Dr. Mohammad Mahtabi is an assistant professor of mechanical engineering in the UTC College of Engineering and Computer Science. Photo by Angela Foster.
To say that injection molding is common in the world of manufacturing is underselling it.
Injection molding is everywhere in manufacturing.
Making the molds—used to manufacture multiple automobile parts, milk jugs, flexible pipes, plastic gas cans and thousands of other products—is mostly done in China, is expensive and can take months to finish.
Research now taking place at the University of Tennessee at Chattanooga is intended to reduce cost by 90% and reduce the time to finish the molds to about two weeks, enhancing U.S. manufacturing competitiveness.
“Basically, we are trying to make what is being now made but with a different approach,” said Dr. Mohammad Mahtabi, assistant professor of mechanical engineering in the UTC College of Engineering and Computer Science and lead researcher on the project.
Dr. Erkan Kaplanoglu, interim head of the Department of Engineering Management and Technology, director of the Biomechatronic and Assistive Technology Lab and an associate professor of mechatronics, was co-principal investigator of the project.
A $105,000 grant from the REvV! program at Oak Ridge National Laboratory started the research in September. UTC received $70,000 and $35,000 went to STRACT Corp., a company co-founded by Chantz Yanagida, who received a mechanical engineering degree from UTC in 2019.
The research process involves 3D printing, which uses a blend of metals to create a special alloy, chemical solutions, electricity and specific temperatures to produce physical objects.
“No one has done that,” Mahtabi said. “There is a lot of trial-and-error. A lot of factors are involved in such a process.”
Injection molds are created by fusing together pieces—known as “die plates”—to create the shape of the part needed, be it a car’s interior door handle or a Lego toy. Under heat and intense pressure, whatever material is used to make the part is injected into the mold.
As it is now, preparing die plates for injection requires extensive hand polishing to make their surfaces completely smooth. It’s the most expensive and time-consuming part of the process, Yanagida said.
“It’s not the actual making of the plates, it’s the polishing,” Yanagida explained. “You have to spend hundreds and hundreds of hours hand polishing these plates to get them to the right surface finish.”
The UTC research team is testing how to make die plates immediately ready to use without polishing. STRACT is providing 3D-printed plates for testing in the project.
“We have files for injection molding plates that we’ll be printing to supply Dr. Mahtabi with test samples for his research,” Yanagida said.
Mahtabi said the ORNL grant, which funds the project through September 2024, is not expected to produce an end product. He said that more funding, perhaps a grant from the National Science Foundation, will be needed to continue.
“More money—significantly more,” he said, “will be needed to take this into production level.”
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