by clicking the arrows at the side of the page, or by using the toolbar.
by clicking anywhere on the page.
by dragging the page around when zoomed in.
by clicking anywhere on the page when zoomed in.
web sites or send emails by clicking on hyperlinks.
Email this page to a friend
Search this issue
Index - jump to page or section
Archive - view past issues
FLEXO Magazine : March 2011
Plants & Processes Attack Scrap!!! It can Make or Break a converter By robert Moran With materials cost at the typical flexible packag- ing converter ranging between 60 percent and 85 percent of sales, sensitivity to scrap is on the rise. Today ’s flexo printers are continually developing and implementing waste reduction campaigns, with two factors common to every approach: measurement and control. Duncan Darby, PhD, an instructor at Clemson University ’s Center for Flexible Packaging, emphasizes these facets of reducing waste to students in his converting and plastics packaging classes, as part of a curriculum developed at the industry ’s request. “Cost modeling is in demand,” says Darby. “Printers want new hires to understand it. They expect them to have ex- perimented with it, as well as be capable of analyzing data collected and drawing conclusions from it.” According to Darby, scrap comes in several forms: trim, makeready and print-run. Some scrap is routine and to be expected as a result of normal pressruns. Then there is what Darby calls “catastrophic scrap,” the result of mechanical mishaps and malfunctions that shred paper, spew ink or otherwise destroy materials on a grand scale. So much is at stake with this latter form of scrap that Darby issues a warn- ing whenever he has the chance: “Catastrophic scrap on one large order can eat up the year ’s profit!” It’s a warning he repeated for the benefit of approximately 60 converters in a day-long workshop, “Scrap Reduction Through Scrap Prevention,” hosted by Nordmeccanica Group and its adhesives-making partner Henkel Corp. at Nordmec- canica’s North American headquarters in Edgewood, N.Y. in February. Darby, the session’s keynote speaker, maintains today as he did then that plants need to concentrate on different kinds of scrap depending on the type of runs they do. “Plants with short runs and frequent job changes need to concentrate on makeready scrap. Plants with long runs and few job changes need to concentrate on run scrap. All plants need to concen- trate on catastrophic sources of scrap.” Given estimates of press scrap at 5 percent to 9 percent of material and laminator scrap at 3 percent to 7 percent, it is clear to see that waste reduction is a sound strategy, accord- ing to Darby. He is not shy in offering strategies for reducing waste, and advises preparing for scrap according to category so as to avoid catastrophe. Trim ScrAp Trim scrap makes sense when graphic needs can be built into the print design. Examples include edge lines and register marks. Darby says trim scrap also proves valid when machine design minimizes web movement—starting with the unwind. Edge guides are important and can help the situa- tion, but they are far from the be-all and end-all. A simple routine maintenance program will minimize web movement and therefore assist in reducing trim scrap. The objective here is to keep rollers level. A supplier’s ability to consistently deliver straight edges on the substrate also weighs into the equation. mAkereAdy ScrAp Shorter machines, combined with quality tension controls, will consume less material as the press gets up to color and quality. Smaller adhesive reservoirs will also assist in achiev- ing lower lamination waste. Duncan Darby, PhD 14 FLEXO March 2011 www.flexography.org Sound Strategies • Accurate mixing of adhesives, in correct ratios, will afford consistent laydown. • Surface treatments and tension controls can reduce wrinkle and tear issues. • Keep rollers level to deliver straight edges on the substrate consistently. • Build graphic needs—edge lines, register marks, etc. —into the print design. • Limit roll changes and other process upsets. FLX_March11.indd 14 3/18/11 1:32 PM