CASE STUDIES
Mack Molding
The Mack Molding industrial computer business case studies shown below represents only one example of Mack Molding’s manufacturing services for the computer & business equipment market . It is not intended to provide a comprehensive listing of Mack Molding’s involvement in any industry.
ATM Machine
A leading provider of off-premise ATMs, and Mack Molding 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, the customer 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 was 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, the customer used the structural foam process to obtain the impact and stiffness its ATM panels required. But with a goal of further lowering cost, Mack Molding recommended the external gas process, which it licensed from CGI. Mack Molding 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.
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. 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. With internal gas assist, Mack Molding 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. Mack Molding was 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
With external gas, the customer can produce a large cosmetic part that is structurally strong at a lower cost. Mack Molding was able to use larger rib-to-wall ratios with external gas, so the customer is 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.
In addition to trusting Mack Molding’s advice based on their existing working relationship, cost played a major factor. In a mature market, price needs constant attention, and the customer was looking to cut costs. Additionally, Mack Molding partnered with them on investing in the new technology. realizing it would benefit both organization. In short, Mack Molding is a partner in our customer’s businesses.
For more information about this or other Mack Molding industrial computer business case studies, contact sales.south@mackmolding.com.
