The figures fluctuate - albeit at a high level. More than 50 percent of shipping parcels are said to consist not of the actual goods, but of air and filling material. The situation is familiar and can be felt every day: at the latest when the parcel service arrives at the door with the ordered delivery, the joy of the delivery is followed by the annoying act of disposing of the packaging components and filling materials properly.

Revolution of the standard carton
Opitz Maschinentechnik in Kalefeld, 30 kilometers north of Göttingen, has set out to revolutionize the world of standardized folding cartons with its Vario 558 volume reducer. The aim is to reduce the standardized shipping cartons of different carton widths, which are often far too large in online retail, to a minimum.

In the first station, a camera or ultrasonic sensor measures the height of the product in the carton and uses this to determine the fold heights or the depth of the cuts at the four corners of the carton. The height of the product and the variable carton size always determine how deep to cut and at which position the blades of the Vario 558 must stop in the corners of the standard cartons.

Individually defined basic formats with different heights and correspondingly embossed grooves. The folding crates are optimized to achieve maximum efficient packaging and transport safety with minimum volume. © SEW-Eurodrive

The cardboard flaps are then folded in one after the other thanks to the cuts and prepared horizontal grooves, fixed at the correct height by a hold-down device and finally sealed. Opitz is a proven expert in wet gluing technology, which, unlike plastic adhesive tapes, performs important sealing functions. This property is particularly important for high-priced products, as it prevents unauthorized access to the package - or at least makes it visible. The special feature of the volume reducer is that it can process cartons of different widths.

Opitz relies on servo technology in a multi-axis system for the motion sequences in the Vario 558 due to the high demands on precision and dynamics. This motion control solution was developed together with SEW on the basis of the Movi-C modular automation system. The special feature: with this new complete solution for automation tasks, the machine could be implemented with a tailor-made mix of centralized and decentralized drive technology - without having to compromise on integration or interfaces.

Smaller control cabinets
SEW used the new Movi-C double-axis modules for the stationary tasks. They drive the cutting gantry and the material flow within the machine. The use of double-axis modules, which are connected to each other as a multi-axis system for optimum energy efficiency via the DC link, makes the installation leaner and also reduces the required control cabinet space. "The control cabinet has become noticeably smaller. Space is a constant issue for our customers; it's actually always in short supply," explains owner Günther Opitz.

The wet glue head approaches from above to seal the box. © SEW-Eurodrive

Another issue is energy efficiency. This is why the individual processes are coordinated in terms of timing. For example, the lifting units are never raised at the same time in order to limit power consumption. Instead, the time offset means that the braking energy generated during lowering at one point is used for lifting at another work station. As a result, this network saves energy and cuts expensive peak loads.

Decentralized CMP ELVCD (Extra Low Voltage Compact Drive) low-voltage drives were used for the cutting process itself. Their task: linear adjustment of the blade positions in conjunction with servomotor-driven electric cylinders. This solution is one of the key results of the collaboration between Opitz and SEW in the early engineering and design phase of the drives. In the experience of programmer Helge Sünnemann, programming the movement functions within Movi-C proved to be very easy. "SEW makes life easy - especially with the prefabricated modules that I only have to wire up."

Fewer cables thanks to decentralized technology
Decentralized servo technology provides several advantages in the volume reducer. Firstly, the total cabling effort is noticeably reduced because no cables are required between the control cabinet inverter and the motor. In this case, drag chains would have been unavoidable. However, these are subject to wear, increase the frictional resistance and mass inertia as well as the required installation space in the machine design. The ELVCD low-voltage servo drives on the gantries, on the other hand, weigh little, have sufficient power and are supplied via a looped-through power and communication bus.

An electric cylinder moves the cutting systems in the length and width of the respective folding box dimensions. © SEW-Eurodrive

This architecture opens up good opportunities for Opitz to design modular packaging solutions. The use of decentralized servo drives opens up the possibility of adding further drives to the network without having to question the general installation or touch the control cabinet plan.

A look inside the volume reducer from Opitz shows the benefits that can be achieved with an integrated system of centralized and decentralized drive technology. The Movi-C modular automation system from SEW-Eurodrive also paves the way for future applications with modern communication interfaces as well as modularity and openness for machine expansions towards complete systems. Stefan Kattner/as