Flexible Packaging recently caught up with Uli Jorgens, sales director, flexible packaging, Karlville, for an overview of all things slitting/rewinding.
Q: What’s new in slitting/rewinding? Did you release anything new at Drupa?
A: For us, it’s important to continuously enhance key sections of our slitter/rewinders – like slitting concepts, differential rewind systems and tension control – to improve finished roll quality and simultaneously improve productivity. We made advancements in finished roll handling to reduce operator-influenced downtimes. Further, recipe storage for the important parameters to produce the same roll quality over and over again with different operators is an enormous help obtaining consistent rewind roll quality. At Drupa, we successfully displayed our compact entry-level slitter/rewinder model, HSC. We offer this machine at a great value and short delivery time.
Q: Minimizing inefficiencies seems to get a lot of attention when it comes to this equipment. What are some of the biggest inefficiencies with slitters/rewinders, and what’s being done to reduce these?
A: Reduced downtime increases efficiency. A slitter/rewinder is the final equipment in the production process of flexible packaging material. In many companies, it is the last chance for a quality check. As a result, the operator also inspects the material for defects. To do this right, the machine has to run at a reduced speed, stop at a recognized (or flagged) defect, cut the defect out, make a splice and continue. To eliminate this time-consuming function, there are two solutions. One, add an inspection machine with 100 percent defect detection. Defects are stored at forward run, displayed and out-of-spec defects are selected, running direction is reversed and the inspection machine stops automatically at each selected defect to be removed. Two, the printer has 100 percent defect detection, a roll mapping is created (selection of defects) and transferred to an inspection machine with workflow. The inspection machine runs forward and stops automatically at each selected defect to be removed. Both solutions guarantee defect-free material to be laminated and transferred to a slitter/rewinder, which now substantially increases production. Even though equipment is added, it increases production, eliminates the need to rely on the operator qualification of defect detection and reduces returns considerably.
Another improvement is to reduce the operator-influenced time of rewind roll change. There are quite a number of solutions offered like turret rewinders, rewind roll push-off and unloading systems, auto-finished roll labeling and packing concepts.
Q: Why is the selection of the proper rewind shaft technology so significant? Can you briefly detail when an application would require either a direct friction, indirect friction or locked core shaft?
A: Selection of the three systems mentioned depends on the type of material you need to rewind. A locked core shaft or air expandable shaft is torque controlled and works well for paper. Any flexible material has to be rewound on two-speed controlled differential rewind shafts by alternating the slit strips. Without going into details about a differential rewind shaft concept, and assuming I understand the question, direct friction applies to closed-loop tension control using a tension-measuring roll. Indirect friction applies to open-loop programmed tension control. Direct friction works well for locked core winding, but isn’t suggested with differential rewind shafts. Indirect friction or open-loop tension control works very well, specifically if the necessary parameters for winding the perfect roll can be stored and uploaded by code each time the product is run.
Q: One point that gets overlooked is that of ergonomics as it pertains to the equipment. Can you describe the importance of this and what’s been done to improve on this?
A: Ergonomics are an important part of efficiency, safety and overall appearance. More and more slitter/rewinder manufacturers pay attention to this fact and incorporate ergonomics at the design stage. Ease of operation, clean design and appearance make the operator proud to work on such a machine, and the operator proudly takes ownership of the equipment. The desired result in efficiency is quite remarkable.
Q: Is there anything else you’d like to share about slitting/rewinding?
A: A converting operation has to include a sufficient budget for the slitting/rewinding equipment. Being the last machine to select, other equipment usually has first priority. It happens quite often that a slitter/rewinder has to be purchased from the remaining budget. But understand that a slitter/rewinder has a considerable impact of producing a quality product.