Additive Manufactured Grip System Made Lightweight and Durable With EOS Technology 

The hand is one of the defining stepping stones of human evolution: with its thumb opposing the other fingers, the human hand is an ideal tool for gripping, exploring, and working. As such, it is the key to cultural activity and technical progress. Industry often exploits this ingenious principle: one of the processes for which machines are used is the automated gripping of almost any desired part for transporting to the next operational step.

Such gripping machines are masterpieces of engineering. Kuhn-Stoff GmbH & Co KG has dedicated itself to specialized engineering through the application of EOS additive manufacturing technology. The process entails the formation of machine parts, layer by layer, from plastic powder that is melted with a laser beam. In this way, Kuhn-Stoff has developed and produced an extremely lightweight, strong, and durable bronchial gripper for Wittmann Robot Systeme GmbH, in Nuremberg, Germany. Four of these grippers sit on a support frame with integrated pneumatic ducts.

The customer is a manufacturer of robots and automation systems. Kuhn-Stoff was asked to re-design a mechanical gripper that raises, transports, and then sets down machine parts from a production machine via a pneumatic mechanism. The following requirements were established: the gripper should be lighter than its predecessor, while still being capable of moving the required loads. The complexity of the design should be simplified and the part must be able to satisfy efficiency criteria.

The significance of the weight comes down to physics: grip systems such as this must work quickly in order to move as many machine parts as possible within a given unit of time.

The fact that mass is inert means that force must be applied to set it in motion – the heavier a load is, and the faster it moves, the greater the forces necessary for both acceleration and deceleration.

Quite apart from the viewpoint of energy efficiency, this fact also has particularly negative consequences on the durability of the system: the greater the forces in play, the higher the wear on the machine.

The previous version of the gripper was made from aluminum, rubber tubes, and multiple connecting elements, and was expensive to produce. The layer manufacturing experts from Kuhn-Stoff set themselves the goal of significantly simplifying the design. The new structure of the machine part should contribute to a portion of the weight reduction. Another portion should be arrived at through structural optimization of the remaining parts – one of the central advantages of additive manufacturing. As work began it soon became clear that the new gripper could be produced as a single piece, without the need for post-production finishing or further assembly.