Tick Tick Boom: Engineering alumni use 3D printer to make explosives

Though the Chattanooga-based consulting firm E&G Associates may only have a few employees, the consulting firm is already solving problems from some of the biggest companies in the manufacturing and pharmaceutical space. Now they’re taking on one of their biggest challenges: helping the U.S. Navy use 3D printing to make explosives.

E&G Associates offers engineering consulting for bulk solids processing industries. What are bulk solids? Think coffee beans. Millions and millions of coffee beans. One of E&G Associates clients is a large coffee manufacturer who needed to move beans from 1,500-square-foot silos to small, individual cans. The E&G team created a system to help the manufacturer distribute the coffee beans more evenly and efficiently.

Founded by Dr. Bryan Ennis, former UTC associate professor of civil and chemical engineering, E&G Associates employs Ennis’ two sons, Benjamin and Brandon, along with Naseem Jibrin and Michael Winn. The group are all are recent graduates of the UTC College of Computer Science and Engineering. With multiple degrees in chemical and mechanical engineering between them, the group felt prepared to work with big-name clients.

“I thought the engineering program at UTC was fantastic. I learned a lot. It’s a smaller program, but I don’t feel that I left there lacking,” Brandon Ennis said.

Though Ennis didn’t have much experience in working with solids processing before he graduated, he felt ready to take on the challenge.

“If you believe that you are taught well and apply yourself, you may not get it right, but you just have to say, ‘I just spent four years learning this. Let me go out and actually apply what I’ve been taught,’” he said. “And if you have the confidence to do that, I think it’s a pretty easy transition for students to make.”

E&G Associates is moving from coffee beans to plastic explosives after receiving a $150,000 federal grant from the Small Business Innovation Research program. The group is currently researching methods to print explosives of various shapes and sizes using a Hewlett-Packard 3D printer. Using a technique called “powdered bed fusion,” the group is testing various materials such as nylon powder infused with explosive material, polymer additives and printer ink to create an explosive.

“The printer spreads the nylon powder and then prints on that flat layer of powder with the ink. Then the printer passes a heat lamp back and forth to make the dark areas melt. And that’s how you get your parts,” Jibrin explained. “The process is repeated in three steps. Spread a layer, ink the specific selected areas and fuse with heat lamps. You do that over and over again until you build a part.”

The Navy was specific in wanting to use a commercially available 3D printer. “It’s a lot of development effort to try to come up with a machine or printer. They want to be able to take the technologies that are already available,” Benjamin Ennis said. “Instead inserting a spool of nylon into the printer like with traditional 3D printing, they want to insert spool of explosive material.”

With an office located on Chattanooga’s busy North Shore, the group can’t test their 3D-printed explosives themselves. They’ve partnered with the explosives engineering department at the Missouri University of Science and Technology (MST) to use their facilities.

MST’s Energetics Research Facility houses two blast chambers, safety and handling test equipment and several measurement devices. E&G Associates has happily made several visits, looking forward to the day where they can safely detonate their 3D-printed explosive.

“We’ll test in a chamber that’s basically a giant metal tube. It’s about eight feet high with inch-thick walls,” Benjamin Ennis said.

“With a bunch of high-speed cameras to capture everything,” Brandon Ennis chimed in.

“Hearing protection required,” Michael Winn said.

“Oh yeah, it’s going to get wild,” Jibrin said as the group laughed.