Triton, the leading provider of off-premise ATMs, and Mack Molding have launched the first custom molded part into commercial production in the United States using the external gas injection technology developed and licensed by Cinpres Gas Injection (CGI) Inc. Banking on what was then an unproven technology, Triton not only made a bit of plastics processing history with its decision to go with external gas-assist, it also solved sink and cost issues.
The application is Triton’s recently introduced 8100 Series cash machine, a low-cost ATM for low-traffic locations. Measuring 11.5″x17″x4″, the front fascia on the money dispenser requires strength to handle direct impact and normal field abuse, as well as premium aesthetics to match the other front panels on the unit.
In the past, Triton used the structural foam process to obtain the impact and stiffness its ATM panels required. But with a goal of further lowering cost, Mack recommended the external gas process, which it licensed from CGI. Mack worked closely with both CGI (Ann Arbor, MI) and MSI Moldbuilders (Greenville, SC) during the design and tool development phase.
Squeezing out sink & savings
Sink marks are small depressions in molded part surfaces that are opposite thick sections, and are caused by internal stresses as the plastic cools. External gas technology is designed to yield sink-free surfaces over ribs and bosses by “forming a pillow of nitrogen around the part’s core that uniformly presses the cushioned core against the cavity, gently squeezing out any sinks,” explains Ken Kincaid, Mack technical engineering manager.
It takes a little more than gas to mold it right, though. “Designing appropriate features into the mold to contain the gas and prevent it from seeping around to the cavity side or through parting lines is critical,” says Kincaid. “But it doesn’t have to be an all-or-nothing gas deposit.” One of the beauties of external gas is that you can design features into the tool to isolate the gas in just the areas where you need it, making it possible to take advantage of the benefits of both internal and external gas in the same part.
Internal and external gas assist share many similarities, and both have been used to solve sink problems. When deciding between the two processes, the critical factor is part design.
“With this particular part, there are six different types of mounting features and about 30 internal ribs, all randomly located,” explains Kincaid. “With internal gas assist, we would have had to link all the ribs and bosses to a single gas channel or to multiple channels. External gas assist made material management much easier and tool engineering much less extensive.
“The result is a solid part with no gas holes, no voids, and no read-through from gas lines on a show surface,” he adds. “We were also able to reduce cost on the project with a smaller press, efficient material usage, and less design/engineering man-hours.” The 195.5 sq. in. fascia is molded in a 300-ton press of PC/ABS resin. By comparison, conventional molding would have required a 600- to 850-ton press.
Sold on the process
Steve Langen, program manager at Mack’s Southern Operations, says Triton is sold on the external gas process. “They’re using technology to gain an edge over their competitors. With external gas, they can produce a large cosmetic part that is structurally strong at a lower cost. We’re able to use larger rib-to-wall ratios with external gas, so they are getting the structure they’re used to with structural foam, can locate ribs where they want them, and in general, are enjoying more design freedom.”
But why would Triton risk a new product launch on a commercially unproven technology? “One of the most important reasons is that we have a very good working relationship with Mack at both the engineering and sales levels,” says Triton Mechanical Engineering Manager Scott Hoelzel. “We trust their advice.”
The second reason is cost. “Our market is no different than many other maturing markets in that it requires constant attention to price. To stay competitive, we have to always be looking for new places to cut costs. In this instance, technology was the solution.
“The final reason is partnership,” adds Hoelzel. “External gas technology is a patented process, so there are upfront licensing costs. Mack bore some of that initial cost burden itself, realizing that using the technology would benefit both companies.”
In the future, Triton hopes to use external gas to reduce costs further by replacing paint with molded-in texture. “Right now, we’re painting the fascia to match other existing parts,” says Langen. “But eventually, Triton would like to further reduce cycle time and material costs by eliminating paint altogether.”
In addition to the fascia, Mack molds the control panel and an optional topper for signage out of structural foam for both the 8100 and 9100 Series ATMs, which are standalone units for retail establishments. Mack also molds the control panel and trim for the RT 2000, an external, 24-hour through-the-wall ATM for merchants.
Contacts: Steve Langen, Mack Program Manager
Ken Kincaid, Mack Technical Engineering Manager
Steve Ham, Cinpres Application Engineer
Triton is a leading manufacturer of ATMs and ATM management software with more than 135,000 installations in over 23 countries worldwide. Markets include financial institutions, convenience stores, airports, hotels, resorts, restaurants, shopping centers, casinos and many other non-traditional locations. For more information, visit www.tritonatm.com.
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