No access! Seals: the guardians for bearings and housings

Seals are veritable superheroes! They protect the bearing and housing by retaining the lubricant in the bearing. This prevents the ingress of damaging environmental influences such as dirt particles, drafts or humidity. This is extremely important, as these influences impair the lubrication and the running characteristics, thus rendering the bearing unit unusable. The use of suitable seals provides for reliable, long-term protection and extends the service life of the bearing. However, when selecting the correct part, a few important things need to be taken into account to ensure that the seal can perform its task reliably.

What types of seal are available?

First of all, it is necessary to determine for which bearing unit the seal is required. There are various types of sealing rings, which differ from each other with regard to their size, material and design. Shaft seals consist of a metal housing and a rotating internal sealing lip that minimises the egress of lubricants out of the bearing. Rubber seals, on the other hand, are generally installed in front of housing units and prevent the ingress of foreign matter.

Which materials are used to manufacture sealing rings?

Not only the choice of the correct model but also the selection of the sealing material is essential for comprehensive protection of the bearing. The correct material depends on a number of different factors such as rotational speed, temperature (fluctuations), humidity, the lubricant used and the level of pollution in the immediate environment. Some materials are unsuitable for certain areas of application. The sealing lips of radial rotary shaft seals are often manufactured using types of rubber such as NBR (nitrile butadiene rubber) or FKM (fluoro-rubber compound). The most widely known example of the latter is the Viton brand. NBR excels, above all, due to its elasticity as well as its oil and grease resistance, making it interesting for diverse lubricants used in bearings and housings. However, this material is less able to withstand intense heat exposure. NBR is the most commonly used material for sealing rings. FKM designates a group of various types of rubber. These possess a high level of thermal stability, which relates to their resistance to both high and low temperatures. Hence, they are particularly in demand for applications that require thermal stability.

Which other configurations are available?

The standard shaft seal has a single lip. There are, however, shaft seals available that have an additional lip. This forms a reliable seal between the internal and external areas of the bearing or the housing. An optional version with an additional spring guarantees uniform loading over the entire circumference of the seal.

In the PICARD online shop you will find an overview of all the seals in stock, including special versions, as an individual menu item on the home page.