Exlar: Power and efficiency over high quality
Exlar Electric Roller Screw Linear Actuators and Rotary Servo Motors, designed and manufactured by US private company Curtiss-Wright, are an ideal solution for a wide range of Linear and Rotary Movement Applications, specially where high power and big forces are required.
Exlar® actuators offer significant advantages to the performance of a machine with superiority in positioning, accuracy, repeatability, stiffness, space requirements, friction, efficiency, long life and maintenance. The quality and performance of our actuators and Roller Screws allow us to solve the most challenging, unique and critical customer applications. Compatibility with nearly any servo control allows Exlar® actuators to be used in advanced closed-loop Servo Systems. Most of these actuators operate for years before requiring maintenance, many in harsh environments operating 24 hours a day, seven days a week.
Exlar’s product portfolio covers a wide range of performance specifications and capabilities in high forces movement solution applications over automotive, packaging, food, oil and gas, power and process control and many other industries.
Curtiss-Wright is a technology driven, global leader in the design and manufacturing of Exlar® Roller Screw Linear Actuators, Rotary Servo Motors, and electronic products for motion control applications.
Exlar was founded in 1986 to develop a true electro-mechanical actuator to replace hydraulic and pneumatic cylinders. To meet this challenge, Exlar created a linear actuator which converts traditional rotary motion to linear motion based on a unique design where integrates a robust and efficient threaded roller mechanism into the center of a high performance brush-less servo motor. This combination resulted in an all-electric actuator which is extremely compact, yet delivers similar performance to a hydraulic cylinder. Exlar Roller Screw actuators provide forces up to 40,000 pounds force and linear speeds up to 60 inches per second, and a life expectancy 15 times longer than ball screw technology.
Exlar, excellence in actuation
The need for a better alternative: Electric Actuation
In a familiar industrial world with fluid power systems (hydraulics and pneumatics), Curtiss-Wright’s Exlar® Corporation recognized the need to develop a new and improved form of actuation. The new method would need to:
- provide better positioning performance
- obtain greater control flexibility
- eliminate fluid leaks
- improve energy efficiency
- maintain the robustness and reliability of existing technologies
Understanding the difference
Hydraulic Cylinders, while robust and reliable, require pressurized oil and significant maintenance to achieve consistent levels of positioning accuracy. Fluid leaks are common, causing both end-product and environmental contamination. Pneumatics also has advantages, but fail to provide a viable solution where positioning, stiffness, and accuracy are required.
Industry was ready for a cleaner, more efficient and more accurate solution.
The logic behind “all-electric” actuation
Since electrical power is readily available and is in fact needed to create fluid power, it seemed a logical place to start, developing an all-electric solution would:
- Eliminate the primary source of inefficiency: the conversion of electrical power to fluid power and then to the desired mechanical motion.
- Be easier to operate since control systems universally depend on electrical signals.
Evaluating the existing options, along with the advantages and disadvantages, was key to Exlar creating Superior Electric Actuation Solutions for linear and rotary motion.
Why to consider Roller Screw Technology
Roller Screw Basics
A Roller Screw is a mechanism for converting Rotary Torque into Linear Motion in a similar manner to Acme Screws or Ball Screws. Unlike those devices, Roller Screws can carry heavy loads for thousands of hours in the most arduous conditions. The difference is in the way the Roller Screw is designed to transmit forces. Multiple Threaded Helical Rollers are assembled in a planetary arrangement around a threaded shaft (shown in the picture) which converts the motor’s Rotary Motion into Linear Movement of the shaft or nut. This makes Roller Screws the ideal choice for demanding, continuous-duty applications.
Exlar Roller Screws vs Hydraulics & Pneumatics
In applications where high loads are anticipated or faster cycling is desired, Exlar’s Roller Screw Actuators provide an attractive alternative to the Hydraulic or Pneumatic options. They do not require a complex support system for valves, pumps, filters and sensors. Exlar units take up much less space and provide a long operating life virtually with no maintenance. Fluid leaks do not exist. Noise levels are significantly reduced. Additionally, the flexibility of programming the profiles and positioning dimensions are more than desirable in many applications.
As expected, with higher load capacities, the roller spindles provide many advantages. In many cases the estimated useful life of an Exlar Roller Screw system is of the order of 15 times greater than that of a Ball Screw with similar characteristics. On the other hand, the typical speed of the ball screw is limited to 2000rpm or less due to the interaction between the balls with each other during their recirculation. In contrast, the Exlar spindle rollers are fixed in planetary construction and there is no contact with each other, even working at 5000rpm, which allows to produce comparatively much higher linear movement speeds.
Exlar Roller Screws vs Ball Screws Performance
Loads and Stiffness: Due to design factors, the number of contact points in a ball screw is limited by the ball size. Exlar’s planetary Roller Screw designs provide many more contact points than possible on comparably sized ball screws. Since the number of contact points is greater, roller screws have greater load carrying capacities, plus improved stiffness. Plus an Exlar Roller Screw actuator takes up much less space to meet the designer’s specified load rating.
Travel Life: As you would expect, with their higher load capacities, Roller Screws deliver major advantages in working life. In many cases the Roller Screw will have an expected service life that is 15 times greater than that of the ball screw.
Speeds: Typical ball screw speeds are limited to 2000 rpm and less, due to the interaction of the balls colliding with each other as the race rotates. In contrast, the rollers in a Roller Screw are fixed in planetary fashion by journals at the ends of the nut and therefore do not have this limitation. Hence, Roller Screws can work at 5000 rpm and higher, producing comparably higher linear travel rates.
Roller Screw based electrical linear actuator, mechanical actuator, servo-motor and servo-amplifier and AC controller integrated.
Roller Screw based electrical linear actuator, mechanical actuator, servo-motor and servo-amplifier and DC controller integrated.
Roller screw based linear actuator, integrated motor and actuator in a single compact unit.
Universal solution for a multitude of rod-style actuator applications, up to 15 kN forces, 833 mm/s maximum speed, up to 1525mm stroke.
High forces linear actuator, up to 177 kN, maximum speed up to 1500 mm/s, strokes up to 2400mm, compatible with wide range of standard motors
EL Series of explosion proof actuators is deal for valve control, as well as many other applications in hazardous environments.
Electrical rotary actuator, mechanical actuator with and without geared output, servo-motor and servo-amplifier and AC controller integrated.
Electrical rotary actuator, mechanical actuator with and without geared output, servo-motor and servo-amplifier and DC controller integrated.
Brushless servo motor technology, high torque and small package size, continuous torque ungeared up to 69 Nm and maximum speeds up to 5000 rpm. Geared output up to 100:1
ER Series of explosion proof rotary motors and gearmotors are proper solutions for many applications in hazardous environments.