High-performance linear guides used in medical application

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Varian Medical Systems is using Schaeffler's KUSE six-row ball monorail guidance system on its patient couches, with no failures experienced in ten years.

High-performance linear guides used in medical applicationVarian Medical Systems (VMS) UK, which manufactures radiotherapy machines, is using precision linear guidance systems on its patient couches to help speed up and improve the safety and reliability of cancer treatment. Over the last 10 years, the linear guides have operated without any failures.

The guidance systems, supplied by Schaeffler (UK), are being used by VMS on the company's latest Acuity range of radiotherapy machines and Exact patient couches. VMS produces more than 600 patient couches each year in the UK. Each couch uses multiple Schaeffler KUSE six-row ball monorail guidance systems, which offer high accuracy, rigidity and load-carrying capacity. KUSE systems have a full complement rolling element set with integral lubricant reservoirs.

Derek Flanagan, Manufacturing Manager at VMS UK, comments: "Schaeffler has been supplying Varian for several years now and our working relationship is very good. Varian and Schaeffler have very similar cultures, in that both companies are always looking to continuously improve their products."

According to Flanagan, Varian specifies Schaeffler's KUSE linear guidance systems for patient couches because of their high rigidity, high static and dynamic load-carrying capacity, smooth running and good lubrication characteristics. He adds: "We also subject Schaeffler's linear guides to in-house tests, which involve the guides being extended to their maximum length and subjected to very high moment loads.

"With the guides in operation on the patient couches, the cancer patient sees benefits in terms of improved comfort, faster treatment cycles and quieter operation. Treatments that used to take 20 minutes, can now be completed in as little as two minutes."

Precision positioning

Medical staff see improvements as well, in terms of motion management. The linear guides enable more precise positioning of the couch, which helps to ensure that more of the healthy tissue is spared during the radiotherapy treatment process. Furthermore, the faster cycle time means that more patients can be treated, which should result in shorter waiting lists are reduced.

Flanagan says: "As the manufacturer of the couch, we see benefits in terms of product performance, reliability and safety. For example, we have not had a single failure of a Schaeffler linear guide in ten years. In fact, so pleased are we with the guides that we have awarded Schaeffler UK our annual Varian Supplier of the Year Award on seven separate occasions in the last eight years."

Schaeffler's KUSE system is available in various sizes, from 20mm up to 55mm guideway widths. The guidance systems are also available with Schaeffler's Corrotect anti-corrosion coating.

For more information on Schaeffler's range of linear guidance systems, go to or telephone the marketing department on +44 (0)121 351 3833 and ask for free copies of brochures LP7 and PMT.

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