At the end of the press run the finished labels have to be cut into sheets, folded, or put on a roll. Rewinding printed products onto rolls is by far the most common post-print procedure in the narrow web industry, and to accomplish that task many manufacturers provide a wide variety of machines.
A rewinder can be a simple spindle located at the end of the press. It can be an inline turret rewinder with multiple roll spindles. Offline machines abound, from the basic tabletop units to the complex inspection slitter rewinders manufactured by Rotoflex, Omega and others.
Rewinders are designed to handle rolls of certain sizes, and substrate types must be taken into consideration by the operator when a rewinder is engaged.
Web Techniques, of Fenton, MO, has been manufacturing rewind tables for 26 years, according to its president, Ken Barstow. The company offers three models: the WT-25, the WT-25LC and the WT-25LCI. These are machines with few moving parts that rewind finished rolls at high speed. The maximum roll diameter they can accommodate is 24".
"Our most popular machine is for a seven-inch roll," says Barstow. "We also build a 10" version. But there's a weight restriction on the 10" model. It's hard on the operator, and I wouldn't ask an operator to lift a 95-pound roll onto that machine." Web Techniques has made tables for wider rolls, but only as custom orders.
The speed of a tabletop rewinder is quite fast. "There's no pinch roller or drive roller like there are on regular slitter rewinders," Barstow says. "Since we're pulling from the rewind, as the roll builds in diameter the speed increases. The maximum speed at the start of the roll can be 350 feet a minute, and by the time we get up to 18" in diameter the speed could be from 1,500 to 1,800 feet per minute."
Features on Web Techniques' various models include the ability to count by roll length, by the exact number of labels, and to view with a stroboscope. Options can involve the integration of a camera or bar code reader, and the ability to detect missing labels or unremoved matrix.
Turret rewinders are found inline at the end of the press, and are constructed to create successive rolls of labels without interruption of press speed. To accomplish this, the rewinder features a turret out of which multiple spindles protrude--anywhere from two to six, depending on the manufacturer. When one roll is completed, the turret turns to ready the next core to receive more...