Twin lasers employed in the AB Graphic Sabre Xtremecut shapes in labels.
Today, the laser beam is employed in uncountable manufacturing functions, as well as in medical and scientific fields. In the label converting industry, we are familiar with its role in the creation of the microscopic cells of anilox rolls.
In other industries, lasers are used to cut shapes in a multitude of materials, having long replaced the metal cutting tools of old. In the label business, however, steel dies are king. Solid metal tooling has proven itself to be eminently reliable in producing precise, repeatable shapes. In recent years we have seen the steady growth of flexible magnetic dies, which have received high praise from converters for their precision, durability and lower cost.
Prominent though it might be in other industries, the laser has somewhat of a bumpy history in the label industry. One of the early issues was speed: The pace of the cut was slow, and on a complex shape even slower. Another issue involved the laser's inability to maneuver quickly around right angles or acute angles. In order to make the sharp turn, the beam slowed by microseconds before resuming its task. During that brief period, the heat of the beam would penetrate not only through the label facestock but also through the release liner. As label converters and their customers are aware, such burn-through can cause havoc on a high-speed label application line.
Delta Industrial's Edge laser cutter is available as part of a customized finishing system or installed inline in a printing press.
It can be placed either in a fixed position or moved from station to station via a shuttle.
"When we came out with our technology five years ago, laser cutting had a bad name," recalls Mike Bacon, VP of sales and marketing for Spartanics, Rolling Meadows, IL, USA. "There was browning on the edges, cut-throughs on the liner, shapes with too much dwell time at the points. What has happened since then, as with any digital technology, is that software has gotten better."
Several manufacturers of laser cutting equipment for the label industry report that interest in the systems has been on the increase lately.
"Acceptance is gradual," says Al Spendlow, vice president of AB Graphic International, "and there are two reasons. First, the technology was not suitable for all products and materials. Developments in laser control, the focal points and other materials, and an understanding by the manufacturers of the issues – and overcoming those issues – have broadened horizons for end users and those we sell the systems to. The technology is getting better to the point where we think it is a commercially viable product for digital label printers." AB Graphic, which is based in England, manufactures the Omega Sabre Xtreme laser cutting unit.
"Interest among label converters in laser diecutting is similar to what digital printing went through a couple of years ago," observes Bacon. "They are asking, 'What's the technology? Is it where it needs to be now? Will it save us money? Will it allow us to get into new markets?' For the past three years we have answered those questions because the quality is now good, the awareness is out there, and they have the ability to run the press without having tools and a lot less scrap from changeover." The recession, he notes, put a damper on sales. "We were selling at a good clip when that came along."
The digital nature of the laser cutter means that the die shape comes to the machine directly from prepress, which means that there is virtually no limit to the range or frequency of shapes to be cut. "The shape is pre-programmed using a graphic file, CAD or bitmap, that allows you to select lines within a shape that you want to cut," says Mike Wagner, a salesman for Delta Industrial, Minneapolis, MN, USA. "Especially for companies that want to do completely toolless processing, it's a very nice thing. They can cut inline in any shape they like." Delta's Edge laser cutter can be installed into a printing press, and can be moved to different stations.
Universal Laser Systems manufactures a range of laser diecutters.
Operation, Hillman adds, is simple. "Download the artwork, select material in the materials database to download the optimized laser setting, then press 'Start.' No tooling is required, and turnaround is in minutes rather than days. And it's easy to operate – no technical training is needed."
AB Graphic's Omega Sabre Xtreme utilizes twin CO2 lasers to cut infinite shapes in substrates. One laser cuts a mirror image of the shape being cut by the other. The system, along with most others being manufactured today, makes use of what is called a galvo system. "Galvos are series of mirrors that direct the beam through several prisms to the substrate," says Spendlow. "The laser does not move. The beam is shot and the mirrors direct it to the material at a very high speed."
Another type of system, in which the laser itself moves to make the cuts, is used primarily in other industries. "The gantry system is basically an XY plotter," says Bacon. "Either the sheet moves under the laser, or the laser itself will move around above the web. Those are good in a lot of electronic applications because they are more precise, though they are quite a bit slower. We tell customers that our galvo system has a variance of ±2 mm, but we feel it's more like ±1 mm, and that's enough for most label applications."
Cutting speed was an issue in the past, and though it's quite a bit higher today, conventional metal diecutting can run faster. Still, the improvement is noteworthy. Bear in mind that a simple shape will allow the laser to cut much faster; the more complex the shape, the slower the performance of the beam.
AB Graphic declares that it's Sabre Xtreme can cut 150 mm circles at a web speed of 85 m/min (280 fpm). By contrast, it will cut 50x50 mm squares, four across, at 40 m/min (130 fpm).
"Speed is sometimes a concern for label cutting with a laser," says Mike Wagner of Delta Industrial. "I have heard figures like three to eight meters per second for the speed of the galvo head that swivels to perform the cut."
"The speed and efficiency of laser cutting depends on the complexity of the artwork, the material being laser cut and numerous other factors," says Hillman. "However, laser systems are flexible enough to make simple cuts at high speed as well as to slow down laser travel speed to precisely cut intricate patterns."
Does a laser produce the same cut as does a metal die? "In a galvo system, wiht a stationary laser, we cut more or less at an angle. On a wider web the angle of the cut will be more pronounced. But when you run thin material, and most label stocks are thin, the angle of that edge is minimal." Bacon adds that the edge does not have to be perfectly identical to a metal cut. "We are burning material away. People are concerned about auto application, and that's not an issue if it's set up properly."
Lasers indeed burn material away. The resulting gaseous waste is sucked out of the chamber as the cut is being made, subjected to multiple stages of filtration, and finally exhausted.
What kind of learning curve does the operation of a laser diecutter pose? "It's fairly simple," says Mike Bacon of Spartanics. "After we install a machine, we download the necessary software for transferring cut configurations. It basically removes any difficulties. We will install a machine and quote five days for installation and training. By midway through the second day the operator is training on the machine."
AB Graphic's Omega Sabre Xtreme
AB Graphic International is planning to make its next generation Sabre Xtreme, due for launch early in 2011, accessible to potential customers, according to Spendlow. The new version will feature modifications to the electronic controller that determines positioning, as well as improvements in speed and accuracy of the focal point of the laser, he says.
The company has made an arrangement with the owners of Digital Dogma, an all-digital label converter in Santa Fe Springs, CA, USA, to allow others to observe and test the laser cutter. "We will be showing customers around to get the full experience," says Spendlow. "We will be able to have customer files uploaded to Digital Dogma, and they'll print, diecut and ship within 24 hours. They will be able to see what their users can expect."