- Oil seals can be used as dust seals, but when dust is serious or to protect other seals, special dust seals are often used.
- The dust-proof seal of hydraulic machinery is mostly rubber, the air-pressure machinery is mostly felt (square or trapezoid), the hydraulic cylinder for aircraft and cold zone work uses metal to deal with the icing on the outside of the piston rod, and the chemical sector also uses metal to prevent sticking on the piston rod.
- The square or trapezoidal dust ring belongs to the packing seal in the sealing mechanism. The dustproof ability is related to the tightness of the contact. The tighter the contact, the better the dustproof ability, but the greater the friction resistance. Wedge wipers are virtually indistinguishable from lip rings, relying on the contact force of the lip tip to scrape away dust and dirt. Its frictional resistance is small, but the angle between the lip tip and the shaft surface has a great influence on sealing and wear. When the lip tip is outward, the included angle can be satisfied as long as it is greater than 4°, and when the lip tip is inward, the dustproof effect is not good.
- The contact state of the lip and the shaft surface also directly affects the dustproof effect and the wear of the lip. Several common contact situations, among which the normal contact state, thin oil film, good dustproof effect, less wear, too tight contact and wide contact surface, change the contact angle, make the lip tip lift, not only poor dustproof effect, but also friction. The resistance is large, the contact of the lip tip is insufficient, and the friction is not large, but it cannot be dustproof; the contact angle of the lip tip is too large, the dustproof effect is short, and it is easy to wear and tear, which becomes the cause of serious oil leakage.
- Dust seals are extremely important for protecting critical hydraulic equipment components. The infiltration of dust will not only wear the seals, but also greatly wear the guide sleeve and the piston rod. The impurities entering the hydraulic medium will also affect the function of the operating valve and the pump. In bad cases, these devices may also be damaged. The wiper can remove any dust on the surface of the piston rod without damaging the oil film on the piston rod, which is also beneficial for the lubrication of the seal.