Today, the actual production of sheet-metal parts is already automated to a high degree in many companies. Nevertheless , there is in many cases still a great potential for rationalisation in the peripheral material-handling and material-flow functions. In order to increase the productivity in this area, and to make operations more economical, it is necessary to closely examine all possible actions to see whether they can be optimised and rationalised further by means of automation. Frequently, such automation seems difficult because the process has to transport and handle too many different products and other items, which means that the costs for automation equipment are unacceptable.

However, universal, flexible handling and material-flow solutions can very quickly make funds available for investments in rationalisation projects. A typical example of such systems is vacuum-gripper systems which, in contrast to specially designed and expensively manufactured mechanical or pneumatic grippers, can be constructed almost completely from a modular system and can, in general, also be used very flexibly. The intelligence and performance of a flexible vacuum-gripper system, combined with a controlled handling or robot system, ensures that the production machines are operated at their maximum efficiency and that the set-up times needed for conversion are reduced to a minimum. Further advantages of such a system are lower plant-investments and more continuity and quality in the production process. These were also the reasons why Messrs. E.G.O. in Oberderdingen purchased several palletizing systems for more rational production of mounting brackets for radiators.

Large-area vacuum grippers not only
solve handling problems...

E.G.O. was founded in 1931 and is today, with about 6,800 employees and a worldwide turnover of 520 million Euros, one of the market leaders in the sector of parts for electrical appliances such as hotplates, radiators, tubular heaters, thermostats, energy regulators ad switches for domestic cookers and washing machines. The impressive quantities of parts produced each day – 45,000 hotplates, 86,000 radiators, 77,000 tubular heaters and 68,000 energy regulators – clearly demonstrate why all of the company's factories in Germany and abroad have to work day and night to meet the demand. Such large quantities and the need for a reproducibly high product quality can be achieved only with high-performance machines, a high level of automation and qualified employees. For this reason, E.G.O. invests regularly in the most modern production equipment. Wherever possible, ties equipment is designed and built by their in-house engineers. The competence for process solutions and machines leads, in turn, to a greater production depth such as that which occurred recently in the manufacture of HiLight radiators. As part of the production process, thermal insulation elements need to be fitted in the mounting brackets for the radiators. For this, fully automated production equipment and a fully automatic palletizing station for stacking and unstacking.
The gripper system fro this had to solve many different problems, since the mounting brackets and intermediate layers of cardboard had to be handled and the brackets had uneven surfaces and holes and are produced in various diameters, which meant that the number of brackets per layer can vary. Furthermore, the heights of the layers and the thickness of the cardboard separators may vary. The problem was made even worse by the fact that the layers of brackets may be curved to a greater or lesser degree and the system had to work in very dusty surroundings.
Detailed examination of the problem showed that the handling tasks could be executed with magnetic or mechanical grippers or with combined mechanical-vacuum grippers, but the grippers would be very complex and expensive and would probably not provide the necessary process reliability.

Large-area gripper modules for an
intelligent universal gripper system

The vacuum specialists J. Schmalz GmbH in D-72293 Glatten were consulted and offered, with the large-area vacuum-gripper systems FX, an extremely practical and economical solution. The large-area vacuum-gripper systems FX are gripper modules with integrated vacuum generators, and several such modules can be combined to form a large, universal gripper system. The modules, which are delivered ready for installation, each have a vacuum generator and a sealing mat made of hard-wearing but flexible special foam, but are still very compact and light, which means that they have only a minor effect on the performance of the handling or robot systems with respect to the maximum load, the dynamic movement and the traversing speeds. The large-area vacuum-gripper systems FX are powered by compressed air, which means that there is no need for costly and impeding cables on the robot or the gripper system. With the aid of the large-area vacuum-gripper system FX, Schmalz were able to meet all requirements specified E.G.O. and, at the same time, make the work for the in-house engineers there much easier, since they did not have to design and manufacture the systems.
Furthermore, the large-area grippers are delivered as "complete systems" which can be mounted quickly and easily on the linear handling system.
In order to achieve the necessary output of 40,000 parts per day in  three shifts, E.G.O. built four palletizing/stacking units and ordered two large-area vacuum-gripper systems FX for each unit. The working sequence is as follows: the mounting brackets are delivered from the press shop on Euro pallets, each of which carries up to 30 layers of brackets with sheets of cardboard between the layers. The brackets are manufactured in six different diameters from 165 to 250 mm and weigh between 120 and 500 grams. Accordingly, the layout of the layers is different for each size, with between three and five rows of brackets per layer. When the pallet full of brackets arrives on the roller conveyor, the handling device with its large-area vacuum-grippers starts to unstack the brackets and place them on the feed band of the machine for insertion of the thermal-insulation elements.

FX proves its value in multi-shift operation
and under rough operating conditions

After insertion of the elements, the large-area vacuum gripper picks up the brackets and places them on a waiting Euro pallet. Between the two pallet stations (unstacking/stacking), there is a storage area for the layers of cardboard. The stacking systems fetches these layers from there and places them between the newly stacked layers of brackets.

The handling units equipped with the large-area vacuum-gripper systems FX have now been in use for more than one year and have proved their value. As previously mentioned, the factory operates in three shifts and, in spite of the various versions of the mounting brackets, the height variations, the curvature of the layers and the dusty surroundings, there have been no handling problems of any kind. The flexible mountings of the large-area grippers and the flexible foam sealing mats compensate easily for the tolerances and curvatures, resulting in extremely reliable handling of the parts and the intermediate sheets of cardboard. For fast and accurate positioning of the brackets and sheets of cardboard, the blow-off function of the integrated vacuum ejector, which is powered by compressed air, is activated for 0.5 seconds during each positioning operation. This blow-off function also helps to keep the flow resistors in the gripper free of dust. To date, these very small holes have never become blocked  and the sealing mats show only minor signs of wear after more than a year of industrial use.

The advantages of the large-area vacuum-gripper system FX, such as universal handling of all products and the load carriers (if necessary, the FX could also handle the empty Euro pallets without problems) and of the sheets of cardboard, have convinced the responsible persons at E.G.O. in all respects. For this reason, they have now purchased 12 further large-area vacuum grippers for the palletizing systems in the factory in the USA.

Pictures in a high resolution are availible on request!