Causes of Deformation in Thin-Walled Bearings During Heat Treatment
One of the main reasons for deformation in thin-walled bearings is the uneven expansion and contraction between the surface and interior of the bearing during heat treatment and cooling. This is accompanied by thermal stress and microstructural stress due to phase transformations.
When overall plastic deformation occurs, it typically manifests as expansion or contraction along the bearing’s diameter. In cases of local plastic deformation, increased roundness or cylindricity errors are observed. Because the cooling rate of quenching oil is significantly faster than the heating rate in the furnace, and thin-walled bearing rings have poor rigidity, most deformation occurs during the cooling stage.
Many factors influence the deformation of thin-walled bearing rings during heat treatment. Any method that reduces thermal and structural stress during the process can help minimize deformation. From a process standpoint, this includes:
Lowering the quenching temperature
Properly controlling holding time
Increasing quenching oil temperature
Reducing the stirring speed of quenching oil
Thin-walled bearing rings with large outer diameters are especially prone to deformation under certain thermal and structural stresses due to their weak rigidity. Thus, a suitable heat treatment process must be designed to control both types of stress.
Recommended Heat Treatment Process for Thin-Walled Bearings
The standard process includes:
After lathe processing, apply appropriate stress relief annealing. During quenching:
Control the heating temperature precisely
Adjust the cooling rate reasonably
Use water glass, asbestos rope, or refractory clay to block the oil circuit before quenching
Perform heating in a protective atmosphere to reduce cracking
Optimize oil tank structure to prevent straight tank or trumpet-shaped cracking effects
These improvements can help effectively manage deformation and maintain dimensional accuracy.
Importance of Proper Thin-Walled Bearing Selection
Selecting the correct thin-walled bearing ensures optimal working performance and extended service life of the host machine. It significantly reduces downtime, lowers maintenance costs, and increases operational efficiency. Therefore, both design and manufacturing teams, as well as maintenance personnel, should prioritize careful bearing selection.
General Steps for Selecting Thin-Walled Bearings
Understand Operating Conditions
Gather detailed information on the bearing’s working environment, loads, speeds, temperature, and required durability.
Determine Bearing Type
Based on working conditions, stress levels, and service life requirements, calculate or choose the appropriate bearing type. Then verify its expected lifespan.
Check Load Rating
Evaluate whether the selected bearing’s load rating meets performance needs.
The primary considerations are required service life and load capacity.
Additional factors include bearing type, design, dimensions, tolerance class, and internal clearance.
