variation Elimination in plastics

Abstract

Plastic formation processes are carried out using several techniques, such as injection molding and extrusion, in industries. However, these processes often suffer from volumetric shrinkage, which has led to defects and dimensional instability in the final products. In this work, a thermo-mechanical stability criterion for eliminating Volumetric Shrinkage Variation (VSV) in the plastic formation process is developed. It utilized the production of test specimens with differing shrinkage levels from an injection molding equipment for experimentation. MATLAB software simulation technique was chosen and Analysis of Systems (ANSYS) integrated Finite Element Method (FEM) for analysis were used to compare the volumetric shrinkage variation for multiple experimentation conditions. The VSV for each line of experiment was subject to the melting temperature, mold temperature, holding pressure, injection time and packing time. Results obtained gave R² value 0.0057 which depicts a not-good dependence of VSV on melting temperature. The mold temperature, however, had a strong effect on VSV with (R² = 0.937) in the molded plastic part and can be used to predict the variation. Weak correlation was also observed in injection time and holding pressure. The results clearly provide a design point at which production of the experimental plastic could yield a better output with minimal volumetric shrinkage variation of 0.78690.