Linear actuators work by moving an object or piece of equipment in a straight line, moving an object extraordinarily accurately and repeatably if required. The first reason for designing a linear actuator into a system is for the necessity to move a payload in a linear fashion rather than a rotary one. As most conventional electric motors are rotary, a linear actuator is used to transform rotary motion to linear motion.
The electrical motor is generally connected to the linear actuator by a flexible coupling or a belt, enabling the motor to be mounted either axially or perpendicular to the linear actuator. Quite a lot of motor sizes might be mounted to these actuators depending on requirements.
Linear actuators have incorporated linear bearings that support the moving payload, as well as rotary bearings that help either the lead screw, ball screw or belt pulleys. This then allows them to operate as ‘stand-alone’ units, making them easy to mount into existing machines and eliminating the need to design/manufacture very costly custom parts. To extend the load capacity and stability of a linear actuator system, they can be paired up with the payload carried between them, resembling in an XY gantry style stage. In this case, a shaft or belt is commonly used to keep the 2 actuators in sync with each other.
Features of Linear Actuators
Linear Actuators have the following features:
Easy upkeep or upkeep free
Protection scores available for some models
Suitable for harsh environments
Rugged and reliable
Industries and applications for Linear Actuators
Linear Actuators can be utilized in various applications that require a load to either be lifted, lowered, pushed, pulled, rotated or positioned. Linear Actuators are utilized in industries together with:
Material dealing with
Types of Linear Actuators
Picking the correct type of linear actuator to your motion application can help you achieve the best results. Lead Screw Actuators, Ball Screw Actuators and Belt Actuators are three types of linear actuators that can be utilized in varied applications to produce motion.
A Lead Screw Actuator uses a plain screw/nut arrangement to translate the rotary motion from a motor to linear motion. A manually pushed screw or an AC induction motor are essentially the most commonly used strategies to supply the rotary motion, as they’re generally used in low cost and low precision applications. The ability of the actuator to ‘back drive’ is reduced over ball screw actuators due to the low efficiency of the screw/nut. In some applications, this can be an advantage as it helps to keep the payload stationary whilst not in motion. Applications embody agricultural equipment and guide lift systems, where safety and reliability are more critical than precision and performance.
A Ball Screw Actuator makes use of a high precision nut with recirculating ball bearings that rotate around a ground screw thread. In principle this is very similar to a standard ball race with the load being transmitted by the rolling balls. The significant advantages of this system are high-precision and low friction, giving a very efficient methodology of converting rotary motion to linear motion. Stepper or servo motors are generally used to provide the rotary motion. Ball screw actuators are well suited to repeatable indexing and quick cyclic applications reminiscent of machine tools, scientific devices and medical systems.
Belt actuators work where a belt is carried between two pulleys and hooked up to the moving carriage, then as the belt rotates the carriage is pulled alongside the actuator. One of many pulleys is driven by a motor which is generally mounted perpendicular to the actuator and matched using a flexible coupling. They offer a relatively low-cost different, as they inherently have a lower level of precision. Belt pushed linear actuators are superb for long journey and high linear speed applications comparable to packaging and automatic materials dealing with systems.