Paper 23: Thermoplastic Gears

Abstract

Over the past decade there has been considerable progress in the use of thermoplastic materials for gears. This has stemmed from the introduction of new polymers, the up-grading of established plastics by the introduction of fillers such as glass fibres, experience over a wide range of applications, and improved production techniques. The technique of injection moulding is outlined and details are given of making prototype gears using simple and quickly made cavities. Work is in progress to improve the accuracy of existing tooth forms and new tooth shapes are being evaluated. Long-term testing is yielding data on creep and fatigue characteristics which are vital factors in the life of thermoplastic gears. Some of these data are presented in graphical form.