Understanding Options in Laser Cutting Technology
By Paul Dirienzo, Director of Engineering
Spartanics (www.spartanics.com)
In the past year or so many converters in Europe as around the globe have taken the first steps towards acquainting themselves with the advantages of adding tool-free laser cutting technology to their operation. Not all laser cutting systems are alike, however, and having a clear understanding of how to match the features of a laser cutting system to application requirements is required to get the optimal return-on-investment from laser cutter purchases. In this article we’ll discuss the range of features now available in the global marketplace and how to begin to best zero in on the laser cutting system most suited for your range of applications.
Lower cost vs. higher cost systems
You can expect a cost difference of up to 20 % between laser cutting systems made from high-end components and those that are made with components of lesser quality. As a manufacturer of both high-end and more affordable laser cutting systems, we estimate that nearly four times as many converters –but certainly not all-- will be adequately served by lower cost systems.
Converters are well advised to seek sources of laser cutting technology that are not married to particular component suppliers. Rather, reputable manufacturers of laser cutting systems are able to access the best-match components (laser source, laser scan heads, etc.) and integrate them with software controls that deliver a total solution best-matched for the range of applications that a particular converter handles.
Quality
Knowing your real quality requirements is the first step in zeroing in on whether your converting operation is better served by low cost or higher quality laser cutting systems.
However, there is a baseline of quality that should ALWAYS be achieved such as avoiding burn-through marks during cutting. If a laser cutting system presents burn-throughs it usually reflects a poorer quality of software engineering to operate the laser power and especially at the start of a cut. Control of the laser intensity during the entire cutting sequence should be considered a non-negotiable whether a system is high-priced or low-priced. There are systems at all price levels that can and cannot achieve this level of quality and thorough investigation is required.
The wattage of the laser should be carefully considered. Most of the commercially available lasers have the best laser beam quality with full power. If you end up using only 10% of the laser power from your laser source you can expect significantly diminished laser beam quality. For example, a converter making kisscuts with easy-to-cut materials that has a 300 watt laser in their cutting system may be using only a small portion of available laser power and would be better suited by a lower watt laser. A converter making many throughcuts, including more difficult to cut release paper, which also wants to achieve high cutting speeds would need that 300 watt laser.
The smaller the maximum working area the smaller will be the spot size of the laser. Smaller spot size means better cuts because the energy is concentrated and you need less laser power to achieve the same depth of cut. Less heat is transferred to the material being cut is always the desired scenario. One of the differences you will find in lower-priced systems is that they are likely to use air cooling for lower power lasers, as opposed to the more costly water cooled lasers of high-end high laser power systems.
The edge quality that a particular laser cutting system delivers will vary with the spot size of the laser. In systems with smaller working fields (e.g. 200 x 200 mm field size) this is not as much an issue and one can expect both the better high-end and lower-priced systems to have a 210 micron spot size. If the working field is larger, however (e.g. 300 x 300 mm field size) one needs to be able to make due with a 280 micron spot size when considering the lower-priced system. As an example, generic label converters might be well-served by a system with such larger spot sizes but those involved in RFID applications might need the greater precision in cutting edge quality.
Smaller spot sizes not only affect edge quality of the cuts but also will have bearing on cutting speed. It is very important to verify that a system can maintain the desired edge quality and cut-to-print accuracy at the maximum cutting speed of the system. Some of the more poorly designed laser cutting systems cannot maintain cut-to-print accuracy over time. Lower cost laser cutting systems are likely to use sensors for registration and will not achieve the same registration accuracy of the higher end systems that use sophisticated camera technology to deliver the very tight tolerances in cut-to-print registration that some applications require. If these camera systems are fully integrated with the laser scan heads they are able to apply the offset values to keep cuts to a precise registration. Here too, it is not only the quality of the camera but the underlying software engineering that has great bearing on the tolerances that are achieved at varying speeds.
Range of Materials
Generally speaking, lower-priced laser cutting systems do not have the same range as their high-end counterparts when it comes to the variety of materials that they can handle. It is always important to thoroughly test a laser cutting system’s ability to handle the particular substrates used in your converting operation.
Features Determining Production Rate
Lasers with a smaller spot size are able to cut faster. The speed of cutting is not identical with web speed. Better quality systems – both high and low-priced—make use of state-of-art algorithms for optimizing cutting sequences. In many instances this will involve splitting an image up into multiple images for higher web speeds, in addition to determining the best cutting sequences. And to reiterate, one must make sure that a system is able to maintain tolerances for edge quality and cut-to-print registration at the faster speeds.
Software, and software integration, is what determines the ease-of-use and operating characteristics of the laser cutting system. Higher quality laser cutting systems seamlessly integrate software controls for lasers, web, camera registration, slitters, rewinders and lamination, while lower-priced systems usually do not have cameras, nor integrate inputs from slitters, rewinders or laminators. This greater sophistication does not necessarily translate into more complex operating requirements. Quite the contrary, you will find that the top end laser cutting systems are tuned to handle the complexities of laser cutting behind the scenes. In these systems, software for various functions (registration, web control, laser powering, laminating, slitting) provides constant feedback and communication to other system components for streamlined operation. An operator’s work is relatively simple because the software does the difficult jobs automatically.
Suggested Method for Specifying Laser Technology
To begin sourcing the best laser cutting technology for your converting operation, you must first determine your application requirements in terms of: complexity of geometries to be cut; production rates required; sheet vs. web; type of materials (PET, ABS, polycarbonate, etc.). One is best served by contacting several manufacturers that build laser cutting systems to request that samples be run on your materials using a few of your part configurations. The manufacturers should then be able to recommend the model of their laser cutting systems that will be correct for cutting your parts from your materials. Of course, it is very important to ensure that these manufacturers are equally adept at creating lower-priced laser cutting systems AND more sophisticated technology such that they can deliver best-match solutions. If a laser cutting system integrator is married to particular components – whether they are lasers, scan heads, etc.—consider it a red flag that they are not set up to match laser technology to real application requirements.
After receiving your cut samples from the prospective manufacturers of laser cutting systems, and after receiving their recommendations on the proper model of laser cutter and their budgetary pricing, request a personal visit to manufacturers of interest to see actual cutting of your parts and materials. If you spend one day at the individual manufacturers you should be able to get a good feel for the degree of difficulty cutting your parts. A visit also provides an excellent opportunity to see their plant, to understand their people that you could be dealing with in the future, and to examine the ease of use of importing drawings of parts into the laser cutter and converting the drawings into a useable cutting path. As with any equipment purchase, it’s also advisable to determine the extent of service support that is available from each manufacturer, as this can make the difference between a relatively short period and a much longer period of downtime in the future.
The best case scenario of comparative shopping would also include use of laser cutting system manufacturers’ contract manufacturing services. These would provide not only proof of concept but would allow expert software integrators to fine tune operations to your exact application requirements.
In summary, reputable manufacturers of laser cutting technology will offer a range of options on equipment features that will determine the quality, cost, and production rates. The more expensive systems will feature laser beams with the smallest spot sizes, greatest versatility with a range of substrates, fully integrated software controls for seamless integration of lasers, web, camera registration, slitters, rewinders and lamination. Converters that do not require tight tolerances may be better served by lower cost laser systems with a somewhat larger spot size. A systematic review of how all available laser systems can handle jobs is always recommended, including use of contract manufacturing services as trial runs whenever possible.
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Paul Dirienzo is Director of Engineering for Spartanics (www.spartanics.com) which manufactures laser cutting systems and tool-based die cutting systems among other technology used by worldwide converters. Spartanics is headquartered in the U.S. and maintains a sales and service office in Hanover, Germany. Inquiries can be forwarded to
+49 521-32 95 035
khj@spartanics.com .
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