The reasons for random fracture of gears
There are many reasons for random fracture of gear teeth, mainly including:

1) Random fracture is usually caused by tooth defects, pitting, peeling, or other stress concentration sources forming excessively high local stress concentrations at that location.
2) Under the action of alternating stress, defects such as inclusions and fine grinding cracks in the gear teeth continuously propagate, leading to random fracture of the gear teeth.
3) Excessive residual stress caused by improper heat treatment can also cause local fracture of the gear teeth.
4) Excessive load or inadequate tooth shaping can cause random fracture due to excessive meshing impact load.
5) The damage to the tooth surface caused by gear tooth misalignment can cause random fractures at the waist or root of the gear teeth.
6) Large foreign objects entering the meshing area can also cause local tooth breakage.