Motor quality problems caused by unsuitable bearings

Motor bearings are always the most discussed topic in motor products. Different motor products need corresponding bearings to match them. If the bearings are not selected properly, there may be problems such as noise and vibration that directly affect the performance of the motor. impact on service life.

Deep groove ball bearings are one of the most widely used types of bearings. Motors in special operating environments have different requirements for bearings. If necessary, specific requirements should be put forward for bearing materials and manufacturing processes.

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The noise of deep groove ball bearings can be transmitted through structure conduction or air medium. The rotating deep groove ball bearing itself is the source of sound or vibration, causing bearing vibration or noise, mainly from the natural vibration of the bearing and the vibration generated by the relative movement inside the bearing.

In the actual use process, the selection of bearing grease, filling amount, bearing installation and later maintenance and use all have a direct impact on bearing operation. Therefore, in the design stage, manufacturing stage and customer use and maintenance stage of the motor, necessary and standardized maintenance should be carried out on the bearings to avoid motor quality problems caused by the bearings.

Motor bearing selection should focus on factors
1
Selection of special specifications for motor bearings

●Special materials: stainless steel bearings are recommended if good anti-rust performance is required, or if they work in corrosive environments such as salt water;

●High temperature tempering treatment: the use temperature is relatively high, if it exceeds 150 degrees, it is required to adopt high temperature tempering heat treatment method for the bearing ring. 180 degrees or 220 degrees, or 250 degrees etc. are selected for the environment.

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●Freezing treatment: After quenching and before tempering, add a process of freezing at a low temperature of minus 70 degrees. The main purpose is to reduce the content of retained austenite inside the ring and improve the stability of the bearing’s dimensional accuracy.

2
Sealing structure and material selection of motor bearings

The purpose of the bearing seal is to prevent the leakage of lubricant in the bearing part, and to prevent the external dust, moisture, foreign matter and other harmful objects from invading the inside of the bearing, so that the bearing can run safely and permanently under the required conditions . In the following situations, the choice of pre-filled sealed bearings with grease can be given priority.

●The bearing is not required to run permanently.

●Under the operating conditions of medium and low speed, load and temperature.

●Requires low production cost.

●The parts where it is difficult to add lubricant, or those who do not need to add lubricant in the future.

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Using this type of bearing, the design of the bearing shell (box) and its seal can be simplified, and the manufacturing cost can be greatly reduced: when the use conditions are not harsh, it can even run for a long time. It is widely used in industries such as household appliances, vehicles, and motors. .

3
Selection of Grease for Motor Bearings

In addition to rolling contact, deep groove ball bearings have considerable sliding contact. Therefore, the main purpose of the bearing is to reduce the friction and wear of various parts of the bearing, and to avoid high temperature melting. Whether the lubrication method and the lubricant are appropriate or not will directly and greatly affect the performance and durability of the bearing. Generally speaking, grease has the following functions.

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●Reduce friction and wear;

●Frictional heat conduction and removal The heat generated by the bearing due to friction needs to be conducted to other places or taken away by the intermediary of the lubricant, so that the temperature of the bearing drops, and the lubricant and the bearing can maintain long-term operation.

●Relieve the concentration of local stress.

Classification of GreaseLubricating grease is made of lubricating oil such as mineral oil or synthetic oil as base oil, adding a thickener to become semi-solid, using it as a carrier to maintain the base oil, and adding various additives to improve performance. Therefore, the properties of grease are determined by the type and combination of base oil, thickener and additives. There are many ways to classify lubricating grease. Generally, it is classified by the type of thickener, which is divided into two categories: metal soap base and non-soap base. Due to the continuous development of new thickeners and additives, the performance of lubricating grease has been greatly improved, so when selecting grease, it is necessary to fully grasp the characteristics of the latest and different greases.

4
Installation and use of motor bearings

Rolling bearings are precision components and should be installed and used in a standardized manner. When the bearing is installed, the mating ring should be stressed, that is, when the bearing is pressed onto the shaft, the inner ring of the bearing should be stressed, otherwise the outer ring of the bearing should be stressed; and when the assembly of the shaft and the bearing chamber is satisfied at the same time, the bearing must be ensured. The inner and outer rings are stressed at the same time. Under any conditions, the bearing cage should not be subjected to external force.

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5
Vibration and noise level selection for motor bearings

The noise of deep groove ball bearings can be transmitted through structure conduction or air medium. The rotating deep groove ball bearing itself is the source of sound or vibration. The vibration or noise of the bearing mainly comes from the natural vibration of the bearing and the vibration generated by the relative movement inside the bearing.

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Natural vibration—the inner and outer rings of the bearing are thin-walled rings, which have their own inherent vibration modes. Usually, the first natural frequency of motor bearings is between a few KHz .

Vibration generated by relative motion inside the bearing – the real surface geometry of the inner and outer rings and steel ball surfaces, such as roughness and waviness, which will affect the sound quality and vibration of the bearing, among which the steel ball surface has the greatest impact.


Post time: Apr-26-2023