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Digital Printing

Digital Dilemma, Part One

Would a printer purchase benefit your sign business?

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Chances are, if you don’t already own a digital printer, you’re considering purchasing one. Today, an entry-level printing system’s price tag — whether it’s a time-tested, thermal-transfer printer or a new inkjet system — makes such units affordable for nearly all signshops. Technological advances, including production-speed improvements, print durability and format size, are additional reasons you should seriously consider going digital. The new generations of eco-solvent printers are especially exciting — they feature exceptional resolutions and good production speeds. Plus, they don’t require special, topcoated vinyl. As exciting as new technology is, before you commit, you should seriously think about which digital-printing system is right for your business. When contemplating such a decision you should consider the following: Market focus. Focus on which market segments your shop will serve — vehicle graphics, POP, exhibit/tradeshow graphics, backlit signs, banners, window graphics, floor graphics, etc. The choices are endless. Also, it’s important to consider digital-printing media types. Cast and calendered vinyl, banner and flexible-signface material, foamboard, expanded PVC, paper and floor-marking film are available. Because you can’t satisfy everyone, the key is to focus. Customer requirements. Depending on the market, customer expectations may vary. Some clients may demand a sharper print than others. Further, a print resolution that’s adequate for a vehicle graphic may be unacceptable for a POP display. Thus, you need to consider your customer’s resolution requirements, which involves determining viewing distance. For example, because fleet graphics and outdoor signage will be viewed from distances greater than 50 ft., a 180-dpi resolution may be acceptable. On the other hand, tradeshow posters, which are viewed more closely, require printing resolutions of 760 dpi or higher. Break-even point. Based on your shop’s monthly fixed costs, calculate the sales volume needed to pay for the equipment purchase. To arrive at this break-even point, divide your monthly fixed costs by your average profit margin. The fixed costs associated with buying a digital printer could include the loan payments, equipment depreciation and maintenance contracts, plus a percentage of the rent, utility costs and insurance. Justifying a printer’s cost and all the extras isn’t too difficult. For example, if your fixed monthly costs equal $1,000, and you operate your business at a 40% average profit margin, your break-even point is only $2,500. If your break-even analysis suggests sales won’t cover your fixed costs, along with your direct material and labor costs, you have two alternatives: Rework your plan, or outsource the printing until your sales justify an equipment purchase. Sales forecast. The bigger your investment, the more you need to focus on marketing and sales. In other words, determine to whom you’re going to sell before making an equipment purchase. If you don’t, you’ll probably struggle to find work to fill the machine’s capacity. In your sales and marketing plan, include a target and sales forecast that lists how much you’ll sell (see ST, October and November 2003, pages 20 and 30). Start-up costs and cash flow. Do you have enough money to get started and make your monthly payments? How will a printing system’s additional expense affect the rest of your business? If your break-even analysis indicates profitability, crunch more numbers to determine your company’s projected net profit and whether you have the available cash to cover your start-up costs and pay your monthly bills. You should also establish a profit goal. What’s an acceptable return on your investment? If your return is less than 15%, the venture probably isn’t worth the trouble. Training, system maintenance and total system cost. Determine the type and amount of system training a distributor provides, the learning curve for your employees and whether a service agreement is available. If the system breaks down, what service does a distributor provide? Also, consider routine maintenance tasks and estimated annual costs for parts replacement and maintenance. When will printheads need to be replaced? When calculating your fixed monthly expense, consider more than just the printer payment. Other associated costs could include the workstation, software, peripherals, a scanner, digital camera, laminator, ventilation hood, maintenance agreement and training. Finally, it’s important to know a finished graphic’s cost per square foot. Inkjet printers Inkjet systems print by spraying ink onto a substrate, without making contact with the print. Earlier units offered minimal printheads. However, today’s more sophisticated units, with more nozzles, greatly improve production times. The latest generation of eco-solvent printers boasts outputs as high as 300 sq. ft. per hour. Furthermore, maximum production speeds for the new flatbed printers, with UV-curable inks, reportedly reach 1,000 sq. ft. per hour. Overall, printheads’ engineering design changes have improved print quality, and, most importantly, different inks can be used with the new printheads to create greater outdoor durability. Inkjet printers offer lower capital investment, photorealistic print resolution (180 to 1,440 dpi) and large-format capabilities. Plus, they’re compatible with various substrates. Ink is important because it determines what media types the printer accepts. No universal ink system works with all print media, so it’s important to ensure that the printer, ink and media are compatible. Furthermore, ink type determines whether you need topcoated vinyl or uncoated film. If you need to purchase topcoated media, consider what type will work in your printer and how much it will cost. Printers that use waterbased inks require expensive topcoated media. Dye-based inks’ downfall is lack of durability, compared to thermal-transfer and electrostatic printing technologies. Even solvent-based, pigmented inks have limited exterior life, especially if prints are subjected to harsh climates. Inkjet technology requires drying time, overlaminates and, in many cases, topcoated vinyls. Plus, some systems are limited by slow production speeds. Future inkjet improvements will likely include higher resolutions, increased production speeds and longer outdoor durability. Continuous flow and DOD Continuous-flow inkjet systems provide a constant stream of ink droplets. Using positive and negative electrostatic charges, some droplets are deflected into a gutter; remaining droplets are deflected to the print surface. The ink, which is directed into the gutter, is typically recirculated. Drop-on-demand (DOD) systems, the most common, sign-industry, wide-format print devices, don’t use a gutter system to recirculate the ink. Instead, the ink is only expelled from the printhead when needed. DOD systems can be divided into the two following categories: thermal inkjet and piezo inkjet. Thermal inkjet. This type of printer channels ink into a chamber. The inkjet printhead contains a heat resistor that super-heats the dye-based ink to temperatures as high as 750°F or 400°C. In microseconds, the liquid ink boils and becomes a gas.

In a thermal-inkjet system, the heat resistor turns on and off to control the ink droplets. As the nozzle opens, the heated ink explodes through the printhead onto the substrate. As the waterbased ink dries, it bonds to the surface.

Thermal-inkjet printers typically use dye-based inks, although a few systems can print pigmented inks. Historically, thermal-inkjet systems’ intense heat disallowed printing with pigmented inks. The heat structurally altered the pigment, destroying the color, and residue from overheated inks clogged the inkjet nozzles.

Compared to piezo printheads, thermal-inkjet printheads aren’t very durable and require routine replacement. Generally, the ink requires filtration to strain out impurities. Without filtration, the printheads clog quickly. Along with ink and substrate, the printheads are considered consumables. (Note: When calculating your fixed expenses, remember to include printhead replacement costs.)

The thermal printheads’ consistent orifice size is critical in controlling image output and maintaining quality control. As thermal technology has improved, ink droplets have become smaller, which improves print resolution and provides photorealistic images.

Although inkjet systems are more affordable than other primary technologies, such consumables as printheads and specially topcoated vinyls can significantly add to the finished print’s cost.

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Moreover, fluctuations in shop environments affect all electronic printing equipment. Although output from inkjet printers remains relatively consistent under temperature and humidity shifts, the ideal signshop environment would include temperature and humidity controls.

For example, Ad Graphics (Pompano Beach, FL) has one room for its inkjet printers and another for its 3M Scotchprint® electrostatic systems. For optimal performance, each room is zoned for its own environmental control.

Piezo inkjet. Piezo-inkjet technology is also popular in the sign industry. In piezo units, inks are mechanically forced through the printhead. The ink doesn’t boil. Instead of undergoing four phase changes, it only undergoes two — from liquid to solid. As a result, thicker inks and pigmented inks can be used. Of course, pigmented inks are more outdoor durable than dye-based inks.

Thermal-inkjet systems became popular due to their low purchase cost. And today, many signshops house such units. However, because of the sign industry’s demand for more durable prints, interest in piezo systems is steadily growing.

Piezo-inkjet printers work like an electric oil can or squeeze bottle. Ink is drawn from a reservoir into the piezo-electric transducer. As an electric field is applied to the compression chamber, the chamber walls contract and force or squeeze out the ink. Application of another electric charge also causes the chamber to expand, which sucks in new ink to refill the piezo "oil can" chamber.

Among piezo-printing systems, three operation modes are used in printhead design: normal, shear and coupled. In normal mode, the top chamber wall flexes. With systems using shear mode, the two side walls flex. In the combined mode, all three chamber walls flex, which expels the ink from the chamber faster, increasing production speeds.

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Although piezo printheads are more costly than thermal-inkjet printheads, they’re more durable and reliable, and rarely experience clogging. Piezo systems can use a wide range of inks, including water- and solvent-based, and UV-curable. These systems also accommodate thicker pigmented inks, which yield greater outdoor durability. Furthermore, piezo systems don’t subject the ink to super-heated temperatures, and some inks printed using piezo systems dry rapidly, which improves production time.
 

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