Performance of selective laser sintered polyamide spur gear under dry and lubricated conditions

Abstract

The durability of a selective laser sintered (SLS) polyamide gear was evaluated using an in-house gear test rig under dry and oil-lubricated conditions. The lubricated SLS gear exhibited inferior contact fatigue performance at lower torques than that under dry conditions. Cyclic contact stress coupled with sliding motion diffuses the lubricating oil into the porous subsurface and reduces the contact fatigue strength of the gear tooth. The failure of the SLS gear under dry conditions exhibited the polishing effect, thermal softening with surface cracks, and thermal bending at 1.8, 2.5, and 3.5 Nm, respectively, whereas failure of the SLS gear under the oil-lubricated condition was only pitting for all the considered conditions. The lubricated gear exhibited superior performance at a higher torque than the gears in the dry-running condition, owing to its improved thermal stability.