How various gear types affect the performance of industrial actuators

Learn how gears relate to the performance of electric actuators, and how they ensure an optimal actuator efficiency. Find out more about the durability and functionality of plastic and steel gears for industrial actuators.

What gear types are commonly used for electric linear actuators?

There are many types of gears in electric linear actuators, but the two gear types, plastic and steel gears, are commonly used for industrial actuators. Both types of gears come in different forms:

Spur gear is characterised by having straight teeth. Spur gears have a high efficiency, even in environments with high temperatures. However, the high efficiency comes at a cost, since these gears generate more noise compared to other types.
Helical gear is a good choice, when you want a smooth and silent operation. However, these gears offer a lower efficiency compared to the spur gears, and the axial thrust of the gear shafts generate heat, which must be considered in the overall actuator design.
Worm gear makes it possible to reduce the noise by increasing the gear ratio before running the actuator. Increasing the gear ratio equals using a gear wheel with a larger diameter. Worm gears of plastic often have a low efficiency, since this type of gearing is self-locking. If you need to further increase the self-locking ability, it will in some cases be necessary to add a brake.
Planetary gear is made from smaller gears circling a larger gear wheel. Typically, this type of gearing is very robust and efficient due to the equal distribution of force through the gear wheels. It provides a high gear ratio in a compact size and is used in several industrial actuators.

What are the main differences between plastic and steel gears?

There are pros and cons with any type of gear for actuators.

When comparing plastic gears to steel gears, plastic gears generally have lower efficiency and are more sensitive to high temperatures. However, if an actuator is used within its specifications, for instance, by running the actuator to its end stop each time or by avoiding mechanical blocking, the gear material will not be affected and will not influence the actuator’s overall performance or service life negatively.

Plastic gears are low-noise, which make them suitable for environments and applications where a low noise level is important.

Industrial actuators can be used in harsh environments with heavy loads, many duty cycles, or high temperatures. In such cases, steel gearing, including spur and planetary gears, prove the necessary robustness and efficiency needed for optimal actuator performance. Steel gears are not limited by fixed duty cycle restrictions, as the generated heat from a moving actuator will rarely reach levels high enough to harm the gear material.

Still, most LINAK^® industrial actuators have a set duty cycle of 20% to ensure that generated heat will not affect other actuator components.

Did you know?

Typically, linear actuators are designed with one gear connected to the motor and spindle. In this way load and speed can be adjusted by changing the spindle pitch. By using a second gear step between the spindle and the motor, even more performance variations are possible using the same actuator type.

A good rule of thumb when choosing an actuator is to multiply the load and speed required to get the efficiency. This will get you a good indication of the type of actuator you need.