An actuator is a device that converts energy into movement. A linear actuator moves a load in a straight line. The energy source that operates an actuator can be hydraulic (fluid-based), pneumatic (air pressure-based), or even electric.
Hydraulic cylinders can produce tremendous force because they can handle higher pressures. This is essential for operating heavy construction equipment, for example. However, in many industrial applications, moving machinery – and controlling that movement consistently – is what matters most. Pneumatic actuators, or cylinders, are often ideal for these applications.
There are other key differences between hydraulic and pneumatic cylinders that give each of them distinct advantages or disadvantages for use in certain applications.
As noted above, hydraulic cylinders are well-matched for applications that require substantial force. They can produce as much as 25x the force that a pneumatic cylinder can generate, as well as higher horsepower per weight. One of their main advantages is their ability to hold torque and force without continuous application of fluid pressure from the power source. This is because fluids are not compressible.
On the downside, hydraulic actuators can leak, and the leaked fluid invites contamination that can cause damage to internal or external working parts. It also takes an assortment of other equipment to operate hydraulics – motors, pumps, fluid reservoirs, etc. And hydraulics are very noisy, even when outfitted with noise-reduction equipment. All this makes this type of actuator too unwieldy for many environments.
These cylinders are driven by air pressure rather than a fluid. Air can sometimes be less efficient as a power source because it can be compressed, causing the actuator to lose pressure. The air compressor must be located relatively close by, and it has to run continuously. It is also possible for the air to become contaminated by equipment lubricants, which increases the risk of damage.
The bottom line is that pneumatic actuators operate at lower pressures and speeds than hydraulic cylinders. For many applications, though, this is an advantage. Pneumatic cylinders provide highly reliable, consistent linear motion, with accuracy tolerances within 0.1 inches and repeatability tolerances within .001 inches. They can also perform reliably in extremely high or low temperatures.
In addition, because pneumatic actuators have no motor and use no hazardous materials, they can easily meet mechanical safety requirements.
To achieve maximum efficiency, it is important to size pneumatic actuators accurately for the job at hand. W.C. Branham manufactures four different types of pneumatic actuators, each available in a variety of bore sizes.
While pneumatic cylinders may be the best choice for your industrial application, choosing the right one(s) for your project can be complex. No worries. If you need help spec’ing, W.C. Branham is happy to help.