EOAT
Vacuum Gripper
A vacuum gripper is end-of-arm tooling that holds a workpiece by pulling air out from between one or more suction cups and the part surface, so atmospheric pressure presses the part against the cups.
What it is
A vacuum gripper is a type of end-of-arm tooling (EOAT) that grips a part by suction. One or more suction cups seal against the workpiece, air is evacuated from the sealed volume, and the pressure difference between the low-pressure cup and the surrounding atmosphere clamps the part in place.
It's the standard pick tool for flat, smooth, or lightweight items: cartons, sheet metal, glass, panels, bagged goods. On palletizers you'll often see a bank of cups on a large tool plate handling whole layers of boxes at once.
How it actually works
The holding force is the pressure difference across the cup multiplied by the effective sealing area, minus whatever the seal is leaking. Atmospheric pressure is about 101 kPa, so the ceiling on force is set by how much of that you can subtract inside the cup and how much cup area is actually sealing. A bigger cup or a deeper vacuum gives you more grip; a leaky seal or a porous surface bleeds it away.
Two source styles do the pumping. An ejector (Venturi) uses compressed air blown through a nozzle to entrain and carry away cup air, with no moving parts at the tool. An electric or mechanical vacuum pump draws the cups down directly. Either way, a vacuum switch or sensor confirms the part is held before the robot moves, and letting air back in (or a positive blow-off pulse) releases it. Because holding force depends on seal quality and surface finish, the same tool that lifts a clean steel blank easily may not hold a warped or dusty part at all.
How it differs
- TCP (Tool Center Point) · A vacuum gripper is the physical grasping hardware; the TCP is the programmed reference point offset to that tooling. You still define a TCP for a vacuum tool, typically at the cup face or the center of a cup bank. The gripper is the mechanism; the TCP is the coordinate the controller drives.
Where you meet it in the field
- FANUC M-410iC/185 · A high-payload palletizer commonly fitted with a vacuum tool plate to pick full box layers, where cup count and seal area are sized to the layer weight.
Common questions
- Why won't a vacuum gripper hold my part even though the pump is running?
- Holding force depends on a good seal and enough sealing area. A porous, warped, dusty, or textured surface lets air leak past the cup lip, so the pressure difference never builds. Undersized cups for the part weight cause the same complaint.
- Do I need compressed air for a vacuum gripper?
- Only if it uses an ejector (Venturi) generator, which runs on shop compressed air. Electric vacuum pumps draw the cups down without an air supply, which is why they show up where compressed air is scarce or expensive to run continuously.
- Can a vacuum gripper lift anything a mechanical gripper can?
- No. It needs a surface a cup can seal against, so it's poor for open lattices, very rough castings, or oily parts. Mechanical grippers grip on geometry and don't care about surface porosity, but they need clearance around the part to close their jaws.