Manufacturer Rethinks Adhesive Dispensing Process, Saves 33 Hours of Maintenance Per Week Stepping back to get a fresh perspective is sometimes the best way to solve a problem. That's the approach taken recently by a major paper goods manufacturer looking for a more efficient way to dispense vinyl acrylic adhesive on their assembly lines. As a result, productivity is up 10% and they are saving as much as 33 hours of maintenance-related downtime per week. To help meet growing demand, the company purchased three pre-owned assembly machines. While the equipment was in sound mechanical condition, some refurbishment was required before it could be installed on the shop floor. The top priority for the production engineer was finding replacements for the original adhesive dispensing devices, which had been removed by the previous owner. Known in the industry as "gluepots," these heavy machined brass reservoirs use a gear-driven wheel to transfer a band of adhesive onto the paper stock. Gluepots were already in use on several other machines, and the company was familiar with their limitations as well as their capabilities. Though effective, the gluepots required a significant amount of maintenance, as well as frequent adjustment to compensate for wear and changes in adhesive viscosity. To keep production running smoothly, a series of regular maintenance procedures needed to be performed at the beginning and end of every shift. At the start of the shift the gluepot was coated with a release agent, filled with adhesive and installed in the machine, a process that took about 15 minutes. Thirty minutes before the shift ended, the operator had to stop the machine, remove the gluepot, discard any unused adhesive, and thoroughly clean the reservoir and mechanical parts for the next shift. During peak production periods when the machines run 24 hours a day, a single gluepot receives more than 11 hours of scheduled maintenance a week. With three new machines on the way and product demand continuing to grow, the company needed to find a more efficient adhesive dispensing method. Retrofit Provides Low-maintenance Alternative During their search, the manufacturer contacted EFD (East Providence, RI), who specializes in precision dispensing equipment. After discussing their setup and objectives, EFD recommended the Model 725DA, a compact dispense valve with several unique features that made it ideal for this application. First was the low-maintenance design. Unlike gluepots, the pneumatically operated 725DA's moving parts do not come in contact with the adhesive. Instead, a machined polymer diaphragm separates the valve's internal parts from the fluid chamber, which ensures long. trouble-free operation. Since adhesive is supplied from a pressurized tank rather than an open reservoir, there is no contamination or waste, so frequent cleaning is unnecessary. Second, no elaborate fixturing was required. All the manufacturer had to do was fabricate a simple bracket to hold the valve in position, then attach an air line to actuate the valve and a fluid line to supply adhesive from the tank. Since the machines were already outfitted with infrared sensors and solenoids, those devices could be used to initiate the dispense cycle. A third feature that the company found particularly useful was the 725DA's adjustable piston stroke, which controls both fluid flow and snuffback. With the gluepots there was no way to adjust the length of the bead, so it ran the full length of the stock. At times this caused the products to stick together, resulting in an extra production step in which the operator had to manually fan each stack before sending it on to the next station. In contrast, the valve's fast open-close stroke and snuffback feature would allow the bead to start and stop a specific distance from the edge of the stock, improving both quality and production flow. And the price came as a pleasant surprise--all three assembly machines could be fitted with dispense valves for less than half the cost of a single gluepot. Impressed by the 725DA's capabilities, the company decided to give it a try. "At the time, this was something totally new for us," recalls the engineer, who remembers their mood as being guardedly optimistic. "We didn't know anything about dispense valves and weren't sure how well they would perform in our application." Once the valves went into operation, however, any doubt quickly disappeared. Productivity Increases 10% The lack of maintenance on the EFD valves has virtually eliminated downtime on the new machines and increased productivity by at least ten percent. "At the end of the shift, the operator coming off steps away from the machine and the new operator steps in without missing a beat," the engineer says. "We're producing thousands more units per shift." He estimates that the new approach also saves three hours of wear and tear a day on each machine. "With gluepots, we had to leave the machines running during breaks and meal times to keep the glue circulating. With the valves, we just shut down the machines when we leave, then cycle them a couple of times when we start back up. Even if a machine has been idle over the weekend, there's no problem--we might have to change the dispensing tip, but that's about it." Pleased with the results of their new approach, the manufacturer is planning to retrofit their other machines with the EFD valves. "If someone was looking for adhesive dispensing equipment that is maintenance-free, I'd tell them this is the way to go," the engineer concludes. "We've been running these valves for almost a year now, with no problems at all." -------------------------------------------------------------------------------- To learn how EFD equipment can help you improve your dispensing processes, please e-mail info@efd-inc.com, or in the USA call our Fluid Application Specialists at 800-556-3484.