Electro-Mechanical Cylinders: The Better Alternative to Pneumatic and Hydraulic
When it comes to choosing a rod-style linear actuator for your application, three types of power sources are often considered; pneumatic, hydraulic, and electromechanical. Pneumatic and hydraulic actuators operate on differential fluid pressure whereas electromechanical actuators are driven by an electric motor. This technical brief will review the advantages and disadvantages of each option to help Design Engineers make the proper decision on which is best for both their project and company.
Pneumatic Actuators are typically used in applications which involve moving relatively light loads back and forth between its two end positions. Key advantages include low initial startup costs for multi-axis systems, high speed availability, block driving capability at the end positions, and short stroke length possibility. Key disadvantages include a continuous requirement for available compressed air, the potential for air leakage leading to inefficiency and sunk costs, no variable speed availability, minimal positioning accuracy at intermediate positions, and relative cost for stand-alone (single axis) applications. Based off of this, it can be concluded that pneumatic actuators are a smart choice for simple motion applications where force and speed control are not critical.
Hydraulic Actuators are typically used in applications which involve high forces, usually 25 times (or more) larger than pneumatic actuators of the same volumetric frame size. Key advantages include high force capability, high speed availability, block driving capability at the end positions, and overall good reliability. Key disadvantages include the requirement for a pump and compressor making start-up costs expensive, potential for liquid leakage and sunk costs, potential for environmentally hazardous situations due to oil spills, no variable speed availability, minimal positioning accuracy at intermediate positions, and the requirement for periodic maintenance on the system. Based off of this, it can be concluded that hydraulic cylinders are a smart choice for heavy duty applications in non-cleanliness critical environments where high forces are required and speed control is not critical.
Electromechanical Actuators are used for sophisticated machinery where the demand for complex control of position, velocity, acceleration, and force throughout the entire range of motion are needed. Accordingly, the one key advantage of electromechanical actuators is superior multi-axis coordination of the system with true motion control of each axis (using integral encoders), outputting multi-level positioning accuracy, synchronized motion availability, and speed/force control over the entire stroke range of the actuator. This level of controllability can often be used to eliminate the need for lengthy changeovers when switching from one product to another in applications such as labeling and packaging. Another key advantage involves energy consumption reduction, which is becoming increasingly more important for cost controls and environmental sustainability. Pneumatics and hydraulics have compressors/pumps which must constantly work to hold proper operating pressure. Additionally, to produce useable work, they go through a two-stage energy conversion process resulting in low overall energy efficiency. Electric actuators on the other hand only use power when they are performing work and convert the electric energy directly into mechanical power, which can yield efficiencies upwards of 90% for ball screw versions. Finally, electromechanical actuators offer a cleaner solution as they don’t have any possibility of fluid leakage and spillage.
Disadvantages of electromechanical actuators include no ability to block drive at end positions, therefore requiring the need for mechanical or proximity end switch incorporation, and limited speed availability based off the motor used.
In market segments such as industrial automation and machine building, where position, speed, and force are subject to variation and control, Design Engineers are migrating away from pneumatic and hydraulic actuators and moving more toward electromechanical actuators. Phoenix Mecano offers a broad range of electromechanical actuators ranging from 25 pounds drive force all the way up to nearly 6,000 pounds drive force per actuator, with synchronizing options available from stock. Our Application Engineering team is available to discuss your project needs, properly size your actuator, and help make you a shining star at your company. Contact us anytime at 301-696-9411 or go online to review our electromechanical actuator offering at http://www.phoenixmecano.com/products/mechanical-components/electric-cylinders-drives/