| 1 | Required Thrust | Calculate the theoretical extension force with: F = P × A, where pressure is in N/mm² and piston area is in mm². | At 6 bar: Ø32 ≈ 482 N; Ø40 ≈ 754 N; Ø50 ≈ 1,178 N; Ø63 ≈ 1,870 N; Ø80 ≈ 3,016 N; Ø100 ≈ 4,712 N. | Use the actual operating pressure and include friction, tooling weight, acceleration, and external resistance in the calculation. |
| 2 | Bore Size and Safety Margin | Select a bore that provides more force than the calculated load. A margin of approximately 25% to 50% is commonly used for normal applications. | If the calculated load is 600 N, a Ø40 bore provides about 754 N theoretical thrust at 6 bar before losses. | A larger bore increases force but also increases air consumption, overall size, and cost. Avoid selecting the bore from load weight alone. |
| 3 | Operating Pressure | Cylinder force is proportional to pressure, but the available plant pressure may fluctuate during peak demand. | 6 bar = 0.6 N/mm²; 5 bar = 0.5 N/mm². A 10% pressure reduction produces approximately 10% less theoretical force. | Size the cylinder using the minimum reliable working pressure rather than the highest possible compressor pressure. |
| 4 | Stroke Length | Stroke is the distance the piston rod must travel to complete the movement. | Common machine strokes include 25 mm, 50 mm, 100 mm, 200 mm, and 500 mm. | Choose a stroke slightly longer than the required travel only when necessary. Excessive stroke can increase rod bending, cycle time, and installation space. |
| 5 | Mounting Style | Mounting should support the cylinder without transmitting excessive side load to the piston rod. | Typical options include front flange, rear flange, foot mount, clevis mount, trunnion mount, and tie-rod mounting. | Use rigid mounts for straight-line loads. Use clevis or spherical joints where the mechanism pivots or alignment changes during the stroke. |
| 6 | Rod Diameter and Buckling | Long, slender rods are more vulnerable to buckling under compression. Buckling risk increases with stroke length and unsupported load. | For long compression strokes, consider a larger rod, guided load, reduced load, or a shorter unsupported length. | Do not use the cylinder rod as a structural guide. Add external guides when the load creates bending, twisting, or offset forces. |
| 7 | Rod End Design | The rod-end connection must match the motion, alignment, and load direction of the mechanism. | Common designs include male or female threads, clevis ends, spherical rod eyes, and fork-style connections. | Use a spherical connection for minor angular misalignment. Use a threaded rod end for simple axial force transfer with accurate alignment. |
| 8 | Cushioning and Speed | End-of-stroke cushioning reduces impact energy and noise, especially at high speed or with heavy loads. | Adjustable pneumatic cushioning is useful for variable loads; external shock absorbers may be needed for high kinetic energy. | Use flow controls to regulate speed. Meter-out control is often preferred for stable motion when the load can overrun the cylinder. |
| 9 | Environment and Materials | Temperature, moisture, dust, washdown, and corrosion affect seal life and material selection. | Standard pneumatic designs are often intended for clean, dry air and moderate ambient conditions; special applications may require corrosion-resistant materials or seals. | For wet or dusty areas, confirm the required protection, wiper design, lubrication method, and seal temperature range before selection. |
| 10 | Air Consumption and Cycle Rate | Air consumption rises with bore size, stroke, pressure, and cycle frequency. | For a double-acting cylinder, approximate free-air consumption per cycle is based on the extension volume plus the retraction volume, multiplied by absolute pressure ratio. | Check valve capacity, tubing size, compressor capacity, and cycle time. A smaller bore may reduce air use, but it must still meet the required force and speed. |