Plastic bearings cut wear and tear

Tom Shelley reports on the latest advances in polymer bearings for linear systems, and the results of a recent competition to showcase their usefulness The latest polymer bearings suffer a third less wear than their immediate predecessors and 15% less friction. Such materials greatly enhance reliability and reduce costs in an increasing number of applications, as has just been illustrated in the just held Manus competition, which had 42 entries, all of them innovative, even though it was restricted to the UK and Republic of Ireland. The newest material has been designated iglidur J200 by makers igus, and advances on its immediate predecessor iglidur J. Applications include a new Drylin W double rail system with square cross section rails instead of round. The bearing material runs inside round housings in the carriage, which can still pivot about the rail. Advantages of the square cross section include the ability to increase clearance on one side, to allow the introduction of a controlled amount of compliance, not possible with a circular rail inside a circular housing. The winner of £2,500 and the 'Gold' award in the Manus (which is Latin for hand) competition was Copley Motion Systems LLC for their tubular linear motor. Igus polymer bearings product manager, Matthew Aldridge, told Eureka that it used a single iglidur L100 tubular polymer bearing for the whole length of the motor, which would have been impossible to devise using any other technology. This greatly reduced their costs. The motors use electronically controlled electromagnets acting on thrust rods that are filled with a succession of permanent magnets. The invention of Hugh-Peter Kelly, they have been featured in Eureka several times, including once on the cover. The company is based in Basildon. The winner of £1,000 and the Silver Award was General Vacuum Equipment based in the North West of England for its use of polymer bearings in its GVE Vacuum metalliser to coat films. Previously, the company used steel backed PTFE bearings which had to be greased either every week or in some cases every day. Replacement with iglidur Z has totally eliminated the need for grease lubrication maintenance. £500 and the Bronze Award went to Wolfe Designs, also based in the North West of England for using iglidur X and iglidur Z to replace steel needle roller bearings in its patented scissor lifts. These have neutral buoyuancy, with springs compensating for weight so they can be raised using one hand. The lifts are made of aluminium and weight is crucial, and Mr Aldridge is convinced the project would have stopped if the company had not discovered the polymer bearings. The judging of the competition was led by Professor John Hetherington, Head of Engineering Systems at Cranfield University. The plastic plain bearings used did not have to be ones made by igus for the purposes of the competition but most of them were. igus (UK) Pointers * Latest iglidur J200 bearing material for Drylin W two rail slides wears one third less and has 15% less friction than its iglidur J predecessor * A just held competition has produced a number of commercial product designs that depend on polymer plain bearings either to keep costs down or to be able to function at all