Why PU Casters are Better Than PA Casters in Low-Temperature Environments

In cold environments below 0°C, especially between -10°C and -40°C, caster material performance is easily affected by low temperatures. PU (polyurethane) casters generally perform better than PA (nylon) casters. The core reasons are as follows:

Resistance to Low-Temperature Brittleness:

PA: Molecular hydrogen bonds strengthen at low temperatures, causing a sharp increase in rigidity. However, it is susceptible to brittleness and cracking below -10°C, significantly decreasing its impact resistance.

PU: Molecular chains contain flexible segments, maintaining elasticity at low temperatures. High-quality, cold-resistant PU can maintain impact resistance at -40°C and resist cracking.

Elasticity and Rolling Performance:

PA: At low temperatures, it completely loses its elasticity and becomes rigid, resulting in loud noise, jerky movements, and axle loosening.

PU: Its excellent elasticity helps cushion uneven surfaces, ensuring smoother and quieter rolling.

Dimensional Stability:

PA: It has high water absorption. When low temperatures are accompanied by changes in humidity, freezing of water or shrinkage of the material can cause dimensional changes, affecting smoothness.

PU: Extremely low water absorption, minimal low-temperature shrinkage, dimensional stability, and reliable wheel-axle fit.

Long-term durability and adaptability:

PA: Prolonged low temperatures or freeze-thaw cycles can accelerate aging and cracking.

PU: Cold-resistant modified PU (such as adjusting the soft segment or adding plasticizers) can significantly improve low-temperature toughness (down to -50°C), offering wide formula adjustability and improved resistance to long-term low-temperature aging. PU's elasticity also protects soft surfaces (such as cold storage vinyl flooring) at low temperatures.

Notes for special scenarios:

Low-temperature, high-load bearing capacity: High-hardness, cold-resistant PU (Shore A 85-95) is required.

Presence of grease/chemicals: Anti-swelling PU models are required.

Extreme cold (below -40°C): Professional cold-resistant PU casters are essential.

Summary:
PU (especially cold-resistant modified types) significantly outperforms PA in terms of elasticity retention, embrittlement resistance, dimensional stability, and durability at low temperatures, making it the preferred choice for cold storage, cold chain operations, and outdoor low-temperature operations. PA casters are brittle and noisy at low temperatures and are only recommended for use in cost-sensitive scenarios where temperatures are around 0°C.