By Markus Klemm
Systems Integration, User-Friendliness and Production Output
The quality improvements that are possible when high resolution camera systems communicate to scan head control software to determine required X/Y offsets is only one example of the benefits of systems integration in top quality laser cutting machines. The extent of systems integration in one or another laser cutting system can largely determine how user-friendly they are to operate and has great bearing on the production outputs that can be achieved. For example, older systems required users to obtain a separate camera system, and required operators to additionally master the camera control software. In contrast, today¡¯s better quality laser cutting systems come with cameras fully integrated with the laser software. Operators do not have to learn set up of a separate camera system, as this is now done directly from the laser control software, and in the best-in-class systems only takes three simple steps.
The better quality laser cutting systems with full integration of all system components are in fact the only laser cutting machines one can find in the market today that work seamlessly with variable images from digital printers. These better quality laser cutters allow one to create laser jobs with multiple pictures with different geometries and different step-ups. This is only possible in today¡¯s fully integrated laser cutters where there is ongoing communication between the PLC and the camera system. It¡¯s a good illustration of why laser cutters that do not feature a high level of systems integration are now obsolete machines. They simply can¡¯t keep up with the demands of working with variable data and variable images for which digital printing is so ideally suited.
In today¡¯s systems with a high level of systems integration, there is a new ability to vary the job stop criteria by part count rewound, by rewinder diameter, or the rewinder roll length. Here too, this is only possible because the software that controls inputs, outputs, and the laser cutting per se work in concert and are fully communicating with each other.
This same systems integration feature of top quality systems also facilitates the fastest setup of repeat jobs. This is because all the machine parameters needed for a specific job--web speed, dancer arm pressure, camera system settings, etc.--are saved in one file. This means that at the very start of the job you can achieve required cut-to-print accuracy without having to fuss with reloading parameters for different system components separately.
You also can always identify the better laser cutting systems that have full systems integration by their smart stop systems, which are lacking in lower quality laser cutters that are devoid of systems integration. These smart stop systems monitor all possible fault conditions such as web breaks and off-positioning of the dancer arm, or full rewinder rolls. When there is a fault condition anywhere in the system it pauses and the error message is displayed on the operator screen. Such smart error messaging facilitates maximum throughput and is only possible in fully integrated systems where there is seamless communications between operating software for registration, lasers, laminators, slitters and rewinders.
Thus, the upshot of systems integration in the better quality laser cutting machines is a faster throughput. Though throughput varies from one plant to another, and one job to another, a reasonable expectation is that throughput with today¡¯s better quality laser cutting machines will be significantly faster than what is possible with non-integrated technology.
Better yet, estimating production time is now automated by the software in today¡¯s better quality laser cutting machines. These systems¡¯ software creates a database that stores laser settings for various types of cuts (e.g. kisscuts, creases, etc.) for the particular substrate being cut. Using this data, the same software capability that optimizes a job for web speed will calculate this optimum web speed and the production rate that is possible. This job simulation is done by the software, before the job is run, and gives users of today¡¯s better quality laser cutters an ability to make very accurate cost projections of new job runs.
Selecting System Components
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, Spartanics estimates that nearly four times as many users but certainly not all--will be adequately served by lower cost systems. It is important to know that your source for laser cutting technology is not married to particular component suppliers. Best-match components for particular applications (laser source, laser scan heads, etc.) can be sourced worldwide. Lower cost systems can produce high quality outputs IF the underlying software engineering and systems integration are expert.
Knowing your real quality requirements is the first step in zeroing in on whether your 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 and ensuring that there is a crisp narrow cut precisely following the artwork geometry. A laser cutting machine must have a high quality laser source with a small spot size to achieve these results. In label applications, this also allows for much better control of the heat transmitted to the release paper on the back of labels. Inferior laser sources with larger spot sizes often make it difficult to remove the cut labels because melted adhesives cause the labels and release paper to stick together. If a laser cutting system presents burn-throughs it usually reflects both a poorer quality of software engineering to operate the laser power and an inferior laser source with a large spot size. The soft marking capabilities of today¡¯s better quality laser cutters should be considered as a non-negotiable feature, 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. Many of the commercially available lasers have the best laser beam quality with full power. For lasers of that type, if you end up using only 10% or less 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 sometimes use lower cost air cooling for lower power lasers, as opposed to the more costly water cooled lasers. The edge quality that a particular laser cutting system delivers will vary with the spot size of the laser.
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.
Features that bear on user friendliness and ease of operation are found in both the low-priced and high-end better quality laser cutting machines, reflecting the high level of systems integration in better quality laser cutters at all price points. Smart stop systems, job simulation software, automatic image splitting and optimization for web speed, variable job stop criteria, and one step job setups of all operating parameters make these systems straightforward to operate, even for lightly skilled workers. Because the software is handling most operations behind the scenes--registration, web control, laser powering, laminating, slitting--and because there is full communication between different system modules, the operator¡¯s work is relatively simple because the software does the difficult jobs automatically. Obsolete technology does not have these various features for ease-of-operation. Some out-of-date designs do not even give operators the capability to change job settings while the laser cutting machine is operating, nor directly on the machine. These type of laser cutters, that force operators to stop cutting operations entirely and reload a job from scratch saddle users with unnecessary drags on production that today¡¯s better quality laser systems bypass altogether by giving operators numerous ways to amend job parameters without shutting down the production line.
Suggested Method for Sourcing Laser Cutting Technology
To begin sourcing the best laser cutting technology for your 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. Better quality laser cutters, both low-priced and high-end, include complete remote diagnostic capabilities.
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.
Markus Klemm is, R&D Software Engineer, of Spartanics of (www.spartanics.com) which engineers and 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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