Reducing Sink Mark Defect of Cup Plastic Injection by Biodegradable Material with an Injection Rate
DOI:
https://doi.org/10.14456/rmutlengj.2025.4Keywords:
Plastic injection molding, Shrinkage, Biodegradable, Injection parametersAbstract
In this research, the issue of shrinkage in coffee cup sleeves filled with biodegradable plastic materials is investigated. Polylactic acid (PLA) and coffee grounds are two combined materials that are difficult to form by injection molding. The quality of the coffee cup sleeves declined as their surface was reduced. This study aims to investigate the effects of varying plastic injection molding parameters, including clamping force, injection pressure, injection rate, and cooling time, on shrinkage in the molded parts. The goal is to determine the optimal conditions for reducing shrinkage in the molded parts. The experimental results indicate that adjusting the injection speed rate to 40 cm³/s and the injection pressure to 54 bar significantly reduces shrinkage in the molded parts, thereby markedly improving the surface quality of the product. The results provided an important guideline for the development of injection molding technology employing bioplastic materials with higher viscosity than generally synthetic plastics. Other bioplastic goods can be produced using this method with favorable outcomes.
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