Rod-type pneumatic actuators are driven by air—specifically, compressed air, which is what determines the actuator’s rigidity. Typical pneumatic actuators have a stiffness factor of < 100 N/mm. Rodless electric actuators, on the other hand, use either a belt or ballscrew as their drive medium and are powered by a mechanically coupled motor. For these actuators, the belt or ballscrew determines the actuator’s stiffness. For example, a typical AT10-style, steel-reinforced belt used in quality rodless actuators has a stiffness factor of 7 kN/mm. And ballscrews are even stiffer: a typical 25 mm x 700 mm-long ballscrew has a stiffness factor of 100 kN/mm.
Speed control refers to not only the actuator’s maximum speed, but also its path speed. Having dynamic speed control along the path of travel yields smoother motion. It also allows you to vary the speed, either speeding up or slowing down as your application requires. For the smoothest motion, select an actuator with a high degree of dynamic speed control.
Similar to speed control, position control can be static or dynamic. The more control you have over the position of your actuator, the more control you have over motion repeatability and flexibility:
If your application requires smooth motion, multiple position stops, and high repeatability and flexibility, then electric actuators are your best bet.