With the ever increasing drive to find greener, more energy efficient solutions for actuation, electric cylinders are fast overtaking hydraulic cylinders as the choice for motion control applications. In addition electric actuators make fewer mechanical demands and this simplifies machine design, operation and maintenance.
By eliminating the need for oil, Exlar, manufacturer of electric servo actuator systems, delivers an environmentally friendly solution that often outperforms the traditional hydraulic system. “Unlike conventional ball screw actuators, Exlar electromechanical actuators are engineered around planetary roller screw technology. The only true replacement to hydraulic cylinders, these roller screw actuators offer a much longer product lifespan than ball screw actuators, making them an attractive motion control solution,” explains Kevin Lombard, general manager of Tectra Automation.
Exlar’s planetary roller screws are capable of 17 t of equivalent force, have strokes of up to 1,2 m and frame size of up to 216 mm. The screws have an outer nut, which is connected to an inner screw by a set of three or more planetary roller screws. By driving the outer or the inner using a servomotor, very high linear forces can be transmitted and high speeds and unparalleled accuracy are achieved.
Many applications use two parallel linear actuators. However, controlling two hydraulic or pneumatic cylinders at the same speed, pressure and position is very complex. A servomotor makes it easy as one is set one up as a master and the other is commanded to follow. The servomotor contains an encoder, which enables the user to pick up the position to five micron accuracy. Thus electrical solutions are preferred in applications that require high accuracy because they are easier to control than hydraulic systems.
Servo electric systems can be configured to draw no power during stopped motion, as opposed to hydraulic systems that need pressure and power to retain position. This contributes to their energy efficiency. “Servo electric systems offer at least 80% efficiency compared to 50% at best in hydraulic systems. This 60% energy saving can fund the complete retrofit of a hydraulic system to electric. We supply them to customers building motion simulators, for mine vehicles, and into the petrochemical industry for opening and closing precision valves,” says Lombard.
Electric cylinders also offer other important benefits:
* No waste such as hydraulic fluid to dispose of.
* Reduced maintenance as electric actuators have no oil hoses or seals to leak and repair or hydraulic fluids that need replacement.
* Reduced risk as there are no potentially dangerous high pressure oil leaks or flammable oils as typically found in high temperature applications.
* A smaller footprint as there are no hydraulic power packs and reservoirs.
* Quick-connect cables for faster and easier installation.
* Simpler tuning and axes that are easier to synchronise.
* Straightforward cost installation analysis compared to the cost analysis of plumbing a hydraulic system.
* Lower noise levels of typically 30%.
* Reduced stress on machine parts due to the precision and control of electric servo driven systems, and better load control that results in longer tool life.
* Higher cycle rates through shorter reaction times.
Exlar actuators are suited to a broad range of mobile and harsh environment applications in industries such as medical assembly, machine tools, plastics, glass, textiles, military, assembly, and food and beverage. “Some recent applications where these actuators have been successfully used include a paper mill, a hydroelectric generation dam and a coal diverter gate,” concludes Lombard.
For more information contact Kevin Lombard, Tectra Automation, +27 (0)11 971 9400, [email protected], www.tectra.co.za
| Tel: | +27 11 971 9400 |
| Fax: | +27 11 971 9440 |
| Email: | [email protected] |
| www: | www.boschrexroth.africa |
| Articles: | More information and articles about Tectra Automation |
© Technews Publishing (Pty) Ltd | All Rights Reserved
printer friendly version