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What is a Low-Temperature Bearing

A low-temperature bearing does not refer to a bearing that operates stably in high-temperature environments (as opposed to high-temperature bearings), but rather a bearing designed with special materials and structural designs to reduce the friction coefficient, thereby minimizing frictional heat. This allows the bearing to maintain a low temperature even during long-term operation.

 

Bearings with an operating temperature below -60℃ are considered low-temperature bearings. They are mainly used in various liquid pumps, such as liquefied natural gas pumps, liquid nitrogen (hydrogen, oxygen) pumps, butane pumps, liquid pumps for rockets and missiles, spacecraft, and so on.

 

Operating Temperature of Low-Temperature Bearings

The operating temperature of a low-temperature bearing reflects the material technology and manufacturing level of the bearing. It is primarily measured by the temperature difference between the bearing's outer ring and the injected cooling oil during operation. A lower operating temperature means a longer bearing lifespan and higher performance.

 

Categories of Low-Temperature Bearings

Low-temperature bearings are usually single-row deep groove ball bearings and cylindrical roller bearings.

 

For bearings experiencing seizure at low temperatures, the external factor is temperature change, while the internal factor is the different thermal expansion coefficients of the shaft, frame, and materials. When the temperature range is large, different materials shrink at different rates, reducing clearance and causing jamming. Therefore, for equipment with a wide operating range, including equipment used in low temperatures, it is necessary to calculate the expansion coefficients of materials and, where possible, use materials with similar expansion coefficients for better results.

 

Additionally, in structural design, it is advisable to avoid using a conical roller bearing at each end of the shaft. In such a structure, the longer the distance between the two bearings, the higher the chance of jamming. If a pair of tapered bearings is installed at one end of the shaft, they can serve as shaft positioning, constraining axial movement. The other end of the shaft, used with a rolling bearing, only restricts radial forces, allowing limited axial movement along with axial temperature changes.

 

Material Selection for Low-Temperature Bearings

Selection of Bearing Steel for Low-Temperature Bearings

Low-temperature bearings are often made of stainless bearing steels 9Cr18 or 9Cr18Mo, and can also be made from beryllium bronze, ceramics, and other materials. Under extremely low working temperatures (extreme temperature -253℃), if the working limit requires -253℃, 6Cr14Mo material can be chosen but must be used in a vacuum environment.

 

During the use of low-temperature bearings, attention should be paid to issues such as overheating caused by poor lubrication, so it is important to select suitable lubricants.