The models of PD oil seal and TC oil seal are different, so PD and TC can tell us that there is a difference between them, and they are the codes that distinguish the models. \x0d\ The skeleton and spring of the oil seal are made of metal, and the main parts such as the sealing lip are rubber. According to the use environment, oil seals can be produced with different rubbers to meet the sealing performance and requirements. The most commonly used oil-resistant rubber is nitrile rubber, which is one of the most commonly used rubbers for oil seals and O-rings. It can be said that it is the most widely used rubber seal with the lowest cost at present. Polypropionate rubber, silicone rubber, fluororubber and polytetrafluoroethylene are also commonly used in the manufacture of oil seals. \x0d\ tc oil seal is the name of oil seal, which is a double-lip oil seal with self-tightening spring completely covered by rubber. Generally speaking, oil seal often refers to this TC skeleton oil seal. \x0d\ As for the letter PD in front of the oil seal specifications, it means that ordinary manufacturers often add abbreviated letters in front of the specifications to indicate the use of oil seals, as follows: W (springless type), PD (low-speed common type), PG (high-speed common type), SD (low-speed dual-port type), DG (high-speed dual-port type) and so on. The expression method of oil seal specification is: dxDxH (inner diameter x outer diameter x height) unit-mm.