If the compressed air fails, the magnet continues to hold the load. No backup system is required for this. This means low investment and maintenance costs and simple control. To illustrate the relationship between compactness and magnetic force: A #115 millimeter Powergripper weighs around 9.5 kilograms and safely lifts a load of around 175 kilograms and has a holding force of 527 kilograms.

Closed magnetic circuit with neodymium magnets
Compared to conventional magnetic grippers, which are designed for the same purpose but for thin sheet material, a Powergripper with the same diameter is 3.5 times stronger. Goudsmit has developed a closed magnetic circuit with neodymium magnets that come into direct contact with the product to be moved via steel poles. This pool configuration was calculated using FEM analyses and has been optimized so that the circuit reacts less sensitively to a larger air gap between the poles and the object to be picked up.

This ensures optimum holding force and even rusty products can still be moved safely. The magnetic gripper is designed with a specially mounted piston construction that has been tested for a service life of at least one million operations.

This power gripper is less suitable for thin-walled products. Below a wall thickness of ten millimetres, the lifting force is relatively reduced. A normal gripper is better suited for this. Tests show how the lifting forces of Powergripper and normal grippers relate to each other, which gripper is intended for which product and which holding force is safe.

Possible applications
In a robot application, the Powergripper is used to pick up or hold solid and heavy steel parts such as castings, hot-rolled profiles, solid bar material and thin-walled welded constructions. These magnetic grippers are also used to pick up steel workpieces for machining processes, such as in sawing machines, cutting machines and welding and grinding processes.

The on/off position can be determined using commercially available sensors, which can be mounted in slotted holes specially provided for this purpose. It is also possible to attach two or three Powergrippers to each other with special coupling strips for heavy lifting work, such as lifting tons of hull parts in ships. The magnets can be switched on and off with the aid of a simple pneumatic control using a 5/2 or 5/3 valve. as

Hall 12, Stand B153