Bearing PV Value

The maximum operating PV value of EPH plastic bearing is 1.35 N/mm²·m/s. It means the load capacity of the bearing is inversely proportional to speed. Refer to Diagram EPH-1 for details.

Bearing Load, Speed and Temperature

The maximum static load of EPH plastic bearing is 90 MPa. Refer to Diagram EPH-2 for the maximum compressive deformation of the bearing under this load. The actual working load of the bearing shall be slightly less than 90 MPa. The load capacity is also affected by operating speed and temperature. Higher speed (Vmax: 1.0 m/s) will raise frictional temperature, and temperature rise (Tmax: 200°C) will gradually reduce the bearing load capacity. Refer to Diagram EPH-3 for load variation with bearing operating temperature.

Friction Coefficient of Bearing

Diagram EPH-4 shows that under constant load, the friction coefficient of EPH plastic bearings in rotary motion decreases slightly as speed increases. Diagram EPH-5 shows that under constant speed, the friction coefficient of EPH plastic bearings in rotary motion gradually decreases with rising load, especially when the load is below 30 MPa. Diagram EPH-6 indicates that the friction coefficient of EPH plastic bearings barely changes when the mating shaft roughness is Ra 0.1~0.4 μm. However, the friction coefficient rises rapidly when the shaft surface roughness exceeds Ra 0.4 μm. The recommended shaft roughness is Ra 0.1~0.4 μm.

Wear and Shaft Material

Diagram EPH-7 shows that EPH plastic bearings are compatible with most shaft materials under low-load rotary motion. For high-load rotary operation, hardened steel shafts deliver particularly superior performance (see Diagram EPH-8). EPH plastic bearings work well with stainless steel shafts for oscillating motion, while carbon steel shafts and hardened steel shafts are preferred for rotary motion.

Chemical Resistance

EPH plastic bearings feature excellent chemical resistance and can withstand most acids and alkalis.

Water Absorption

EPH plastic bearings have a moisture absorption rate of 0.1% under standard atmospheric pressure, with a maximum water absorption of 0.3% when immersed in water. Its ultra-low water absorption will not cause changes in bearing performance or dimensions, making it highly suitable for humid environments.

UV Resistance

When EPH plastic bearings are exposed to ultraviolet radiation for a long time, material surface degradation will occur and compressive strength will decrease.

Installation Tolerance

Tolerance of EPH plastic bearing after press fitting