(1) Lip damage
The skeleton oil seal will lead to high temperature carbonization and wear failure of rubber after long time use.Abrasion of the seal caused by long continuous sliding contact between shaft and oil seal at high speed and high temperature.The circumferential velocity of the shaft is also a key factor affecting the sealing effect. The greater the contact pressure between the lip of the oil seal and the shaft surface, the higher the relative motion speed, the faster the temperature rise caused by friction, and the higher the temperature will be. As a result, the lip will be worn, burned and chapterized, causing the seal failure and shortening the service life of the oil seal.
(2) Shaft wear
Due to long-term use, of the reducer shaft seal wear out-of-tolerance, some severe cases, even a v-shaped grooves, once this groove is formed, the oil seal lip diameter and the diameter of axle interference quantity is small, the oil seal lip contact with axial pressure drop, the oil film oozes out easily from the trench, eliminates the skeleton oil seal sealing function;The surface roughness of the shaft has great influence on the performance and service life of oil seal.Rough too low, oil is easy to extrude from the sealing contact surface, so that the oil film thin, resulting in lip heating.The roughness is too high, and the lip is easy to be scratched after the shaft rotates at high speed, which makes the sealing surface become hairy, the friction moment increases, and the lip is quickly worn and causes leakage.
(3) Influence of eccentricity
Eccentricity refers to the difference between the inner circle of the lip and the surface of the shaft.It causes uneven contact between the oil seal lip and the shaft, so the radial compression force of the oil seal is not uniform, heating is not uniform, the wear of the lip is not uniform, making the oil seal easy to leak and damage.There are many reasons for eccentricity:
(1) surface eccentricity in shaft machining or eccentricity in bearing after installation;
The inner diameter and outer circle of the lip of the oil seal are different;
The installation hole (shell) of oil seal is different from the axis center.
(4) Influence of deteriorated oil
The modified oil contains a large number of small particles, most of which are oxides, harder than metals. Although the particle size is only 0.1~3 m, it is easy to suspend in the oil and circulate with the oil in the box. Once the oil reaches the lip of the oil seal, it will aggravate the wear of the lip and shaft of the oil seal.