The wear resistance improvement of fibre reinforced polymer composite gears

Abstract

This paper presents experimental investigations into the wear performance of non-reinforced POM (Polyoxymethylene) and 28% GFR POM (glass fibre reinforced POM) gear pairs; polymer running against polymer is a little studied but important system. All the gears were manufactured locally by injection moulding. The injection mould design and manufacturing process are briefly described and progress in the control of injection moulding processes for polymer and fibre reinforced polymer gears is discussed. A specifically designed polymer composite gear test rig was used for this research. Performance differences for the POM and GFR POM gears are observed, notably their loading capacity and failure modes. Both POM and GFR POM gear pairs, showed a clear wear transition torque for a given running speed. Above the transition torque the wear rate accelerated rapidly causing thermal failure, while below the transition torque the gears had a very low specific wear rate. Significant performance enhancements were seen for the GFR POM gears, with an increase of around 50% in load carrying capacity when compared to the non-reinforced POM gears. The wear mechanisms are briefly discussed, noting that most data available for polymer gear design is not representative of these polymer against polymer pairings.