Computerized dispensing provides ink management
- Published: April 01, 1995, By Fallon, Martin J.
It was a big week for Malcolm Clare, operations vice president, Transprint USA, the country's largest gravure printer of heat-transfer designs used to create fabrics for apparel and home furnishings.
While responding to a peak in demand, his hatching area had broken a new record, creating more than 500 different colors in one 24-hr. period - one new ink every 2.8 min.
Better yet, each of those colors was formulated with three quarters recycled material, which meant that the number of cans on the shelves in inventory had begun to decline. Transprint's new computerized color-management system was at work.
"These achievements are indicative of several trends in our industry," Clare said. "In our particular business segment, we're seeing more and more short runs as the variety of fashions in clothing and home furnishings expands.
"And, the patterns our customers order are becoming more elaborate, which means more cylinders and more inks for each run," he said. "Our four-color libraries comprise 12,000 colors supporting about 2,000 designs."
Transprint prints an average of 1.6-million sq. m of transfer paper each week at its Harrisonburg, VA, facility. Some run lengths may be as short as 500 m, and from that length, the trend continues downward.
"This means we need more inks to keep the presses fed. The average number of colors per run used to be around five," Clare said. "Two years ago, we were formulating about 170 batches/day.
"Now the average is closer to six or seven colors for each run, and we're up to about 500 runs each week. So, our color matchers and ink makers have been exceedingly busy."
The fastest growing sector of Transprint's business is heat-transfer printing for home furnishings. Designs are gravure printed on paper using dyes that vaporize when heated and chemically bond to woven fibers.
Transprint's market is competitive. To be ready for the projected escalating demand without risking its reputation for quality, customer service and production efficiency, Transprint decided to automate its color-dispensing system.
"Previously, all our colors were formulated by hand," Clare said. "The critical factor was the skill and the color eye of the batching-area staff. But we had come to a point where adding more people wasn't the answer."
To collaborate in the development of a new color-management system, Transprint chose Precision Dispensing Inc., West Chester, PA. Precision Dispensing creates computerized, recipe-based batching systems.
Driven by sophisticated software, the hatching systems are also designed to perform a variety of management and data-gathering tasks which Transprint saw as essential to preparing for the demands of its long-term growth.
To keep capital costs manageable, Precision's systems are basic, modular and flexible. But they are capable of being customized to whatever degree a process requires.
Joining Clare on the project from Transprint were Don Dovel, ink room supervisor; Tom Garth, maintenance supervisor; and Bob Fellows, vice president of research and development.
The first step in the development process was to determine the specifications for a system that would suit a high-quality gravure printer specializing in a large number of small production runs.
The Precision team brought an extensive background in computerizing many types of production processes to the task. The team's programming know-how and practical engineering experience was complemented by years of defining customers' operating requirements and to see how automation might improve process efficiency.
"Most important to us was that the system provide total-color management," Clare said. "Merely dispensing ink wouldn't meet our needs."
The new system would have to be able to formulate up to 600 colors/day over three shifts to accommodate demand forecasts coming in from the sales department.
Next in priority was the extensive inventory of colors left over from previous jobs. "That inventory was growing," Fellows said.
After each run, about 18 lb. of ink remains in press sumps. It isn't economical to discard the leftover colors, and disposal requires compliance with strict environmental regulations and record-keeping, which is expensive and a time-consuming distraction for management.
"Reusing the returned colors was our preferred solution," Fellows said. "We calculated that if each new ink can be formulated out of at least 72% of returned ink, our inventory will begin to decline."
The control software must be capable of making the best selection from among the wide variety of colors in the returned-ink inventory as the starting point for new formulations.
To ensure accuracy, the system should be gravimetric. Since the colors are solventborne, the dispensing machinery should be explosion proof and enclosed to retard evaporation.
The dispenser must be capable of formulating batches from one gallon to 50 gallons, with any number of ingredients. Accuracy in weighing ingredients is also essential. Accuracies to .1 g are possible.
For the times when a customer orders a second shipment, the colors must be repeatable, a criterion determined eminently important. Color management must also be integrated with the company's existing computerized print-order scheduling system.
"With the number of jobs we're doing each shift, it's critical that we have the right ink in the right quantity, with the right viscosity, at the right press, at the right time," Clare said.
The first step in designing the control software was for Transprint's technical department to create formulas for each color in the extensive inventory.
The system was installed on PCs because they are easy to maintain and convenient to upgrade. By design and after training, Transprint's technical staff are able to support their own system.
Dispensing hardware was constructed of easily available, American-made parts for reliability and ease of maintenance. To minimize turnaround time, the controls were designed so that dispensing valves operate at full flow. The software determines how long to keep each valve open, so exactly the right amount of color is added.
A master server networked to the PCs maintains the system's databases and performs all scheduling and reformulation calculations. Operator PCs at dispensing and weigh-in stations monitor activities and record inventory additions and retrievals.
Programmable-logic controllers receive recipe information from the computer in the dispensing area and activate the dispenser.
"With our data-management capability, we can track down every job showing how much color was made, when, by whom, on which cylinder it was used, and where the inventoried material is now," Fellows said. "The system also automatically monitors the amount remaining in each of the drums from which the inks are dispensed, reminding us to refill when required."
For environmental reporting, the system automatically tracks the use of solvents and other materials deemed hazardous and prints the reports.
As job orders come in from the show room, a schedule is created and down-loaded to the dispensing-systems computer. As each job comes up, the computer selects the cans in inventory that most closely match.
Each can into which color is blended is assigned a control number. To formulate an ink, the operator retrieves the selected can from inventory and places it on the dispenser scale.
The starting weight is verified, and the new colors are added. Before the can is transported to the press room, a bar-coded label is automatically printed. This label indicates the color, the press, the job and the cylinder.
When ink is returned to inventory after a run, it's weighed and then a new label is printed. The batching-area staff, using hand-held bar-code readers, input the can number, the color, the weight and the shelf on which it is stored into the database.
"It's natural that we had skeptics in the batching area when we started the automation process," Clare said. "But today, everyone is enthusiastic about the many things that we can do.
"And our big week kicked off a big month in which we saw our color inventory reduced by about 800 gallons. I know for sure because our new reporting system tracked it," he said.
Martin J. Fallon is president of Precision Dispensing Inc., West Chester, PA. He has been a production-line supervisor, systems analyst, product manager and financial vice president for companies in several fields.
