The task is well-known: the new machining centre for sheet-metal parts has been installed, or the performance of an existing machine could be higher, except for the fact that loading it with blanks and removing the finished parts takes too much time and too many people. This challenge has now been solved: with the aid of vacuum lifting devices, loading and unloading of machines can be done more rationally, faster and more safely by only a single person. The only drawback is that the users of machines for processing sheet metal are prepared to invest large sums in such machines, but hesitate to create the necessary environment with respect to material flow and handling of the blanks and finished parts. This is almost literally an anachronism, since it means that the full performance of the machine, for which the user has paid, cannot be fully utilised. With the aim of achieving more rational production and a higher throughput with fewer operators, making work for the operators easier, and ensuring the reliable and safe handling of the heavy metal sheets, the responsible persons at the medium-sized sheet-metal company Pro Metall Blechverarbeitung GmbH in Achern-Fautenbach decided to invest in a vacuum handling system for loading and unloading an existing laser-cutting machine and a stamping press/nibbler.

The solution: handling of sheet-metal parts with vacuum

The possible suppliers of such a vacuum lifting device had to take the following requirements into account: The device was to be used for loading both machines with small, medium and large sheet-metal blanks (with dimensions up to 3000 x 1500 mm) with thicknesses of 1 to 20 mm. These blanks weigh up to about 700 kg each. The finished parts to be removed may have holes and apertures, and their contours may be undefined. A further problem is that some of the blanks are oily and/or have dirty surfaces and that this should have no negative effects on the reliable and safe handling. Furthermore, the handling system must be suitable for multi-shift operations, since Pro Metall runs them in two shifts, five days per week. The handling system must therefore possess a correspondingly high level of technical reliability and availability. After consideration of all pros and cons of mechanical, magnetic and vacuum-assisted handling devices, the company decided to purchase a complete handling solution from the vacuum specialist J. Schmalz GmbH in D-72293 Glatten.

The modular handling system

The loading and unloading system comprises a vacuum lifting device VacuMaster Comfort 750-6 and a wall-mounted slewing crane WKL 6/1000. The vacuum lifting device is delivered as a complete unit and is simply suspended from the hook of the crane. The crane, with a slewing angle of 180° and a jib length of six metres covers a large area over and around the machines. It is capable of lifting loads of up to 1000 kg, while the VacuMaster Comfort 750-6 can handle objects weighing up to 750 kg. The VacuMaster Comfort 750-6 for horizontal handling tasks is constructed completely from standard components and has an integrated vacuum pump with automatic energy-saving function, an ergonomically designed operator handle, a chain hoist and a cross-beam with six suction pads. These suction pads are mounted individually on springs and joints, thus permitting the precise and reliable handling of even thin, flexible metal sheets without deformation. The controls (chain hoist up/down and vacuum on/off) are integrated into the operator handle, which permits easy and precise movement of the loads. To prevent inadvertent release of the suspended load, the "vacuum off" function requires two-hand actuation.

Summary

Now that the handling system has been in use for some time, the responsible persons at Pro Metall Blechverarbeitung GmbH are extremely impressed with the resulting performance increase and the optimisation of the processes. Whereas two persons were generally needed for loading and unloading the machines, this task is done today by a single person using the vacuum lifting device. Furthermore, it is no longer necessary to use a fork-lift truck for this work. The operator, who loads the machine on his own, still has sufficient time to manually remove and stack smaller finished parts, which means that the productivity has increased by about 50%.