Which caster material is more durable for carpet floors, polyurethane or polypropylene?

Carpet Caster Material Durability Comparison: PP vs. PU

On carpeted floors, polypropylene (PP) casters are generally more durable than polyurethane (PU) casters, but this depends on the carpet type, load capacity, and frequency of use.

Abrasion Resistance: PP is Better

PP: High hardness (approximately 85-90D), a smooth surface, and a stable molecular structure. It effectively resists friction and abrasion from carpet fibers, making it less susceptible to scratching, chipping, or deformation even with frequent use on short-pile/flat-woven carpets. It is particularly resistant to rough carpets or gritty environments (such as entrances), reducing abrasive damage and slowing wear.

PU: Softer (approximately 65-85A), its elastic surface is prone to microcracks from prolonged friction with carpet. Dust and grit can easily become embedded in the wheel surface, accelerating wear. On long-pile carpets, it can easily become entangled with fibers, increasing resistance and abrasion, potentially leading to wheel diameter reduction and seizure.

Environmental Adaptability: PP is More Suitable

Temperature: PP has a wide temperature range (-20°C to 100°C) and is less susceptible to brittleness, softening, or deformation at high and low temperatures. PU has weaker temperature resistance, becoming brittle and sticky at high temperatures (>60°C) and cracking at low temperatures (<0°C). It also ages rapidly in environments with large temperature swings.

Chemical: PP is more resistant to chemical corrosion (such as carpet cleaners). PU may swell and lose its elasticity with prolonged contact.

Structural Stability: PP is More Stable

Load-Bearing Capacity: PP offers high rigidity and minimal deformation within the rated load, making it less prone to wheel collapse or axle misalignment. It is suitable for stable load-bearing applications such as office chairs and light shelves. PU has good elasticity but lacks rigidity. Long-term full loads can lead to elastic fatigue, resulting in reduced wheel diameter, increased resistance, and even delamination.

Impact Resistance: PP is more impact-resistant and less likely to crack when a carpet encounters an obstacle; PU is more susceptible to dents or tears when subjected to heavy impact.

Exceptional Scenarios: PU May Be More Advantageous

On long-pile/thick carpets, PU's elasticity can reduce wheel sinking and "stuck," potentially making it more durable than PP, which is prone to fiber entanglement (PP requires anti-tangling design).

In low-frequency, light-load (<20 kg) applications (such as home sofas), PU wears similarly to PP, and its quieter performance is more pronounced.

Summary:
In most carpet applications (especially short-pile carpets, high-frequency use, medium-to-low loads, and large temperature fluctuations), PP casters offer superior durability. Their high hardness, friction resistance, and resistance to extreme environments make them more suitable. PU may only offer advantages on long-pile carpets and low-frequency, light-load applications, but its overall wear rate and environmental adaptability are slower than PP. For long-term durability, PP is a more reliable choice.