Prevention of Rubber Oil Seal Failure

1. Quality inspection of the skeleton oil seal When working, the radial force of the oil seal lip on the shaft causes an oil film with a thickness of about 2.5mm between the interfaces, which is the essence of the skeleton oil seal's sealing effect. First of all, check the appearance quality, the surface of the oil seal must be smooth and clean, free of defects such as burrs, cracks, bubbles, missing corners and impurities embedded; the edge of the oil lip is sharp, without gaps, burrs and unevenness; the contact between the lip and the shaft The width is generally 0.13 to 0.5mm, and the optimal width is 0.25mm; the bonding between the rubber and the reinforcement ring should be tight and no loose, the reinforcement ring should not be displaced, and the inner and outer surfaces should not expose iron; the embossed characters on the oil seal plane indicate“Shaft diameter×outer diameter×high”, manufacturer name and trademark, the handwriting should be clear. Secondly, measure the size of the oil seal with a vernier caliper, and it is best to use a standard plug gauge to measure the inner diameter to check whether the tightness is appropriate. If the inner diameter of the oil seal is greater than 30-90mm, the tolerance is -1.0-+0.7mm; if the height is greater than 4mm, the tolerance is -0.3-+0.40mm. According to the needs and conditions, the oil resistance test can be carried out, at (70±5) After soaking in No. 25 transmission oil at ℃ for 24 hours, the weight change should be -3% to +5%;±5) After soaking in the mixture of No. 120 gasoline (75%) and benzene (25%) at ℃ for 24 hours, the weight change should not exceed +20%. According to the requirements of the manufacturer, the oil seal edge should have an appropriate amount of interference with the matching journal. If it is too large, it will affect its service life, and if it is too small, the sealing performance will deteriorate. 2. The main points of replacing the oil seal or shaft parts and refueling (1) Before installation, the appearance of the oil seal should be carefully checked according to the regulations. The edge and outer surface of the oil seal lip must be coated with clean oil, and a special tool should be used for press fitting. Make sure that the tool is perpendicular to the plane of the seat hole of the body, and the oil seal should be press-fitted to the seat hole evenly and orderly to avoid crooked or Excessive force may damage the oil seal. (2) When measuring the diameter of the oil seal edge, it is not necessary to remove the spring, but carefully arrange the oil seal by hand to make the inner ring as smooth as possible. You can measure several positions and take the average value. When measuring, the force should be appropriate, and the deformation should not affect the measurement. (3) There should be no burrs, sharp edges, etc. on the journal or the chamfer of the seat hole matched with the oil seal. (4) When overhauling the body, it is necessary to install new shaft parts, pay attention to whether the oil seal spring is in good condition. The shaft is oiled, and it is best to install it while rotating to prevent the oil seal from being damaged. (5) For the overhauled engine, in principle, all the oil seals on the body should be replaced. The aging of the oil seal is difficult to distinguish with the naked eye. It is a wise move to replace all the oil seals when the engine is overhauled. (6) It is sometimes difficult to judge the oil leakage at the lip and outer circle of the oil seal. In this case, the engine can be turned off. After it has completely cooled down, dip in an appropriate amount of gasoline to clean the oil seal and its surroundings at the suspected point of leakage. After the gasoline has evaporated, evenly spray the leakage with chalk dust. Restart the engine and observe carefully. It will be obvious that there is leakage between the oil seal lip and the journal, or the oil seal and the seat hole. If there is leakage at the lip, in addition to observing whether the oil seal lip is defective, it is also necessary to carefully check whether there are scratches, spots, burrs, etc. on the journal. Apply glue to the outer circle of the oil seal and the inside of the seat hole, and then use special tools to carefully press it for emergency use. Company website: https://www.orksealing.com/