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Characteristics of PTFE oil seals

Update:2018-09-22

First, materials features

PTFE also called teflon or plastic king(F4), is copolymer of tetrafluoroethylene monomer. It has the following features:

1. Self-lubrication: The surface of PTFE materials have outstanding self-lubrication, almost all viscous substances cannot adhere to its surface.

2. Chemical stability: All chemical resistance, strong acid, strong base or strong oxidizing agent and organic solvent have no effect on it.

3. Anti-wear: Friction coefficient of PTFE materials is extremely low. Only 0.02, is 1/40 of rubber.

4. Thermal stability: The cracking temperature is above 400℃, therefore, it can work at the range of -200...350℃.

Second, filled modification

Virgin PTFE seals are not wear resistance. If it is practical, it must be filled with modification. We use two ways: one is inorganic filled modification, add glass fiber, carbon fiber, graphite, molybdenum disulfide etc. to PTFE raw materials. The other is organic filled modification, add polyphenylene ester, polyphenylene sulfide etc to PTFE raw materials. 

Through modification, the wear resistance of PTFE was improved by 2000 times, the rigidity and thermal conductivity were increased, which made PTFE oil seal meet the requirement of long life.

Third, sealing principle

The lip of PTFE oil seal is pulled into trumpet shape during processing. Due to the memory shrinkage function of PTFE after drawing, the friction generated during work causes the lip to shrink continuously, so needn’t springs’ help.

Fourth, products features

1. Rubber oil seals used a spring-pressed sharp lip, the contact surface width of the shaft is only 0.3-0.5mm. PTFE oil seal adopts a spring-free wide lip power structure with a shaft contact surface width of 5-7mm. It can keep enough oil film, and not sensible to axis of the shaft. It can normally work during radial runout 0.4mm working condition.

2. The inner wall of the PTFE oil seal is engraved with a thread groove opposite to the shaft turning. When the shaft rotates, an inward thrust is generated to prevent the fluid from flowing out. This thrust is so high that it can seal the pressure of 1.0MPa (single lip) and 3MPa (double lip) fluid, and the rubber oil seal is only 0.03MPa.

3. PTFE oil seal anti-friction, especially suitable for oil-free or low-oil operation, even if it is reactivated after long-term shutdown, it can immediately have low friction characteristics, rubber oil seal is only suitable for oil working.

4. PTFE oil seal is especially suitable for high speed rotating applications, the line speed can reach 30m / s, NBR rubber oil seal high line speed 10m / s.

5. The maximum temperature of PTFE oil seal can reach 350 °C, and the maximum temperature of fluororubber oil seal is 200 °C.

6. PTFE oil seal can seal water, acid, alkali, solvent, gas, etc., rubber seal can only seal oil, grease.