Material selection of machine tool shaft parts

The machine tool spindle is the most important shaft part in the machine tool. The working conditions of the spindle are different for different machine types. According to the size and type of the load on the spindle when it is working, it can be roughly divided into four categories: (1) Light-load spindle. The working load is small, the impact load is not large, and the wear of the shaft neck is not serious, such as the main shaft of a common lathe. This type of shaft is generally made of 45 steel, quenched and tempered or normalized, and high-frequency surface quenching is used to strengthen the parts that require wear resistance. (2) Medium load spindle. Medium load, severe wear, and certain impact load, such as milling machine spindle. Generally, it is made of alloy quenched and tempered steel, such as 40Cr steel. After quenching and tempering, the wear-resistant parts are required to be surface hardened. (3) Heavy-duty spindle. The work load is large, and the wear and impact are serious, such as the combined machine tool spindle with large work load. It is generally made of 20CrMnTi steel, which is carburized and quenched. (4) High-precision spindle. The work load of some machine tool spindles is not large, but the accuracy requirements are very high, and the deformation after heat treatment should be extremely small. Wear should be minimal during work, such as the spindle of a precision boring machine. Generally, it is made of 38CrMoAlA special nitrided steel. After quenching and tempering, it is subjected to nitriding and dimensional stabilization. In the past, almost all spindles were made of steel, and light-duty and medium-duty spindles have been made of ductile iron.