By Markus Klemm
A preliminary step to sourcing the right laser cutting technology is to first determine if laser cutting capabilities are a good addition to your finishing department. There are numerous advantages to laser cutters as compared to tool-based die cutting systems. Most of these advantages derive from the tool-free nature of laser cutters. Because there are no tools, there are no costs for tools or production delays for time to make tools. This is the major reason why laser cutters provide a rapid prototyping niche for those that use them. Laser cutting systems are called digital die cutters because they can take any vector-based digital image and import it into their operating software to set up a job. Today’s best-in-class laser cutting systems can complete set up from these imported digital images in just a few minutes. The ‘digital die cutter’ term that is used interchangeably with laser cutting speaks to this advantage that tool-free cutting systems provide, especially when used in combination with digital printers. This combination allows one to move from artwork to finished product in just a few hours, or even less for very short runs.
In tool-based mechanical cutting, there are always intrinsic limitations from the physical contact between the cutting edge and the material being cut. A laser cutting systems bypasses that situation, which makes them able to cut many materials that are very difficult or impossible for tool-based cutting systems to handle. For example, cutting adhesives is far easier with laser cutting systems because of the tendency of adhesives to literally gum up the works in mechanical cutting systems. Similarly, the ability of tool-free laser cutting 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 that cutting abrasives with mechanical cutting systems is often prohibitively expensive because dies have to be continuously replaced. Here too, tool-free laser cutting systems sidesteps this problem altogether.
The relative ease with which laser cutting systems create special features is also a considerable advantage. Perforations, score lines, kiss cuts, consecutive numbering, creasing, personalizing and other special features are done as a matter of course by laser cutting systems. This is especially the case with today’s laser cutting technology that uses far superior software engineering to precisely control the movement of laser beams making cuts. In fact, the only relevant physical limitation in laser cutting systems is the width of the laser beam--for example, in 200 mm x 200 mm 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 cutting system. 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 requirements of full production runs. While there are many applications 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 using them for full production line capabilities. For one thing, today’s laser cutters are generally galvanometer (galvo) 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 a whole or the whole sheet of material 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 laser beam, which, in turn, ensures that cutting quality is maintained even at higher cutting speeds. The upshot of all these combined speed improvements is that today’s laser cutters do far more than prototype samples; they are used for full production runs without creating production bottlenecks. (Manufacturers’sclaims on linear cutting speed are not meaningful in most instances. Actual cutting speed is determined both by the complexity of the artwork and ability of the control software to optimize cutting in that geometry, as example below.)
Another misconception that one still finds is that laser cutting 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 operated 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 cutting 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 laser cutting technology. For example, polycarbonate 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 substrate. 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 machine components near the laser beam from the corrosive action of PVC cutting byproducts and that appropriate filtering systems are added to protect operators from noxious fumes.
The real disadvantage of laser cutting technology--and the reason that most companies that use laser cutters do so in conjunction with one or another tool-based cutting system--is that it is less cost-effective for many relatively straightforward long run applications which are not beyond the reach of mechanical cutting. If part geometries are easy for a physical tool to achieve, if the substrate is not too thin, too sticky, too abrasive or in some other way troublesome for a physical die, and especially if it involves a relatively long run length where the cost of the die becomes a negligible factor, tool-based cutters (platen presses, rotary die cutters, electro-optically controlled gap press technology) often prove the better finishing tool.
Markus Klemm is R&D Software Engineer, of Spartanics (www.spartanics.com) that manufactures a range of automated equipment for laser cutting, die cutting, screen printing, card punching, counting, and inspection used by global label manufacturers, converters, printers, card manufacturers, among others finishing flat stock material.
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