Electric rotary actuators drive components rotationally via electromagnetic power from a motor. They typically provide control and indexing capabilities to allow multiple position stops along strokes. The rotational element for electric rotary actuators can be either a circular shaft or a table. Circular shafts often include keyways while tables provide a bolt pattern for mounting other components. Both single and double shafts are available. Important dimensions include shaft or table diameter and shaft length or table height. The length of the shaft is measured from the body of the actuator. The table height or thickness does not include the actuator body. With some electric rotary actuators, the angle can be adjusted via screws or other stop adjustments. With other devices, the angle can be adjusted on both ends of the angular stroke. Special features include cushioning to soften stops, position feedback devices such as encoders and potentiometers, and magnetic bands that can be read by a switch.
Performance specifications for electric rotary actuators include supply voltage, repeatability, maximum torque, load capacity, linear stroke, operating temperature, and rotation angle. Supply voltage is the nominal voltage supplied to the motor. Repeatability is the degree to which a position can be duplicated. Maximum torque is the required range of torque output. There are two types of load capacity: axial load capacity and radial load capacity. Axial load capacity is the required axial or thrust load capacity of the output shaft or table. Radial load capacity is the required radial load capacity of the output shaft or table. Linear stroke, another performance specification, is the travel distance between the fully retracted and fully extended rod positions. Operating temperature is a full-required range. Rotation angle is the degree to which the actuator can rotate before reaching its travel limit. Typically, electric rotary actuators provide a maximum rotation angle of 45°, 90°, 135°, 180°, 225°, 270°, 315°, or 360°.
There are a variety of applications for electric rotary actuators. Some devices are designed for semiconductor manufacturing operations. Others are suitable for laboratory or medical use. Electric rotary actuators are used in the electric power industry, high-power switching gears, and packaging applications. In the automotive industry, manual and electric devices are used in car seats. Chrome-plated steel components are suitable for dry, indoor applications. Hybrid devices that use molded thermoplastic threads inside a metallic shell can extend actuator life. For applications that require rotational motion less than one revolution, electric rotary actuators can mount right at the equipment joint without taking up space with long stroke lengths.