Considerations when choosing a linear actuator

Normal electric motors create a circular motion, but a linear actuator creates straight line motion to move something. Linear actuators come in three main types: hydraulic, pneumatic and electromechanical. To push the load, the hydraulic version uses pressurised liquid, the electromechanical version uses electricity, and the pneumatic version uses compressed air.

Image Credit

MachineDesign magazine has an in-depth description of the way the three types of actuator work for those who want to see the technical detail.

For many manufacturers and designers, what matters is how suitable each is for particular types of application, so let’s look at each.

Hydraulic linear actuators

These have a higher force output than the other types of linear actuator and can easily operate at 210 bar. The bore sizes can range from 12mm to 355mm. They are capable of dealing with high-force requirements and can give a constant force; however, they tend to be noisy and need regular maintenance to avoid leaks and other problems. They are also large.

Image Credit

Pneumatic linear actuators

These now use linear position and proximity sensors to give positional feedback, which has improved their performance. The pneumatic types tend to be lower cost, are simpler, and can be very precise; however, they can be prone to faults related to loss of air pressure and have a typical pressure rating of 10 bar – much lower than the hydraulic models.

Electromechanical linear actuators

These use electric current and a magnetic field to send the linear motor component backwards and forwards. They have the advantage of much higher speeds and fewer components, which means they are lower maintenance and more reliable that the air and fluid actuators. They can be positioned very precisely and reprogrammed when necessary, so they are very useful in injection moulding applications; however, they are more expensive and often unsuitable for use in hazardous areas. They are available from specialists such as

How to choose which linear actuator you need

You need to consider the force required, the distance the load needs to move, the speed it needs to achieve, and the precision that is required. You can then add in the required life, robustness and cost. Rate these in order of importance, which will help you to filter out those that are unsuitable and to choose the best one for your installation.

Leave a Reply

Your email address will not be published. Required fields are marked *