What are the main failure modes of gear machining

Tooth surface damage: for the open transmission gear or the closed transmission gear with unclean grease, due to the relative drag between the meshing tooth surfaces, some hard abrasive particles enter the friction surface, which changes the tooth profile and increases the side clearance, resulting in excessive thinning of the transmission gear and tooth fracture. Under normal conditions, only when the lubricating grease is mixed with abrasive particles can the tooth surface abrasive particles be damaged in operation.

Tooth surface plywood: for transmission gears with high speed and light load, the temperature of the meshing area is too high due to the large sliding friction between the tooth surfaces and large normal acceleration. Once the lubrication standard is poor, the oil slick between the tooth surfaces will subside, which will make the stainless steel of the two transmission gears blunt and touch immediately, resulting in mutual bonding. When the two tooth surfaces have relative speed again, the hard tooth surface will tear off part of the raw materials on the too soft tooth surface along the drag direction to produce grooves.

Fatigue pitting corrosion: when the two transmission gears meshing with each other touch, the interaction force and recoil force between the tooth surfaces cause contact stress on the surface of the two working surfaces. Because the position of the meshing point is changed and the transmission gear does regular movement, the contact stress of gear processing is changed according to the pulsating cycle system. Under the effect of such alternating contact stress on the tooth surface for a long time, small cracks will appear at the knife lines of the tooth surface. With the change of time, such cracks will slowly expand horizontally on the surface. After the cracks produce a ring, the surface of the transmission gear will fall off slightly and produce some fatigue pits.