One would think, therefore, that laser beams would have replaced rotary dies a long time ago. Or if not replace, then take a position alongside them in the converting marketplace. The reality is that they are available and they get the job done, but there are so few of them in use that they are seldom a topic that comes up in discussions with converters.
The main reason is price. Some of the units cost in the hundreds of thousands of dollars. Some perform only laser cutting, while others are part of post-print converting equipment and can handle many finishing tasks.
Another reason is speed. While one company's product claims to cut labels at speeds of up to 500 meters per minute, other units are nowhere near as fast. When the image to be cut by the beam is intricate, the cutting process gets slower.
The advantage of utilizing a laser beam to cut shapes in pressure sensitive labels is that the converter can do away with steel tooling. Budgets for new and replacement dies are huge. A laser cutter can cut the same shapes as the tools can, and can cut different shapes on the next job. It simply takes its instructions via a computer interface.
One of the systems available for narrow web converters today is manufactured by Spartanics, of Rolling Meadows, IL, USA. According to CEO Tom Kleeman, the unit has an unwind, a laser that performs kiss cutting and through cutting, a rewind and a scrap web removal system. It features a 200 Watt laser that cuts in a field 250mm square, about 10" inches on a side.
"We are able to cut in a number of ways," Kleeman says. "The unit can index the web forward, stop in the cutting field and cut the specified pattern, or it can cut the web in a continuous motion. Also, we can make the cutting area longer by stitching together images, if, for example, an image is 6" x 18"."
Kleeman explains that two basic approaches are used in the mechanics of laser cutting. "In the galvo-type system, which our equipment uses, the laser beam passes through two sets of steering mirrors; we manipulate the mirrors to point the beam around the cutting field. That has the advantage of being very fast. It takes very little time to move the mirrors around, but it is somewhat limited in the size of the cutting field."
The other approach is similar to a gantry tower, in which the beam "moves around like a pen plotter, similar to a child's Etch A Sketch. It tends to be slower, but you can get to larger cutting fields more easily."
The term galvo, Kleeman says, comes from galvanometer, a limited rotation DC motor. The mirrors in Spartanics' system are powered by servo motors.
How fast does it go? Kleeman says that a cut the size of a credit card, two across on the web, can be run "in the realm of 10 meters per minute, about 30 feet a minute."
Laser cutters began to show up in the narrow web market in the late 1990s. One of the first was a prototype machine that appeared at Comco's booth at Labelexpo. Slowly others were introduced, but they never took off.
One of the early concerns was that the laser beam had a tough time making a sharp angle, of 90° or greater. The problem was that in making the turn, the mechanical equipment that moved the beam had to make an adjustment that caused the beam to linger just a bit too long on the material being cut. If it was a pressure sensitive laminate, there was a risk that the beam could cut through the liner at that corner. Cuts and tears in release liners can cause entire webs to break at any point in the converting process.
"There have been improvements," says Kleeman. "We don't lose the integrity of the beam these days. We address the liner burning issue through our software. It's a proprietary application that runs the cutting job. The laser power can be modulated to regulate the beam where necessary. We maintain the same spot size over the cutting field by making adjustments through the software."
Preco, headquartered in Lenexa, KS, USA, also produces a laser cutter utilizing the galvanometer technology. "Our Lightning Bolt LB3000 series are single unit converting systems designed for handling a variety of web materials," says Jim LaPoint, the company's director. "Cutting, kiss cutting, scoring, and perforating can be achieved at speeds up to 200 inches per second, depending on the type of cut and the type of material."
He describes the laser operation as a "three-axis motion control system that directs the laser beam precisely over the cutting area. The motion control system is supported by Windows Lightning Bolt control software."
The galvanometric system is also used by Cartes Equipment, of Moglia, Italy. The company's Laser 350 system handles a web 350mm wide (13.7") and claims to have a maximum cutting speed of up to 500 meters per minute.
AB Graphic International's Omega Sabre Extreme is a complete finishing system that enables file download from the internet; creation of digital files for printing, laser cutting and slitting, and complete output containing variable information and laser cut labels. The company, based in Bridlington, England, maintains that laser cutting eliminates the costs and investment in tooling and related equipment, as well as the accompanying lifting and storage.
Who owns these systems today? Tom Kleeman says that Spartanics' customers "tend to be the larger companies, and the
|The laser beam's fiery cutting is seen in action in AB Graphic's Omega Sabre Extreme unit.|