Gripper systems are indispensable for industrial robots or handling systems as they form the connection between the workpiece and the handling system. Grippers are operated pneumatically or electrically and are used for gripping, holding, positioning and orienting the workpiece or tool. Normally, gripper systems are mounted on the outermost or last axis of handling systems and are connected to the main power cable.
Gripper systems can have different functionalities. They operate mechanically, pneumatically, electrically or adhesively.
Mechanical grippers resemble a human hand and have one or more fingers. These gripper systems can have several rigid joints, but are usually also flexible and bendable. They are usually pneumatic, i.e. they are operated by compressed air. Mechanical or electrical actuation is also possible.
Pneumatic grippers have vacuum cups or suction cups that pick up the workpiece using suction in order to transport it for further processing. In addition to vacuum technology, the workpieces to be processed can also be clamped and moved using pressure. If pneumatic grippers cannot be used because the surface of the workpiece does not permit the creation of a vacuum, e.g. if it is porous or holey, adhesive gripper systems usually provide an alternative solution.
When their gripping surfaces, which have tiny hairs, are pressed onto a workpiece, Van der Waals forces are generated that can be used to lift the workpiece. If the adhesive gripper is slightly tilted sideways with control, it releases its grip again. The advantage of adhesive grippers is that they do not require power and are therefore extremely energy efficient.
Electric grippers with magnetic function attract and hold the workpiece magnetically. A distinction is made between two types of magnetic gripper systems: permanent magnet grippers and electromagnetic grippers. Once the workpiece has been lifted by a gripper with permanent 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 set down again easily.
Mechanical grippers from Festo are moved by an internal drive and transform the drive motion into a gripping motion. This movement of the gripper jaws is referred to as a stroke. Depending on the stroke and gripping force, workpieces of different sizes can be gripped and handled. Grippers with a long stroke are offered by Festo in both pneumatic and electric versions.