Shaft seals prevent lubricants from escaping the bearings and unwanted contaminants from entering machinery. They are vital components in mechanical equipment. Depending on your application, you will have chosen a suitable material. If you’re unsure about which material is right for you, Industrial Seals Expert offers guidance in that area, too.
Quality control: Out of the box, into the spotlight
Due to the delicate nature of some shaft seals, they should be handled with extreme care. When removing one from its packaging, avoid touching the seal with any sharp tools. Following careful removal, perform an inspection of the seal using a flashlight. This will reveal any discrepancies or deterioration that may have occurred in transit or storage. If your specific seal design requires a garter spring, you should check to be sure that the spring hasn’t been displaced out of its groove.
So, transportation packaging has been removed and the seal is showing no signs of wear and tear. The next step: preparing your workstation.
Preparing your workstation: Something in the air?
Industrial Seals Expert recommends a clean working environment when performing any installation or replacement. It is particularly important that the area is free from dust, dirt, and other contaminates. If any sediment comes into contact with the garter spring, seal, or the components that they protect, this could lead to premature failure and interrupted operation. The area should also be free from ozone-producing equipment, such as electric motors.
Temperatures between 5 and 40°C are suitable for a seal installation. Sealing materials will shrink or expand at certain temperatures. But sometimes, extreme temperatures cannot be avoided. If, for example, a seal is being installed in very cold locations, a heating gun can be used to warm the seal or the surrounding area.
An experienced installer with suitable tools, working in a clean environment, is recommended to ensure effective installation.
Installation: Set your seal in place
SKF recommends coating both shaft and seal with a thin layer of lubrication to help facilitate installation. This is essential for rubber–covered seals. For metal-cased shaft seals, the bore must be lubricated but it is not imperative that the seal is. Seals with an auxiliary, contacting lip can also be lubricated between the sealing lip and auxiliary lip to reduce friction during the installation. This does not apply to silicone rubber seals and seals with hydrodynamic features, other than SKF WAVE lip designs.
Use of a hydraulic press is recommended to position and hold the seal in place. If your seal is designed to sit flush to the wall of the housing bore, it should be installed at a right angle to the housing bore axis (see graphic below). Continue to apply pressure to the outside diameter of the seal to ensure it is held correctly in place.
When it comes to pressing the seal up against the retaining ring, seal installation tools such as pliers, shanks, and holders can help make things easier.
If your seal will be used in heavy industrial applications, it might be that it is surrounded by a metal case. This type of seal may not necessitate a special installation tool, nor would it be practical to use one. Instead, the metal-cased seal should be knocked in using a dead blow hammer and a wooden block which sits over the seal (see graphic below). This ensures full energy transfer with little impact. Apply hammer blows evenly and sequentially to prevent the seal from skewing or tilting as it is falling into place.
Visibility is key during any seal installation. You should be able to see the sealing lip at all times, ensuring is not damaged or bent backwards during the process.
One final consideration. If you are installing a seal onto a stepped shaft, an installation sleeve (see graphic below) must be used. Similarly, a thin-walled installation sleeve must be fitted around the seal to ensure it isn’t damaged as it passes over grooves, threads, and gearing.
Congratulations, you’ve installed your shaft seal. Now that’s complete, there are numerous things you can do to improve reliability and prolong shelf life. Check our Ask the Expert article to find out how to keep your seals in good condition.
It is also important to remember that our guide should be only used as a reference alongside manufacturers instructions. There are many types of shaft seals for different applications. Always contact your supplier if you are unsure.