1. Core hypothermia hazards
Lubrication failure: The viscosity of grease increases sharply at low temperatures, the fluidity becomes poor, and oil film rupture and dry friction and wear are prone to occur.
Material embrittlement: The low-temperature toughness of ordinary bearing steel decreases, and micro-cracks are prone to occur under start-stop impacts, and even the rolling elements are broken.
Stuck and locked: Different metal materials have different low-temperature shrinkage rates, which can easily lead to smaller bearing clearances and sticking.
Rust and Freeze: Water vapor condenses and freezes inside the cavity, which will directly corrode the bearing raceway and increase component loss.
2. Key protective measures
1. Lubrication adaptation
The low-temperature lithium-based grease using PAO base oil can still maintain fluidity at -40°C, and the low-temperature torque is ≤3000mN·m.
The oxidation rate of grease slows down at low temperatures, but the inspection cycle needs to be shortened by 30% compared with normal temperature to prevent the grease from hardening and clumping.
2, material and clearance optimization
Priority is given to high-nickel-chromium bearing steel (such as AISI 440C), whose -40°C impact toughness is 40% higher than ordinary GCr15.
Adjust the radial clearance to group C3 to offset material shrinkage at low temperatures and avoid bearing lockup.
3. Sealing and external protection
Replace fluororubber (FKM) material seals to prevent ordinary rubber from hardening and losing elasticity at low temperatures, causing oil leakage and snow intrusion problems.
When used outdoors, a PC ice and snow isolation cover is installed, and a ≥10mm drainage hole is provided at the bottom to prevent snow from melting and water accumulation.
4. Operation and maintenance specifications
Before starting the machine, preheat the bearings to above 5°C and adopt the step-by-step starting method of inching → no-load operation to avoid cold shock.
When operating in an environment below -20°C, reduce the rated load by 20% to avoid brittle fracture caused by impact loads.
Regularly monitor bearing vibration and temperature, and immediately stop the machine for troubleshooting if abnormal noise or jamming is found to avoid expansion of the fault.
