The motor shaft is a cylindrical object that passes through the middle of the motor bearing or the middle of the wheel or the middle of the gear, but a small part is also square. A shaft is a mechanical part that supports the rotating part and rotates with it to transmit motion, torque or bending moment. Generally, it is in the shape of a metal round rod, and each segment can have different diameters. The parts that perform rotary motion in the machine are mounted on the shaft.

Motor bearing is a kind of special bearing specially used in electric motor or motor. The bearing used in the motor is a part that supports the shaft, it can guide the rotation of the shaft, and it can also bear the parts idling on the shaft. The concept of bearing is very broad. There are four types of bearings commonly used in motors, namely rolling bearings, sliding bearings, spherical plain bearings and oil-impregnated bearings. Common motor bearings are rolling bearings, that is, bearings with rolling elements. Sliding bearings generally refer to bearings without rolling elements, that is, bearings for sliding motion, and some of them are Boundary Lubricants.

1. Carbon structural steels such as carbon steel 35, 45, and 50 are widely used because of their high comprehensive mechanical properties. Among them, 45 steel is more widely used. In order to improve its mechanical properties, it should be normalized or quenched and tempered. For unimportant or less stressed shafts, carbon structural steels such as Q235 and Q275 can be used.

2. Alloy steel Alloy steel has high mechanical properties, but is more expensive, and is mostly used for shafts with special requirements. For example, for high-speed shafts using sliding bearings, low-carbon alloy structural steels such as 20Cr and 20CrMnTi are commonly used. After carburizing and quenching, the wear resistance of the journal can be improved; the rotor shaft of the machine works under high temperature, high speed and heavy load conditions. For high temperature mechanical properties, alloy structural steels such as 40CrNi and 38CrMoAlA are often used.

For the shaft blank, forging is the priority, followed by steel; for larger size or complex structure, cast steel or ductile iron can be considered. For example, the use of ductile iron to manufacture crankshafts and camshafts has the advantages of low cost, good vibration absorption, low sensitivity to stress concentration, and good strength. The mechanical model of the shaft is a beam, and most of it rotates, so its stress is usually a symmetrical cycle. The possible failure modes are: fatigue fracture, overload fracture, excessive elastic deformation, etc. Some parts with hubs are usually installed on the shaft, so most of the shafts should be made as stepped shafts, with a large amount of machining.