Teflon Teflon PTFE oil seal? Stainless steel double lip oil seal
Introduction to polytetrafluoroethylene (PTFE) oil seal
Walther Simmer invented rubber in 1929 Skeleton oil seal. People have been using rubber materials for the past hundred years. The more widely used materials are NBR and fluorine rubber. The former is low-cost, but has poor temperature resistance and sealing performance, and leakage is serious; the latter has significantly improved temperature resistance and sealing properties. , but the cost is higher, and it still has some undesirable characteristics of ordinary rubber materials: such as poor wear resistance, short service life, particularly sensitive to the eccentric reaction of the shaft, etc., and leakage is still relatively common. ?
In the early 1980s, companies such as Mather and National in the United States successively developed and successfully used filled polytetrafluoroethylene (PTFE) oil seals to replace lip-shaped rubber oil seals, successfully solving the problems of water and oil leakage in rubber skeleton oil seals.
1. Material advantages: Polytetrafluoroethylene (PTFE), also known as Teflon/Teflon or Plastic King (F4), is a polymer of tetrafluoroethylene monomer. It has The following advantages;
1. Chemical stability: Almost all chemical resistance, strong acid, strong alkali or strong oxidant and organic solvent are not effective on it.
2. Thermal stability: The pyrolysis temperature is above 400℃, so it can work normally in the range of -200℃~350℃.
3. Anti-friction property: The friction coefficient of PTFE material is extremely low, only 0.02, which is 1/40 of rubber.
4. Self-lubricating property: The surface of PTFE material has outstanding self-lubricating properties. Lubricity, almost all sticky substances cannot adhere to its surface.
Second, filling modification: However, pure PTFE is not wear-resistant. If it is to be practical, it must be filled and modified. We use two methods: one is inorganic filling modification, adding glass fiber, carbon fiber, graphite, molybdenum disulfide, etc. to PTFE. The other is organic filling modification, adding polyphenylene ester, polyphenylene sulfide, etc. to PTFE. Through modification, the wear resistance of PTFE has been improved by 2000 times, and the rigidity and thermal conductivity have been increased, allowing the oil seal to meet high life requirements.
3. Sealing principle: The PTFE oil seal lip is drawn into a trumpet shape during processing. Since PTFE has memory shrinkage ability after drawing, the friction heat generated during work will cause the lip to shrink continuously. Therefore, there is no need for the help of the spring. It will hug the shaft tightly, prevent it from having any gap with the shaft surface, and compensate for wear.
Four. Product advantages: Compared with rubber oil seals, polytetrafluoroethylene (PTFE) oil seals have the following advantages:
1. The rubber oil seal adopts a spring-pressed sharp lip, which is in contact with the shaft. The contact surface width is only 0.3-0.5mm. The PTFE oil seal adopts a spring-free wide-lip dynamic structure, and the contact surface width with the shaft is 5-7mm. This can maintain a sufficient oil film and is not sensitive to the eccentricity of the shaft. It can still work normally under the working condition of 0.4mm jitter.
2. The inner wall of the PTFE oil seal is engraved with a threaded groove that is opposite to the direction of the shaft. 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 fluid pressure of 1.0MPa (single lip) or 3MPa (double lip), while the rubber oil seal is only 0.03MPa?
3. PTFE oil seal has excellent friction resistance. It is especially suitable for working in oil-free or low-oil conditions. Even if it is restarted after a long shutdown, it can immediately have low friction characteristics. Rubber oil seals are only suitable for working in oil-filled conditions. 4. PTFE oil seal is particularly suitable for high-speed rotation applications, with a linear speed of up to 30m/s, and NBR oil seals with a maximum linear speed of 10m/s.
5. The maximum operating temperature of PTFE oil seal can reach 350℃, and the maximum operating temperature of fluororubber oil seal is 200℃.
6. PTFE oil seal can seal water, acids, alkalis, solvents, gas, etc. Rubber oil seal can only seal oil and grease. ?
Five: Product applications: air compressors, engines, thermal oil pumps, vacuum pumps, chemical pumps and other pumps, reducers, bearings, mixers, blowers, machine tools, gear boxes, crankshafts, hydraulic motors , chemical treatment equipment and various professional equipment, especially suitable for applications that traditional rubber oil seals cannot meet. Generally, the service life of PTFE oil seal is 20 times that of ordinary oil seal.