Machine tool gears are divided into three categories according to working conditions: (1) light load gears. Rotational speed is generally not high, mostly made of 45 steel, by normalizing or regulating the quality of treatment. (2) gear. General use 45 steel manufacturing, normalizing or tempering after the high frequency surface hardening, to improve the bearing capacity and wear resistance of gears. For large-size gears, it is required to manufacture 40Cr and other alloy steel. Most of the gears in the drive system and feed system of the general machine tool belong to this category. (3) heavy-duty gears. For some working loads, especially the gears with high running speed and heavy impact load are mostly made of 20Cr and 20CrMnTi carburizing steel. After carburizing and quenching treatment. For example: Some important transmission gears in the gearbox.