When designing a pneumatic system, choosing the right cylinder is crucial. If you choose a cylinder that is too small, your machine will literally lack power. If you choose a one that is too large, you will waste compressed air and money. In this blog, we explain exactly how to calculate which cylinder diameter (bore) you need at a specific working pressure and the desired force.

The basic formula: Force = Pressure x Surface area The force that a pneumatic cylinder delivers depends on two factors: the air pressure you supply and the piston surface of the cylinder. In pneumatics, we often use this formula: F = P x A Where: F (Force): The force in Newton (N). P (Pressure): The pressure in Pascal (Pa). In practice, we often calculate with bar (1 bar = 10 N/cm2). A (Area): The effective surface area of the piston in m2 or mm2.

Step 1: Determine the required force (F)

Before choosing a cylinder, you need to know how much mass you want to move. Note the difference between horizontal and vertical movement:

• Vertical movement (Lifting): You fight directly against gravity.

• Horizontal movement: You fight against the frictional resistance.

Golden rule: Always add a safety margin of 25% to 50% to the theoretical force required. This absorbs internal friction in the cylinder and pressure losses in the hoses.

 

Step 2: Piston diameter influence (Bore)

The diameter of the cylinder (also called the 'bore') determines the surface that the air pushes against. The larger the diameter, the more force the cylinder delivers at the same pressure.

Note the difference: Outgoing vs. Incoming stroke

• Outgoing stroke: The air pushes against the entire surface of the piston.

• Input stroke: The piston rod takes up space. As a result, the effective surface area is smaller and the cylinder therefore delivers less force when retracting.

 

Step 3: Determine workload

The standard working pressure in most industrial environments is around 6 bar. Although compressors often go up to 8 or 10 bar, it is wise to base your calculation on 6 bar. This ensures that your system works reliably even if the pressure in the network fluctuates a bit.

Handy Table: Force at 6 bar (most common). (Note: 10 Newtons is approximately equal to 1gk of pulling force.)

 

 

Summary: What should you pay attention to?

1. Determine the load: How many kilograms need to be moved?

2. Choose the direction: Is the movement horizontal or vertical?

3. Calculate the diameter: Use the 6-bar standard and calculate the diameter of the required Newton.

4. Check the stroke length: How far should the cylinder protrude? (For long strokes, pay attention to the risk of buckling of the piston rod).

5. Installation space: Does the cylinder (e.g. an ISO 15552 or a compact cylinder) physically fit in your machine?

Need help with the calculation?

At Pneuparts.com, we have all the expertise in-house to help you make the right choice. Do you have a specific challenge or are you unsure about the required diameter? Contact our specialists!

 

 

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