The use of sleeves on printing presses is considered a necessity in the wide web industry. Remounting a plate on a cylinder several feet long is a painstaking task that requires accuracy and physical prowess, as does moving the roller into the print station. Affixing the plate to a sleeve for future use saves sweat and time, which translate to cost savings.
In the narrow web business, sleeves are in use to some extent, but not to the degree that they are on wider presses. The main reason is that mounting a plate directly onto a narrow cylinder can be accomplished fairly quickly by a skilled operator. Installing the plate cylinder into the press is a one-person operation requiring little exertion or time.
But sleeves find a home in narrow web among those shops that run repeat jobs on a regular basis. In a busy plant, using a sleeve-mounted plate shaves minutes, sometimes more, off of production time, which translates directly to dollars in the pocket.
A simple process
Sleeves are manufactured of several materials, among them polyester, fiberglass, photopolymer and urethane. They are ordered to fit a specific press.
The mounting process is simple: A standard photopolymer plate is affixed to a sleeve rather than to a solid cylinder. Standard stickyback tape is used. The sleeve, with the mounted plate, is then slid onto a mandrel — a cylinder with air holes. Standard plant compressed air, at 80-85 psi, is forced through the mandrel to allow the sleeve to slip onto the cylinder. When the air is shut off, the sleeve lies snug in place, and the assembly is dropped into the press.
“Sleeves are becoming more and more popular in narrow web,” says Stanley W. Cox, vice president of Econo Products, Rochester, NY. “Your makeready time is reduced. After the job is run, the operator detaches the sleeve and stores it away, with the plate still mounted, for use when the job has to be run in the future.”
Sleeve manufacturers offer a long list of cylinder ODs that are available, and which cover most applications. “If your volume is sufficient,” Cox says, “the sleeve makers will make a sleeve the right size for you.”
Econo Products markets sleeves manufactured by Rossini North America, of Buford, GA, whose parent company is based in Italy. According to David Frank, director of sales, the Georgia facility is devoted to making sleeves from fiberglass and from urethane.
“For narrow web, we supply two types of sleeves,” Frank says. “The thin Type A is a smooth-ground, continuous-wound fiberglass sleeve for direct plate mounting. Type B is of similar construction, but the finish on the exterior is rough, and is specifically for rubber coverings. Rubber covered sleeves can be used for continuous laydown of tint or varnish, or can be laser engraved for a continuous image.”
Most sleeves in use over the years are of thin material, but Rossini also makes a brand called Evergreen, which is a sleeve with thicker walls. “Typically the thickness begins at 80 thousandths of an inch, and can go up to one inch in thickness,” says Frank. “It utilizes a urethane that is applied to a fiberglass core, and smooth ground to specific diameters for plate mounting. A one-inch thick walled sleeve equates to six inches in repeat.” Thick walled sleeves are mounted in the same manner as thinner sleeves.
Frank adds that Rossini supplies “a fair number of sleeves to companies with presses in the 20" to 30" range, many of them doing cartons.”
In the round
Advances in technology are having an impact on sleeve manufacture and use.
“If you take the process up a notch and use rubber for printing, you can coat rubber onto a sleeve, then grind it down to the right OD or repeat for the printing cylinder,” says Stanley Cox. “Then you put it in a laser engraver and etch away the rubber you don’t want. What you end up with is a continuous sleeve, with no seam.” (Label & Narrow Web will publish a feature article in the November/December 2002 issue on the subject of computer-to-plate technology and its use in narrow web.)
“This type of plate is more popular with gearless presses, where you can dictate the speed and repeat easier without having to use the gear teeth. It offers quicker makereadies,” Cox says. “In narrow web, probably very few are laser etching. Most are in wide web, with presses that range from 45" to 63". That’s where sleeves are most commonly used.
“For narrow web, a lot of sleeves are coated with rubber for applying UV lacquers and other coatings, where you want continuous application.”
A different type of sleeve has emerged from MacDermid Printing Solutions, of Atlanta. Mark Borski, general manager of the Flex-Light sleeve business, explains that the “performance sleeve” is covered with displaceable urethane, which he describes as “a high performance flexo platform. In fact, it has shown the highest performance in the industry, and has been tested by the FTA, by Fox Valley Technical College, as well as others.”
The product is called Eliminator, and though it has been manufactured for seven years, it has been finding its way into the narrow web market over the last two.
“It is a 100 percent solid urethane layer applied to a sleeve — not a foam, which is traditional for all conventional flexo cushions, which can collapse over time,” Borski says. “Ours is a solid, non-compressible layer that displaces under loads — it does not compress. This displacement phenomenon allows it to not break down over time, allows the plate to roll through the nip at its true length, and keeps the speed match of the plate and the substrate the same all the time. Plate wear and friction are greatly diminished by this product.”
The Eliminator is not thin, he adds. “We typically like about a quarter-inch of thickness, a good cushion to make this material work. It actually squeezes out behind, displaces a slight bulge of material behind the nip — barely a couple of thousandths of an inch. The plate likes this better, and it actually travels through the nip at a shorter radius.”
MacDermid produces the Eliminator as a sleeve or on a sleeve. “We can coat the narrow web cylinder directly, as a permanent cover on a roll,” notes Borski.
Another difference with this product is in the mounting tape. “Plates are mounted with very thin transfer tape, which is inexpensive, and is about five thousandths of an inch or less in thickness. The tapes come in a wide variety of adhesion packages, and can be selected by the printer based on the needs of the job.”
The sleeves division of Stork Rotaform, based in Charlotte, is seeing growing interest in its gravure print sleeves. These function as do solid engraved cylinders, but they weigh a fraction, which saves money in labor and shipping.
“The sleeves are nickel based, which gives them elasticity, robust character and the clamping force that they need,” says Harry McCoy, sales and marketing manager for the division. “On top of that is a copper layer, in which the engraving is made. Then we add chrome to give it durability.” The thickness of the sleeve is 0.014". Application to the mounting cylinder is through compressed air.
Most gravure presses are wide, and this is where the sleeve finds its greatest use. “Instead of a 500 pound cylinder, this weighs from five to 15 pounds,” McCoy says. “It’s a really economical way to move an image around the country from engraver to printer. It can be shipped FedEx overnight, instead of by truck over two days or more.
“And its disposable. Solid cylinders get reworked, so you often have two-way shipping. It’s not necessary with the sleeve concept. When you want a new one you call up the engraver, and he makes it and ships it.”
Though the expense of engraving remains the same, the gravure sleeve offers ease of handling, as well as storage.
“It’s not a new idea,” McCoy says. “In the past eight years the response has been kind of weak, but in the past year and a half it has been great. We have stepped up our development work on it. The gravure industry has seen flexo take a lot of its business, and they’re looking at the reasons for that. Many flexo houses use sleeve technology, and this is a way to compete.”