Pneumatic Cylinder Force, Speed and Air Consumption

How is pneumatic cylinder force calculated?

Force is gauge pressure times piston area: F = p × A, where A = π × D² / 4. On the retract stroke the rod reduces the area to the annulus A_h = π × (D² − d²) / 4. With 1 bar = 0.1 N/mm² and area in mm², force comes out in newtons.

This is the theoretical force. An efficiency covers seal friction. For moving loads the cylinder is not used to its full force, so a load margin is left.

Air consumption

Each stroke fills the cylinder volume with compressed air. Its equivalent at atmospheric pressure (free air) follows from the compression ratio r = (p + p_atm) / p_atm. For a double acting cylinder one cycle uses V = (A + A_h) × L × r. Multiply by cycles per minute for the mean consumption. The compressor and air preparation unit are sized on that total.

Example

A cylinder with a 50 mm bore, 20 mm rod and 200 mm stroke works at 6 bar. The theoretical push force is 1178 N and the pull force 990 N. The compression ratio is 6.92, giving 5.0 litres of free air per cycle. At 10 cycles per minute the consumption is 50 L/min.

Why is speed not given by a formula?

Air is compressible, so piston speed does not depend on flow alone. Load, valve size, tube length and the flow control setting all matter. This tool takes the stroke time you enter and returns the mean speed and the free air flow the valve must pass at that speed. For real speeds, use the manufacturer's sizing software or measure.