Stiffness (Linear Guide)
The stiffness of a linear guide describes its resistance to elastic deformation under load. For roller guides it is significantly higher than for ball guides due to line contact, and is decisive for the achievable machining accuracy.
Definition
Stiffness is the ratio of applied load to resulting elastic deformation (N/µm or kN/mm). High stiffness means: for a defined force, the system deforms only minimally. In linear guides, a distinction is made between stiffness under normal loads (perpendicular to the direction of travel) and under tilting moments. Roller guides with line contact achieve approximately two to three times the stiffness values of comparable ball guides — at the same installation size.
Influence on Machining Accuracy
Low stiffness leads to position-dependent displacement of the tool under cutting force, impairing the dimensional accuracy of the workpiece. In machine tool engineering, high guideway stiffness is therefore a key criterion. Besides the rolling element geometry, preload, number of carriages, rail spacing, and assembly forces also influence the system stiffness.
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