What is a linear actuator? How does a linear actuator work? What are the uses and applications of linear actuators? How do I know which linear actuator is the right one? At REGNER®, we design and manufacture some of the most advanced and finest linear actuators in the market, so over the last 25 years we have learned a thing or two about linear motion. Next, we give you answers to some of the questions you may have concerning linear actuators.
Advantages of using electric linear actuators
A linear actuator is essentially a device that produces motion in a straight line. Mechanical, hydraulic, pneumatic, and electrohydraulic actuators are all used, but electric linear actuators—that is, devices that transform electric power into a linear movement—are the most popular. The success of electric actuators is due to their unique characteristics:
- Quiet and clean
- Cost-effective and energy-efficient
- Safe operation
- Easy control and electronic programming
- Simple installation and assembly
- Compact dimensions
- No maintenance
Furthermore, actuators are highly configurable devices. Speed, stroke, dimensions or load, among other features, can be adjusted to fit virtually any application. Fields as diverse as industrial automation, construction, the automotive, household equipment or health care equipment industries, machine tools, and computer peripherals use electric linear actuators to generate motion.
How does an electric linear actuator work?
A gearmotor transforms electric power into circular motion. Motion drives a spindle to a nut, which is attached to a rod. The motion is thus converted from rotary (spindle) to linear (nut).
To make sure actuators can be used in all kinds of assemblies, they present different types of rod ends (mounting holes, clevis brackets, screws, t-slots). Actuators may also present integrated overcurrent protection systems that cut current off in case of obstruction or excessive load, and the device components are protected from dust or water with sturdy housings and reliable sealing. Connectors, cable lengths, and mounting brackets are all customized depending on the purpose of each specific actuator.
Motor position is one of the most relevant features in actuators. The motor can be installed perpendicular to the spindle axis (with an additional intermediate gear that transfers force) or in line to the spindle axis (hence in-line actuators). This configuration reduces the overall dimension of the actuator and is perfect for installations with space limitations and elegant designs.
How to choose the right linear actuator
Choosing the right actuator for an application enhances the final product value and increases efficiency while reducing costs. If you are unsure about which linear actuator to choose, consider each of the following elements.
- Force (load). The amount of strength (in Newtons) required for the actuator to work properly. It is determined by the weight of the object you are moving (that is, the load held by the actuator), the transmission angle, the torque, and the friction. It is extremely important to be precise in this point to optimize the configuration. Overestimating force requirements will result in a slower actuator, or an oversized one that will impact costs and weight. On the contrary, underestimating the requirements can cause overloads or a shorter service life.
- Speed. The rate at which the linear actuator must move (in millimeters per second). Additionally, force and speed are directly related to power (Power = Force · Speed), so based on these two values you can also calculate the approximate motor power you will need.
- Stroke. The distance that the load must travel, usually measured in millimeters. Stroke has a direct bearing on the overall dimensions of the actuator.
- Retraction length (center to center). The distance between the two mounting holes when the rod is completely retracted. This measurement is essential to plan the integration of the device into the assembly, and it must be established considering the length of the stroke.
- Power supply. Choose between Direct Current (DC) or Alternative Current (AC), and determine voltage (in Volts) and, if necessary, electric current (in Amperes).
- Duty cycle. The percentage of time in which the actuator can be active, relative to a whole period. For example, an actuator that is in motion for 2 minutes out of 20 has a duty cycle of 10 %.
- Environment. The actuator will need a greater or lower protection degree depending on its operating environment. A low ingress protection (IP) grade will be acceptable for indoor applications, while outdoor applications or environments exposed to dust or water will require a higher IP rating.
- Added features. Depending on the final application, an actuator should be equipped with extra features such as limit switches, position feedback devices, control boxes or controllers.
- Connectors and brackets. Cable lengths, connectors, mounting holes, rod end types, brackets, and housing colors must be specified to ensure perfect assembly integration.
- Assistance. If you still have any doubts or need further information, please contact us.