Premature and Extended Contact Behaviour of PA 6 and PA 6,6 Gears

Recently, plastic gears are given higher importance due to their reduced weight, cost-effectiveness, lower noise, and vibration. Among the plastic gears, polyamide (PA) gears are primarily used because of their ability to run under dry conditions. However, while running under such conditions, the lower stiffness of the polymer induces the load-carrying teeth to deform elastically during the engagement. As a result, an extension to the path of contact occurs, i.e. an initial contact at the beginning and a pro-longed contact at the end of the meshing cycle. This extended contact affects the load-sharing ratio, contact stress, and bending stress induced in the gear pair. Furthermore, the contact between the deformed tooth and the adjacent tooth gives rise to pitch line fractures (PLFs) and flank wear. In this work, simulations were done to study the defection behaviour of the common polymer gear materials, PA 6 and PA 6,6, under elastic loading conditions. The effect of the extended contact on the gear tooth’s bending and contact stress behaviour was also investigated.