How to choose better oil seal?

At present, synthetic rubber is the main sealing material required for oil seal manufacturing. Since the selection of sealing material and structure design are the main factors affecting the sealing performance and service life of oil seals, it is very important to correctly grasp the performance of rubber to properly select the rubber sealing material used. What kind of rubber is suitable for oil seal material? This should be decided according to the associated parameters of the oil seal, namely: the radial force on the shaft should be high enough to prevent the oil seal from leaking and low enough to maintain a certain oil film thickness to keep the frictional heat low; the oil seal should have sufficient interference to overcome the influence of eccentricity in use; the area of the lip in the contact area is also one of the deciding factors. The oil seal material directly affects the above three parameters, because the material changes with time and temperature, and each key parameter changes with it, for example: with the increase of temperature, the modulus of the material decreases and makes the radial force of the oil seal material change. Thermal expansion, material swelling caused by sealing medium, softness and hardness of the rubber material all affect radial force and interference amount.

For the above reasons, the following characteristics should be considered when selecting oil seal materials: oil seal materials are compatible with sealing medium, oil seal materials do not swell and harden due to sealing medium; oil seal materials have good heat resistance and wear resistance; oil seal materials have moderate elasticity and can adapt to changes in shaft roughness and eccentricity.

Since there are many changes in the formulation of rubber seal materials, new seal materials are constantly appearing and existing seal materials are constantly being improved. For the current manufacture of oil seals commonly used are mainly nitrile rubber, polypropionate rubber, silicone rubber, fluorine rubber and polytetrafluoroethylene, etc.