2.  PRESSURE: Oil Seals cannot endure a lot of pressure. You need to understand your machinery’s pressure capabilities and ensure you use the correct seal to withstand its pressure levels.

3.  TEMPERATURE: Similar to the pressure level, you need to know what temperature your machinery can operate at. You need to choose a seal that can withstand the heat or cold. PTFE have the widest rang of temperature, making them a safe option when you are uncertain of the range.

4.  SHAFT SPEED: As different shafts move at different speeds you need to consider the runout, the housing bore, and oil type being sealed. Ensure you select a seal that will not suffer from abrasions or spiralling.

5.  TYPES OF FLUID: Numerous oil seals can interact with oils, fuels, grease, water and more. However, know exactly what type of fluid the rotary shaft seal will be in contact with will ensure the longevity of the seal and the machinery.

6.  AMOUNT OF LUBRICANT: Seals perform better when lubricated but some machines will go through some dry spells. When this occurs using a leather or PTFE seal will be more beneficial as those type of seals can operate with less lubrication.

oil seal: how to install it correctly

Have you found the right oil seal for your application? The next step is a precise and error-free assembly, so that the oil seal is fitted without being damaged. If you are replacing an existing oil seal, you must first disassemble it with the same care and precision. In this article, you will read all about the different steps of an appropriate (dis)assembly process that contributes to optimal operation within the application.

Preparing the oil seal installation

Successful assembly first requires careful preparation. By following a few simple steps, you significantly increase the chances of a flawless assembly.

• When repairing, remove the old oil seal
• Select the correct oil seal size
• Check the oil seal
• Make a thorough inspection of surfaces in contact with oil seal
• Gather the right assembly tools

When repairing, remove the old oil seal

When it involves a repair, you must first remove the old oil seal. To remove an oil seal, it is important to use the right tools to avoid damaging the shaft and bore. The best solution is therefore to pull out the oil seal without having to completely dismantle the shaft. This can be done by making a few holes in the oil seal with an awl and a hammer. You can then use a hook to pull the oil seal out of its seat. You could also screw some screws into the holes and then slowly pull out the screws to extract the oil seal from its housing. Be careful not to damage the shaft or housing in the process.

If the shaft or housing gets damaged, it must be repaired. If you replace only the oil seal, but the shaft or bore remain damaged, then there is a chance of premature failure or leakage. You can easily repair the shaft, for example using an SKF Speedi-Sleeve.

Select the correct oil seal size

By first finding out the dimensions of the inner and outer diameters and the height of the bore, you have all the data for the correct size of the oil seal. Of course, the oil seal must also be able to withstand the pressure, temperature and medium it is exposed to within the seal during the manufacturing process. You can read more about this in our oil seal selection guide.

Check the materials and surfaces

Before installing the oil seal, it is essential that the oil seal, shaft and bore are not damaged. So, ensure that the surfaces the oil seal comes in contact with do not have any sharp points or burrs. The sealing lip is fragile, so any minor damage to it can cause leakage. Also, make sure the oil seal is clean. Even a small amount of dirt can cause a leak. Therefore, never use a pre-used oil seal for the assembly.

Use the right assembly tools

Assembling the oil seals is only possible with the right assembly tools. Due to the high risk of damage during assembly, it is important that you have tools with which you can work carefully. A bearing fitting tool set is ideal.

Provide the shaft with a ramped edge

Because the inner diameter of the oil seal must be stretched during assembly, it is necessary for the shaft to possess a ramped edge. The angle at which the ramped taper should be chamfered is 30° a 50°. If a flange or keyway is present on the shaft, it is best to use a bushing. The bore should also have a chamfer of 30° over at least 1 mm on the ramped side. Be sure to round off the edges properly in the process.

Prepare the shaft and prevent damage

A final step in preparation for assembly is to lubricate the shaft, sealing lip and bore with sufficient oil. This will allow the oil seal to slide more easily over the shaft and prevent dry running after the first rotation. Always use oil or grease that is compatible with the oil seal material. In addition, when sliding over the shaft, the oil seal comes into contact with the keyway, threads and grooves. By taping or covering the shaft at the location of these irregularities with oil-soaked paper, the oil seal can be mounted without damage to the sealing lip.

Assembling the oil seal

If you have prepared the assembly properly, then you are already largely on your way to a successful installation. The assembly of the oil seal itself is not complex. It is, of course, important that it is done properly in view of the longevity and reliability of the seal.

Installation of the oil seal

When you start the actual installation make sure that the oil seal is always facing the right direction. So, not facing outwards, but always with the spring facing the side of the medium to be sealed. The oil seal must then be pressed into the bore. Use appropriate tools, such as a bearing fitting tool set, to ensure that this is done evenly. The oil seal must never be forcefully hammered into the bore.

Assembly problems with the oil seal?

It is quite common for a groove to develop at the sealing lip at some point due to long-term use. As a result, the new oil seal no longer fits and seals properly. It is not strictly necessary to replace or repair the entire shaft. Take a closer look at the dimensions first. It may be possible to fit with a slightly narrower or wider oil seal next to the groove. Alternatively, using the Speedi-Sleeve repair kit, repair the running surface under the seal.

Below is a list of other problems you may encounter when fitting oil seals.

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Author

Stijn de Cnop

Product Manager of Sealing & Polymer Technology

Product Manager of Sealing & Polymer Technology

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