Material selection of large gear machining

Material selection of large gear machining

As we all know, the transmission and operation of machinery cannot be separated from the participation of gears, especially large mechanical equipment. When belt drive and chain drive cannot meet the transmission requirements of large mechanical equipment, large gear is the best choice for mechanical equipment with high accuracy requirements.

1. Requirements for materials

The quality and parameters of the gear are directly related to the normal operation of the equipment. Therefore, in the process of machining large gears, special attention should be paid to some details related to the overall quality of gears.

The most important point is the selection of materials. Today, we mainly discuss the material selection in large gear machining.

Unlike ordinary gears, large gears have large volume, large center distance and large torque. The materials suitable for ordinary gears are not necessarily suitable for large gears. What material can be selected for the big gear?

II. What materials can be used?

We know that gears have high requirements for hardness and fatigue resistance. Can carburized steel meet the material selection criteria for large gear machining? Generally, 20cr or 18crmnti can be used as raw material for carburizing gears, and sometimes nitriding can also be selected. After carburizing or nitriding, the hardness of the steel is greatly improved, and the Mohs hardness can reach HRC58~63. This carburized steel not only retains the characteristics of impact resistance, high toughness and wear resistance, but also improves the hardness. It can be used to process large gears to withstand impact load or high-speed operation.

However, the carburized steel will change the tooth shape after carburization, so it needs to be reshaped, and the cost is relatively high.

45 steel is the most common and commonly used gear material in this case, mainly used for processing ordinary cylindrical gears. So, can 45 steel be used as the material for machining large gears?

45 steel belongs to medium carbon structural steel. Due to its low carbon content, moderate material properties, low hardness and poor toughness. However, due to its good plasticity, it can be used to manufacture large gears with large tooth surface roughness, low load and low speed after quenching and tempering.

We just mentioned nitriding. If 38crmoAIA material is nitrided, the material with small deformation and high wear resistance can be obtained. This material can be used for machining high-speed large gears.

These are the main materials for machining large gears. If large gears are used for special purposes, they need to be processed with more complex materials.