Approximately one year ago, RJay Matkin walked the PTXPO show as an attendee, taking in the exhibits, including Sodick Plustech’s. There a machine ran Matrix Tool’s entry into the first ever Hot Shots injection molded part contest — a showcase part that would would earn Matrix both the competition’s awards — Technical Sophistication and Achievement in Molding Efficiency/Economics.

In March 2023, Matkin, director of molding operations at Ultradent Products Inc. (South Jordan, Utah) was once again attending PTXPO and once again checking out the exhibits, but there was another reason Matkin was at the show: to support Ultradent’s entry into this year’s Hot Shots competition — the Umbrella cheek retractor — which was one of six finalists being judged by fellow molders.

“I remember the Hot Shots competition and attended PTXPO last year,” Matkin says. “When Plastics Technology sent an e-mail about the Hot Shots competition this year I thought about some of our more complex processes and part designs, and I picked our Umbrella.” Matkin notes the the 2K part is just one of the challenging components Ultradent makes that defy traditional plastic molding. Just like Matrix Tool, Ultradent’s part would also sweep the competition winning both awards for the maker of dental materials, devices and instruments.

New 2K Design

When it was first imagined, the winning part was designed for a single-cavity, hand-loaded process, where the substrate was molded on one machine, then tool and material were switched to overmold the second shot. “It was very, very labor intensive,” Matkin says, with the earlier design utilizing two single-cavity molds — one to mold the frame and the other to hand load the frame and overmold the second shot.

The new Hot Shots winning design switched to a tool with complex cavities and cores, including an ejector plate that must hold and rotate the substrate for overmolding The two-component part is molded by Ultradent on a 350-ton Arburg press with a secondary E-Multi injection unit from Mold-Masters. The part, which is designed to hold a patient’s mouth open comfortably, features several thin-to-thick sections, with the soft bumpers around the frame made of Versaflex PP over molded using the E-Multi auxiliary injection unit and six different valve gates in various locations. “The mold’s really complex,” Matkin says. “There are a lot of different shutoffs, which represented another challenge with the project that was difficult to overcome.”

By switching up the design, Ultradent saw a boost in productivity, with a 75% increase in cavitation in the two-shot tool. Cycle time was greatly reduced, going from two-and-a-half minutes per part to 33 seconds for four parts, with significant labor savings as well, since the hand-load single operator step was eliminated. The new design also reduced scrap by 50%. In the past, if the over molding process was done incorrectly, the part was not only scrapped but it required an all new frame to be molded.

In the end, Matkin, along with Michael Card, Ultradent’s technical molding manager, and Royce Castleberry, molding manager, had two awards to take home from Chicago, in addition to the submitted parts, beating out some stiff competition. “There was incredible competition, incredible parts, we were going against,” Matkin says. “They had us really nervous about the competition. I knew our part was complex, but I’ve been in injection molding for many years, same as my colleagues, and I grew up reading Plastics Technology. I never really imagined ourselves being involved in the Hot Shots competition and winning this.”