Inviting researchers to resolve the weak link in 3D printing

February 2018

The federal government has put out a call for researchers to work on a major problem in additive manufacturing, a technology that is quickly changing the way various industries turn out metal parts. For specific applications, this new process, popularly known as “3D printing”, replaces the traditional casting of liquid metal in molds with computer-controlled use of metal powders, which are deposited in thin layers and individually welded with laser beams to build a component up from scratch.

The resulting product can be as strong as its traditionally cast equivalent, but it can also be lighter, easier to make, or have a more complex design. However, quality assurance and low production rates are still problematic, with a key point of control being the quality of the powder. More specifically, while features such as the flowability and density of metal powders are readily determined, it remains impossible to check how the powder is performing as each layer is placed during additive manufacturing.

That information is crucial to Canadian-based metal powder producers who export into a global market that should grow rapidly as additive manufacturing becomes more widespread. Researchers at the National Research Council of Canada (NRC) have been working with these companies to help them analyze how modifying the characteristics of their feedstocks might decrease or eliminate faults in a finished component while increasing production rate.

“It comes down to measuring much more closely the density of the powder layers to have better control on the deposition of powder during 3D printing operation,” explains Milena Sejnoha, Director of research on materials and processes in the NRC’s Automotive and Surface Transportation (AST) Research Centre in Boucherville, Quebec, which serves also aerospace, defence, and construction sectors. “If Canadian suppliers can contribute to a more instrumented approach, it would contribute to the whole field of additive manufacturing.”

Building and designing such equipment has therefore become one of the latest “challenges” posed by Innovative Solutions Canada, a program from Innovation, Science and Economic Development Canada that was launched with the last federal budget. In this case, the NRC is participating as a sponsor for the challenge, which offers prospective participants up to $500,000 to work with Sejnoha and her colleagues on developing a system for determining the density of each additive powder layer in real time.

Her group is collaborating with another NRC AST Research Centre’s facility in London, Ontario, where research director David Muir has witnessed the appetite for additive manufacturing among that region’s many industrial parts producers.

“There is a huge, growing opportunity out there,” he explains. “Additive manufacturing offers a number of benefits to industry and society as a whole.”

Those benefits start with reducing the time and cost of turning out strong, light components from new materials, which has a wider impact on considerations such as energy use, pollution, and greenhouse gases. The prospect of having unprecedented control over the structure of finished components has been especially appealing in aerospace manufacturing, which is consumed by a desire to maximize strength and minimize weight. GE Aviation recently fulfilled that desire with a new turboprop engine containing some 15% fewer working parts than its predecessors, thanks to 3D-printed components that could not have been built in any other way.

GE Aviation recently launched its Advanced Turboprop engine, made from 3D printed components that would have been too intricate to produce in any other way.

GE Aviation recently launched its Advanced Turboprop engine, made from 3D printed components that would have been too intricate to produce in any other way. Photo credit: GE Aviation

Such dramatic progress is still expensive, largely because of the need to ensure the quality of the final product. If the challenge posed by the NRC can be met, however, it would eliminate one of the most elusive aspects of meeting that need, which starts with the quality of the metal powder input.

“We’ve got 100-plus years of experience in metallurgy by conventional means,” Muir concludes. “This new technology will help us look at how the powder affects the final part quality and the process itself.”