Vacuum-assisted loading and unloading of sheet-metal machine tools saves money and uses fewer people which provides a considerable productivity increase for only a small investment.
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 uses too many people. This challenge has now been solved: with the aid of vacuum lifting devices, loading and unloading of machines can be done 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 means that the full performance of the machine, for which the user has paid, cannot be fully utilized.
With the aim of achieving a better flow through of production 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 a medium-sized sheet-metal company 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 1500mm) with thicknesses of 1 to 20mm. These blanks weigh up to about 700kg 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 they run them in two shifts, five days a week. The handling system must therefore possess a correspondingly high level of reliability. 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 Schmalz (represented by Millsom Materials Handling in Australia & New Zealand).
The modular handling system
The loading and unloading system comprises a vacuum lifting device VacuMaster Comfort and slewing crane. The vacuum lifting device is delivered as a complete unit and is simply suspended from the hook of the crane. The crane covers a large area over and around the machines; it is capable of lifting loads of up to 1000kg, while the VacuMaster Comfort can handle objects weighing up to 750kg. The VacuMaster Comfort 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 accidental release of the suspended load, the "vacuum off" function requires two-hand actuation.
The handling system has been in use for some time, and the customers 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%.