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Linear Actuator Torque Calculation Guide

Posted on December 20, 2018 by Anna
What are the physical characteristics you pay attention to, in an actuator? What are the most important parameters you consider? Although actuators are mainly responsible for linear motion, their rotational motion characteristics make a difference, too. The reason is simple: the actuators produce torque. When it’s transmitted to a drive system, it causes linear motion.

Electric actuator torque calculation is a task thousands of engineers and technology enthusiasts worldwide dedicate their skills to. We prepared this short review along with a linear actuator torque calculation formula to increase your awareness and help to fulfill this task.

What Is Torque and Why Do We Need to Calculate It?

Torque is a physical quantity that belongs to the list of the most important technical characteristics of an actuator. This is the equivalent of force in rotational movements. If you apply torque to an object, it starts to rotate around the axis. This axis is called the pivot point. Distance from the torque applied to the pivot point is the moment arm. Torque may refer to a moment of force. The difference is that torque actually produces the rotation around the pivot point. A moment, in fact, is force applied to a distance without producing the rotation. But why is that so important? Pneumatic actuator torque calculation is highly important due to the great customer demand for vehicles with extra efficient and economy features. We are all looking for cars that need less fuel, and have better safety and reliability. Besides, there are legal requirements for emission. Torque is significant for the development of a powerful modern engine. Torque and rotation speed are the physical quantities needed to calculate mechanical power. Torque calculation for the actuator is also an important component of testing. With the help of torque transducers, the in-line torque measurement is performed. This plays a huge role in mechanism optimization.

Industries and Mechanisms That Widely Use Actuators

To calculate actuator torque, we first need to understand how widely those tools are used. Most modern mechanisms need them for high-quality performance:

Linear Actuator Torque Calculation Guide 1

General Industry

Different types of actuators are essential for clamping, tensioning, positioning, tilting of devices and mechanisms.

Materials Handling

Actuators help to turn and position containers with various materials, including dangerous ones. They are also necessary for guiding operating valves. 

Robotics

Torque calculation is important in robotics. Both DIY robots and advanced engineering rotate thanks to actuators.

Marine Industry

Linear actuators are widely used to open and close hatches of motorboats. They enable cargo handling and hatches swinging, as well as many other significant processes. Motors, cylinders, screws, valves, and other different types of tools and equipment perform well thanks to actuators. Those actuators that produce push and pull motions convert the rotating movement of the motor into linear motion. The rotary actuators produce a rotary motion which can be converted to linear, too. In both cases, it is necessary to calculate torque of actuator and then proceed to the next steps.

What Is Torque Calculation and How to Find It

Linear actuator torque calculation means finding the rotational force the electric actuator can apply to the valve or other components of the mechanism to close it or to make it move. Since the torque is a vector quantity, the calculation consists of 2 primary components:

Defining the Direction

You need to use the right-hand rule to define the torque’s direction. Curl your right-hand fingers from the direction of the radius towards the direction of the force. When it is all done correctly, the thumb points in the right direction.

Defining the Magnitude

First of all, we will talk about torque as a physical quantity. Let’s analyze the simplest scenario. In the case when the force is perpendicular to the axis of rotation, the formula is quite simple: Linear Actuator Torque Calculation Guide 2 where τ is the torque, F is the force applied and d is the distance from the pivot point. However, usually it is not so simple, and the angle between the F and d vectors must be taken into account. So, the formula is as follows: Linear Actuator Torque Calculation Guide 3 In many sources, torque may be noted with a capital “T” instead of τ that we use here.

Torque Calculations in Details

Now, we know how to calculate τ or the amount of turning effort produced by the actuator. However, the torque calculation pneumatic actuator requires much more attention and effort than the simple example above. In this case, we need to explore several types of torque that have an impact on your project:

Design Torque

This is the maximum magnitude of the torque required to supply in a particular application. It is determined by the actuator’s design. It must be taken into account when calculating the torque your project demands.

Load Torque

It is responsible for supporting the weight of the load.

Friction Torque

Linear Actuator Torque Calculation Guide 4This is the force required to overcome friction between moving parts of the actuator. Its magnitude depends on the material the actuator is made of. Friction torque is zero for hanging load. 

Acceleration Torque

The movement may include some inertia, too. In order to overcome it, the acceleration torque is taken into account.

Cushion Torque

The angular deceleration depends on the cushion torque of the actuator.

Demand Torque

This is the torque needed to do the job. You need to know the load torque, the friction torque and the cushion torque to calculate it accurately. Linear Actuator Torque Calculation Guide 5

Analyzing the Results

It is time to analyze what you have. Note that when deciding on the tool that fits your needs best, it is necessary to understand all the product’s requirements and limitations of every single component. The results you obtain are important for motor sizing. The equipment performance depends on the accuracy of your calculations. These calculations are also your way to understanding what acceleration may occur and what load the mechanism can hold. Here are the most important outcomes to keep in mind:
  • If the cushion torque is higher than industry standards, the damage is possible;
  • If the demand torque is higher than the torque the actuator can supply, it will move too slowly, and will not be able to perform the needed task;
  • If something remains unclear, contact us and let’s discuss the results more thoroughly.

In Conclusion

Most manufacturers provide detailed information about the technical features of the tools and devices they provide. However, the necessity to calculate actuator torque may occur in your project. This task requires diving deep into calculations and gain a clear understanding of the processes. Follow our guide to calculate the results properly - or contact us and let’s do it together.
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