Community Waste Plastic Recycling System Through Plastic Injection Molding

摘要

High demand for plastic worldwide has resulted in increasing environmental pollution. To make the plastic manufacturing process more environmentally friendly, recycling of waste plastic must be considered. In view of this a social enterprise called Me.reka Makerspace aims to use waste plastic to produce recycled plastic products using injection molding. However, injection molding is a complex process. In the past Me.reka experienced numerous failures resulting in defective plastic products and cost wastage. To assist with Me.reka’s objective, this study aimed to recommend a process capable of producing good quality recycled plastic products that meet dimensional accuracy and surface roughness requirements. Literature review done on plastic waste separation techniques, plastic properties testing for injection molding, and ventilation systems. Manual plastic sorting was found to be the best for Me.reka, where it can separate all 7 types of plastics collected by Me.reka with the highest accuracy and efficiency and the lowest cost. The melt flow rate of specific plastic type can determine its compatibility for use in the injection molding machine. Furthermore this study found that the best ventilation system for Me.reka Makerspace’s plastic injection molding facility was the displacement ventilation. It is expected that with the installation of an efficient ventilation system, the hazardous gasses produced during the process will be efficiently expelled thus protecting the health of workers. With regards to injection molding, a mold design was made for a book cover mold by applying the applicable mold design principles. However, this mold was later sent for testing at another facility. A flowerpot mold that had arrived at Me.reka which required immediate testing was tested instead. Through testing, improvements were made to the mold and the molding process by finding out the optimum injection molding temperature for the waste plastic used and the mold sprue diameter required to produce a well formed molding.