MOTION SYSTEMS HANDBOOK
Common linear-motion options in 2020 Typical linear-motion arrangements consist of rails or shafts, carriages and runner blocks, and some type of moving element. Engineers differentiate these systems by the type of surface interaction (sliding or rolling) and the type of contact points — as well as how the design’s rolling-element recirculation works if applicable. In fact, slides and rails are more advanced than ever, with advances in materials and lubrication setups (to help designs last longer in harsh applications), innovative rail geometries (to help designs withstand more misalignment and load than ever), and modular guide mounts (to boost load capacity and minimize deflection). One word of warning here: The term linear guide can refer to any one of several different component types depending on the context.
Unlike plain-bearing linear guide taxonomy (which is fairly consistent) the terminology for ball and roller linear guides is quite varied. That said, the term linear guide often indicates a standalone rod assembly, rolling-element slide, or other mechanism for guiding loads. In contrast, many (though certainly not all) manufacturers use the terms linear slide and linear rail to indicate linear-motion guide elements in builds complete with some mechanical drive. The term linear stage generally implies a design with linear-guide elements, a reinforced frame, and actuation components of some type — with or without motor. No matter the permutation, linear-motion rails, guides, and ways enable motion along an axis or rail either through sliding or rolling contact. Myriad moving elements can produce either sliding or rolling support. These include ball bearings, cam roller sliders, dovetail bearings, linear roller bearings, magnetic bearings, fluid bearings, X-Y
Shown here is a Cartesian gantry involved in the production of printed circuit boards (PCBs).
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DESIGN WORLD — MOTION
8 • 2020
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