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FLEXO Magazine : August 2009
TECHNOLOGIES & TECHNIQUES PRESS BUYER’S GUIDE Keep on Rollin’ Thermoset Polyurethane Rollers Offer Superior Longevity A s someone in the printing/converting industry, you know that roller toughness and longevity count. The Achilles heel for many applications is the roller surface, where challenges such as cut-resistance, abrasion resistance and load bearing capabilities can make a dramatic difference in the productivity of a plant. Because roller changeover and resurfacing are both time-consuming and costly, many plants run theirs as long as possible in order to maximize production until replacement is mandatory. “In many applications there is no in-between, the rollers are either operable or defective,” said Matt Menges, president of Menges Roller Co., Wauconda, IL. “But the toughness and impact-resistance of the surface covering can improve wear life by months or even years.” For example, Menges says, in the steel coil industry, coils are stretched almost as tight as piano wire. Because the steel is very abrasive and usually has rough edges, cut-resistance is a major factor. As a result, standard rubber-coated rollers wear out relatively quickly, resulting in both maintenance, loss of product and downtime costs. FLEXIBLE ADVANTAGES One of the solutions to greatly improving the wear life of roller coverings is the use of more advanced materials than can be tailored to an application. The use of thermoset polyurethane (TPU) plastic, for instance, provides the toughness and abrasion-resistance needed by most applications while at the same time allowing the latitude to make the coating as hard or soft as the application requires. Some of the properties available by various TPU formulations include: superior abrasion resistance, chemical resistance, cut resistance, impact resistance, high tear strength, fl exibility and broad temperature operating range. LONGEVITY, SAVINGS AND SAFETY A graphic demonstration of the powerful benefi ts of TPUcoated rollers may be found in the production of blown-fi lm packaging at PPC Industries, Pleasant Prairie, WI. Because PPC runs its plants 24/7 for 365 days a year, the company’s engineering, production and maintenance people decided to investigate TPU-coated rollers to see how much additional longevity they could provide. “The whole idea behind this was to get more life out of the rollers because they are expensive to replace and changeover requires a very big effort,” explained Tom Gussarson, PPC purchasing manager. “So, we’re hoping to get two-to-three times the service life out of these TPU-coated rollers as we do from a standard rubber roller, which is about a year.” PPC initially installed TPU-coated nip rollers on a blown fi lm system about 18 months ago. Since then the bag machine nip roller and winder nip rollers have also been replaced with TPU models. 80 FLEXO AUGUST TPU rollers are lighter than traditional rollers. Photo courtesy Menges Roller Co. TPU rollers are lighter than traditional rollers. Photo courtesy “We produce several different plastic bags with writing on them,” noted Gussarson. “These bags are used for medical and food customers who require that messages be printed on the fi lm. Any time you have printing on bags, that fi lm must be treated through a corona system. The corona treatment causes added ozone, some of which lingers in the plant, especially in the area of the top nip roller, which is 60ft. in the air.” Gussarson stated that the ozone exposure will deteriorate standard plastic- or rubber-coated rollers, causing them to dry out and become brittle and crack. This condition would normally accelerate the need for roller replacement. “The TPU rollers hold up much better when exposed to ozone,” Gussarson said. “In fact, they are almost immune to the problem.” In addition to productivity, another major goal with adopting the TPU-coated rollers was the avoidance of having to replace large, heavy rollers that are sometimes at considerable heights. For example, the rollers on our top nip section are 60ft. up, are 5ft. to 10ft. wide and can weigh between 4,000lbs. and 6,000lbs. “That size makes the effort to change the rollers a major one,” said Gussarson. “Plus there is also a safety consideration. While we are very safety conscious, avoiding accidents requires reducing the exposure to incidents, so if we can reduce the frequency of changing those rollers, that is also a signifi cant benefi t.” ■ ABOUT THE AUTHOR: This article was submitted by Menges Roller Co. Menges offers new and replacement rubbercovered rollers for the printing, converting, metal processing, plastics, paper, and textile industries. The fi rm specializes in steel, tube, stainless steel, cast iron, carbon fi ber composite and aluminum roll cores from 48in. in diameter and 30ft. in length. For more information, contact 847-487-8877, info@ mengesroller.com, or visit www.mengesroller.com. 2009 www.flexography.org