Rao, P., Datar, N., and Kulkarni, S., "Migration Phenomenon in Gear Teeth of Hypoid Crown Wheels (Ring Gears) - Controlling and Eliminating the Same in Manufacturing," SAE Technical Paper 2016-28-0214, 2016, doi:10.4271/2016-28-0214.
The paper talks about the migration phenomenon that is observed in gears. The phenomenon discussed here is that observed on hypoid gears which due to their high spiral angles cause the issue to be more sensitive, but the analogy to other gears is applicable. Mahindra manufactures hypoid gear sets for its axles in-house that go on a wide range of its products; with performance benefits also come the stringent quality requirements for hypoid gear sets.Migration is the phenomenon that causes the furling or unfurling of individual gear teeth with respect to each other. This in effect causes the circular tooth spacing between two teeth to become non-uniform.This has a direct effect on the performance of the mated gear set. While irregularly spaced teeth directly affect the gear class, they also lead to direct rejection since this distorted mated gears set has high transmissibility error and hence gives out a wrong final ratio that has a profound effect on the overall efficiency of the axle and also on the fuel efficiency of the vehicle.