31 July 2013
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Gripping concept sticks with adhesive tapes

Automation leader Festo has come up with an energy free gripper concept for use in pick and place and assembly system applications.

The grippers are lined with Gecko Nanoplast, a silicone film with a thickness of about 0.34 mm and with microscopic elements on one of the sides. These elements stick to any smooth and flat surface, even when wet, oily and soapy and do not require pneumatic suction to operate.

The concept is known as NanoForceGripper and it can grasp objects such as drinking glasses or display modules with almost no expenditure of energy. This new technology thus supplements Festo's existing grasping technologies based on pneumatics.

Gecko Nanoplast foil is manufactured by Gottlieb Binder in Germany and is modelled on nature. It is the key component on the underside of the gripper, having 29,000 adhesive elements per square centimetre. These sucker like elements, based on the natural model of the gecko, adhere securely and permanently to the surfaces of the object to be handled. This effect is due to extremely small intermolecular forces of attraction – so-called van der Waals forces.

As part of the Bionic Learning Network, Festo has made use of this effect in devising the new, energy-efficient gripper. In collaboration with development companies, renowned universities and institutes – in this case the Zoological Institute of the University of Kiel – Festo has set out to transfer efficient principles from nature to automation technology.

Energy-free gripping and energy-efficient grasping are entirely new features for grippers that operate with a push-push mechanism. Holding objects without expenditure of energy has not been possible before. A grasped component can then be permanently held in place by the gripper, without the need for energy input. The intermolecular forces, which allow secure, permanent, residue-free gripping of a workpiece, do not require a supply of energy to establish a connection.

Only the disengagement of this bond, which is necessary for depositing the workpiece, must be effected by means of a corresponding opposing force; peeling the nanostructure from the surface of the grasped workpiece has proven highly suitable here.

This peeling process is effected by means of a structure with the Fin Ray Effect, which is modelled on a fish's tail fin. When a force is applied, the flat structure is deformed into a curved surface. The effective foil-coated gripping surface becomes increasingly small, and the gripped component is gently released.

A push-push mechanism within the gripper displaces the adaptive structure when the gripped part is deposited, without the need for any additional actuators or control components. This principle functions in a similar way to the locking and release mechanism commonly found in ball-point pens. An extremely small amount of energy is required, just enough to pick up and release an object.
This involves upward displacement of a few millimetres from the origin along the lifting axis, which allows either the necessary contact pressure to be applied in order to grasp an object, or the fin-ray structure to be deformed in order to release it.

With the NanoForceGripper, Festo has developed a gripping device whose advantages lie above all in energy savings and in dispensing with the need for actuators and control devices.

This new gripping concept shows what energy-efficient automation of the future could look like and demonstrates that there is still a great deal of energy savings potential even in existing automation components such as grippers.

Author
Paul Gay

Related Websites

http://www.binderuk.com.

Related Companies

Binder UK Ltd

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