Roll Up Your Sleeves
Quality and damage control for higher line screens demands renewed attention to anilox roll cleaning practices and methods.
By Susan Friedman
Oven cleaner just won't cut it. When it comes to anilox roll cleaning, package printers are having to muster some heavier duty enthusiasm...and exercise care.
"Before higher line screens, cleaning didn't have to be as thorough because anilox rolls didn't provide the quality they provide now," says Torben Rasmussen, president, Flexo Wash. Anilox roll prices have doubled right along with line screens, and now the concern is preventing these rolls, which have thinner cell walls, from being damaged, he adds.
Converters continue to favor less rigorous cleaning routines. According to Steve Woodard, sales and service manager at ARC International, manually cleaning rolls with stainless steel or brass brushes is still the most common method. "It can do an adequate job if done regularly, before problems start," he states.
Cleaning agents used with brushes can create roll surface erosion if they have a higher ph than the inks. Laser-engraved anilox rolls that hold up best are those with a corrosion-resistant undercoat, which functions as a barrier between the roll's steel core and ceramic coating, Woodard notes.
Hand cleaning can also take a lot of trial and error, because few solvents can remove all types of inks and other contaminants, notes Praxair Region Sales Manager Jan Ashfield. "One cleaner that works perfectly well with ink A may not work well with ink B," he comments, adding that ink suppliers are the best source of guidance on this issue.
Brushes' popularity often leads them to be used even when they are ineffectual. "After 440 line screens, using brushes and powders is like putting a square peg into a round hole," says Ray Marro Jr., president of CR Products.
Clean-up acts
Heavy-duty cleaning methods that package printers have already taken a shine to—including baking soda blasting, plastic media blasting, ultrasonics and heated solutions—are heeding the industry's call for faster, damage-free cleaning at 1,200 to 1,500 lpi.
