The bearing structural design influence on temperature rise

Jun 09, 2023

We all know that the temperature during the use of bearings affects their life. The influence of structural design on temperature rise can be divided into four categories:

1. Shape and quantity of rolling element.

2. Cage shape and material.

3. The impact of installation and use on temperature rise.

4. Process technology.

1. The shape and number of rolling elements

Generally, the operating temperature of ball bearings is lower than that of roller bearings. The higher the load of ball bearings, the higher the temperature rise. But the operating temperature of roller bearings is not sensitive to the increase of load. Under the same conditions, the temperature rise is higher when the number of rolling elements is small. This is because under the same load, the number of rolling elements is small, the load of rolling elements is increased, the elastic deformation of the contact surface is increased, so the friction torque is increased. The greater the load, the more significant the tendency.

2. Cage shape and material

The temperature rise of the bearing is related to the amount of lubricant.  The operating temperature of bearings without cages is generally higher than that of bearings with cages. Bearings without cages are prone to irregular movement of the rolling element, but if the clearance is guaranteed, the same speed can be achieved as bearings with cages. The stamped cage is generally guided by the rolling body, and the operating temperature is usually lower than that guided by the card-made cage ring, and the weight of the card-made cage is heavier than that of the stamped cage, so the sliding friction of the guiding surface is large and the temperature rise is high. 

In addition, in the form of the cage guided by the ring, the temperature rise of the bearing guided by the outer ring is usually lower than the inner ring, because under the action of centrifugal force at high speed, the lubricant is thrown to the outer raceway and the outer ring guide surface, so that the inner ring guide surface is in an oil-poor state. The lighter the material of the molded cage, the lower the temperature rise. 

3. Effect of installation and use on temperature rise

For the tapered roller bearing with pre-loaded position, the pre-loaded amount is reduced due to the running of the guard edge and the end face of the roller, so the temperature of the bearing during the running period also decreases accordingly. 

With the increase of preload, the temperature rises sharply, and the surface roughness of the ring channel has a direct effect. Therefore, in actual work, there are both the requirements of the process for the oil stone, and the experience in the use of the oil stone and the grinding wheel. The key to ensure the surface roughness of the channel is to select the oil stone with suitable material and particle. Abrasive is mainly divided into: corundum and silicon carbide, the latter's finishing surface roughness is much better than the former. The hardness of the former also directly affects the surface roughness, W10 is the best, the latter W5 is the best. Using the same equipment, the same parameters and different oil stones, the processed channel surface roughness is not the same, at least two small differences. This selection of the oil stone plays a key role in the final grinding of the ring channel. In the test with the oil stone manufacturer, it was found that in order to reduce the surface roughness of the channel, the choice of abrasive material and particle size is key, because the smaller the particle size of the abrasive, the lower the surface roughness of the channel. 

4. Process technology

In order to reduce the roughness of the channel surface, we must pay attention to the processing method and comply with the process.

This point is different in the machining bearing outer diameter and the channel. Taking grinding processing as an example, it will be found in processing that in order to improve the surface roughness of the bearing ring, the lapping machine is selected to first grind the processing datum of the bearing ring, that is, the outer diameter or the inner and outer diameter, to ensure the geometric accuracy of the ring groove grinding. Therefore, in the actual processing, the processing of the datum surface is very strict, which is the basic guarantee of the channel processing.

FV brand bearings are all using the most suitable process and cage design to ensure the quality and service life of bearings.