Basic knowledge of PTFE oil seals

The filled polytetrafluoroethylene (PTFE) oil seal replaces the lip rubber oil seal, which successfully solves the problem of water leakage and oil leakage of the rubber frame oil seal.

1. Advantages of PTFE oil seal material

Polytetrafluoroethylene (PTFE), also known as Teflon or plastic king, is a copolymer of tetrafluoroethylene monomer, which has the following advantages:

(1) Chemical stability: almost all chemical resistances, strong acids, strong bases or strong oxidants and organic solvents do not work on it.

(2) Thermal stability: the pyrolysis temperature is above 400℃. Therefore, PTFE can work normally in the temperature range of -200℃～300℃.

(3) Friction reduction: The coefficient of friction of PTFE material is extremely low, only 0.02, which is 1/40 of that of rubber.

(4) Self-lubricating property: The surface of PTFE material has outstanding self-lubricating property, and almost all viscous substances cannot adhere to its surface.

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ptfe micropowder

2. PTFE oil seal filling modification

Pure PTFE is not wear-resistant, so to make it practical, it must be filled and modified. We use two methods: one is inorganic filling and modification, adding glass fiber, carbon fiber, graphite, molybdenum disulfide, etc. to PTFE. The other is organic filling and modification, adding polyphenylene resin, polyphenylene sulfide, etc. to polytetrafluoroethylene (applicable to water purification, food, medicine sealing). Through filling and modification, the wear resistance of PTFE is increased by 2000 times, and the rigidity and thermal conductivity are increased, so that the oil seal can meet the requirements of high life.

3. PTFE sealing principle

The lip of the PTFE oil seal is drawn into a trumpet shape during processing. Since PTFE has a memory shrinkage ability after being drawn, the frictional heat generated during the work will cause the lip to shrink continuously, so it does not need the help of a spring. , it will hold tightly on the shaft, so that there is no gap between it and the shaft surface, and can compensate for wear.

4, the advantages of PTFE oil seal

Compared with rubber oil seals, polytetrafluoroethylene (PTFE) oil seals have the following advantages:

1) The rubber oil seal adopts a spring-compressed pointed lip, and the width of the contact surface with the shaft is only 0.3-0.5mm. It maintains a sufficient oil film, and is not sensitive to the eccentricity of the shaft, and can still work normally under the condition of radial runout of 0.4mm, nikkiso group ptfe powder suppliers .

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

3) The PTFE oil seal has excellent anti-friction properties, especially suitable for oil-free or oil-less work. Even if it is restarted after a long-term shutdown, it can immediately have low-friction characteristics.

4) The PTFE oil seal is especially suitable for high-speed rotation applications, and the speed can reach 30m/s.

5) The PTFE oil seal can be leak-free.​

5, PTFE oil seal application

PTFE oil seals are mainly used in air compressors, engines, gearboxes, motors, pumps, air conditioners, mixers, automated precision machinery, robots, chemical processing equipment, pharmaceutical and food processing equipment, etc., especially suitable for traditional rubber oil seals. satisfied application.

6. PTFE oil seal installation requirements

The design of PTFE oil seal installation and installation parts can refer to NOK oil seal VAJ type or CFW-Simmerring oil seal B2PT type.

PTFE oil seal is a product with high technical content.