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FLEXO Magazine : October 2009
www.flexography.org OCTOBER 2009 FLEXO 53 the works in mechanical cutting systems. Similarly, the ability of tool-free systems to reliably handle thin substrates is a big advantage. In these thin substrate applications, cut-to-print registration is not constrained by the physical limitations of weighty dies interacting with flimsy substrates. Another example is in the better handling of abrasive materials, which literally wear mechanical dies down. Such material is often prohibitively expensive to cut because dies have to be con- tinuously replaced. Here too, tool-free laser cutting systems sidestep this problem altogether. The relative ease with which laser cutting systems create special features is also a considerable advantage. Perfora- tions, score lines, kiss cuts, consecutive numbering, creas- ing, personalizing and other special features are done as a matter of course. This is especially the case with today 's laser cutting technology that uses far superior software to precisely control the movement of laser beams. In fact, the only relevant physical limitation in laser cutting systems is the width of the laser beam---for example in 200mm x 200mm working fields or greater, the spot size can be as small as 210 microns in best-in-class systems. While any die-based cutting system would have difficulties in producing corners that are less than 30 degrees, this is not in any way challenging for a laser. And, laser cutting technology also allows one to skip the step of creating mechanical knicks to facilitate parts extraction as is typically required with a tool-based cutting mechanism. There are limitations to laser cutting systems, as with any technology, but also there are mistaken notions as to what these limitations are. In some quarters, laser cutters are thought of only as prototyping tools and not up to the require- ments of full production runs. While there are many applica- tions where laser cutting may be slower as compared to platen presses, rotary die cutters or optically-registered gap presses, they are considerably faster than the earlier laser cutting systems that used to predominate. In fact, most users of today 's laser cutting systems are being used on a full production line. For one thing, today's laser cutters are generally galvo (galvanometer) type lasers that make minute adjustments in mirror angles to move laser beams around artwork. This galvo mechanism is considerably faster than gantry systems with XY plotters that physically move lasers as the material is being cut, not just the laser beams. Newer galvo technology takes this speed improvement to the next level by fine tuning software to shave milliseconds off of most operations, with a combined effect of significant speed improvements. The higher the wattage of the laser, the faster the cutting proceeds in most applications. The difference today is that faster 200- watt and 400 watt lasers that were prohibitively expensive five or so years ago are now available at competitive prices. These new lasers also make a higher-quality beam, which in turn ensures that cutting quality is maintained even at higher speeds. The upshot of all these combined speed im- provements is that today 's lasers do far more than prototype samples; they are used for full production runs without creat- ing production bottlenecks. Another misconception that one still finds is that laser cut- ting is a dangerous operation that burdens a workplace with safety risks. Though it may seem counterintuitive to some, laser cutting systems are in many ways a safer alternative to tool-based cutting systems. The initial installation of a laser cutting system takes care to eliminate the chance of stray beams creating workplace hazards if workers do not wear safety glasses. Tool-based systems, on the other hand, pose a continual risk of severe worker injury if they are not oper- ated properly. Although such accidents are rare, they can be catastrophic. Costly injuries to tooling are somewhat more common, such as when technicians leave tiny screws in a cut- ting area that end up destroying the custom tooling. It is also thought, and correctly so, that laser cutting systems cannot handle any and all substrates. However, the boundaries of that limitation continue to shift along with better engineering of technology. For example, polycarbon- ate substrates used to be beyond the reach of laser cutting technology because of the laser cutters' tendency to leave poorly cut edges with a heavy brown discoloration on the sub- strate. This is still true of the thickest polycarbonates, but not so with the thin polycarbonate substrates that older systems couldn't tackle. Unfortunately one can still find laser cutting systems in the marketplace that leave edge discolorations on thin polycarbonates, but there is no reason to settle for this substandard technology. Many still think that PVC (polyvinyl chloride) is not a good match with laser cutting technology, but that notion too is a bit out-of-date. It is possible to cut PVC materials, so long as additional components are added to protect the existing ma- chine components near the laser beam from the corrosive ac- tion of PVC cutting byproducts. Appropriate filtering systems must be added to protect operators from noxious fumes. FIGURE 2. A laser cutter machine cutting a label. FIGURE 3. The many applications that can be laser cut. TECHNOLOGIES & TECHNIQUES
Sustainable Fall 2009