What are the types of tooth surface damage?

The failure of the gear mainly occurs on the tooth surface, and there are mainly the following five damage conditions.
1.Wear：
Insufficient lubricating oil, The oil is not clean, Tooth flanks had worn.
The wear makes the tooth thickness thinner and the tooth backlash increases, causing impact and in severe cases, the overload will be broken.

2.Plastic deformation：
Under overload, due to material yielding the tooth surface will have plastic flow,
mostly occurs on gears with low hardness.

3.Scuffing：
Also called scratches. Due to heat and load, the oil film will be destroyed due to the instantaneous high temperature, so that the raw metal tooth surfaces are in direct contact, causing the tooth surfaces to stick together.

4.Pitting：
Under long-term contact stress the tooth surface produces fatigue cracks, and the cracks continue to expand, causing small pieces of metal to peel off and form pits.
When the pitting is severe, vibration and abnormal sound will be generated.

5.Bending fatigue：
Also called tooth chipping, when the tooth surface is loaded, the largest bending stress at the root of the tooth, when the bending stress exceeds its ultimate stress, overload fracture or fatigue fracture occurs.