Effects of lubricant on the surface durability of an injection molded polyamide 66 spur gear paired with a steel gear

In this study, a lubricant was utilized to improve the performance of an injection molded PA66 gear, and evaluations were carried out using a power absorption test rig. The observation of scuffing on the test gear under lubricated conditions in the gear tooth between the start of active profile (SAP) and the lowest point of single tooth contact (LPSTC) confirmed the maximum predicted gear tooth temperature in this region. A lower film thickness between the SAP and LPSTC region compared to the pitch region also contributed to the scuffing failure. The failure morphology of the test revealed tooth subsurface cracking in the pitch region and scuffing in the flank region under dry and lubricated condition respectively.