There are several reasons to consider segmented-bearing technology. For example, conventional bearings tailored to unusual needs often take too long to get or cost too much. What is readily available often isn't quite right. And to top things off someone usually has to tear a whole machine apart just to replace an inexpensive bearing.
The features in segmented bearings overcome these hurdles. The bearings have a ball retainer assembled from several self-contained ball-retainer segments. Each segment includes at least one ball track with a load-bearing portion and a return portion. This provides greater design flexibility than traditional bearings because instead of selecting a traditional bearing from a list of industry-standard dimensions, designers can fit segmented bearings into their specific envelope.
Segmented bearings also simplify tooling requirements and reduce concept-to-production lead times by as much as 50%. The bearings can be molded with a two-part tool instead of multiple-slide-cam-action tooling. And the bearings can be assembled with simple in-and-out assembly tools instead of complex tools for handling multifaceted parts.
Segmented bearings also help reduce prototype costs because simple tooling reduces the potential for error. This reduces costs for tooling initiation by as much as 50%. Simpler tooling also lets designers experiment with a wide variety of materials and build bearings for harsh environments. The accompanying chart shows common segmented-bearing materials and their properties.
Segmented bearings are also easier to maintain than traditional bearings, which often require removing the bearing housing, other attached components, and the shaft and its peripheral components. In contrast, segmented bearings can be slid out of the bearing housing, disassembled for removal, and then reassembled on the shaft for reinstallation.
Segmented bearings are recommended for retained (nonpress fit) or light press-fit applications. The units can also be used as the core of steel-sleeve bearings for heavy press fits with housings, or in applications with bearings held in place by a setscrew.
This information supplied by Al Ng, Chief Engineer, Linear Bearings Strategic Business Unit, Thomson Industries Inc., Port Washington, N.Y.