Festo has unveiled an entirely new class of electric actuators, based on very high performance linear motors. The first product in this class is an ultra precise linear motor axis with an air bearing, which is available for immediate delivery. Subsequent products, due to be launched progressively throughout this year, include three types of electric cylinder, all featuring tubular motor technology.
According to Festo’s Drives Manager, Nigel Dawson, the use of linear motors for highly dynamic positioning applications, especially those requiring accurate repeatability, has proved something of a black art. Festo intends to change this, so that system designers eventually come to regard linear motors as just another actuation technology choice. To bring this about, Festo has come up with a tubular design that can be integrated in actuators with the same form factors as the company's pneumatic products.
Festo’s new ELGL-LAS linear motor axis employs a magnetically preloaded air cushion bearing to ensure very precise positioning and excellent linearity. The motor is a conventional linear synchronous design; the stator takes the form of a fixed bed, and the windings in the moving carriage are fed with drive signals from the motor controller. The carriage features an integrated displacement transducer to provide digital position feedback to the controller, and up to three carriages can be used on the same bed and controlled independently. The carriage also contains a series of embedded permanent magnets to provide an integrated locking brake function – the carriage is only free to move when the air cushion overcomes the magnets’ attraction to the fixed bed. Furthermore, the use of an air cushion bearing minimises friction in the guide components, making lubrication and routine maintenance unnecessary.
At launch, there is a choice of six ELGL-LAS linear motor axes; one model has a standard stroke length of 1 metre, while the other five models provide 2 metre stroke lengths and offer a variety of different acceleration, speed and thrust ratings. The most powerful 2-metre axis can handle acceleration rates of up to 50 metres/second/second and speeds as high as 4 metres/second, and can produce a continuous force of 349 N, with a peak rating of 463 N. All six models have a very high repetition accuracy of ±0.01 mm. The 2-metre models are available ex-stock; Festo will also produce models with stroke lengths up to 6 metres, to special order.