What are the types of ball screw seals?

In most applications,the best way to protect ball screws from contamination is to use ball screw wiper on each end of the ballnut.Manufacturers use different terms to describe the various ball screw sealing options,but most offer 3 basic types of seals:non-contact,full-contact and high performance versions.

●Non-contacting ball screw seals

Non-contact seals leave a very small gap between the seal and the ball screw shaft;the most common design is the plastic labyrinth seal.The lack of contact between the seal and the ball screw shaft means that these designs do not increase friction and running torque.However,they can allow smaller particles and fluids to enter the ballnut,so they are primarily used in environments where contaminants are present in the form of larger solid particles.

Labyrinth seals leave a slight gap between the seal and the ball screw shaft,so they do not increase friction or drive torque.

●Full-contact ball screw seals

There are several forms of seals that make contact with the outside diameter of the ball screw shaft.The simplest is the brush seal.While brushes do not maintain a tight,continuous seal against the ball screw shaft,they are very effective at wiping or brushing off larger contaminants and preventing them from entering the ballnut.Brushes are often used in combination with other types of full contact seals,such as lip seals or segmented seals with preloaded "fingers"

Both lip seals and segmented seals are designed to be in full contact with the raceway of the ball screw shaft,providing excellent sealing against fine particles such as ceramic dust and liquids.Segmented seals typically use a spring mechanism to preload the protruding"finger"on the ball screw shaft.Lip seals are molded to match the profile of the screw cross section,ensuring no play between the seal and the ball screw shaft.

Brushes are a good choice when the main contaminant are larger particles(such as wood or metal chips).

The sectional wiper uses a circular spring to ensure that the protruding "finger" remains in contact with the ball screw shaft.

The internal profile of the full contact lip seal matches the cross-section of the ball screw shaft exactly.

It is important to note that while full contact seals offer the best protection against fine particles and fluids,they do increase friction and drag torque,which should be taken into account when sizing and selecting motors.This additional friction can also lead to heat generation,which can affect lubrication.

●High-performance ball screw seals

Each manufacturer has its own"high performance"seals or special condition seals.These range from double and triple-lip seals,to combinations of two or more seal types,to full-contact seals designed for low-friction operation.While standard ball screw seals are typically made of Viton,manufacturers offer other materials,such as EPDM,that can withstand extreme high and low temperatures and are resistant to specific chemicals.

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