White Papers

Learn more at www.igus.com/drylin by Matt Mowry Product Manager, drylin ® linear systems, igus ® Inc. Linear plain bearings are becoming commonplace in today's manufacturing industry. As technologies and material sciences have advanced, so have the capabilities of linear plain bearings, particularly those made of plastic, such as the drylin ® series of self-lubricating linear bearings from igus ® . This whitepaper will compare how they outperform a competitive linear plain bearing technology, which uses a PTFE-based, bonded liner, in both wear and friction testing. Originally, linear plastic plain bearings were developed to replace recirculating ball bearings. Unlike ball bearings, plastic plain bearings are designed to run without maintenance or external lubricants, like oil or grease. Not only is the upfront cost per bearing lower, so is the overall cost of ownership. There are also technical benefits to plastic bearings, the main advantage being that they are self-lubricating. Since they do not require any external lubrication they are well suited for dirty or wet environments, and are also ideal for sensitive food or laboratory applications, as they eliminate the risk of contamination. They are lighter weight, able to withstand higher static and shock loads, are corrosion-resistant, and perform better than ball bearings in applications with high accelerations. drylin ® Plastic Linear Bearing Design drylin ® linear bearings are designed using dry-tech plastic composites from igus ® . These consist of a base polymer, reinforcing fibers, and particles of solid lubricants. The bearings are injection molded, homogenously blending the plastic material, and exhibit constant coefficients of friction and self-lubricating properties throughout their lifetime (see images below). As the bearing system begins to cycle, tiny deposits of solid lubricant are transferred into the microfinish of the shaft, lowering friction, increasing lifetime, and eliminating the need for additional external lubrication. The geometry of drylin ® linear plastic bearings also makes them unique. Grooves along the bearing's inner diameter serve two purposes. First, they minimize thermal expansion and result in a more tightly toleranced running clearance than a typical sleeve bearing. Additionally, they act as "dirt channels" in aggressive environments by allowing debris to pass easily through the system. drylin ® E7 plastic linear plain bearings vs. PTFE-lined plain bearings Microscopic view of igus plastic bearing material Cross section of igus plastic bearing Debris passing through the bearing's dirt channels

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