Reasons for the motor reporting axis issues

Motor shaft seizure? Is it a rolling bearing or a sliding bearing? There are basically several reasons: 1. Insufficient lubrication; 2. Overloading; 3. Defects in the bearings themselves; 4. Wear or defects at the shaft journals; 5. Vibration caused by loose footings, leading to bearing damage and shaft binding; 6. Poor alignment with the rotating equipment, resulting in deformation of the bearings or shaft. All of the above reasons can potentially lead to it

The most likely causes of the bearing alarm are the entry of foreign objects into the bearing or a lack of oil in the bearing housing

Motor shaft seizure occurs when the bearing heats up rapidly due to internal or external factors during operation, causing the inner ring of the bearing to stick to the rotor shaft; in severe cases, this can destroy the motor. There are many causes of motor shaft seizure accidents, which can be mainly divided into internal and external causes. The internal causes of the motor include: poor quality of bearings ； The quality of the grease is poor ； The amount of grease added is inappropriate ； Improper maintenance procedures ； Vibration exceeds the limit when the motor is running ； There is shaft voltage on the rotor. The main external causes for motors include: installing non-outdoor-type motors in outdoor areas or washing the motors with water ； The motor mounting foundation is not solid ； The ambient temperature around the motor is too high. The aforementioned motor shaft-seizing incidents were mainly caused by internal issues with the motors. Fault mechanism analysis: (1) There is an interference fit between the inner ring of the motor bearing and the rotor shaft, with no relative movement between the two contact surfaces. However, after the motor drives a load, slight relative motion is likely to occur. The contact pressure at the interface causes plastic deformation of the microprotrusions on the bonding surfaces; when this plastic deformation becomes sufficient, metal adhesion occurs. Under the repeated action of slight external vibrations, shear occurs at the adhesive points, causing the bonded metal to detach; the surface at the site of shear becomes oxidized. Due to the tight fit between the two surfaces, it is difficult for debris to be removed, which in turn acts as an abrasive and accelerates the process of fretting wear. This repeats over and over, eventually leading to component damage. (2) At the initial stage of motor operation, the condition between the coupling components is good, the relative motion is normal, and no fatigue or wear has occurred on the surfaces. As the equipment operates for longer periods, the lubricant is consumed and its lubricating effect diminishes; the friction factor between the mating parts increases, leading to wear, with the amount of wear growing over time as the equipment continues to operate. When two in-contact surfaces in relative motion rub against each other, scratches appear on the surfaces; adhesive wear occurs as a result of solid-state welding. The micro-protrusions that form when two contacting surfaces are scratched undergo deformation due to the high contact pressure; the metal surface film breaks, allowing the pure metal surfaces to come into contact with each other, which leads to solid-state welding and the formation of adhesive points. During relative motion, the adhesive point is sheared, and part of the metal is torn off. Under high-speed continuous operation, the processes of adhesion, shear, and tearing repeat continuously. At the same time, as metal is torn off and enters the grease, the lubrication effect suffers significantly, leading to more severe wear. The heat generated by friction cannot be dissipated in time, causing the surface temperature to rise sharply; this destroys the oil film and reduces the strength of the surface material, resulting in thermal adhesive wear. Prevention measures: 1. Thoroughly inspect the quality of bearings before installing the motor. Conduct a careful visual inspection as well as measure the bearing clearance before installation; bearings that do not meet the standards should not be used at all. Additionally, where conditions permit, it is advisable to use branded bearings with quality guarantees for important motors. 2. Select the right grease: Due to their different design conditions, various motors have varying requirements regarding the lubricating grease to be used. The selection of general lubricants is mainly based on two considerations: (1) the choice of viscosity. The viscosity of lubricating grease is a fundamental factor in the formation of a lubricating film. For medium load and medium speed operating conditions, medium viscosity lubricating grease should be used ； For high-load, low-speed operating conditions, use lubricating grease with high viscosity ； For low-load, high-speed operating conditions, low-viscosity lubricating grease should be used. (2) Selection is based on temperature conditions, taking into account factors such as load level and rotational speed. Generally, when the operating temperature is <80°C, the oxidation reaction is not significant ； When the temperature exceeds 80°C, for every 10°C increase, the oxidation rate doubles, and the lifespan of the lubricating grease is reduced by half. Therefore, it is necessary to select lubricating grease that meets the requirements based on the operating conditions of the motor, while also paying attention to the amount added; otherwise, it will not be able to provide the necessary protection, and instead it will increase friction during bearing operation, leading to premature fatigue, reduced service life, and **an increased likelihood of failures. 3. Ensure the quality of motor maintenance (1) Motor maintenance must be carried out strictly in accordance with the established procedures. Experience has shown that incorrect installation methods are the main cause of damage to the bearings. It is necessary to resolutely put an end to the reckless practice of assembling bearings by cold hammering without heating. The end cover must be installed correctly, with special attention paid to the fit between the inner and outer rings of the bearing, the shaft, and the end cover. (2) Control the bearing heating temperature properly. Generally, the heating temperature for bearings is ≤105°C, using either oil heating or oven heating. (3) Add grease strictly in accordance with the standards (for motors running at 3000 r/min, add 1/3 of the amount to the bearing cavity) ； Fill 1/2 of the bearing chamber for a motor with a speed of 1500 r/min). When the motor is operating normally, lubricant should be added at regular intervals and in the prescribed amounts, in accordance with the guidelines (25g of lubricant should be added every 1,000–1,500 hours of operation). At the same time, pay attention to changes in oil drainage, the environment, and operating conditions, and analyze specific issues on a case-by-case basis. (4) For motor maintenance, secondary alignment is carried out. Aligning and centering motors and pumps is a highly specialized task. For motors that are put into operation after maintenance, performing a second alignment after one week of operation can effectively reduce the occurrence of shaft seizure incidents. (5) Strengthen the condition monitoring of operating motors. It mainly involves the monitoring of the operating temperature and vibration levels of motor bearings; the duty personnel are required to use infrared thermometers to measure the online temperature of these bearings every hour, while technicians regularly use vibration meters to determine the vibration acceleration values of the bearing housings. The bearing temperature of a standard motor should be ≤95°C, and the vibration level should be kept within the range specified in Table 1. (6) For large motors, regularly monitor the level of shaft voltage. When the voltage is on the rise or the current approaches 500mA, promptly check the degree of degradation of the shaft insulation and take immediate action to restore normal conditions and stop the generation of shaft current.