Design, construction, and testing of a thermoplastic extruding machine

Abstract

This project presents the design, construction, and testing of a thermoplastic extruding machine intended for the recycling of waste plastic materials into useful products. The study was motivated by the need to provide a locally fabricated and relatively low-cost alternative for small-scale plastic recycling applications. The methodology involved a review of plastic recycling and extrusion processes, engineering design and analysis of the major machine components, selection of suitable construction materials, fabrication, assembly, and experimental testing of the completed machine. The extruder was engineered to possess a nominal processing capability of 20 kg/h and included a hopper, heated barrel, single power screw, electric motor, belt-drive mechanism, bearings, reduction gearing, and die. Locally available materials were used for the fabrication of the major components. During operation, crushed thermoplastic material was introduced through the hopper and conveyed by the rotating screw through the electrically heated barrel, where the material was intended to melt and pass through the die. Testing was conducted under no-load and loaded conditions. The machine was able to provide enough heat to melt the crushed plastic, but it was unable to extrude continuously through the chosen die. The main restrictions found during testing were improper die size and geometry, which limited the flow of the molten material, and insufficient temperature control, which caused the plastic to overheat. The machine cost ₦123,350 to fabricate, including labour, materials, and other expenses. While the test findings show that better temperature control and die redesign are required to accomplish dependable continuous extrusion and enhance the machine's operational efficiency, the study shows that it is feasible to fabricate a thermoplastic extrusion system locally