There is a general trend in automation toward servo-controlled linear electric actuators, and away from pneumatic power.
Advantages of electric actuators over pneumatic devices
A major reason for the shift is the ability to program the devices, as more and more automation systems are designed to be flexible. This flexibility is needed both for the adjustment capability for certain processes, and for the ability to rapidly change configuration in order to produce different items.
A linear servomotor makes adjustment of the working parameters – speed, position, force, etc. – a very simple matter. Pneumatic devices, in general, are manually adjusted. Since there is no real feedback (servo) capability, this adjustment is time-consuming and inaccurate.
Linear motors have the ability to move to any number of positions, while pneumatic devices are normally limited to two positions.
The initial cost of pneumatics can be lower than electric actuators. However, the maintenance and running costs are significantly higher for a pneumatic system. There is the energy wasted each time an air cylinder exhausts pressure to the atmosphere, and the cost of replacing parts such as compressors, air prep equipment, shock absorbers etc.
Different Linear Actuator Options
– precise, fast, high acceleration, high moving mass, high force.
– fast, accurate, with instant feedback, high acceleration and speed, force control.
– fast, low cost, less accurate.
Screw Driven Actuators
– heavy duty, high force, accurate, slower.
– heavy duty, lower initial cost, short life span.