Industrial Automation

Difference between Linear and Rotary Actuator

What do you mean by Actuators?

  • An actuator is defined as a machine element that transforms energy into physical movements.
  • An actuator needs a control device that is governed by a control signal and an energy source.
  • Typically, the control device is a valve.
  • The energy level of the control signal is very least 
  • When an actuator accepts a control signal, it needs to respond by converting the energy from the source into mechanical movement.
  • The required source of energy may be electrical voltage or current signal, pneumatic signal, hydraulic fluid pressure, human power, or other mechanical forces.
  • Basically, Actuators are classified based on the nature of their output motion.
  • Actuators are categorized into two groups such as linear and rotary
  • Each of these types is available in various versions and configurations to help achieve the desired result.
  • The end purpose should be the decisive criterion for selecting linear and rotary actuators for our application.

Linear Actuators

  • A linear actuator continues to move a component in a straight line path, most likely back and forth.
  • It employs belt and pulley, rack and pinion, or ball screw mechanisms to transform electric motor motion from rotary into linear. 
  • They are intended to travel a fixed linear path length and then come to an original position.
  • Installation & Operation of linear actuators are very easy.
  • Integration of these linear actuators in the automated process is easy, hence no maintenance is required.
  • These actuators don’t leak hydraulic fluid, & will operate in harsh environments.
  • There are various kinds of linear actuators available in the market for various applications to generate motion.

Features of Linear Actuators

Linear Actuators have the following features:

  1. High repeatability
  2. Positioning accuracy
  3. Smooth operation
  4. Long life
  5. Easy maintenance or maintenance free
  6. Only some designs have protection ratings.
  7. Ideal for harsh environments, as well as poor weather and environmental conditions
  8. Design is compact 
  9. Higher reliability 
  10. Fail-proof operation.
  11. Rugged and reliable
  12. Safe operation
  13. Versatile

Industrial Applications of Linear Actuators

Linear Actuators can be used in a wide range of circumstances that necessitate a load to be hoisted, dropped, pushed, pulled, rotated, or located.

Linear actuators have applications in a wide range of industrial sectors such as

  1. Packaging
  2. Food processing
  3. Industrial vehicles
  4. Factory automation
  5. Material Handling
  6. Clean energy
  7. Printing
  8. Automotive
  9. Machine tool
  10. Marine
  11. Aerospace
  12. Defense
  13. Pharmaceutical

In contrast to the circular motion produced by a typical electric motor, linear actuators produce motion that is only in one direction: in a straight line. Machine tools and industrial machinery, computer peripherals like disc drives and printers, valves and dampers, and numerous more applications requiring linear motion all employ linear actuators. Hydrostatic Cylinders or Pneumatic cylinders naturally create linear motion, there are several different techniques that may be employed to obtain that motion from a rotating motor.

Rotary Actuators

Rotary Actuators
  • Rotary actuators convert the energy into rotary motion via a shaft that regulates the speed, position, and rotation of the attached equipment.
  • Because the applied force is aimed away from the axis of rotation, the permitted force is not      limited by the distance traveled, resulting in greater flexibility in application.
  • A typical case of a rotary actuator is an electric motor.
  • The electric signal generates a magnetic field in the motor’s stator, and the rotor rotates in rebuttal to this input.
  • Rotary Actuators provide excellent accuracy.
  • Torque output of these Actuators is very high 

Features of Rotary Actuators

  • Zero backlash
  • Hollow shaft
  • High torque with compact configurations
  • Constant torque during full-angle rotation
  • Compatibility with a Large variety of diameters
  • Holding torque is two times as strong including forward driving torque.
  • Easy maintenance or maintenance-free
  • Ideal for harsh environments
  • High repeatability
  • Positioning accuracy
  • Achievable degree of rotation is from 90 degrees to full 360 degrees.

Industrial Applications of Rotary Actuators

These Rotary Actuators are also used in various industrial applications that require a rotary movement or torque to regulate the speed and rotation of attached equipment. 

Rotary Actuators are employed in various industries like

  1. Robotics including 6-axis robots, 
  2. Gantry robots and 
  3. Manipulators
  4. CNC machine, 
  5. Grinding machine 
  6. Lathe machine
  7. Special machines like bending machine
  8. Medicine equipment
  9. Aerospace applications
  10. Flight simulators
  11. Defense Industry
  12. Semiconductor industry
  13. Radar and monitoring systems

The torque and operating speed of a rotary actuator can be used to characterize it. A rotary actuator’s torque can be stated in one of three ways:

  1. The torque available to move an object from rest is known as the starting torque.
  2. The load must apply stall torque in order to stop a running actuator.
  3. The torque available at any given speed is known as running torque.

Differentiate between Linear and Rotary Actuators?

Linear Actuators Vs Rotary actuators 

Linear ActuatorRotary Actuator
A linear actuator produces a push-pull motionRotary actuator produces rolling motion
Arm tooling end slides between two pointsArm tooling end moves in a circular path
Linear actuators include a motor and a gear axle thread.Rotary actuators include a central shaft, hollow cylindrical chambers & stationary barriers.
The output motion of the linear actuator is normal to the output shaft.The output motion of rotary actuators is tangent to the shaft.
Linear actuators bear a compact build and design.Rotary actuators bear an angular path
Linear Actuators travel for a short distance and retain their original positionRotary Actuators travel for infinite and repeated spins
Linear actuators offer easy installationRequire calculation of the angle of rotation
The path is a straight line like  back and forth motion in the case of Linear actuatorsPath is circular in angular degrees w.r.t mid-point
Traveling distance is restricted in linear actuatorsTraveling      distance is not restricted in rotary actuators

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