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FLEXO Magazine : November 2009
50 FLEXO NOVEMBER 2009 www.flexography.org PLC and the camera system. It's a good illustration of why la- ser cutters that do not feature a high level of systems integra- tion are now obsolete machines. This same feature of integrating cameras with machine controllers allows today's high-quality systems to automatical- ly compensate for variations in prints, such as those that are created by shrinking as inks dry. These laser cutters automati- cally account for variations in step-ups from one part design to the next, and can only do so because of that ability for the machine controller to communicate with the camera system. Because of this, the software and the machine controller can automatically determine the step-up of each job. They are self-calibrating and operator input is not required to measure or input step-ups. Antiquated technology that does not have this level of systems integration simply has no mechanism available to automate the start of jobs, the calculation of step- ups, or to compensate for variations in step-ups created by other steps in the production process. In today 's systems with excellent integration, there is a new ability to vary the job stop criteria by part-count rewind, by rewinder diameter, or the rewinder roll length as shown in Figure 25. 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. The same features also facilitate 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 param- eters for different system components separately. You also can always identify the better laser cutting sys- tems 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 condi- tion anywhere in the system it pauses and the error message is displayed on the operator screen. Such smart error messaging fa- cilitates maximum throughput and is only possible in fully integrated systems where there is seamless communications between operat- ing 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 an- other, 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. These systems' software creates a data- base 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 before the job is run, and gives users the ability to make very accurate cost projections of new job runs. SELECTING SYSTEM COMPONENTS You can expect a cost difference of up to 20 percent be- tween laser cutting systems made from high-end components and those that are made with components of lesser quality. Manufacturers of both high-end and more affordable laser cutting systems estimate that nearly four times as many us- ers---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 world- wide. Lower cost systems can produce high quality outputs if the underlying software engineering and systems integration are higher end. Figure 26 outlines some of the key differences between lower cost and high-end systems, and the obsolete technol- ogy that they both replace. Knowing your real quality require- ments is the first step in zeroing in on the type of system that's right for you. 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 FIGURE 25. One of the screens used by the operator. TECHNOLOGIES & TECHNIQUES
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