Gripper systems are indispensable elements for industrial robots or handling systems because they represent the connection between the workpiece and the handling system. Grippers are pneumatically or electrically operated and are used to grip, hold, position and orient the workpiece or tool. Normally, gripper systems sit on the outermost or last axis of a handling system and are connected to the general power line.
Gripper systems are subject to various effects. They function mechanically, pneumatically, electrically or adhesively.
Mechanical grippers resemble a human hand and have one or more fingers. These gripper systems can consist of several stiff articulated joints, but in general they can also be flexible and pliable. They are usually pneumatic, that is, operated by compressed air. A mechanical or electrical drive is also possible.
Pneumatic grippers involve vacuum cups or suction cups that draw in the workpiece in order to transport and machine it. In addition to vacuum technology, the workpieces to be processed can also be clamped and moved using the pressure principle. If pneumatic grippers cannot be used because, for example, the surface does not permit the generation of a vacuum, e.g. in the case of porous or holey structures, adhesive gripper systems usually provide a remedy.
When their gripping surfaces, which are equipped with tiny hairs, are pressed onto a workpiece, Van der Waals forces are generated that can be used to lift the workpiece in real time. If the adhesive gripper is tilted sideways slightly and in a controlled manner, the adhesion is released again. The advantage of adhesive grippers is that they require no electricity, making them extremely energy efficient.
Electric grippers with magnetic function attract and hold the workpiece magnetically. Two types of magnetic gripper systems are distinguished here: permanent magnet grippers and electromagnet grippers. With permanent magnet grippers, once the workpiece has been lifted by the magnet, it must be removed by another system. Electromagnetic grippers are switched on and off by electrical energy, which is why workpieces can be gripped and also set down again in an uncomplicated manner.
Mechanical grippers from Festo are moved via an internal actuator and convert the drive motion into a gripping motion of the gripper jaws via a transmission ratio. This movement of the gripper jaws is referred to as stroke. Depending on the stroke and gripping force, workpieces of different sizes can be gripped and handled. Festo offers both pneumatic and electric grippers with long strokes.