Oil seal is a kind of seal, which is widely used in seals. Because of its good sealing performance, good performance characteristics, low price, simple structure and convenient installation, it is accepted by the majority of customers.
The problem of water leakage and oil leakage of rubber skeleton oil seal was successfully solved by replacing lip rubber oil seal with PTFE oil seal. At present, nitrile rubber and fluororubber are widely used. The former is cheap, but its temperature resistance and sealing performance are poor, and the leakage is serious. The latter has obvious improvement in temperature resistance and sealing performance, but the cost is high. Moreover, it still has some undesirable properties of ordinary rubber materials, such as poor wear resistance, short service life, especially sensitive to eccentric reaction of shaft, etc Elephants are still common. Filling PTFE oil seal instead of lip rubber oil seal successfully solved the problem of water leakage and oil leakage of rubber framework oil seal.
1、 Advantages of PTFE oil seal material: 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 resistance, strong acid, strong base or strong oxidant and organic solvents, etc. have no effect 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: PTFE material friction coefficient is very low, only 0.02, is 1 / 40 of rubber
(4) Self lubrication: PTFE material surface has outstanding self-lubricating property, almost all viscous substances can not adhere to its surface.
2、 PTFE oil seal filled with pure PTFE is not wear-resistant. In order to make it practical, it must be filled and modified. We use two methods: one is inorganic material filling modification, adding glass fiber, carbon fiber, graphite, molybdenum disulfide and so on into polytetrafluoroethylene. The other is organic filling modification, adding polyphenylene grease and polyphenylene sulfide into polytetrafluoroethylene, which is suitable for water purification, food and drug sealing. Through filling modification, the wear resistance of PTFE is increased by 2000 times, and the steel and thermal conductivity are increased, so that the oil seal can meet the requirements of high service life.
3、 The sealing principle of polytetrafluoroethylene seal lip is pulled into a trumpet shape during processing. As PTFE has the ability of memory contraction after drawing, the lip will shrink continuously due to the friction heat generated in the work, so it does not need the help of spring, it will tightly hold on the shaft, so there is no gap between it and the shaft surface, and it can compensate for wear.
4、 PTFE oil seal application PTFE oil seal is mainly used in air compressor, engine, gearbox, motor, pump, air conditioner, mixer, automatic precision machinery, robot, chemical processing equipment, pharmaceutical and food processing equipment, etc., especially suitable for the application that traditional rubber oil seal cannot meet.
5、 PTFE oil seal installation requirements PTFE oil seal installation and installation position design can refer to NOK oil seal Vaj type or CFW simmering oil seal b2pt type. Polytetrafluoroethylene oil seal is a product with high technical content.
6、 Compared with rubber oil seal, PTFE oil seal has the following advantages:
1. The rubber oil seal adopts the sharp lip pressed by spring, and the width of the contact surface with the shaft is only 0.3-0.5mm. The PTFE oil seal adopts the wide lip dynamic structure without spring, and the width of the contact surface with the shaft is 5-7mm. In this way, it can maintain 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.
2. The inner wall of the PTFE oil seal is engraved with a thread groove opposite to the rotation direction of the shaft. When the shaft rotates, an inward thrust will be generated to prevent the fluid from flowing out. The thrust force is very high, which can seal the fluid pressure of 1.0MPa (single lip) and 3Mpa (double lip), and the rubber oil seal is only 0.03mpa
3. The excellent anti-wear performance of PTFE oil seal is especially suitable for oil-free or low oil state. Even if it is used again after a long-term shutdown, it can immediately have low friction characteristics.
4. Teflon oil seal is especially suitable for high-speed rotating applications with a speed of up to 30m / s
5. PTFE oil seal can achieve no leakage.