Is the rated load capacity of polyurethane casters affected by temperature?

The rated load capacity of polyurethane casters is significantly affected by temperature. The core reason is that the physical properties of polyurethane (hardness, strength, and elasticity) change with temperature, leading to a decrease in actual load capacity or failure. The specific impact mechanisms and manifestations are as follows:

1. High Temperature Environment (above 80°C): Rated Load Capacity Significantly Reduced
The upper temperature limit for conventional polyurethane materials is approximately 80°C. When the ambient temperature exceeds this range, the material softens and its molecular structure relaxes, directly resulting in a decrease in load capacity:

Specific Impact:
When the temperature rises to 80-120°C, the hardness (Shore A) of polyurethane drops from the typical 65-95 Shore A to 40-60 Shore A, weakening the material's elasticity and resistance to deformation. For example, a caster originally rated for 300kg may have an actual load capacity of 150-200kg. If the original rated load is still applied, the wheel body is prone to denting, flattening, or even separation of the wheel core from the wheel body.

When the temperature exceeds At 120°C, polyurethane may thermally degrade, causing the wheel tread to become sticky and crack. At this point, the caster's load-bearing capacity is essentially lost. Continued use will not only completely damage the caster, but also cause the equipment to tip over due to wheel fragmentation.

Typical scenarios include food processing areas near ovens and boilers, logistics transfer operations exposed to the summer sun, and high-temperature drying workshops.

2. Low Temperatures (Below -20°C): Indirect Reduction in Rated Load Capacity
When temperatures fall below -20°C, polyurethane material transitions from an elastic state to a brittle state. While its hardness increases (Shore A may exceed 100), its toughness and impact resistance decrease significantly, indirectly reducing the "actual safety threshold" of the rated load capacity.

Specific Impacts:
When the material becomes brittle, the wheel loses its cushioning capacity. The weight, which would otherwise be dispersed through elasticity, is now concentrated on a localized area of ​​the wheel surface. Even if the load does not exceed the rated value, excessive localized stress can easily cause the wheel surface to crack or break.

At low temperatures, bearing grease may solidify, increasing rotational resistance and requiring greater force to push equipment. This additional impact further reduces the caster's actual load-bearing safety. For example, for a 200kg-rated caster in a -30°C environment, it is recommended that the actual load not exceed 120-150kg to avoid wheel breakage.

Typical Applications: Food cold storage, outdoor winter operations in northern China, and low-temperature laboratories.

3. Normal Temperature Environment (-20°C-80°C): Rated load-bearing capacity is generally stable.
Within the polyurethane material's "optimal operating temperature range" (-20°C-80°C), its hardness, strength, and elasticity remain stable. The caster's actual load-bearing capacity fully matches the stated rated load-bearing capacity, without requiring any additional load reduction.

However, please note: Even at normal temperatures, if the caster is exposed to humid, oily environments (such as food processing and cleaning areas) for extended periods, regular cleaning and maintenance are necessary to prevent dirt and chemicals from corroding the material, which could indirectly affect load-bearing stability (e.g., wheel aging and cracking, leading to a decrease in load-bearing capacity).

Summary: Key Recommendations for Temperature Impact
Prioritize temperature-matching scenarios: If operating in high-temperature (e.g., >80°C) or low-temperature (e.g., <-20°C) environments, choose high- and low-temperature-resistant modified polyurethane casters (e.g., glass-fiber-reinforced polyurethane with a high-temperature resistance of 120°C, or elastomeric polyurethane with a low-temperature resistance of -40°C). The load rating will be re-marked based on the modified material properties; please refer to the product specifications for details.

Derating for Extreme Temperatures: If ordinary polyurethane casters are temporarily used in an environment not designed for them, it is recommended to reduce the load to 50%-70% of the rated value and minimize usage time to avoid caster damage.

Regularly check for temperature impacts: In environments with large temperature fluctuations (e.g., cold chain logistics with transitions between normal and low temperatures), inspect the wheel weekly for signs of softening, embrittlement, or cracking. Replace any damaged casters promptly to avoid safety hazards.