一、Assembly reasons

(1) Due to the reason of pressing tooling, the oil seal is deformed after pressing;

(2) In the assembly process, the oil seal through the thread or spline, resulting in lip scratches;

(3) Due to the low roughness of the oil seal, the pressure loading force is too large, resulting in the failure of the spring or the lip mouth turnover.

二、 Skeleton reasons

Due to the material and manufacturing problems of the oil seal spring, its performance failed.The spring failure form is: the spring is too tight or too loose, too loose spring pressure is small, can not achieve the sealing effect, too tight spring pressure is large, the improper match between the oil seal and the rotating shaft, resulting in abnormal oil seal wear, and finally oil leakage.

三、 the reason of the working medium

The working medium is oil.The choice of oil seal material should consider its compatibility with oil. The poor compatibility of the two will cause swelling, hardening, softening, cracking and so on of the lip, and eventually oil leakage will occur.

四、 lip wear reasons

(1) Cleanliness problem: casting sand, machining iron scraps, oil impurities, etc., a large number of accumulated oil seal lip parts, abnormal wear occurs during work;

(2) The oil seal position is not coaxial with the rotating shaft, and the partial wear and abnormal wear of the lip mouth occur after the oil seal is press-loaded;

(3) poor lubrication of lithium-based grease at the lip of oil seal, dry friction will occur, leading to abnormal wear.

五、The reason of axis

(1) The surface roughness and hardness of the rotating shaft are unreasonable. At present, the roughness of the automobile industry is generally selected not less than 0.8. The parts with the oil seal will be quenched with high frequency and the hardness is not less than HRC55.

(2) There are defects on the surface of the rotating shaft, such as corrosion, scratches, directional knife marks, etc.