As production rates and quality standards continue to increase, manufacturers require motion control solutions that effectively perform at higher speeds, and provide better accuracy, simpler installation, and higher efficiency without increasing costs or maintenance requirements. Significant advancements in electric actuation technology provide optimal motion control in these demanding applications.
By offering superior repeatability, accuracy, greater control, and easy installation, electric actuators provide improved performance and better efficiency than hydraulic or pneumatic alternatives. Not only do electric actuators deliver enhanced performance capabilities, but they also operate at a fraction of the cost of fluid-powered actuators.
Advanced electric actuators also offer multiple components integrated into a single package. This may be the integration of the motor with the mechanical actuator or a complete integration of the motion controller, motor amplifier, motor, and actuator. With a single device housing the power and control components, combined with the electric actuator, these fully integrated products eliminate the need for separate amplifiers in electrical cabinets, and provide a powerful solution in a smaller, more compact package. By utilizing integrated actuators, manufacturers can achieve greater control and distributed motion while still reducing operating expenses.
Electric vs. Hydraulic and Pneumatic Alternatives
In manufacturing today, there is a strong drive toward actuation solutions that operate with greater efficiency. Electric actuation technology has met these requirements and has redefined motion control standards with robust actuator designs and sophisticated features. Electric actuators offer performance capabilities that pneumatic and hydraulic actuators cannot equal.
Electric actuators provide the consistent, reliable performance necessary for a wide range of industrial applications, ranging from injection molding and motion simulation, to process control. In process control applications, the ability to provide repeatable, accurate positioning, even with rapidly changing set points, allows electric actuators to offer accuracy far superior to their hydraulic and pneumatic counterparts.
For demanding applications, electric actuators equipped with roller screw technology offer advanced performance capabilities. A roller screw is a mechanism that converts rotary torque into linear motion, similar to ball or acme screws. Electric actuators equipped with roller screw technology provide the longevity required in applications with higher cycle rates. The higher load capacity and rigidity of planetary roller screws makes them ideal for pressing applications requiring continuous force. The planetary design of roller screws allows them to operate at higher rotational speeds than other screw technologies, making them the ideal solution for high-speed applications.
Fluid-powered actuators do not possess the same capabilities inherent to electric actuators. Since they rely on compressed fluids for operation, hydraulic and pneumatic actuators lack the ability to consistently provide accuracy and repeatability.
In addition to positioning deficiencies, hydraulic actuators introduce other hazards to an application. By using flammable liquids under high pressure to provide motion, hydraulic actuators create a dangerous environment. Leaks that develop in high-pressure, high-temperature systems create safety risks for operators and other individuals in the vicinity of the application.
The cost of power is continually increasing, and rising electricity costs are concerning many companies. Compared to fluid-powered solutions, electric actuation technology is significantly lower in cost to operate, yet provides higher-quality motion control.
Due to the high cost of producing pressurized air, a pneumatic actuator can require double the energy cost of an electric actuator that is performing the same operation. Additionally, the cost of air leaks, which are typically present in pneumatic systems, is substantial. An air leak measuring 0.25" in diameter can result in over $9,000 of wasted energy costs in a year. Similarly, due to low efficiency in hydraulic systems, replacing a hydraulic actuator with an electric actuator can save facilities 60 percent in energy costs.
Hydraulic and pneumatic actuators require the addition of an air compressor or hydraulic power packs to provide the pressurized fluid essential for operation. These devices carry high procurement costs, take up valuable floor space, and are labor-intensive to install. Comparatively, electric actuation systems require less space and installation is greatly simplified.
Another, and perhaps the most important disadvantage to fluid-powered systems is their effect on the environment. Many hydraulic fluids are considered hazardous waste, creating high costs and logistical issues for disposal. These materials are hazardous to the environment if leaked, which can damage their surroundings and contaminate the product being manufactured. They also pose a health hazard to those exposed to them. Compressed air can cause similar issues. Moisture in the air can damage equipment and products, causing mold and other contaminants to be dispersed into the atmosphere from leaks or exhausts. In addition to equipment and product damage, this can also cause serious health and safety risks for those involved.
Along with reliable, precise performance and increased efficiency and costeffectiveness, electric actuator solutions offer complete integration of motion control system elements. This allows for greater flexibility in motion control applications. These sophisticated actuator solutions integrate power, control, and actuation mechanisms, offering solutions that provide position, velocity, and force control from a single source.
Integrating electric controls and power circuitry within the actuator provides a system solution that can be distributed, offering the highest degree of flexibility in a motion application. This complete solution eliminates dependency on external power amplifiers, controls, and expensive cables, as the actuators operate without a stationary electrical cabinet. This provides greater variability in positioning the actuator within the application, and allows for easy installation within applications that have limited space available. These integrated actuators also are ideal for mobile device applications that operate using batteries or DC power. Size and weight are minimized and all required control elements reside on the actuator.
Advancements in electric actuation technology continue to expand the range of capabilities electric actuators offer, allowing increased compatibility with diverse industry applications. With their high-quality performance, integrated solutions, efficiency, and environmentally friendly operation, electric actuators continue to replace fluid-powered technology, providing an optimal solution in motion control.
This article was written by John Walker, Vice President, CSM, at Exlar Corporation, Chanhassen, MN. For more information, Click Here .