Pneumatic Actuators-Cylinders

 
About Air Cylinders

Air cylinders are pneumatic linear actuators driven by pressure differential in the cylinder chambers. One side of a piston flange can be pressurized to provide force and motion with a spring (providing return force after pressure is released), or both sides can be alternately pressurized for bi-directional powered motion. Air cylinders are used in many positioning, actuating and clamping applications. Choices for air cylinder style include tie rod, smooth body, pancake, rectangular, rotating and multiple bore. Tie rod cylinders are held together by exterior tie rods, and are usually in a rectangular bolt pattern. In a smooth-body air cylinder, the cylinder’s body encases the piston. A pancake cylinder has a shorter length and larger diameter than other air cylinder styles. A rectangular cylinder is encased in a rectangular, box-shaped frame. In a multiple-bore cylinder, two or more bores and pistons combined or stacked in same air cylinder. The cylinder can be single or double action. In a single-action device, the cylinder contains pneumatic porting for drive in only one direction. Single-action air cylinders frequently incorporate a return spring to the unpowered position. In a double action device, both sides of the piston can be pressurized for reversible motion. Force ratings can differ somewhat in opposite directions. 

How to Select

Important operating specifications to consider when selecting air cylinders include cylinder stroke and operating pressure range. Stroke is the distance between fully extended and fully retracted rod positions. The operating pressure range specifies the full-required range of operating pressure. Bore size is also important to consider. Additional specifications that should be considered when searching for air cylinders include mounting options, connectors or port size, body material, and features. Common mounting options for air cylinders include face mount, nose mount, double-end mount, front flange mount, rear mount, rod pivot mount, and rear pivot mount. NFPA mounting geometry conforms to standards of the National Fluid Power Association (NFPA). Several standard configurations fall under the NFPA designation. The most common NPT thread sizes are 1/8" NPT, 1/4" NPT, 3/8" NPT, 1/2" NPT, 3/4" NPT, 1" NPT, 1 1/2" NPT, 2" NPT, British Standard Pipe Thread, and Metric Pipe Thread. Common body material choices for air cylinders include aluminum, steel, stainless steel, and thermoplastic.  Features for air cylinders include non-rotating, double end rod, cushions, telescoping, position feedback and magnetic bend. An important environmental parameter to consider is the operating temperature.