The trade with metals and plastics is subject to a dramatic change. In the past, customers generally ordered large quantities of such materials, such as bundles of metal bars or complete sheets of metal. Today, they order only single bars or cut lengths or, in the case of sheets, partial sheets already cut to the required size. The metal or plastics dealer is thus no longer simply a supplier of the raw materials, but a material service provider who makes most of his profit from the pre-processing of the materials and the "just-in-time" delivery according to the customer's requirements, while the value of the actual materials is in many cases relatively low. The reason for this is that, for many companies, the quick availability of the materials is important while, at the same time, they do not want invest a lot of money in keeping their own stocks. This, in turn, means that the metal or plastics dealer has to act as an "external" stockroom. In order to react quickly to the wishes of all their small and large companies, the dealers have to expend their product range and the leading companies in the materials sector now carry not only all sorts of metal products but also plastics. The most important factor for rapid delivery is the quick access to the ordered materials, which are then cut to the customer's specifications on suitable machines, which the dealer must also have available. The machine operator must thus fetch a sheet of plastic from the storage area, place it on a machine such as a mechanical saw, cut it to size, return the remainder of the sheet to stock and pass on the ordered sheet for further processing of the order.

Manual handling of materials is rarely cheaper

In such companies, the manual handling of the materials has, in the past, frequently led to quality problems such as scratches on the surface of plastic sheets when the sheets were pulled off a stack of such sheets, delivered by a fork-lift truck, and slid onto the machine table. These quality problems resulted in complaints from the customers. In addition, the handling process was by no means rational. Furthermore, more and more customers demand such services, which means that the amount of work is increasing steadily. Another negative factor was that the hard physical work involved in handling the unwieldy and heavy sheets caused a gradual demotivation of the workers in the course of time and this was not good for efficient operations. One of the leading German companies in the materials trade therefore decided to reorganise the material flow and handling processes and consulted the vacuum specialists at J. Schmalz GmbH in 72293 Glatten who, in the past, have been able to provide "elegant" ergonomical and economical solutions for many handling tasks with the aid of their vacuum lifting devices. They recommended the use of a vacuum lifting device of the type VacuMaster 250-4. This is a crane-mounted vacuum handling system with four suction pads for the horizontal lifting and lowering of loads weighing up to 250 kg. Schmalz was responsible for delivering the complete solution, including a slewing column crane SKL 5/250 capable of handling the loads and with a 5-metre jib for the flexible handling of the largest plastic sheets in the vicinity of the mechanical saw.

Individual material-flow solutions constructed
from standard components with only low customisation costs

Although the he vacuum lifting device VacuMaster 250-4 was for the most part constructed with parts taken from the standard modular system, certain engineering and safety aspects had to be taken into account. The column of the crane had to be shortened so that it would fit under the low ceiling in the workshop, the dust-extraction system of the mechanical saw had to be combined with the crane installation, and the vacuum handling system had to be designed and erected so that it was protected against collisions with the fork-lift trucks moving around the area. Such problems demonstrate the system-solution competence of Schmalz, who not only provide the vacuum-assisted handling equipment but a complete and optimum material-flow solution which is tailor-made to meet the existing conditions. The material supply company now uses the VacuMaster 250-4 to lift sheets of plastic from the waiting stack, to place them on the table of the mechanical saw, to return the remainder of the sheet to stock after cutting and to pass on the cut sheets for dispatch. In contrast to the previous method, this is all done easily and ergonomically and without scratching the surfaces of the sheets. Gripping with vacuum also leaves no marks or other residues on the sheets and the sheets can be positioned quickly and precisely on the table of the saw, thus reducing the non-productive waiting times and improving the utilisation of the mechanical saw.