Q: What steps should users take to make sure their slitting has a nice, smooth outcome?
Pappas: A smooth outcome generally refers to rewound roll appearance, specifically edge quality. A smooth edge without “rings” is not only a desirable visual for the customer, it also indicates a roll wound with good, consistent tension control and a roll that will perform well unwinding for the customer. Steps to ensure this result begin with slitter design and the selection of the correct blend of controls and tooling for the specific materials to be run. Such items can include closed-loop tension control, correct rewind shafts, correct programming taper, proper lay-on roll type and proper mitigation of air entrapment.
Q: Have there been any new developments in this subsection of the flexible packaging market?
Pappas: Yes, many. Advances in slitting and rewinding technology have been numerous, not necessarily in basic machine design, but more in the components within a slitter. Examples include cut-off and transfer technologies on turreted machines that provide both finished roll last wrap and automatic tail tie of webs to new cores, without foldover or ragged edges. Additional advances include roll design to eliminate air entrapment, allowing higher speeds; shaft design and control technology to achieve better roll edge quality and build and, in many cases, support common shaft rewinding of materials historically wound duplex; dual bowed roll systems for slit separation; and coordination between auto knife placement and laser core positioning systems to provide fast, accurate core placement, saving time and material. New roll discharge systems handle larger diameter, heavier finished rolls, and tree-unloading systems now discharge directly to conveyors leading to remote packing stations. Also, control systems now often incorporate systems that report machine performance directly to customer data collection systems, allowing management to have precise information on production timing.
Q: What are the key points to ensure proper slitting/rewinding?
Pappas: Perhaps the most important point is a comprehensive understanding of the overall mission of the machine. What is the “bread and butter” work, the nature of the jobs? Once that mission is identified, key elements can be identified to ensure the desired performance. The machine must have a webpath optimized for all material, slit width, and core size requirements as well as all ergonomic and safety requirements. Some important considerations include elements to precisely control tension from unwind to rewind; things such as roll surfaces, load-cells, unwind type, drive size and programming; and the right rewind shaft design for the work.
Q: What’s new at your company?
Pappas: In the world of flexible packaging, one of the things we are most excited about is our Model 900 duplex center winder. The 900 is a machine of great versatility; it’s capable of running a broad range of materials including films, laminations, papers and various nonwovens. It can rewind to a maximum 32-inch diameter; run at speeds in excess of 2,500 fpm, depending on the material; provide either shear, score or razor slitting or any combination of the three; slit to a minimum of 1 inch and produce rolls of superior edge quality and roll consistency. It allows convertors who have been running on a 24-inch rewind machine at speeds under 1,500 fpm to meet customer demands for larger rolls and to run them much faster. This is especially important when running thinner films and other products where there is a large amount of footage on a roll. Where finished rolls have lengths over 10,000 linear feet, the time savings of running at 2,400 fpm vs. 1,200 fpm add up to dramatic productivity gains. With the ability to slit as narrow as 1 inch with any of three slitting methods, the 900 can perform on a wide variety of jobs, often eliminating the need to maintain different machines for different jobs.
