a Maintaining and Troubleshooting Lip Seals 
 
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Lip seals require very little specific maintenance.  The only normal maintenance they require is a sufficient amount of the correct type of lubricant.  Since lip seals that protect a bearing installation are normally exposed to the bearing's lubricant, their lubrication is applied without any additional maintenance.  Lack of lubrication may cause the seal's lip to directly contact the shaft, allowing friction to wear it away or tear it, causing leakage,  As you already know, lubricants that are incompatible with the material type of the seal's flexible components can lead to chemical breakdown of those components.

When working around an installed lip seal, follow these good practices:

1.  When painting a machine, be sure to cover the seal to prevent the paint from getting on the lip or shaft.

2.  While cleaning the shaft or surrounding area, don't let the seals contact any agents or fluids that could damage them.

3.  If changing the type of lubricant in a machine, check catalogs or other literature provided by the seal manufacturer to ensure that the new lubricant is compatible with any installed lip seals.  In fact, this recommendation should be extended to all non-metallic components installed in the machine.

When problem with lip seals do occur, the troubleshooting hints in the table below may help you identify the cause and corrective actions.

Troubleshooting  Lip Seals
Trouble Probable Cause Corrective Action
Excessive shaft wear Shaft material too soft Check hardness of shaft.  The hardness should be a minimum  of 30 on the Rockwell C scale.
Abrasive contaminants Check lubrication for presence of contaminants.  If found, determine source, rectify, and inspect bearing(s).
Excessive leakage of lubricant Insufficient or uneven contact between the sealing lip and shaft Check and correct shaft-to-tip clearance and ensure that runout is within acceptable tolerances for the type of seal installed.
Overstretched lip Properly install new seal.
Nicks, cuts, or tears in lips Properly install new seal.  Be sure to handle the seal carefully and to inspect the shaft for surface flaws.
Hardened, brittle sealing lip Monitor seal's operating temperature.  Install seal of a material type suited to the temperature.
Excessive pressure If practical, monitor lubricant's operating pressure in the seal's location.  Install seal of a design and material type suited to the pressure.
Damaged garter spring Replace spring or entire seal.  Be sure to avoid rough handling and installation procedures that will lead to spring failure.
Excessive wear of lip Rough shaft finish Check that shaft surface is smooth.
Lack of lubrication Check that lubrication system is functioning properly.
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The information for this article is pulled from Thomson Education Direct's self-study course covering Bearings and Lubrication. 
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