A simulation test for wear in injection moulding machines

Glass-filled polymers are known to produce considerable wear on the barrels and screws of injection moulding machines. A few model tests simulating the tribological conditions in the injection moulding machine have been developed for finding the appropriate coatings and treatments to combat the wear. However, in these tests the simulation of the conditions inside the barrel of an injection moulding machine is not complete and only some of important modes of wear are tested. In this study, a new wear tester has been developed to more closely simulate the conditions of wear which occur inside the barrel of an injection moulding machine. The concept of the tester is similar to that of the ASTM rubber wheel abrasion tester with some additions to ensure the requirements of closely simulating the conditions of wear. In this study, we have used the tester to assess the wear of untreated, chrome plated and nitrided steel by glass-filled nylon as a function of temperature and to analyse the wear mechanisms occurring. Under the studied test conditions, the best performance was achieved by nitrided steel. The wear rate of untreated steel and chrome-plated steel increases as the temperature rises but the wear rate of the nitrided steel is effectively constant.