The demand for large-format graphics printed on rigid substrates is stronger than ever. Wide-format printer manufacturers have responded with an overwhelming number of UV-curing flatbed printers that can handle the job. The technology behind these machines has improved vastly over the years, with better ink formulations, better media handling options and improved print speeds.
在钢板上进行大幅打印图像需求日益渐增。宽幅打印机生产厂商已经生产了大量的能够处理这项工作的UV平板固化打印。
We asked some flatbed printer manufacturers to offer up some tips on working with UV-curing flatbeds, with an eye toward getting good, consistent results and avoiding common pitfalls that those new to the technology might encounter.
我们也询问了一些平板打印机生产厂家，让他们提供一些在UV平板固化技术上的一些要点，视觉上变得更好，也有同样的结果，避免那些新的技术上会出现的共通性问题。
UV-Cure Lamps
UV固化灯
One of the key components to any UV-curing printer is the UV light source that serves to cure the inks. Many of the lamps in today's machines use wide-spectrum mercury vapor lamps (also called arc lamps, or H-bulbs). However, a growing number of machines today use LED lamps to effect a cure.
所有UV固化打印机最重要的结构之一就是固化墨水的UV灯源。现在很多打印机上用的灯都是光谱比较宽的水银蒸汽灯（也称为弧形灯，或者H电灯泡）。然而，今天大量的打印机都是用的LED灯固化的。
"LED lamps have advantages over mercury vapor," says Guy Cipresso, vice president sales and business development at Novus Imaging, Moultonborough, New Hampshire. "LED lamps run cooler and lamp life is much longer—estimated 1,000 hours for mercury vapor vs. 20,000 hours with LED lamps."
“LED灯比水银蒸汽灯的优势更大，”Guy Cipresso说到，Novus Imaging, Moultonborough, New Hampshire的销售运营部的副总。“LED灯会渐渐冷却，灯的使用寿命也会更长一点—估计水银蒸汽灯照明1000小时vsLED灯可以照明2000小时”
"The market has started shifting away from H bulbs," says Dave Cich, a founding partner with Vanguard Digital Printing Systems, Suwanee, Georgia. "LEDs use less electricity, so overall operation cost is less. They also emit less damaging UV light, so they are safer for the operator to run." And, because LED lights require no warm-up time and can be turned on or off instantly, "so there are no lamp shutters opening and closing that can get covered by overspray," he adds. "Plus, LED machines require less maintenance and are more dependable."
“H灯泡市场已经转移了，”Dave Cich提到,Vanguard Digital Printing Systems, Suwanee, Georgia的创始人。“LED灯耗电量低，综合起来的操作花费也是比较低的”这些灯放出更少的有害的紫外线，所以操作者运行这些机器的时候也会更安全一点。而且，因为LED灯温度要求不高，所以可以随时打开或关闭。”所以也就不存在通过喷涂来覆盖的开关灯头的百叶窗，”他补充到，“另外，用LED的打印机也不用经常维护，可靠性更高点。”
Joe Garcia, managing director-Americas, for StratoJet USA, Santa Fe Springs, California, notes that constantly turning mercury UV lamps on and off can wear them out sooner, so he offers one way to prolong lamp life. "Try to get all of your printing files ready each day so they can run consecutively during production. That will minimize the number of times that you turn off the lamps and can help them last longer," he says.
Joe Garcia,for StratoJet USA, Santa Fe Springs, California, 美国公司的主管，提到经常开关UV灯的话，机器容易坏，所以他提供了一种方法可以延长灯的使用时间。“为了打印每天必要的文件，生产时打印机是要连续工作的。这样的话就可以大大减少关灯的时间，这样的灯的使用寿命也就会更长一点”他补充到。
Also, the UV intensity of a mercury vapor lamp will diminish over the life of the lamp, Garcia says, adding that "most UV printers have lamp power settings, so be sure to start with the lowest setting and move up in intensity as needed over time. You will know when you need to move to a higher intensity when your prints begin to have some tackiness to the touch. Once you’ve reached the highest intensity and you start to get that tackiness, that is a sure sign that it's time to replace the UV lamp."
另外，水银蒸汽灯的紫外线亮度是会随着使用时间慢慢减弱的，Garcia说到，“大部分UV打印机都有灯电源设置，可以以最低强度设置开始，慢慢的随着需要调整灯照强度”当打印机的打印头有粘合物的时候，你就知道该把打印灯的亮度调亮一点了。一旦达到最高强度，打印机头有粘合物的时候，那就该换UV灯了。
Cich recommends that operators clean the lamp's glass at least once a week because overspray can get on the glass which will negatively affect curing. "Also, be sure that your printer's power source is clean and at the recommended voltage. If power fluctuates, or is below the manufacturer's recommendations, it will shorten the life of the bulbs."
Cich推荐到，操作者至少需要一周清洗一次灯头的镜面，因为过度喷涂会黏附在镜面上，容易影响固化的效果。另外，要确保打印机的电流稳定，是在推荐电压的情况下。如果电流不稳定，或者比制作人员推荐的电压低，这样会缩短灯泡的使用时间。
"Inspect and clean the lamp(s) reflectors and quartz plates daily to remove dust, powder, smoke and misting," Cipresso says. "Change the air filters as required to ensure the best air cooling for the lamps. Inspect to make sure the lamp shutters are opening completely."
“每天要检查清洗灯头镜面和石英盘，去除灰尘，粉末，烟雾之类的，”Cipresso说到“按要求改变空气过滤器，确保灯头在最好的空气下冷却的。检查确保灯头的百叶窗是完全打开的。”
Cich prefers that operators change the lamps sooner rather than later. "When inks are not fully curing, change the lamps," he says. "In the long run, it probably is not worth the extra week or two you gain by increasing the setting." He also recommends that you "change both bulbs at the same time, because if you change only one, the newer bulb will be stronger and that can lead to cure-banding," Cich says.
Cich更偏向于让操作者提前还灯头而不是延后。“当墨水没有完全固化的时候，就该换灯头了”他说。“从长远来看，可能不值得多耗费一两周，最好是通过增加设置。”他还建议到，换灯头的时候把灯泡也换了，因为如果只换一个的话，新的灯泡亮度会比较强，可能会导致固化结块。”Cich说。
Cich, Cipresso and Garcia all seem to prefer LED-based UV-curing systems for flatbed printers. "UV LED cure systems do not have the problems of mercury vapor, since lamp intensity remains constant for the life of the LED," Cipresso says. However, there is a catch.
Cich，Cipresso和Garcia似乎都更偏爱在平板打印机上安装LED的UV固化系统。“UV LED固化系统不会存在水银蒸汽灯上出现的问题，因为LED灯使用期间灯的光照强度是恒定的。”Cipresso说。然而，现在还是存在一个问题。
"The down side of LED lamps is that they can cost a lot more than mercury vapor lamps," says Cipresso. "LED lamps emit a narrower light wavelength than mercury vapor, so inks may not cure properly at the highest print speeds on certain substrates. This means you may have to make additional cure passes which reduces productivity. However, LED technology is evolving rapidly, and as the lamps performance become more robust and demand increases surely the price of LED lamps will decrease," he says.
“LED灯头的另外一个方面就是在花费方面可能比水银蒸汽灯多，”Cipresso说。“LED灯发出的光波长度比水银蒸汽灯短，所以在某个特定的材料上，最快速度打印时，墨水不会马上固化。这就意味着还需要多增加几次固化，这样就会降低生产效率。然而，LED技术发展的很迅速，当灯头的性能越来越好，需求增加，自然而然地LED灯头的价格就会降低，”他说道。
Static Buildup
静电增强
Print jobs often must be printed onto plastic sheet substrates such as PVC, Sintra, corrugated plastic, styrene, and etc. But plastics are prone to picking up static electricity, and depending on the ambient conditions within the shop, sometimes the static charge in the plastics can cause printing defects. Ink particles are attracted to the charged areas of the substrate like a magnet, deflecting them from their intended path. This results in printing complications such as clogged nozzles, dust attraction, and overspray. However, there are ways to minimize the levels of static in the shop.
打印工作一定是要在塑料板材上打印的，像PVC,Sinta,起皱塑料，苯乙烯之类的。但是塑料很容易产生静电，车间内的环境条件影响比较大，有时塑料中的静电会导致印刷出现不完整。油墨粒子会被带电基材像磁铁吸引，偏离预期的路径。这样就会引发各种并发症如喷嘴堵塞，吸灰，和过喷。但是，还是有办法可以把车间内的静电降到最低的。
"Always wipe down plastic sheets on both sides with isopropyl alcohol," says Cich. "It cleans the sheet and releases built up static. Humidity suppresses static, so the higher you can keep humidity in the printing area, the better. The ideal level for most printers is around 60 percent relative humidity." He believes that the only true solution is to purchase an ionization bar or static wand. "These printers tend to generate static as the printheads pass back and forth, so it's best to eliminate static right at the area where you are printing," he says.
“经常用酒精擦拭塑料板的两面，”Cich说。“清洁板材就能减少静电的产生。防潮处理可以防止静电，所以打印区域潮湿度越高，就越好。大部分打印机的理想潮湿度是60%相对的”
Garcia says that using a humidifier is a good idea, and he suggests keeping the humidity at levels between 40-70 percent non-condensing. He also suggests using an anti-static spray just before printing.
Garcia说，用加湿器也是个好办法，他还建议让环境保持在40-70%的适度范围内。还有就是在打印前先进行一次防静电喷涂。
Cipresso says there is another option as well. "One of the newest technologies is something called a static neutralizer. All materials have a positive or negative charge, and as the static neutralizer passes over the substrate it detects the polarity of the charge and neutralizes it. Our newest flatbed machine has this technology built into it," he says.
Cipresso说还有另外一个方法。“有一项最新的技术就是被称为静电中和的技术。所有的材料都会有正负电荷，当静电中和通过基材的时候，就能够探测出电荷的正负极，然后中和电荷。最新平板打印机都已经植入了这项技术，”他说。
Preventing Head-Crashes
防止打印机喷头损坏
A head-crash occurs when the printhead strikes the surface of the substrate being printed. For example, a printhead may strike the substrate as it passes over the high area of a warped sheet. This problem can in some cases be very costly to repair since the printhead is the most complex, delicate and expensive part of the printer. Many flatbeds have a crash sensor feature that can lessen the frequency of head crashes, but prevention should be the byword.
当打印机打印时喷头碰撞到板材，打印机喷头就容易损坏。比如，当打印机喷头通过弯板的高处时，就容易撞击板材。有些情况下，这种问题是需要花费很大来解决的，因为打印喷头是打印机上面最复杂，最精细和最昂贵的部分。很多平板打印机都有碰撞传感器功能，可以减少碰撞的频率，但是预防应该还是要做的。
"Store your media flat, so that it does not warp," Garcia says. "You should always make sure the printhead head height is at the manufacturer's spec. Always check for uneven surfaces on the substrate before printing, and make sure that the printer's vacuum table is turned on." The vacuum system can help eliminate minor warps in sheets during printing.
“尽量把板放平，这样板不容易弯。”Garcia说。“应该要随时确保打印机喷头的高度在厂家标注的规格内。在打印前要检查板材表面是否有不平，还要确保打印机上的真空台打开了。”真空系统能帮助打印机消除打印时板材上一些较小的弯曲。
"Always make sure the substrate to be printed has had sufficient time to stabilize in the print environment," Cipresso says. "Inspect the substrates to be printed for warp or other artifacts. On a true flatbed printer it is important to concentrate the bed vacuum to the areas under the substrate to be printed." Operators often use tape to mask off the unused vacuum holes around the substrate and then turn off unused vacuum zones in the table.
“要确保在打印环境中打印有足够的时间来稳定基材，”Cipresso说。“检查打印的基材是弯曲的还是其他形式的。在平板打印机中，把真空床集中到要承印物下面的区域是非常重要的。”操作人员通常会用磁带来屏蔽基材周围的不用的真空小孔，然后关掉操作台上不用的真空部分。
"Always check the corners of the sheet to be printed," Cich adds. "Corners are the most vulnerable to becoming damaged or bent. Be aware of any masking tape that is used on the bed. Bits of tape that come up in little rolls will not set the crash sensors off, and this is one of the top reasons for head damage."
“要经常检查基材的每个角落是否都能打印，”Cich补充到。“角落是最容易受到损伤和弯曲的。注意机床上的所有屏蔽磁带。少量的小幅度卷曲的磁带不会引发碰撞传感器，而且这是喷头受损的主要原因之一。”
Printing onto Glass
在玻璃上打印
As UV-cure ink technologies continue to improve, printing onto super-smooth surfaces like glass becomes more viable. However, it's not a simple "plug-and-play" process. There are some tricks that can help ensure a good bond.
随着UV固化墨水技术的不断提升，像在玻璃这样特别光滑的表面上打印也可以进行了。然而，这不是一个简单的“即插即用”的过程。有一些技巧可以帮助确保两者结合的比较好。
"When printing onto hard-to-print surfaces such as glass, an adhesion promoter is usually necessary," Cipresso says. "Adhesion promoters can also improve durability." He suggests wiping the excess adhesion promoter off as soon as possible after printing since it gets more difficult to remove later on. "Isopropyl alcohol can be used, but be careful not to wipe over the freshly printed image."
“在玻璃这样的比较难打印的介质上，通常需要用到粘合促进剂，”Cipresso说到。“粘合促进剂可以提升耐久性。”他还建议打印之后，尽快去除多余的粘合剂，因为时间久了就更难清除。“酒精可能用的到，但要小心不要把刚印刷的图像给擦除了。”
Cich offers another consideration. "Make sure that the white inks and the colored inks are matched to shrink and expand at the same rate over time," he says. "If they are not matched perfectly, it will lead to an ink failure on glass jobs."
Cich还提了另外一种顾虑。“要确保白色墨水和彩色墨水能够匹配，能以同样的比例收缩扩张，”他说。“如果匹配不好的话，就不能实现在玻璃上的打印工作。”
"Clean the glass thoroughly," says Garcia. "Run the printer's table vacuum at its highest setting, and use only the highest-quality print mode on your unit." He agrees that using an adhesion promoter is a good idea. "Though printing directly onto to glass is okay with most UV inks; it is also true that the printed ink on glass is easy to scratch. To solve this, use a good adhesion promoter (we like to use Supply 55 brand)."
“彻底的清洗玻璃，”Garcia说。“运行打印机真空台，设置要调到最高，配合最高质量的打印模似。”使用粘合促进剂也是可以的。“尽管大部分UV墨水都可以在玻璃上打印；但是在玻璃上打印就特别容易划伤玻璃。要解决这个问题，就要用好的粘合促进剂(我们一般喜欢用Supply 55 牌子)”
Printing Double-Sided with Perfect Registration
通过完美的校准实现双面打印
Double-sided printing requires great accuracy. If you have a board that is out of true by as little as one-tenth of an inch, experts say that over the length of the board your registration could wind up being off by a whole inch off at the end of the board, and the prints will not line up.
双面打印就需要很高的精准度。如果有一个板出现了哪怕几英分的出入，专家都会说，整个板的长度都不行，必须关闭打印，而且打印不用排序。
When printing double-sided with rigid materials make sure you start with substrates that are square and straight," says Cipresso. "This will result in improved front-to-back alignment."
在硬度大的材料上打印的时候，一定要确保基材是正方形的和直线的，Cipresso说“这样也会提高前后面的对齐度。”
Cich adds that most substrates are not perfectly square. To compensate, he offers a simple solution. "You can print onto one side first, and then take an X and Y measurement, and once flipped, move the substrate the above the measurements, and your registration will be perfectly square every time."
Cich补充到，大部分的基材都不是很规则的正方形。为了弥补这一缺陷，他提供了一个比较简便的解决方式。“我们可以现在一面上先打印，然后测量长宽，一旦有了框架之后，把基材放到测量好的框架内，这样每次就能很好的呈现正方形。”
Cipresso says that "a number of flatbed printers have registration pins that can be placed in opposite corners. Aligning the rigid material to these pins will ensure the best accuracy possible when you flip the board to the second side. Of course image orientation will have to be addressed in the image file design for the second side image."
Cipresso说，“很多平板打印机都有可以放在对角上对齐的针。把一块板放到另外一块板上的时候，把这些硬性材料和这些针校准对齐，就能尽可能的提高精准度。当然图像定像一定要在另一侧图像的同一位置。”
Garcia also says that it's best to use the printer's registration pins, "Or you can use the printer's alignment bar if it is equipped with one. Also, set the file to bleed off; print the image edge to edge for best results."
Garcia也说了，用打印机的对齐针就最好，“或者打印机上有的话，也可以用打印机的对齐棒。还有，把所有的文件放到一块，边缘接边缘打印，这样打印出来的效果会更好”
Printing onto an Irregular Surface
不规则平面打印
Most flatbed printers feature a vertical adjustment for the printhead assembly that allows users to print onto various thicknesses of rigid sheet—some allowing thicknesses of as much as four inches or more. But what if you need to print onto a substrate that has an irregular surface, such as a door? Remember, the farther away the printhead is from the printed surface, the less accurate the dot placement.
大部分的平板打印机都有自动垂直调节打印机喷头的功能，这样使用者就可以在各种厚度的硬性材料上打印，有些甚至可以打印4英寸或者更厚的硬性材料基板。但是如果要在不规则的表面上打印怎么办呢？例如门？记住，打印机喷头离打印平面越远，打印的点就越不精准。
Garcia offers some general advice. "Raise the head height to the max tolerance," he says. "And if you are using mercury vapor lamps, set the lamps to max intensity, and print at a very slow speed."
Garcia也给我们提供了一些综合性的建议。“把打印机喷头的高度调到最大容忍值，”他说。“如果是用水银蒸汽灯，把灯调到最大亮度的照明，然后低速打印。”
Printing onto an irregular surfaces such as an iPad cover can be tricky, admits Cipresso. "A Novus customer of ours prints iPad covers his Pictora flatbed. To accomplish this they make a mask in order to concentrate the vacuum on the substrate. The head height was adjusted to allow a sufficient head-to-substrate gap which results in a sellable print with minimal risk of a head strike.
在不规则的表面上打印，例如iPad的封面，这样就会比较棘手，Cipresso承认。“我们有一位Novus客户，就在他的Pictora平板打印机上打印了iPad封面。为了完成这项工作，他们做了一个盖板，让真空台能精准对到基材上。喷头的高度要调节到喷头和板材之间的距离是合适的，这样打印出来的就比较美观，喷头撞击基材的风险也比较小。”
And Cich offers this advice: "First, if your printer allows, print in uni-directional mode," he says. "This allows for any overspray that you would get in a recessed area to be more uniform. Second, if allowed by the printer software, raise the carriage a millimeter above what the printer detects. This will give you clearance if the substrate warps."
Cich还提了这条建议：“首先，如果打印机允许的话，用单向模式打印，”他说。“这样所有不粘合部分也能均匀地贴在表面。其次，如果打印机的软件允许，打印检测的时候提高运输距离一毫米。如果板材弯曲了，还会有一些空隙。”
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