The gear drive transmits the motion and the power between any two axes of space through the meshing of the teeth, and can change the form and speed of motion. Gear transmission wide range of use, the ratio of constant, high efficiency, long service life. In the process of the design and manufacture of the mechanical parts, we should not only consider the performance of the material can adapt to the working conditions of the parts, make the parts durable, but also require the material to have better processing performance and economy, in order to improve the productivity of the parts, reduce the cost and reduce the consumption. If the gear material is not chosen properly, the premature damage of the parts will occur, even failure. Therefore, we should treat the gear selection carefully.

First of all, the mechanical properties of the material are satisfied: the mechanical properties of the material include strength, hardness, plasticity and toughness, etc., which reflect the characteristics of the material during its use. The gear has contact stress in contact with the tooth surface, and the tooth root has the maximum bending stress, which may cause the tooth surface or the tooth body strength to fail. The tooth surface each point has the relative sliding, will produce the attrition. The main failure forms of gears are tooth pitting, tooth surface gluing, tooth surface plastic deformation and tooth breakage. Therefore, the gear material has high bending fatigue strength and contact fatigue strength, the tooth surface should have enough hardness and wear resistance, the core must have certain strength and toughness.

Second, to meet the material's technological performance: the material's process performance is the material itself can adapt to a variety of processing technology requirements. The manufacture of gears should be processed by forging, cutting and heat treatment, so the process performance of material should be paid attention to when selecting materials.

The economic requirements of the third material: the so-called economy refers to the minimum cost to achieve the greatest economic benefits. To meet the performance of the premise, the selection of gear materials should also pay attention to minimizing the total cost of parts.

To sum up, we should start from the actual selection of gear materials, the overall consideration of mechanical properties, process performance and economic aspects of the problem, only reasonable selection can ensure the quality of gears, reduce product costs, thereby improving market competitiveness.