Vacuum Suction Cup Calculator
The holding force a vacuum gripper needs for a part, the force on each cup, the smallest cup diameter and whether the cups you have in mind hold it.
Results
What this tool does
A cup's theoretical holding force is the vacuum times its area: at 60 kPa below atmospheric a 50 mm cup holds about 118 N. When the part slides sideways or the cup sits on a vertical face, only friction carries the load, so the force needed is divided by the friction coefficient: about 0.5 on clean dry metal, glass or wood, but only 0.1 to 0.2 on oily sheet. That is why the same part can need several times as many cups when it is gripped from the side or moved fast across. A safety factor of 1.5 is the usual minimum, with 2 or more for rotating moves, porous parts or uneven surfaces. Real cups hold a little less than the theoretical figure because the lip deforms, so check the force table of the model you choose.
Formula
F = m (g + a) S · F = m (g + a ÷ μ) S · F = m ÷ μ × (g + a) S · d = √(4 F ÷ (n π Δp))
Variables
| Symbol | Meaning | Unit |
|---|---|---|
m | Mass | kg |
ac | Acceleration | m/s² |
lc | How the cup holds the part | — |
mu | Friction between cup and part | — |
sf | Safety factor | — |
vk | Vacuum (below atmospheric) | kPa |
nc | Number of cups | — |
dc | Diameter of the cups you have in mind | mm |
FT | Holding force needed, all cups together | N |
FC | Force each cup must hold | N |
DM | Smallest cup diameter that does it | mm |
FH | Theoretical force of those cups | N |
SR | Safety factor you actually get | — |
OK | Do those cups hold it? | — |
Worked example
- Mass8 kg
- Acceleration5 m/s²
- How the cup holds the part1
- Friction between cup and part0.5
- Safety factor2
- Vacuum (below atmospheric)60 kPa
- Number of cups4
- Diameter of the cups you have in mind50 mm
- Holding force needed, all cups together236.9 N
- Force each cup must hold59.2 N
- Smallest cup diameter that does it35.5 mm
- Theoretical force of those cups471.2 N
- Safety factor you actually get3.98
- Do those cups hold it?Yes, with the safety factor you asked for
Limitations
- Coverage and consumption figures vary between products. Take the values from the manufacturer's datasheet for the product you are actually using.
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
- The formula assumes ideal conditions: no friction losses, no air resistance and no efficiency losses unless you enter them.