Whether you want to move things around, stack them, sort them or even just hold them still so they can be screwed into place, painted or installed, vacuum grippers are often the tool of choice. Industrial production lines around the world use these ingenious aids whenever the parts to be handled have a relatively smooth and even surface - and even that isn't essential these days. However, conventional vacuum grippers are noisy - and then some. That's because most use compressed air, a noisy process that requires heavy machinery and expensive technology, all of which also stifles flexibility. On top of all that, the process eats up a whole lot of energy. A group of researchers headed by Professor Stefan Seelecke from the Center for Mechatronic and Automation Technology (ZeMA) of Saarland University is at HANNOVER MESSE 2018 to show there is another way.
The team's innovative suction gripper holds and moves objects at least as securely as its noisy cousins - but without compressed air, which makes it quiet, energy efficient and suitable for cleanroom use. All it takes is a few short current pulses to generate and break a powerful vacuum with lightning speed. To do that, bundles of wire no thicker than a hair are used, which exhibit shape memory and can tense and relax in relation to impulses. Professor Seelecke explains the basis of the process, which lies in the shape memory of the nickel titanium alloy: "Shape memory means that the material remembers its original shape and returns to it after it has been deformed. When a current is passed through the wire, it heats up and its crystal structure changes, making it shorter. When the current is removed, the wire cools and it becomes longer again." Thanks to this special property, the new suction grippers are not dependent on electric motors or compressed air, which makes them quiet, lightweight, adaptable and cheap to manufacture and operate.