How do Rotary Shaft Seals Work?

For engineers, the rotary shaft seal is not a new term. Rotary shaft seals are used in rotating parts where they help to prevent dust, water, dirt or other manufacturing particles from entering while maintaininga lubricantenvironmentin the rotary shaft.

Today, there is a wide selection of different designs available for use in different applications. These designs range from the traditional single and double lip elastomeric patterns to the modern PTFE designs. With such unique designs engineers find it easy to choose the best design that fit a specific situation

How do they work?

The rotary shaft seals’ unique designs can trace their roots from the elastomer component which is a metal insert and a spring. They were discoveredas a way to protect the bearings that helps inrotating of the shafts. The most important part is the areabetween the rotary shaft and the sealing lip edge.

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Rotary shaft seals work by clutching and retaining the lubrication element in a relatively thin layer that is found between the lip and shaft. The hydrodynamic action that result from the rotating shaft, creates a pumping action that helps in the sealing process. The spring on the shaft ensures that there is constant force towards the shaft thus levellingthe edge of the sealing lip to the required width.

The rotary shaft seals performs two important functions. First, it helps in maintaining the the lubricating system. Today, there are many different types of lubricants, but generally, the bearings are either oil or grease lubricated.

Secondly, the seal helps in the removal of the outward material which if left intact, can contaminate the lubricant system or damage the bearing. The level of contamination that needs to be removed depends on the nature of application. The most common factors that may lead to contamination include moisture, water, as well as dry materials such as sand, dirt, dust or small particles that may be generated from the manufacturing processes.

Rotary shaft seals work

Extending the seal’s life span

As an engineer, it is wise to master the tricks of extending the life span of rotary shaft seals. In this context, the ability of the rotary seal to maintain the lubricant factor in the system and remove any form of contamination will help extend the life component of the equipment. Similarly, this helps in maintaining the equipment by reducing its exposure to excessive frictional heat. The amount of frictional heat generated depends on the operating equipment. Internal pressure, type of lubricant, shaft surface, lubricant level, and the operating speed are just a few of the conditions that need to be checked regularly.

A good engineer should be able to tell that an increase in shaft speed may result to an increase in temperature in the sump. If not controlled, the increase will lead to increase in pressure inside the housing. The pressure will push the seal up and can cause untimely seal failure within no time. This will lower the life component of the rotary shaft seal.

Well, there you have it. An easy guide on how to use the rotary or radial shaft seals. It is easy to understand how the rotary shaft seals work but it is very important to know how to maintain them. This guide offers that in one package.