Analytical and Experimental Investigation to Resolve Surface Related Fatigue Failure in Helical Gears

Abstract

With the improvement of metallurgical process and tools it became possible to modify the material property of the steel to a desired possible level where its torque transmission capability can be enhanced. Case hardening and surface grinding is one such method which is used to leverage the surface durability and core strength of gears. With the enhancement in the torque transmission capability the load per unit area of face width also increased causing huge surface pressure. They are subjected to various conditions of load, speed, temperature, and ambient conditions. Micropitting is one such surface related failure which starts on tooth flank in terms of surface texture change. This may further grow in magnitude and result in catastrophic failure. This research work is performed to compare the results of analytical and experimental investigation for the possible micropitting initiative zone. Analytical approach is carried out by using the KISSsys model and the experimental work is carried out by using a dynamometer test rig to apply the load on the gearbox shaft for a defined load cycle. It was clearly visible that the micropitting has initiated below the pitch line of pinion. Tooth profile is later modified with lead and crown modification. After the application of this modification the tooth profile related failure was not visible for similar load testing cycle.