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Flexo Sustainable : Fall 2013
PRODUCTIVE, GREEN & CaPaBlE Just what is this “barrier to adoption,” and how does UV LED overcome it? Conversations with converters have led to three general areas of concern that new printing and convert- ing technology needs to address. Only systems that can ad- dress all three of these concerns can justify the money spent on adoption of a new system. In other words, new technology must address: • Productivity issues: New technology should improve pro- ductivity and, hence, have a bottom-line impact • “Green” issues: New technology should minimize safety concerns and environmental impact • Capabilities expansion: New technologies should make new processes possible, or else eliminate barriers to adopting existing technologies. In other words, new tech- nology should have a capabilities impact The important thing to remember is that the impact of a new technology rarely comes from a single, large-scale innovation. “ Game changers” are rare in any industry. But, a piece of technology can have a large overall impact by improving many small aspects of a process simultaneously. In short, a series of small-but-significant benefits is often the most realistic option, and it is most likely to make a positive return on investment. With this idea in mind, let’s take look at the impact of UV LED on the printing process. SPEED & SaVINGS Press uptime and press speed are two critical factors in controlling costs and keeping production working as efficient- ly as possible. How does UV LED compare with traditional mercury bulbs where uptime and speed are concerned? Here, there is no contest: • First, LED arrays burn out much less frequently than mercury bulbs • A UV LED array has a lifespan of more than 20,000 hours before it needs replacing • Typical mercury bulbs have a lifespan of 500 to 2,000 hours • UV LED has a more than 10-fold decrease in press down- time needed to replace bulbs • UV LED also has fewer moving parts (no shutter, fans, etc.). This means less maintenance overall—a 75 percent reduction in most cases UV LED systems are solid state, meaning there is no gas to vaporize and excite. The system can be turned on and off instantly, with no warm-up or ramp down, shaving precious seconds off of run time. As for speed, UV LED can potentially cure faster than tra- ditional mercury bulbs, which means that presses can be run at higher speeds without a loss in quality. Faster press speeds means more product produced per hour, higher capacity, and higher profits. While press uptime and speed directly affect the profits to be gained from a press, UV LED also presents a unique opportunity to use energy more efficiently. LED lights emit light over a very narrow range in the light spectrum, typi- cally centered around 395-nm . Mercury lights emit light over a broad range, including the UV spectrum, visible light and infrared light. Visible light and infrared light do not contribute to curing; this light represents wasted energy in the system. In addition, infrared light generates heat, which can create other problems. Thus, LED lights make a much more efficient use of power in the system. (Figure 2). Furthermore, because UV LED lights do not emit infrared light and do not need high voltage to vaporize and excite mer- cury, UV LED systems do not need special fans and blowers to keep the temperature down. Fewer parts to power means less energy consumption. Between the efficient use of energy, lower power require- ments, and no need to produce high voltage, a UV LED sys- tem can realize a whopping 50 percent decrease in energy consumption. And the less energy consumed, the less money spent on electricity. Broad ranging yet conservative cost models indicate that energy savings could reach 80 percent or higher (keeping job size equal) with a UV LED system in place of traditional mer- cury UV. Productivity increases as well with UV LED allowing more jobs to be run in the same amount of time, resulting in incremental revenue. Statistics were gleaned using a 13-in., 8-color press as a model. Similarly, maintenance costs come in significantly smaller, at just 5 percent that of traditional mercury UV. Admittedly, initial cost of implementation is greater. Capital costs associated with installation of a UV LED system run near $2,700 per station,while the rate for traditional mercury UV comes in at just about 75 percent the cost—around $2,000. ENVIRONMENTal IMPaCT The bottom-line impact of UV LED is noticeable, but not miraculous. But, cost considerations are, of course, just one area of concern. Converters have noticed that customers are increasingly asking for environmental friendly products, including post-consumer recycled paper, bio-dynamic inks, and renewable energy processes. New technology that is environmentally friendly can thus provide an added value to the customer. So, just how environmentally friendly is UV LED compared to traditional mercury lamps? Again, the differences are stark. First, UV LED contains no mercury. Mercury is poisonous if directly handled and is a dangerous pollutant. Thus, UV LED eliminates contamination worries. UV LED systems also pro- duce no ozone that would need to be vented to the outside. Second, UV LED consumes much less energy. As stated above, a typical UV LED system uses 50 percent less energy than a traditional mercury lamp. This means a much smaller carbon footprint for the plant. The environment is not limited to the global environment, of course. Machinery can often affect the workplace environ- ment in a number of small but important ways. Every moving part, every heated element, and every waste product has the potential to annoy or even harm an operator. The safest equipment, then, should minimize exposed moving parts, heated elements and waste products. In this regard, UV LED comes out on top. LED arrays are cool to the touch and because there are no fans or blowers to cool the array, there is much less noise as well. In a traditional mercury bulb, a high voltage is used to vaporize and excite the mercury, creating a mercury plasma. But, since mercury is not used in UV LED, there is no heated plasma that can potentially escape, and no high voltage ballasts that can arc or shock an operator. The narrow bandwidth output of UV LED is also a plus here. The lack of short-wave UV (also known as UV-B and UV-C) means that there is less risk of exposure to eyes and skin. Granted, the risk of serious injury from a traditional UV sys- tem is minimal, and such systems have been used safely in printing operations for some time. But, the risks are not zero. Any high-volume shop thus leaves itself open to a safety prob- lem, unless the necessary precautions are taken. Then again, the best precaution is to take away the source of the risk entirely. Here, again, UV LED provides a distinct advantage. aTTRaCTIVE CaPaBIlITIES Two questions that many converters ask are: “Can I do the same things with the new technology that I could with the old?” And, “What can I do that is new?” All the cost savings and environmental benefits in the world would mean little if a new technology could not replicate, or better yet, expand and improve upon existing processes. For this reason, UV LED systems have been tested on a number of substrates in a number of different configurations. UV LED works with a number of substrates, including self- adhesive labels—including coated and uncoated papers, biaxially oriented polypropylene, polyethylene, polyactic acid and synthetic films—shrink sleeves, polyethylene terephtalate glycol-modified, poly-vinyl chloride, biaxially oriented polysty- rene, carton board and unsupported films and laminations. It can work with heat-sensitive and thin substrates, and does well with both rigid and flexible materials. The intensity of the curing can be carefully controlled, allowing for faster or deeper curing depending on the need (something that is difficult to do with typical mercury lamps). And because there is no infrared light to worry about, UV LED is completely film ready. Furthermore, contrary to popular belief, there is a wide variety of inks and pigments tested and available for use with the UV LED system. This includes a variety of coatings (gloss, matte, thermal transfer ribbon, as well as metallic inks and shrink whites. Thus, printed materials can make use of a full range of colors, glosses, and metallic sheens—all of which can make for a more attractive product—without additional curing machinery or processes. With most industrial processes, a series of small-but- significant benefits is often the most realistic option and most likely to make a positive return on investment. UV LED has a significant positive impact on productivity, capabilities, and the environment. Innovations have eliminated many of the out- standing issues with the technology, making it a worthwhile investment. n About the Author: Gregory S. Palm is executive vice presi- dent, new business development, Mark Andy Inc. 10 Sustainable FLEXO FAll 2013 www.flexomag.com www.flexomag.com FAll 2013 Sustainable FLEXO 11 Figure 2: Wavelength Comparison of UV lED and Traditional Mercury lamp