Will Heating Motor Bearings Cause Magnetization

Will Heating Motor Bearings Cause Magnetization

Large-size motor bearings, most of the hot set process for assembly, that is, the bearings will be heated to use the principle of thermal expansion and contraction of metals to complete the assembly of the interference fit with the shaft, which can ensure that the fit surface is not damaged.

There are many ways to heat the bearings, some use oven heating, some use oil heating, some use induction furnace heating, and some use bearing heater heating. Different heating methods have different heating effects, among them, the degree of heating uniformity, heating speed, as well as the contamination of bearings are more concerned about the problem. In the actual application, bearing heater in the industrial application is more widely used, most of the motor manufacturers use this way of heating.

Bearing heater, the use of metal in the alternating magnetic field generated by the eddy current and its own heat, the principle is to have to use a thicker metal in the alternating magnetic field, due to the phenomenon of electromagnetic induction and generate current, thicker metal generates current, the current will be in the metal to form a spiral flow route, the flow of the current and the heat generated by the metal itself is absorbed, the metal will be rapidly warmed up.

In the case of bearing heaters, the bearing is equivalent to a short-circuited, single-turn secondary coil, which passes a high current at a low AC voltage, thus generating a large amount of heat. However, because this heating method induces an electric current, the bearing is magnetized, making it easy for the bearing to attract metal debris during mounting operations. In order to prevent the bearing residual magnetism on the bearing operation, most bearing heaters are equipped with automatic demagnetization program, automatic demagnetization is automatically completed after the heating operation.

When heating, the heating temperature must be effectively controlled to prevent bearing failure; in the technical conditions of the motor products, the maximum temperature of the bearings will be stipulated, on the one hand, for the performance of the lubricant to ensure that the requirements of a more important aspect is the performance of the bearing material protection. In the dismantling process of the faulty motor, from time to time will be found in the motor shaft with magnetic cases, the problem directly reflects the motor running process or fault process caused by the magnetization of the problem should be analyzed at a deeper level.