Wear is the removal of surface material from gears. It can be slow, like a scratch, or quick, like a scratch. There are three types of wear:
Adhesion wear – caused by metal to metal contact, surface bonding together and tearing apart. This may be due to insufficient lubricating oil or improper gear engagement.
Abrasive wear – caused by external particles, such as dust and sand.
Corrosive wear – chemical attack on the gear surface caused by contaminated lubricating oil or additives.
An adherent type of wear that may be caused by insufficient lubricating oil or incorrect gear engagement.
The moderate wear of the gear tooth surface makes the working pitch line clear (arrow). This kind of wear is caused by abrasive in lubricating oil.
The gear is scratched because of the direct contact between metal and metal caused by insufficient lubricating oil under heavy pressure. The horizontal line on the worn surface is the pitch line (arrow).
In the early stage of cutting, there is a frost like pattern of spots on the upper part of gear. The damage is slight at this stage.
Severe cutting damage occurs above and below the pitch line. Usually, the damage will develop rapidly and the gear cannot be used
An abrasive wear.
A particularly serious wear, most of the gear teeth have been worn off due to the accumulation of abrasive particles in the lubricating oil.
Corrosive wear, caused by contaminants or additives in lubricating oil.
The gear surface shown is damaged by chemical action. This wear will continue until the gears are out of service. Chemical wear is caused by contaminated lubricating oil, a mixture of lubricating oil or additives.