Vacuum gripper

A vacuum gripper is the same trick as the suction hook on your bathroom tile, with a pump behind it. Rubber cups press against the object, the air between cup and surface is pumped out, and ordinary air pressure pushes the object onto the cup.

Factories use them for boxes, sheets and bags, because the gripper needs access to only one face and will not crush thin or delicate material. Extra cups can be added for bigger loads.

They fail in predictable ways. A small, dense part offers too little surface for the cup to grab. Porous material leaks air, so high-flow compressed-air systems are used rather than small electric pumps. And because the hold is less rigid than metal jaws, a fast swing can shake a part loose.