How does low temperatures affect the performance of caster bearing grease?

The destructive effects of low temperatures on caster bearing grease performance

Low temperatures can severely damage the physical and chemical properties of grease, leading to lubrication failure and increasing the risk of bearing wear and failure. The specific effects are as follows:

Loss of fluidity and oil film breakdown: Low temperatures cause the viscosity of base oils to increase exponentially. Ordinary lithium-based greases experience a sharp increase in viscosity below -10°C and even solidify below -20°C. Hardened greases lose fluidity and are unable to form an effective oil film, resulting in direct metal-to-metal contact (dry/semi-dry friction) and a significantly increased coefficient of friction (up to 0.1).

Structural damage and functional failure: Low temperatures embrittle and fracture the three-dimensional network formed by thickeners (such as lithium soaps), causing the base oil to precipitate (oiling). However, the precipitated base oil also solidifies and becomes ineffective. Furthermore, additives such as antioxidants and extreme pressure agents become less active or ineffective, rendering them unable to provide protection.

Difficulty in grease injection and uneven distribution: Hardened greases are difficult to inject into bearings and can easily clog channels or damage tools. Even if forced, grease cannot penetrate internal gaps, resulting in a false lubrication condition known as "grease on the outside, oil on the inside." Localized "grease clumps" actually increase resistance and may cause localized high temperatures.

Water mixing exacerbates wear: Water intruding at low temperatures can mix with grease, potentially leading to emulsification failure. When temperatures are too low, water freezes to form hard ice crystals, which scratch the bearing surface during operation (abrasive wear).

In summary: The core hazard of low temperatures is the loss of grease fluidity, structural damage, and functional failure, causing the bearing to degrade from a lubricated state to a semi-dry friction state. Even if the material isn't brittle, insufficient lubrication can exacerbate wear and resistance, shortening its lifespan. Therefore, for low-temperature environments, it is essential to use specialized low-temperature greases (such as synthetic lithium-based greases or polyurea greases, suitable for temperatures down to -40°C) and optimize grease injection methods (such as preheating).

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