Laser Cutting Machines: “Seizing the Digital Die Cutting Advantage”; SGIA Journal; Second Quarter 2006

By Bill Knotts, Spartanics

Moving from artwork to finished die cut printed products within hours is not a futuristic fantasy. By combining digital printing with digital die cutting such quick turnarounds are readily doable. In turn that means that building a niche in rapid prototyping is there for the taking for any digital printer that adds digital die cutting capabilities.

What is “digital die cutting”?

Digital die cutters are another name for laser cutting systems. The laser systems best suited for combination with digital printing presses are usually galvanometer driven. Galvanometer systems use a stationary laser that shoots its beam through moving mirrors as it angles into the correct position for the desired cut. This is in contrast to a gantry type laser system, which is an XY plotter in which the laser beam is always perpendicular to the piece being cut and where the laser as a whole moves along the artwork pattern to be cut.

The basic advantage of a laser cutting system is that it provides a tool-free method for cutting. This means that the time needed to create tools is eliminated, as well as the costs of tooling. Unlike tool-based rotary cutters or optically-registered gap press cutting systems, the tool-free digital cutting systems do not have to contend with the physical limitations inherent in a die. This not only meanslaser cutting can handle many cut features and do special features such as kiss cutting, but also expands the range of materials one can cut. Cutting abrasives is newly practical because the problems of abrasives wearing down tools are eliminated. Adhesives are cut without the problem of dies getting sticky from contact with adhesive layers. Very thin flimsy materials are relatively easy to cut because the problems of edge distortion from the weight of dies are eliminated.

Perhaps the most important advantage of tool-free cutting is that set up time is dramatically reduced. Set up is not much more involved than importing a vector-based drawing from some drawing program to the laser cutting system software. All adjustments are then made in the software, usually in minutes. Tool-based systems, in contrast, often require repeated steps to correctly register dies.

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.

Physical dies have inherent mechanical limitations that are avoided in a tool-free cutting system. When there are sharp corners to be cut, for example, dies can be too brittle to create 30o or smaller angles. While a laser cutting system can make true 90o corners, a tool can be fashioned to do so by forming a metallurgical notch. However, any notch is inherently problematic as it has potential to crack the die. All such bother is eliminated by a tool-free laser-based system.

As with any type of technology, the quality of engineering in various brands and models of digital die cutting equipment has bearing on the quality of the output possible with one or another machine. Withlaser cutting systems the paramount engineering consideration is the precision with which the laser beam is powered on and off as it navigates the required geometries of the given artwork. Much as one needs to control acceleration while driving a car around a curve, one needs to adjust how turns are made by the galvanometer system. If too much laser power is applied when a system angles slowly around a curve it will likely cause burn through holes. Actually, the controls needed on the laser pulses are quite a bit more complex than this simple example suggests. The best laser cutting systems use sophisticated algorithms to optimize synchronization of the laser beam with myriad variables related to part geometry.

Inadequate laser control in inferior systems will also be evidenced by discoloration of cutting edges. For example, the better laser cutting systems are perfectly able to cut thin polycarbonate substrates while the lower quality systems leave telltale edge discolorations.

The best approach to making laser cutting system purchasing decisions is to challenge manufacturers to demonstrate how their particular digital cutting system can handle the specific materials and types of die cutting requirements of a set of applications typical of your operation. The better digital die cutting systems are powered by easily customized proprietary software that can be easily adapted, if needed. The lower quality laser cutting systems are both not as easy to adapt and result in inferior output, usually because they are powered by more generic software that can be used with any type laser but no one specific laser type especially well. Sometimes, a manufacturer can suggest slight adjustments in substrates such as changing grades of polycarbonates that work better with laser cutting. The point is to partner with manufacturers to develop solutions, but to also put them to the test in the process of doing so. The better engineered systems will predictably stand out from the pack, create noticeably better samples and do so on a more consistent basis.

One should also scrutinize job set up requirements for a number of jobs. The better digital die cutting systems are also differentiated by their ease of set up. Laser cutting systems that require extensive programming during job set up should be avoided. Even the most complex job with intricate small parts and special features such as precision kiss cutting should take no more than 15 minutes to set up. Most jobs will take far less set up time than that.

Allowing multiple operating seats that allow remote workers in an art department to do the job set up is often a desirable and practical feature to seek. Non-technical minimally skilled operators should then be fully able to handle a job once it has been setup.

Thus, published specifications of laser cutting systems capabilities should only be considered the prelude to meaningful purchasing decisions of laser cutting technology. Reputable laser cutting system manufacturers can create defect-free samples showing the range of part geometries, special features, and materials that a particular model can handle. In many cases, it is also advisable to enlist the contract manufacturing services of laser system manufacturers as a first step such any and all needed customizations of basic systems to maximize quality and productivity with particular applications are pre-identified in some detail.

The bottom line is that digital cutting systems are a natural complement to digital printing presses that greatly expand product possibilities. In recent years, many SGIA members were among the first to “go digital”. Laser cutting takes an operation one lucrative step further into the digital world.

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