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Nov 1, 2007 12:00 AM
Roman Heredia was frustrated. As plant manager of Chicago-based envelope printer Royal Envelope since 2001, he faced seasonal production problems with static electricity, paper shrinkage and paper dusting. It threatened Royal's reputation for print quality and imperiled tight production and shipping deadlines for customer mailings. Fortunately, he found a simple solution.
“Our business is built on doing things right, and we don't want unhappy customers,” says GM Matt Pusatera. Royal Envelope is a direct mail and direct marketing specialist. He explains, “We print 425 million envelopes a year; mostly four- or five-color jobs. Ninety percent of them go to other printers or fulfillment houses for inclusion in direct mail or direct response packages. They all have tight mailing dates. The envelopes have to be on time, and print quality is crucially important.”
Every year from early fall through late spring, Pusatera and Heredia have faced a variety of seasonal production problems related to dry air in the plant.
Static electricity was the most obvious problem, Heredia says. “Around the sheeter and the press, the charge was so strong, the hair on your arms stood on end any time you went near.” The static caused paper sheets to cling together, resulting in double sheeting and press jams. The jams slowed throughput from Royal's five-color Heidelberg Speedmaster, jeopardizing tight production schedules, and wasting time and paper as the messes were cleared up and jobs restarted.
Static also caused problems in the jogger, making it difficult to get a uniform edge. “We were able to adjust the jogger and eventually get the edge,” says Pusatera, “but it took some time. There's a cost in that.”
Paper shrinkage, mostly in the horizontal dimension, caused curling, leading to feeding problems and jams as grippers couldn't handle the curled sheets. And, bowed and wrinkled sheets meant registration and diecutting problems, causing more waste and downtime. Folding machine speeds often dropped by half to accommodate curled paper.
Dried-out, brittle paper often cracked during sheeting, diecutting and folding operations, creating paper dust in the air that exacerbated respiratory problems among press operators and bindery workers.
Pusatera says, “We found ways to work around the problems so our customers would get quality products, but sometimes it was difficult to accomplish, and it created a lot of stress. The unpredictability of problems made it difficult to maintain production schedules, and even when we were able to stay on schedule, we worried constantly about meeting the needs of our sales force and our customers.”
Problems were sporadic and intermittent, but also quite frequent during heating season. They were so common, in fact, that Heredia says he never tried to keep careful track of how often they occurred. “We tended to accept them as just one of the facts of life, but we always knew there had to be a better way.”
There's nothing unusual about dry air problems in printing plants, but because they typically are seasonal and sporadic, those dealing with the problems commonly misdiagnose them. Printers often incorrectly blame a bad batch of stock, equipment malfunctions or similar issues. Eventually, companies and managers realize that the problems are caused by dry air in the plant and are relatively easy to solve.
When cold outside air is heated, RH drops precipitously. For instance, when 10°F feed air with 50 percent relative humidity (RH) is heated to 70°F, RH levels in the plant air typically drop to less than 10 percent. The colder the outside air, the more precipitous the drop. Even heating air a few degrees can cause dry air problems. Printers frequently encounter static and paper shrinkage problems when RH slips below 30 to 35 percent.
Ideal conditions for printing, folding and diecutting occur when in-plant air is 40 to 55 percent RH at 68 to 72°F. At those levels paper is flexible, paper shrinkage and curling are minimized, print quality is maximized, and cutting, folding and diecutting operations produce far less waste and dusting. To achieve those RH levels during heating season, most printers have to add substantial amounts of water to the air in their plants. In drier climates, it can be a year-round need.
“We realized our problems were tied to heating cold outside air to appropriate in-plant temperatures,” Heredia explains. Summers in Chicago's old Stockyards neighborhood are notoriously hot and muggy with high humidity, and dry air problems are few and far between. But, “In the fall, when we turned on the heating system, the problems would start right away,” he says.
Royal's plant uses a ceiling-mounted, gas forced-air heating system. “It's an ideal way to dry out air,” Pusatera says, “like a series of big blow driers in the building. We knew we had to control the RH in order to control the problems, but we didn't have an effective system.”
Pusatera says that Royal tried using hardware store type humidifiers in the 55,000-sq.-ft. plant's paper storage area. It didn't work. The small humidifiers just didn't have enough capacity and they didn't have the ability to maintain consistent RH levels.
Since many of Royal's customers are printers, Heredia found himself discussing his dry air problems with them. Most had faced dry air problems, and several had introduced engineered humidification systems into their plants with positive results.
The more Heredia listened, the more he became convinced that a whole plant humidification system that controlled RH levels from paper storage through shipping was the answer he was looking for. “I also determined that a high-pressure system was our best choice. It would provide the capacity we needed with lower operating costs and less time and money spent on equipment maintenance.” High-pressure systems don't heat water to create steam, so energy costs typically are lower than those that do.
Heredia investigated high-pressure systems from three manufacturers before deciding on an engineered system from ML System, through ML's exclusive North American distributor, Husson Inc. (Racine, WI). In the final analysis, ML's system capacity, rapid absorption of cool mist and uniform coverage due to an integral fan and the fan's low noise (55 dBA) were the deciding factors.
“Probably any of the fan-driven high-pressure systems could have solved the RH problems, but the ML system's lower noise and absence of wind were a lot less intrusive. It's effective, but it's so quiet you hardly even realize it's there,” Pusatera notes.
Husson installed Royal's plant-wide ML system in fall 2006. Heredia says, “They understood how to get the job done without interrupting our workflow.” Princess 2 humidification units were placed over aisles, allowing fill circle humidification and making maintenance of the units easier.
Husson staff also trained Heredia and his staff on operations, maintenance and trouble-shooting. “It's a proven system, and simple to operate, so with their instruction, we were good to go very quickly,” Heredia says.
Royal's ML system is configured with five ML Princess 2 humidifiers, high-volume (10 gph) mist units in two zones in the paper storage and production areas. Remote humidity sensors in each zone are tied to a central programmable logic controller. To reduce maintenance and eliminate mineral dusting, reverse osmosis (RO) water is plumbed into the system. Any time RH in a zone falls below Royal's 45 percent RH set point, the PLC triggers the Princess units, which produce a cool mist of fine, easily-absorbed droplets until the target RH is re-established.
Pusatera says problems with static and paper curling disappeared within a day or two. “It wasn't like a bell went off. It was more subtle. One day we realized we weren't having double-sheeting and press jams, and we didn't have to slow down the press or the folding machines to accommodate curled stock. Our output was greater, and it was a lot easier to keep with our production schedules. It was a big relief.” Complaints about dry air and nasal discomfort also went away.
Heredia and Pusatera describe themselves as big fans of their ML system and the way it has solved their dry-air problems. Heredia says Royal Envelope's issues with static electricity and paper curling have been reduced to “almost nothing,” with resultant major improvements in misfeeds, jamming and registration, and much less paper dusting.
“The paper is more pliable and easier to work with,” says Heredia. “It doesn't shrink, so our registration and diecutting problems have disappeared. We don't have to waste time working around dry air problems and continually readjusting the production schedule. It would be nice if solving every problem were this easy.”