Meeting Tough Specifications

Boeing has been conducting R&D in additive manufacturing since 1997. It currently uses 3-D-printed parts made from various materials on 10 different military and commercial aircraft production programs.

“3-D printing offers great potential to reduce the cost and weight of aircraft structures and to improve the ability of engineers to design parts purely for their eventual function in a vehicle system,” says Dr. Leo Christodoulou, Boeing materials & manufacturing chief engineer. “It enables the design and production of integral structures, converting an assembly and several structures into one piece.”

Boeing suppliers are using selective laser sintering to make small reinforced polymer parts for environment control system ducts (ECS) for both military and commercial aircraft. Additive manufacturing is now a qualified process at the company for the all-composite, all-electric 702SP (small platform) satellite. “Additive manufacturing provides a mass or cost advantage over conventional fabrication processes for these particular parts on these products,” says Christodoulou.

While 3-D printing composite parts offers many possibilities, there are still challenges in the broader ecosystem of 3-D printing that have to be overcome, says Christodoulou. These include design engineering training and guidelines, maturation of user-friendly software, control over material properties and accuracy, specifications and the certification of parts. The volume and rate at which 3-D parts can be produced must be improved as well.

One key requirement for the aircraft company’s wider adoption of the technology is stabilization of the 3-D printing processes and qualification of the components it produces to Boeing’s exacting standards. “We are deliberate and thoughtful about the introduction of additive manufacturing parts and have a rigorous process for qualification,” says Christodoulou.

The Potential is Great

Perhaps the biggest hurdle to additive manufacturing is that it’s more expensive than traditional composites manufacturing, but that’s likely to change.

“I believe that today the cost is artificially high, but once it starts to get market priced there is no inherent factor that contributes to cost other than the speed,” Bheda says. “So once we solve the speed problem, there is no reason why additive manufacturing ought to be any more expensive than any other process. As a matter of fact, you can argue that it ought to be lower cost because you eliminate the cost of tooling.” The process also dramatically reduces material waste and is more energy efficient than other production methods.

The cost-effectiveness of additive manufacturing depends on the shape of the part, says Ben Dietsch, president of Nona Composites. “It’s more affordable to machine something that is a fairly simple shape, but once the complexity and the depth of the part start to increase, that’s where you see more affordability from a 3-D-printed tool.”