Solutions from Rockwell Automation are being used on a new system of stretch bander machines at a German-based packaging machine builder. The machine builder is a provider of complete packaging systems for the food and beverage sector, pharmaceutical and cosmetic industries, and the family of stretch bander machines has long been a key part of the company’s product range.
Approximately two years ago, the company decided to re-design the system with the help of Rockwell Automation whose Allen-Bradley CompactLogix control solutions, in combination with modern PowerFlex drives and MP-Series servo motor technology, allowed the machine builder to achieve cycle rates of up to 50 cycles per minute.
A single source
The machine builder positions itself as a provider of complete packaging systems, and true to its motto of ‘everything from a single source’, it handles all aspects of an order for its customers – from planning and construction through to delivery and maintenance. Along with its in-house automated production, they often work with external business suppliers too – as was the case with the development of the new banding machine, for which they turned to Rockwell Automation.
The stretch bander produces sleeve wrapped packages, with or without lateral film overlapping. The film is stretched lengthways and the degree of tension is adapted to the product to be packed. As the new system was designed from the outset for use in all segments of the packaging industry, the machine builder specified during the planning phase that the system would have to be able to cope with different product formats while maintaining high machine availability.
The latter is an absolute must in the beverage industry, and customers in this sector consider it a decisive selection criterion when they buy machines. The stretch bander was designed as a modular solution to facilitate its adaptation to specific customer requirements. This has resulted in an open construction that has the additional advantage of easier access to all its parts.
Pneumatics to servo controls
The system is another example of the company’s strategy of moving away from pneumatics and working with servo controls instead. This has several advantages over conventional methods, as a spokesperson from the machine builder explained.
“We used to configure the film tensioning manually, using several different switches. This demanded a fair bit of experience on the operator’s part, as he or she had to get the settings exactly right. The servo controls help make that much, much easier. Today, anyone can adjust the tensioning to the exact degree required using the plus-minus button on the machine.”
Further advantages include higher cycle rates which cannot be achieved without servo drives. “We’re also now able to fulfil customer requirements about where the film’s welded seam is situated. Before, construction considerations meant that the seam’s positioning was more or less pre-defined.”
The improved tensioning capability provided by the servo controller has other advantages. First, the servo’s precision means that less film is needed to package the products and second, there is now no need for a separate shrink tunnel to shrink-wrap them. A hot air unit is sufficient to shrink the film to the right size. The spokesperson added, “The system uses 60% less energy due to the lower heat output alone, and that’s without counting the savings from the hot air unit (which can be turned off), compared to shrink tunnels which run continuously.”
The machine builder selected Rockwell’s Allen-Bradley solution including Kinetix servo drives and the Allen-Bradley CompactLogix PAC, as well as PowerFlex AC drives for the control system. All of the CompactLogix and PowerFlex products were equipped with integrated EtherNet/IP cards. Further Allen-Bradley products were then added, including MP Series motors and modules from the Point I/O family.
“Rockwell Automation solutions provide a higher level of flexibility when customers want to switch from wrapping single products to multi-packs,” added the product manager. “The biggest benefit for us and for our customers is that communications are quicker and easier between CompactLogix and the PowerFlex drives in the control system, as well as between the controller platform and the Point I/O modules. The simple, modular construction of the communication and control systems is a considerable benefit for the end customer.”
The network interfaces included in Rockwell Automation’s solutions also helped to meet the requirements of every application for which the stretch bander is used. EtherNet/IP accelerates the communication between the modules and the control elements. The product manager continued, “The modularity and faster communication helped us to lower the installation costs and the number of switches, connectors and modules in the network.
“We can do this within the controller using one single interface. Because the I/O unit is nearer to the process, we’ve been able to achieve better performance throughout the whole system. Once a system like Point I/O has been installed, the application can be extended with further modules without the need for additional switching mechanisms. The servo drives and components differ from others on the market in that they are more compact. That is a real improvement for us, because the smaller size gives us more machine design flexibility and higher production performance in the same amount of space. The software is a real success.”