An overview of linear actuator & its types

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The linear actuator is used to move a load in a straight line that can be anything from assembly parts, components or even a finished product. It converts energy into kinetic motion or force and can be activated/powered by electricity, air and high-pressure fluid flow. There’re three common types of linear actuators namely pneumatic, hydraulic and electrical. Let’s have a look at the three and their industrial benefits.

Working mechanism

  • Pneumatic linear actuators include a piston inside a hollow cylinder whereas pressure from a manual pump or external compressor moves the piston. Cylinder moves in the piston’s axis thus creating a linear force when there’s an increase in pressure. The piston regains its original state when fluid supply is to the other side or application of the spring-back force.
  • Hydraulic linear actuators operate in a similar manner to that of pneumatic counterparts but, the only difference is incompressible liquid from a pump instead of pressurised air for the cylinder to move.
  • Electrical linear actuator transforms electrical energy into torque. A mechanically connected electric motor then turns the lead screw whereas a ball-nut or threaded lead bearing corresponding patterns to those of the screw prevents the rotation of the screw. The nut is driven with the threads on screw rotation. The direction of the nut movement is directly proportional to the screw rotation which also returns the actuator to its original state.

Industrial benefits

  • Pneumatic actuators

The primary advantage is derived from the simple mechanism. Most of the aluminium-based pneumatic actuators carry maximum pressure rating of 150-psi with a bore size range from ½ to 8-inch. It accordingly translates or converts into more or less 30 to 7,500 lb. force. Then there’re steel actuators having a maximum pressure rating of 250-psi with a range of bore size from 12 to 14-inch thus able to produce force up to 50 and 38, 465 lbs. respectively.

Pneumatic actuators are known for generating accurate linear motion given to their precision. Take for instance 0.1-inches with repeatability of .001-inches. The most typical applications include areas of extreme temperatures with a range of -40 to 20 degrees Fahrenheit. As for the safety and inspection using air, hazardous materials are avoided. They’re anti-explosive and machine safety due to zero magnetic interference.

During the last few years, there has been the wide application of pneumatic actuators for various industrial procedures such as miniaturisation, materials, condition monitoring and electronic integration.

  • Hydraulic actuators

For high-force and rugged industrial applications, hydraulic actuators are preferred since they can generate force approximately 25-times greater than equal-sized pneumatic cylinders. They can operate perfectly in pressures of approximately 4,000-psi. A typical hydraulic actuator can sustain constant force and torque without a supply of fluid or pressure through the pump. These actuators have their motors and pumps placed at a considerable distance with minimal power loss.

  • Electrical actuators

Highest precision-control can be achieved by electrical actuators whereas flexible installation makes them perfect for force generation in a quiet, smooth and repetitive manner. These can be reprogrammed and networked quickly. Immediate feedback for accurate diagnosis and maintenance is another benefit derived from these particular actuators.

Bettis actuators; pneumatic type by Emerson are the best when it comes to different industrial application and uses.

 

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