Digital Magazine

Cylinders and rolls - a quiet revolution

In the past cylinders and rollers were considered less important than the web. However, the desire to produce more product faster, with less waste, and to make machinery last longer has forced manufacturers to look beyond the web and make improvements in other aspects of the process. During the past few years cylinders and rollers have been the beneficiaries of increased R&D, which has led to quantum leaps in their evolution.

An example is the highly abrasion-resistant tungsten carbide coating. Converters can adjust the degree of roughness through grinding. Once applied, TG coating can be finished from mirror smooth to a rough sandpaper-like surface to dial in the exact amount of traction desired and can be applied to nonmetallic surfaces such as composites.

Another innovation is Teflon coating applied to tungsten carbide, giving it a mechanical grip but an adhesive release. "You can have the best of both worlds," says Dr. David Rosium, president of Finishing Technologies, Neenah, WI, and author of the soon-to-be-released book The Mechanics of Rollers. "You have the necessary traction, but coatings and contaminants don't stick." (He adds that converters could solve 90% of their web-handling problems if rollers are properly aligned.)

Recent innovations in plasma coating and thermally applied coatings now give converters the ability to apply ceramics onto nonmetal surfaces. Today's ceramics are no longer brittle. In fact, they can be made more ductile than many machine tool steels. They also have the ability to take high temperatures and provide great resistance to wear and superior dampening. In addition, they're ecologically correct and, because they're so corrosion-resistant, are rapidly taking the place of flake- and crack-prone chrome plating.

Manufacturers have taken advantage of continuing advances in metallurgy as well. "GI30 cast iron wears much better, and increased rigidity and balance realized through new designs have all contributed to a new age in cylinder and roller technology," says Bob Zemaitis, graphic arts technical manager for American Roller, Bannockburn, IL. He reports that nylon has replaced copper plating on rollers, and rubber rollers are constantly evolving, with new robber compounds being developed to improve on-press performance, especially in the area of reduced heat generation.

According to Sean Ward, product manager for Max Daetwyler, Huntersville, NC, laser engraving is the single biggest innovation in cylinder technology in decades. Before lasers, cylinders were mechanically routed by hand, and it would take days, if not longer, for a skilled artisan to engrave a complex pattern.

With digital direct laser engraving, the pattern is first created in a CAD/CAM type of program. The file is then downloaded into a program that instructs the laser when it should fire, for how long and at what angle and width. The laser doesn't burn the rubber but turns it into dust. The result is a perfect, seamless cylinder that's press-ready.

"A mechanical process that used to literally take months to complete has been reduced to where our average lead time now is two and a half weeks," says Katheryn Morris, director of art and marketing for Luminite, Salamanca, NY.

What's next for cylinder and roller development? There appears to be a consensus among those we interviewed that sleeves offer a great potential for growth. Besides being seamless, they're lightweight and stable, combining the best features of D-mount and integral shaft technology.

Although it's true that cylinders and rollers are an old technology, predating the industrial revolution, savvy converters realize they are critical components, especially with the increased emphasis on faster and more efficient production.

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