Laser Cutting Machines: “The Laser’s Edge”; Paper, Film & Foil Converter; August 2006

Revisiting the Laser Cutting Advantage

By Bill Knotts, Spartanics

When laser cutting first hit the converting industry, many converters had been impressed by the promise of laser cutting technology, but decided to bide their time in acquiring tool-free digital cutting systems because they were quite literally not up to speed. The latest generations of best-in-class laser cutting systems CAN be used as full production tools, making it quite timely to revisit the pros and cons of tool-based vs. tool-free cutting. Consider this—

First, a quick recap of how laser cutting technology works…

Lasers cut by melting materials in their beam path. The types of laser systems appropriate for the converting industry use CO2 lasers that pulse on and off to effect cuts. The greater the wattage of the laser, the faster it can operate . There are two basic designs—gantry systems, which are basically XY plotters that move physically move the lasers around the parts to be cut; and galvanometer (galvo) systems that instead make small adjustments in mirror angles to focus and move the laser beam in different directions.

Galvo systems’ design makes them inherently faster than gantry type systems, which are really only a good fit for wide format jobs that cannot be handled cost-effectively by using multiple galvo lasers. The small adjustments in mirror angles that reposition galvo system laser beams take very little time to make, which means that they can be made very quickly.

There are several technological advances that combine to make today’s laser cutting systems functional production tools. For one thing, laser manufacturers continue to come out with better model lasers each year and more reasonable prices. 200 watt and 400 watt lasers are readily available at competitive prices, which was not the case when the first laser cutting systems were introduced to the converting industry. These higher wattage lasers do cut faster for some material situations. Second, it is not only the speed of lasers that has been improved, but also the quality of the laser beams that they produce. With these better shaped beams, it is possible for the galvanometer system to steer the beams faster without compromising the quality of the cutting operations. Third, and perhaps most important, are the many software improvements incorporated into today’s better optimized systems. This better software shaves milliseconds off of most operations such that the combined effect is significant time savings in overall operation, which can be thought of as a ___%significant improvement over the speeds possible in the first generation laser systems of the same wattage.

This better software in today’s higher quality laser cutting technology not only impacts speed, but also facilitates much higher quality cutting without the troublesome burn-throughs and telltale pinholes at sharp corners that plagued earlier generation laser cutting technology. Essentially, what the software now does better is to synchronize the pulsing on and off of the laser beam with the part geometries. This better synchronization explains how laser cutting technology now surpasses the quality possible with tool based systems. For example, any metallurgical (die-based) cutting process would likely have difficulties in navigating corners that are less than 30 degrees, but this is not in any way a challenge for a today’s laser cutting system. Another benefit toBy using a laser cutting system is that one can avoid making the discontinuous cut sections (knicks) used in 90-degree angle cuts, thereby avoiding the potential for rips that such knicks create later in the production process. Similarly , one can avoid the need to create mechanical knicks to facilitate parts extraction by using a laser system. The best-in-class laser cutting systems can create holes as small as a laser beam diameter of 250 microns (0.25 mm).

A word of caution—it is important to THOROUGHLY check out laser cutting technology before purchasing it. Many of the laser systems being sold in the market today use standard lasers that are not customized for converting applications, and do not have the software improvements that underlie better synchronization of laser beams with part geometry. A good reality check usually begins with sending equipment manufacturers samples of both the substrates and artwork in specific applications to ensure that the parts are without the burn-throughs or pinholes that indicate poorly shaped and inadequately controlled laser beams. Many also use contract manufacturing services offered by reputable laser cutting equipment manufacturers as extended production trials of specific laser cuttingsystems prior to purchase.

Once one has proven that a given laser cutting system is up to the quality requirements of the applications at hand, one is then in a position to gain the advantages of adding laser cutting technology to a converting operation. The major advantages derive from avoiding all the tool issues that otherwise need to be managed. Tool production always involves an extra cost and extra delay for tool making. Indeed, for converters building a niche in short runs, avoiding the time delays inherent in tool-based systems can be quite significant, and make job turnaround considerably faster with tool-free (laser-based) cutting systems. The better laser cutting systems can import art work from any vector based drawing system such that set up time can be completed in minutes, a significant contributor to the faster job turnaround time possible with laser cutting for converters with a developed short run niche.

Another big plus of laser cutting technology is its versatility. Laser cutting systems are capable of a wide range of cutting and marking jobs, including kiss cutting, through-cutting, consecutive numbering, personalizing, perforating, creasing, etc. They can handle a wide range of paper, plastic, foils, thin metals, textiles, adhesives, and abrasive substrates. A clear differentiator of laser cutting technology from tool-based cutting systems is their ability to precisely cut very thin or flimsy plastic materials. It is also possible to cut PVC materials, if additional components are added to protect machine components near the laser beam from the corrosive action of PVC cutting byproducts, and if appropriate filtering systems are added to protect operators from noxious fumes.

There are limitations to laser cutting systems. Although the precise definition of “thick” is changing and dependent on material grade, laser cutting on thick polycarbonate substrates continues to be beyond the current systems’ capabilities such that discolorations usually occur. If polycarbonates are too thick for laser cutting, the best technology fit is usually with the high precision optically-registered steel rule die or hard tool cutting systems that can deliver registration accuracy +/-0.1 mm.

For especially long runs with many millions of parts, where the expenses for tooling are insignificant contributors to overall job cost and and the delays for making tooling are insignificant, tool-based cutting systems (rotary die cutters, optically registered gap presses, platen presses) will continue to be the cutting method of choice. For such large orders, if dies can be fashioned to reliably handle the required details of part geometries, there is usually little advantage to laser cutting systems because even the highest wattage modern systems are still a bit slower.

Summary

While prototyping-on-the-fly is a considerable advantage of laser cutting systems, it is now incorrect to think of this technology’s niche as strictly limited to prototyping challenges. The ability to bypass the inherent limitations of tool-based cutting systems, combined with the improved engineering of betterlaser cutting systems, makes them valuable for production length jobs as well, especially when jobs require special features beyond the capabilities of tool-based systems.

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