High-resolution ink-jet coding systems using piezo-electric technology regularly print bar codes on corrugated cases. But these systems are notorious for being fussy about being kept primed with ink. Not only must they be reprimed whenever they're started up or refilled, the slightest bump or vibration can also interrupt the flow of gravity-fed ink. With a separate ink bottle for each printhead, ink changes can also eat away at uptime, especially when using multiple heads. Arcadia Farms, Arden, NC, sidestepped these obstacles when it upgraded the ink-jet case coding system on one of its bottling lines for water, fruit drinks and fruit juices. The new coding system, installed in May '96, relies on a new Centralized Ink Delivery System (CIDS) from Diagraph (St. Louis, MO). The ink system is connected to one of the supplier's Model PEL high-resolution ink-jet coders. The theory behind centralized delivery is quite simple: instead of a separate, external ink reservoir for each printhead, one central ink supply feeds as many as eight printheads. (Currently Arcadia has two printheads on its PEL system, one for each side of the case.) The ink supply tank pumps ink to a small, 3-oz reservoir that's contained inside the printhead's housing. The ink then flows to the printhead via gravity, which is all the pressure that piezo-electric printheads can withstand. Typical piezo-electric-based printheads have an external ink reservoir with several inches of hose connecting it to the printhead. If either the printhead or the reservoir is bumped, moved or vibrated, it can disrupt the flow of ink. With the new system, the relationship of the reservoir to the printhead is permanently fixed inside one industrial housing, thereby ensuring that ink will have a permanent, working path from reservoir to printhead. The centralized pump keeps ink flowing to the reservoir, keeping the system primed, even when the unit is first turned on. "It's always primed," confirms plant manager Jerry Ledford. "We turn it on in the morning, it heats up automatically, and it's working within seconds." Plus, only one ink supply needs to be monitored and changed. Changeover of the ink itself is easier, too. "You can change it on the fly while it's coding," says Ledford. "You don't even have to stop the line." Ledford says a desire to start bar coding cases necessitated a switch to the PEL high-resolution coding system. The company's previous valve-style ink-jet printer couldn't provide the print quality needed for bar codes. Arcadia downsized from a 25-count case (5x5) to a 12-count to encourage consumers to purchase the case as a multipack. As a result, Arcadia is ink-jet printing a UPC-A bar code that allows the case to be scanned at the checkout counter. It's also scanned in customers' warehouses as a distribution code. Ledford reports the strategy is working so far. "We thought it would be a big change, something new and different. It has become so, and we've actually grown because of it." Arcadia itself doesn't use the bar code internally. Another drawback of its former system, says Ledford, was messiness. Ink bottles on the new system have a needle that punctures a membrane as the bottle is screwed in. "So you don't have ink dripping down all over the floor," comments Ledford. The final benefit is that the cost of ink has dropped, according to Ledford. Because older valve-type technology relies on pressure feeding, it consumes significantly more ink compared to piezo-electric technology. "We used to change a half-gallon ink supply each week," recalls Ledford. "With the new system, we haven't replaced the ink cartridge yet in seven months. And it's only a 250-milliliter container." Ink costs, however, are not proportional to volume used. Ounce for ounce, piezo-electric ink is significantly more expensive, so it's not unusual for valve systems to have lower overall ink costs in spite of their higher volume usage, according to Diagraph. Fortunately, says Ledford, Arcadia's experience has been different. "We're definitely saving money with the new coder. That unit will probably pay for itself just in the ink we're saving alone, not to mention the print quality that we achieve."
