(1) is divided from the microscopic point of view.

From the microscopic point of view, according to the different wear mechanisms, gear wear can be divided into four basic types: abrasive wear, adhesive wear, fatigue wear and corrosion wear. Abrasive wear is mainly caused by pear-shaped furrow and micro-cutting; Adhesion wear is closely related to surface molecular force and friction heat; Fatigue wear is the result of surface fatigue crack initiation and propagation under cyclic stress. Corrosion and wear are caused by the chemical action of environmental media. In the actual wear phenomenon, usually several forms of wear exist at the same time, and one kind of wear often induces other forms of wear. For example, the debris of gear fatigue wear moves between two meshing tooth surfaces, which is similar to grinding, which will cause abrasive wear on the contact tooth surfaces. The clean surface formed by abrasive wear may increase the adhesion of molecules, thus causing adhesive wear, and the molecules of gear materials may be corroded and worn due to oxidation or chemical changes with surrounding media. Fretting wear of gears is a typical compound wear. In the fretting wear process, there may be various wear forms such as adhesive wear, corrosive wear, abrasive wear and fatigue wear. With the change of working conditions, the priority of different wear forms is different.

(2) From a macro perspective.

From a macro point of view, according to different wear and tear phenomena, gear wear mainly includes: tooth surface wear, scratch, pitting, crack, peeling and gluing. Tooth surface wear is mainly caused by the relative sliding of two contact tooth surfaces; Wear is due to the pear-shaped groove, and the groove marks and abrasive particles appear on the friction tooth surface along the friction direction. Pitting is a phenomenon that pits are formed on the tooth surface due to metal fatigue damage under the repeated action of contact stress. Peeling is the phenomenon that the tooth surface becomes brittle due to deformation strengthening and falls off after microcracks are produced under load; Cracks are mainly the phenomenon of local rupture of materials caused by repeated action of alternating stress or excessive local stress. Bonding is a phenomenon that when the bonding point on the surface has high connection strength, shear failure occurs at a certain depth in the layer, resulting in serious wear of two tooth surfaces. Due to the combined action of various influencing factors in gear engineering, several wear phenomena may occur at the same time.

2. Measures to prevent wear failure during design:

There are many factors that affect the wear performance of gears. In order to avoid or reduce the wear damage of gears in use, attention should be paid to 1) material performance, 2) hardness, 3) surface roughness, 4) lubrication, 5) load and speed, 6) heat dissipation, 7) displacement design and 8) rotor system dynamics during design and use.

3. Other failure forms:

1) The gear teeth are broken from the root due to insufficient bending strength. The maximum radius of the root circle can be designed; The stiffness of the maximum shaft makes the load on the contact line uniform; Adopt heat treatment to make that wheel core have enough toughness; The tooth root surface is strengthened by shot peening and rolling.

2) Plastic deformation of tooth surface. When designing, we should improve the hardness of tooth surface and use lubricating oil with high viscosity or extreme pressure additives.