What are the design parameters of a motor shaft?
Author:
Release Time:
2025-08-19
Motor The shaft is a cylindrical component extending from the motor and its housing. It is the main support and connection component of the armature part of the motor, and also the output component of the power generated by the motor. The purpose of the shaft is to convert the energy of the motor into its final use. Precision pins and motor shafts are used to provide the motor's speed and torque and are essential components of the motor.
An unreasonable motor shaft design can lead to insufficient shaft radius and stress concentration caused by changes in the installation position, which may cause the shaft to fail catastrophically after a short service life. Therefore, the shaft must meet certain technical requirements.
Strength and stiffness
When the motor is running, the form of mechanical force and torque borne by the shaft varies depending on the type of motor and transmission mechanism. The main forces include: the gravity of the rotor assembly itself, the unidirectional magnetic pulling force caused by rotor eccentricity, the centrifugal force of unbalanced weight, and the load torque applied to the shaft by the transmission mechanism at the shaft extension end. Therefore, the motor shaft must first have sufficient strength to ensure that the shaft does not produce residual deformation or damage during operation and processing. At the same time, the motor shaft must have sufficient rigidity so that the shaft's deflection is within the allowable range during operation. The level of the shaft's critical speed should also be considered, and there should be a sufficient difference between the shaft's operating speed and critical speed to prevent resonance, especially for motors with higher speeds. If necessary, the critical speed should be verified.
Surface roughness
Surface roughness is a very important surface quality control parameter. In the case of sliding bearings, excessive surface roughness will directly destroy the contact surface oil film, thereby increasing bearing wear, but excessively low surface roughness will cause friction between molecules between the shaft and the bearing, which is equally harmful.
Straightness (T.I.R.)
If the straightness of the overall shaft body does not meet the requirements, it will cause imbalance in the shaft core section, causing the motor to vibrate. In the bearing section, it will cause the contact surface between the shaft and the bearing to tilt, resulting in substandard motors with low speed and high current. In the shaft extension section, it will cause the connecting parts to vibrate and generate noise. In short, the straightness of the shaft is a necessary condition for the normal operation of the motor. In special environments, the material of the shaft is required to have a certain degree of corrosion resistance.
In the manufacturing process of the shaft, it is necessary to control the straightness of the shaft to reach certain requirements. This requirement comes from two aspects: one is the transmission accuracy requirements of the application device; the other is the requirements of the motor's own normal operation. The transmission accuracy requirements of the application device come from the user based on the accuracy of its application device, and the requirements of the motor's own normal operation are the result of comprehensive consideration based on the matching clearance between the motor's shaft and bearing, the motor's vibration, the motor's noise, and the motor's performance requirements.
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