In site of this, many users are not prepared to spend money on such devices, although a complete solution constructed from standard modular components is very cost-effective provided that the various components, such as the crane system and the vacuum handling device, are perfectly matched with respect to their design, performance, installation and operation.

Obviously, there are many possible reasons for rationalisation in the production of sheet-metal parts. But this cannot be achieved by simply purchasing a high-performance cutting or bending machine, since the material flow to and from such machines is equally important and offers major potential rationalisation effects. Another important factor is that, for example, the vacuum-aided handling of sheet-metal parts being worked on laser-cutting machines permits two (or more) birds to be killed with a single stone. This is particularly true when, as in the case of dübro Werkzeug GmbH in D-72175 Dornhan, the parts in question are not everyday parts. dübro Werkzeug GmbH has a staff of 50 persons and manufactures circular saw blades for cutting wood, aluminium and steel. The market for such products is very competitive, and the company thus has to optimise its production technology and processes regularly. For this reason, it recently purchased a high-performance laser-cutting machine for fast and flexible production of the blanks from sheets of hardened steel with thicknesses of 1 to 5 mm. These heat-treated steel sheets may be up to 1,000 x 1,500 mm in size and weigh up to 12 kg each, depending on their thickness. In the past, these sheets were lifted onto the table of the laser-cutting machine by one or two persons. The blanks cut from the sheet and the remaining material were also removed manually. Although this is a perfectly normal procedure, it can become hard work for the persons concerned when they have to handle up to 100 such sheets per day. The work often results in unnatural movements and postures which can endanger the health of the operators and even result in industrial accidents.

Efficiency and ergonomy
are not mutually exclusive

Prevention is better than the cure, thought the responsible persons at dübro Werkzeug GmbH, and they developed a plan to make the loading and unloading of the laser-cutting machine much easier. According to technical manager Henning Frey, the original objective was primarily to avoid accidents and damage to the parts, rather than to rationalise production by reducing the idle times of the machine. After a thorough analysis and consultation, the company thus decided to purchase a complete handling system for the metal sheets and the parts produced from them. As supplier, dübro selected the vacuum and handling specialist J. Schmalz GmbH in D-72293 Glatten. The system consultants from Schmalz presented an optimal solution based on modular components from the standard range of vacuum tube lifters JumboErgo with suction pads FM and an aluminium crane system. The maximum load specified by dübro was 35 kg, and the monorail overhead crane system, made from aluminium sections, and the vacuum tube lifter JumboErgo 35 with double suction pad FM were designed to handle this load. The monorail overhead crane was selected because it can cover a larger working area than a slewing wall or column crane and because it is mounted on the ceiling and therefore needs no columns or supports which could get in the way. Furthermore, the quality of the floor in the factory building is immaterial and there is no need for expensive special foundations. The proven ease of movement of the aluminium crane system, which permits fast, safe and ergonomic traversing of the vacuum handling system and the workpieces makes the selected crane solution perfect for the task.

Three-part complete solution from
the modular Schmalz system

The monorail overhead crane can be moved over an area of 6 x 3.5 metres and carries a vacuum tube lifter JumboErgo equipped with a double suction pad FM. This double suction pad is ideal for the handling of workpieces where 100% coverage of the gripper area cannot be achieved, as it is the case at dübro, since the blanks cut from the metal sheets have teeth around their circumference and various holes and slots in the surface. Nevertheless, the 50% coverage needed for safe movement of the workpieces is achieved. In addition, the two suction pads can be moved along the beam of the gripper to permit handling of sheets and blanks of varying sizes with one and the same gripper. The workpieces are gripped and held quickly because the two FM suction pads have a soft, flexible and hard-wearing suction pad made of special foam. This also ensures careful handling of the blanks without damage. Last but not least, a powerful vacuum blower of the type SBL provides a continuous vacuum and this, together with the easy-moving aluminium crane, guarantees safe movement of the workpieces over the entire working area. The workers and management of dübro Werkzeug GmbH are fully satisfied with this complete vacuum handling solution from Schmalz. Only one operator is now needed to handle the metal sheets and blanks with the aid of the vacuum handling system. Handling is also much faster and safer, the idle times of the laser-cutting machine are far shorter, and the health of the operator is no longer subject to the risks of manual handling.