Nature has shown us how it's done and doesn't need glue or suction power: geckos can use adhesion to race over vertical and smooth surfaces and even hold their entire body weight with just one foot. Their secret: millions of tiny hairs on their feet bind to the molecules of the polished surface as they run. Van der Waals forces, weak electrodynamic interactions, ensure that the geckos adhere to pretty much any surface.

Schunk utilizes this functional principle from nature for its new gripper technology Adheso. Plastic pads made of special polymers imitate the fine hair structure of geckos on the adhesive grippers. When gripping, the hairs of the pad press against the surface of the workpiece. This increases the contact surface and the Van der Waals forces take effect. The workpiece can thus be gripped and held without the application of external energy. This offers two decisive advantages for users: Firstly, the effort required for installation and commissioning is minimal, and secondly, operating the holding gripper saves energy costs, as neither compressed air nor vacuum or electricity are required. The adapter plates with integrated bayonet lock developed by Schunk also enable the pads to be changed quickly.

Another advantage of the technology is that components can be gripped very gently and completely residue-free thanks to the adhesion forces. As the new gripping technology works without the application of mechanical force, it handles sensitive workpieces such as delicate battery components, glass vials or plastic films very gently. In contrast to alternative gripping technologies, it leaves no marks on the workpiece. The gripper is also removed from the workpiece without leaving any residue. Philipp Matyssek from Adheso Product Sales at Schunk explains: "Compared to other adhesive grippers, with Adheso there is not just one way of removing the workpiece from the gripper, but four. Depending on how and where users want to place their workpiece, they can choose between a rotating, tilting or pushing movement, as well as pushing off." Alternatively, the machine can also be equipped with an active stripper.

Possible applications from fiber optics to car doors

The special surface architecture adheres to a wide variety of materials and objects and can therefore be used in many different ways. Feather-light glass fibers, the smallest SMD components or micromechanical parts can be handled just as easily as significantly heavier automotive or mechanical engineering components. This is because the pads are easily scalable and are always individually tailored to the desired application. "The only important thing is that the workpieces are as smooth as possible," explains Matyssek. "Because the rougher the surface structure, the lower the gripping force." Adheso is also well suited for one-sided accessibility, for example when separating paper or other flexible workpieces from a magazine. The technology also delivers good results in micro-handling with reproducible positioning accuracies of <0.01 mm.