Linear motion guides are critical in XY positioning tables. But conventional linear guides often use fullball designs that remain in constant contact and generate friction and noise. A new type of linearmotion guide features quiet, low-friction operation in XY tables produced by Jet Edge, Saint Michael, Minn. They're supplied with Type SSR caged-ball guides from THK America Inc., Schaumburg, Ill.
In these guides, the balls are isolated in an elastomeric cage, avoiding constant contact. Caged balls do not weave from side-to-side in the raceway and are positioned uniformly through the load carrying zone, end cap, and return zone of the block. Eliminating metal-to-metal contact reduces heat, friction, and noise. Using ball bar analysis, Jet Edge confirmed significant noise reduction with these linear rails.
The rails also helped meet work-envelope requirements. The company offers more than 52 work envelopes of XY tables and deal with travels from 30 30 in. to 16 16 ft. THK rails meet these design requirements with only one or two pieces. Fewer seams in the rails reduce deviation in machine travel. The linear guide can also be easily replaced. Unlike previous designs, no inserts are required to slide or remove a bearing block from the rail.