With commercially available high-end equipment and specially modified versions of low-cost 3-D printers, Raytheon researchers have created nearly every component of a guided weapon using 3-D printing, including rocket engines, fins, parts for the guidance and control systems, and more.

“Ensuring consistent production integrity will be part of the next steps to realize this vision,” said Dr. Teresa Clement, a Raytheon materials expert who also serves as the chair of the executive committee of America Makes, an initiative of the National Additive Manufacturing Innovation Institute.

3-D printing could someday streamline the manufacturing process, said Leah Hull, additive manufacturing manager for Raytheon.

“When we print something, we have fewer piece parts, so your supply chain becomes simpler,” Hull said. “Your development cycles are shorter; you’re getting parts much faster. You can get a lot more complex with your design because [you can design] angles you can’t machine into metal.”

Engineers at the Raytheon University of Massachusetts Lowell Research Institute are developing ways to print complex electronic circuits and microwave components – building blocks of sophisticated radars used in products like Raytheon’s Patriot air and missile defense system.

The current method of building microscopic circuits involves removing material to create a circuit pathway. In contrast, 3-D printing lays down just the material needed to build the electronic pathway.

“The word ‘printing’ implies lower cost,” said Chris McCarroll, Raytheon director for the institute. “It’s additive manufacturing. When we make integrated circuits [now], it’s all subtractive. We put down very expensive materials and wash away everything we don’t need.”

Circuits can already be printed with inkjet printers. The goal is to print more complicated circuits in three dimensions, with the very high resolution and performance of silicon, he said.

“There’s currently a hierarchy in our manufacturing. We make the structures, the housings, the circuit cards, with the right materials, and then we integrate them into a system,” said McCarroll. “What we see in the near future is printing the electronics and printing the structures, but still integrating. Eventually, we want to print everything together. An integrated system.”

Engineers at the research institute are already able to lay down the conductors and dielectrics needed for printed electronics. They can even lay down carbon nanotubes, tiny structures made of linked carbon atoms, and are working to align them to build futuristic circuits, according to McCarroll.

So could soldiers someday print and assemble missiles on the spot, in the same way that artillery crews custom-load their rounds or weapons handlers mount guidance kits on some types of bombs? McCarroll said that's still a ways off.

“Before a warfighter can print a missile in the field,” he said, “you need quality, controlled processes to fabricate all the component materials: the metallic strongbacks, and the plastic connectors, the semiconductors for processors, and the energetics and propulsion systems. The hard part is then making the connections between these components, as an example, the integrated control circuit that receives the command to light the fuse. At some relatively near-term point you may have to place chips down and interconnect them with printing. Or, in the future, maybe you’ll just print them.”

Yet as clear as the challenges are, so is the promise. “There are folks in industry printing warheads,” said Danforth. “We are printing demos of many of the seeker components. And we demonstrated a printed rocket motor. We’ve already printed 80 percent of what would go into a missile.”