Powering Ahead: The Evolution and Advantages of Electric Actuators

By Andrew Luthen

One of the most common components of mobile or industrial machinery is an actuator. There is a broad range of actuator applications, and each one requires a careful analysis of the working requirements in order to choose the best option. Traditionally, large load requirements have been handled by hydraulic actuators due to the power density that hydraulics offers. However, in recent years there has been development of electric linear actuators that can rival their hydraulic counterparts. It is important to consider the advantages and disadvantages when deciding to spec out an electric actuator over a hydraulic one.

Choosing between electric and hydraulic actuators involves weighing performance requirements, efficiency considerations, maintenance costs, and environmental factors. Electric actuators offer precision, cleanliness, and efficiency advantages suitable for many modern applications, while hydraulic actuators excel in high-force, rugged environments.

One key advantage of electric actuators is that they eliminate the need for hydraulic fluid, which means less maintenance and improved cleanliness. Also, they integrate well with digital control systems and can easily incorporate feedback mechanisms for precise control and monitoring. This makes them ideal for applications such as robotics, steering mechanisms, and precision manufacturing or material handling. Electric actuators are typically more energy-efficient than hydraulic systems, especially during partial load conditions where hydraulic systems may experience energy losses due to pump operation. Additionally, an electric actuator with a lower force rating can often handle the same load that a hydraulic actuator rated at a higher force can handle. However, hydraulic actuators typically can handle higher side loading than is possible with an electric actuator.

The two main types of electric actuators are linear and rotary. Focusing on linear actuators, you can choose between an acme screw or a ball screw, which is used to transfer the rotary motion of an electric motor to linear motion. Acme screws are generally more affordable than ball screws and can handle high axial loads. They exhibit a natural self-locking characteristic due to their thread angle, which prevents the load from back-driving the screw. They typically require less maintenance compared to ball screws, as they are less sensitive to contamination and wear. Ball screws are highly efficient due to their rolling motion mechanism using ball bearings, which reduces friction between the nut and screw threads. This efficiency leads to lower power consumption and heat generation as well as smoother and quieter operation. They offer superior positioning accuracy and repeatability, making them ideal for applications requiring precise linear motion control, such as in CNC machining or in agriculture to position and continually adjust row planters. Whether you choose an acme screw or a ball screw, any linear actuator can benefit from the use of a servo motor, which monitors the position, velocity, and acceleration using feedback sensors and employing control algorithms like PID. Developing a system that utilizes a PLC to control your electric actuator provides additional opportunities to support other implements and access to the latest technology, such as telematics and autonomy. While these technologies are available for hydraulic systems, they are implemented in the valves that control fluid flow, which adds an extra layer that creates more room for error and a delay in response time.

For years, the main limiting factor of electric actuators was that they were suitable only for low-force applications. Today, Quality Hydraulics can provide electric actuators with a wide range of power options, ratings up to 20,000 pounds of force, 78" stroke lengths, speeds up to 40 in/sec, 100% duty cycle, and an IP69K rating in certain models. Controls can range from basic input/output commands to CAN Bus control with feedback. With an increased focus on zero-emission standards and fully electric systems, many are finding that the switch to electric actuators from hydraulic is the next level of progression.

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