Wear of plastic spur gear made by injection molding

The purpose of this study was to investigate the characteristics including the amount and distribution of wear on the profile of the teeth on various combinations of injection molding plastic gears, The study was carried out using unfilled polyacetal, Nylon 66 and their glass fiber reinforced forms, glass fiber reinforced PPS and unfilled PEEK. The test results are summarized as follows: 1. When the engaged gears were manufactured from identical materials, the highest level of wear was recorded for the non-reinforced Nylon 66 gears, followed by the glass fiber 25% reinforced polyacetal gears. The lowest levels of wear were recorded for the unfilled PEEK and polyacetal mixed with silicon oil lubricant gears. 2. When combinations of gears manufactured from different materials were analyzed, the lowest level of wear was recorded for the combination of Acetal and either Nylon or PEEK gears, because the involute gear fitting conditions were close to constant. A low level of wear was recorded when Nylon gears were used due to the low adhesion conditions. 3. The worn gear-tooth profile had a significant influence on the product of the load on each instantaneous contact point and the sliding velocity of the contact point.