Custom plastic bearings enable novel actuator

Igus has injection moulded a special design polymer bearing sleeve to support the thrust rod in a unique linear actuator. This plastic tube boasts an unprecedented length and performance, which other injection moulders can not currently match. It is made from the Igus polymer material Iglidur L100, which has guaranteed low wear, heat resistance up to 100C and no need for lubrication. The ServoTube actuator from Copley Motion Systems (CMS) is an optimal solution for industrial position control. ServoTube is a cost-effective alternative to air cylinders in applications requiring greater flexibility and control. The integral, dry bearing from Igus provides a clean, quiet, maintenance free performance and has a life expectancy far exceeding typical ballscrew solutions. An injection moulder could not be found with a tooling process able to produce the 285mm long bearing, so CMS approached Igus, which agreed to help with the project. Igus examined the best way to injection mould the sleeve bearing at its test facilities in Cologne. New injection mould tooling was developed to enable moulding at six separate points around the top of the bearing rim. Iglidur L100 was the polymer material from Igus selected for the sleeve bearing. Bearings made from this material can run at high speeds and withstand very high temperatures. They are also lubrication free, resistant to dirt and have a long life expectancy. Michael Cowan, Managing Director at CMS, says the polymer bearing 'was fundamental to us achieving our very ambitious performance and cost objectives for the ServoTube actuator product'. The ServoTube linear actuator won first place in last year's Manus plastic plain bearing design awards, which sought to reward innovative applications using polymer bearings. The company was awarded the gold Manus trophy and a GBP 2500 cash prise at the awards ceremony in November 2004.