Design and Fabrication of an Injection Moulding Machine

Abstract

Plastic waste remains an environmental menace around the world but more so in Sub-Saharan Africa. In Kenya, recycling of plastics has been adopted notably for making fencing posts, and this has been an object for job creation. However there is still a lot that needs to be done, bearing in mind that a lot of plastic waste still litters the environment. A table top Injection moulding machine was designed and fabricated to complement already existing efforts towards recycling. In addition to the sound environmental management option this provides, it is hoped that the machine could assist in job creation and more so at local individual levels where idle youths can find an economic activity to engage in. Tensile specimens made from Virgin High Density Polyethylene (HDPE) using the machine, were tested for Ultimate Tensile Strength (UTS) which was found to have a value of 13 MPa and Modulus of Elasticity (E) which was found to have a value of 0.9 GPa and the results are comparable to documented values which were 15 MPa and 0.8 GPa respectively. Recycled plastic was then added to the virgin plastic at various contents to obtain an optimum processing point for the machine. These samples at varying contents of recycled plastic were also subjected to tensile and three point bending test. The general observation was that addition of recycled plastic to the virgin plastic improved tensile and shear strength but declined the tensile modulus of elasticity. Addition of steel wires to the plastic at 60% recycled plastic content, improved tensile strength and modulus of elasticity. Compared to other studies, it was observed that the material obtained could be suited for low strength car bumpers. There is still room for further improvement work on this manually operated machine but results obtained so far are promising as the machine can be used to produce small plastic items such as pegs, complete toys or toy parts, beads and other small plastic items.