Oil seal working principle and oil seal oil leakage measurements

I.Working principle of the oil seal:

1. In the free state, the inner diameter of the oil seal lip is smaller than the shaft diameter and has a certain amount of interference.

2. After installation, the interference pressure of the oil seal cutting edge and the contraction force of the self-tightening spring generate a certain radial pressure on the rotating shaft.

3. When working, the oil seal lip forms a sealing contact ring of 0.25 to 0.5 mm wide under the action of radial pressure.

Under the action of the pressure of the lubricating oil, the oil penetrates into the oil seal edge and forms a very thin oil film between the rotating shaft. The oil film is subjected to the surface tension of the oil to form a “new moon” surface on the outer edge of the rotating shaft and the oil seal cutting edge to prevent oil from overflowing and to seal.

II.Main factors causing oil seal leakage:

The tight seal of the oil seal is the main cause of oil leakage. When the shaft wears and forms a groove, even if the new oil seal is not sealed, the contact pressure of the oil seal lip and the shaft is lowered, and the interference between the diameter of the oil seal lip and the shaft diameter after installation is too small. The main reasons for analyzing the lack of sealing are:

1.Oil seal manufacturing quality is poor;

2.Poor quality of shafts or bearings;

3.Improper use and maintenance;

4.Improper installation;

5.Improper storage, adversely affected by environmental pollution.

III.Oil seal is not tightly sealed and leaks oil:

Measurements are divided into:

1. Master and identify the basic knowledge of counterfeit products, and purchase high-quality, standard oil seals.

2. When installing, if the outer diameter of the shaft diameter is low or there are defects such as rust, rust, burr, etc., use a fine sand cloth or oil stone to smooth it; apply clean oil or grease to the oil seal lip or the corresponding position of the shaft diameter. Apply sealant to the outer ring of the oil seal, wrap the key groove on the shaft with hard paper to avoid scratching the lip of the oil seal. Use a special tool to rotate the oil seal inward. Do not harden the hard seal to prevent the oil seal from deforming. Or the spring is broken and the spring is broken; if the lip is turned over, the spring is detached, and the oil seal is skewed, it must be removed and reloaded. It should be noted that when the shaft diameter is not worn and the oil seal spring is strong enough, do not tighten the inner spring without authorization.

3. Some working conditions are bad, the temperature difference between the environment is large, the dust is too much, and the vibration of the machine is frequent. When the mechanical force of the machine is constantly changing, it is necessary to check, maintain and maintain.

4. If the shaft diameter and bearing wear are serious; oil seal rubber aging or spring failure, etc., repair and replace the corresponding parts in time.

5. For abnormal heating components or assemblies should be promptly eliminated; avoid mechanical overspeed, overload operation, to prevent oil seal lip temperature rise, rubber aging, early lip wear and so on.

6. Always check the oil level of the engine oil. If there are too many impurities in the oil, replace the new oil with the alloy powder and metal iron filings. The oil brand and quality should be changed according to the season requirements.

7. Oil seals that are not used temporarily should be kept in a safe place to prevent oil, dust or sun exposure.

8. When the shaft diameter is worn into a “V” shaped groove, so that the new oil seal lip and the shaft contact pressure can not be used to seal the oil, the oil seal displacement method can be used to make up.

tags:Vacuum Pump Oil
Edited by Catherine Qin / EVP Vacuum Solution

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