What is a Rotary Shaft Seal?

Also known as an oil seal, shaft seal, elastomeric lip seal or any variation of these. It is a simple device for excluding dirt, dust, water or any other contaminant whilst retaining lubricant in rotary shaft equipment. These seals have been developed as a means of protecting bearings of rotating shafts.

How does it work?

The basic principle of sealing is straight forward – the flexible lip is held against the rotating part (usually the shaft) whilst the casing (or O.D.)is pressed into the housing or bore and holds the seal in place. The sealing lip needs some form of lubrication to avoid overheating and is usually energized by means of a garter spring.

How should they be ordered?

The easiest way is to know either the preferred manufacturers part number, the overall sizes of diameter, housing diameter and bore depth. Many of the old traditional names of seal manufacturers have either changed or disappeared in this age of acquisitions. If no longer available, we will advise you and offer a suitable alternative seal. Some designs conform to International Standards such as BS1399 and DIN3760 for metric sizes and seal types, but the majority have been manufactured to suit particular application, hence the enormous selection available. If you have any concerns in getting the correct seal CONTACT US,  we will help in your seal selection.

What materials are available?

Leather is probably the oldest of the lip materials still in common use, but the move towards mass production methods has seen a massive increase in the development of synthetic rubbers which lend themselves to accurate and repeatable injection and compression moulding. Nitrile is the most common elastomer for normal use, whilst Viton is replacing Olyacrylic and Silicone for high temperature application. Viton also has high resistance to abrasion and chemical attack making it a preferred elastomer. New developments in the use of PTFE for Rotary shaft seals has caused great interest particularly for high speed shaft rotation or poor lubrication applications.

Storage & Handling?

There is a British Standard laid down for the control of synthetic rubbers. BS3574 (1989) helps to determine shelf life- an example is for Nitrile and Polyacrylic are Group B rubbers which have a 7 year shelf life, whilst Silicone and Fluoroelastomers (Viton) are group C rubbers and have a 10 year shelf life. PTFE and leather do not come into this category but like others should be kept in the original packing for as long as possible away from direct light, dust and humidity. Finally protect the sealing lip – DO NOT hang seals on nails, wire etc

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