Posted to News on 10th Jul 2009, 13:08
High-precision electric linear actuators use linear motors
Festo is introducing what it describes as an entirely new class of electric actuators, based on very high-performance linear motors. The first product in this class is the ELGL-LAS, an ultra-precise linear motor axis with an air bearing, which is available for immediate delivery. Subsequent products, due to be launched progressively throughout 2009, include three types of electric cylinder, all featuring patented tubular motor technology.
Nigel Dawson, Festo's Drives Manager, states: "Festo's entry in the linear motor-based actuator market will hopefully cause people to re-evaluate their opinions about this type of technology. Until now, the use of linear motors for highly dynamic positioning applications, especially those requiring accurate repeatability, has proved something of a black art. We intend to change this, so that system designers eventually come to regard our linear motors as just another actuation technology choice. To bring this about, we effectively had to reinvent the linear motor, to come up with a tubular design that can be integrated in actuators with the same form factors as our 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 controlled independently on the same bed. 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 bearing minimises friction in the guide components, making lubrication and routine maintenance unnecessary.
Six models
At launch, there is a choice of six ELGL-LAS linear motor axes; one model has a standard stroke length of 1m, while the other five models provide 2m stroke lengths and offer a variety of different acceleration, speed and thrust ratings. The most powerful 2m axis can handle acceleration rates of up to 50m/s2, speeds as high as 4m/s, and can produce a continuous force of 349N and a peak thrust of 463N. All six models have a very high repetition accuracy of +/-0.01mm. The 2m models are available ex-stock; Festo will also produce models with stroke lengths up to 6m to special order.
ELGL-LAS linear motor axes are suitable for applications that demand high positioning accuracy and stiffness. Typically these include electronics assembly, semiconductor manufacturing, medical scanning systems and small parts handling systems. The axes' air bearings are also claimed to make them relatively impervious to dirt, allowing them to be used as transport mechanisms in dusty environments, such as the woodworking industry.
Festo's ELGL-LAS linear motor axes have similar form factors to the company's pneumatic linear actuators, making it simple for designers to mix and match different drive technologies to create task-optimised automation. The company produces a wide range of accessories for the ELGL-LAS axes, including controllers, limit switches, mounting brackets, cables and 'energy chain' cable carriers holders to simply this task further.
Follow the link for more information about the ELGL-LAS linear motor axis.
