Kiss goodbye to cage-creep in linear guides

SKF claims to have cured the problem of cage-creep which can lead to unreliable performance of linear rail guides - or complete failures, in some cases.

Cage-creep occurs when the cage containing the guides` rolling elements edges progressively along the vee of the guideway. This is caused by uneven pre-loading or poor rail alignment, and is exaggerated when the guide is mounted vertically. The cage hits the end-stops of the guideway, causing the rolling elements to skid rather than roll, thus impairing their performance and shortening their lives.

The patented Anti-Creep System (ACS), developed by SKF Linear Motion, is said to eliminate the problem completely. The plastic moulding that forms the cage also encloses a small metal sprocket at its centre. Corresponding small notches are machined at the bottom of the guideway vees to mesh with the sprocket.

As the guideway moves, this arrangement creates a low-duty rack-and-pinion drive. A synchronised movement is created that optimises the cage position throughout the stroke. SKF claims that this ensures consistent positioning of the cage, and eliminates the need for resynchronisation and non-uniform preloads.

The ACS design is also said to do away with the need for end-stops and to make integrated designs easier.

The system has been designed around SKF`s LWRE modular range of precision linear guideways. It offers direct interchangeability with three standard cross-sections, from 18mm by 8mm, to 44mm by 22mm.