KEVOS® MAKEOS · Pneumatics
Pneumatic Cylinder Sizing, Air Use and Running Cost
What bore does this air cylinder need, how much air does it use, and what does that air cost?
Sizing of a double-acting pneumatic cylinder: minimum bore for the load at a recommended load ratio, the next standard bore, extend and retract forces, free air per cycle and average consumption (as the cylinder air consumption tool), peak flow while extending at speed, kinetic energy against the cushion capacity, and the yearly energy cost of the air.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Load force | N | Force the cylinder must produce while moving. |
| Maximum load ratio | % | Largest share of theoretical force to use (about 50–70% for dynamic loads). |
| Supply pressure | bar g | Supply pressure at the cylinder. |
| Rod diameter | mm | Rod diameter of the chosen cylinder. |
| Stroke | mm | Stroke length. |
| Cycles per minute | Full cycles (extend and retract) per minute. | |
| Extend speed | m/s | Piston speed while extending. |
| Moving mass | kg | Mass moved by the piston. |
| Cushion energy capacity | J | Energy the end cushion can absorb (from the cylinder maker). |
| Compressor specific power | kW per m³/min | Compressor power per unit of free air delivered. |
| Running hours per year | h | Hours per year the machine cycles. |
| Electricity price | $/kWh | Cost of electricity. |
Method and formulas
- Minimum bore = √[4F ÷ (π p × ratio)]; next ISO bore from 8 to 320 mm.
- Air per cycle, as free air = (2A − A_rod) × stroke × (p + 1.013) ÷ 1.013.
- Peak free-air flow while extending = A v (p + 1.013) ÷ 1.013.
- Kinetic energy = ½ m v² against the cushion capacity; air cost = consumption × specific power × hours × price.
- Example: 600 N at 6 bar needs a 50 mm bore using 25.006 L/min of free air.
Limitations
- Theoretical forces; seal friction and pressure drop in valves and tubing reduce them.
- Isothermal air use; real use is higher with long tubing to the valve.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Choose a cylinder bore for an automation task
- Estimate compressed-air demand for a new machine
- Show the energy cost of cylinder air
Who it is for
- Automation engineers
- Machine designers
- Maintenance engineers
What you get
- Minimum and standard bore with forces
- Air per cycle, average consumption and peak flow
- Cushioning check and air cost
Interpreting the result
- Oversized cylinders waste air every stroke; lower pressure on the return stroke saves more.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 3421–3425, 3030–3037. Topic reference; no source tables or recommended settings are reproduced.
WORKOS tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
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