How do I calculate pneumatic cylinder force?

Pneumatic cylinder extend force is F = P × A, where P is the supply pressure and A is the full bore area (π/4 × D²). Retract force uses the annular area: A = π/4 × (D² − d²), where d is the rod diameter.

What is the difference between extend and retract force?

Extend force uses the full piston bore area, so it is always higher. Retract force uses the annular area (bore area minus rod area), giving a lower force output.

How do I calculate pneumatic cylinder speed?

Piston speed v = Q / A, where Q is the volume flow rate and A is the effective piston area. For extension, A is the full bore area; for retraction, A is the annular area.

What bore size do I need for a given force?

Rearrange F = P × A to find A = F / P, then D = √(4A/π). Always size up to the next standard bore diameter and include a safety factor of 25–50% for friction and dynamic loads.

Does friction affect pneumatic cylinder force?

Yes. Seal friction typically reduces the theoretical force by 5–20% depending on seal type, lubrication, and speed. A common design practice is to apply a 10–15% friction loss factor.

免費工程工具 — #143

氣缸推力與速度計算器

計算氣動缸的伸出/縮回力與活塞速度。輸入缸徑、桿徑與供應壓力。

F = P × A v = Q / A 伸出與縮回

結果

伸出力 (推力)

—

縮回力 (拉力)

—

缸徑面積

—

環形面積

—

伸出速度

—

縮回速度

—

氣缸伸出力

當活塞伸出時，壓力作用於整個缸徑面積：

氣缸縮回力

縮回時，桿佔據活塞部分面積，減少有效面積：

活塞速度

速度取決於空氣流量與有效活塞面積：

P — 供應壓力
D — 缸徑
d — 桿徑
Q — 工作壓力下的體積流量

標準缸徑尺寸 (ISO 15552)

缸徑 (mm)	桿徑 (mm)	伸出面積 (cm²)
32	12	8.04
40	16	12.57
50	20	19.63
63	20	31.17
80	25	50.27
100	25	78.54
125	32	122.72
160	40	201.06
200	50	314.16

範例 — 6 bar 下的 63 mm 氣缸

已知： 缸徑 = 63 mm, 桿徑 = 20 mm, 壓力 = 6 bar

A_缸徑 = π/4 × 63² = 3117 mm² = 31.17 cm²

F_伸出 = 6 × 10⁵ × 3117 × 10⁻⁶ = 1870 N (190.6 kgf)

A_環形 = π/4 × (63² − 20²) = 2803 mm²

F_縮回 = 6 × 10⁵ × 2803 × 10⁻⁶ = 1682 N (171.4 kgf)

⚠️ 注意： 實際出力會因密封件摩擦而減少 5–20%。為實際應用選型氣缸時，請應用安全係數。