Additive manufacturing moves into the mainstream

When design, manufacturing, and technology meet, the result is something straight out of a science fiction novel – a ready-to-use final product moving from the lab to assembly almost instantly.

Three-dimensional printing has been a viable option for prototypes for many years, but thanks to advancements in machinery and materials, some products can be made ready for immediate use. What took months to design and produce using traditional manufacturing and assembly methods is now less expensive, and can take less than half the time to produce.
 

Efficiency-driven benefits

Improved efficiencies are especially important in aerospace. Bell Helicopter began using 3D printing, also known as additive manufacturing (AM), in the early 1990s for engineering test parts and prototypes. It adapted AM for production parts in 2007.

“With the advancement of the technology, Bell engineers are able to innovate and integrate more easily and on the spot,” states Dr. Cathy Ferrie, senior vice president of engineering at Bell Helicopter. “We’re using 3D printing for a number of items, including some spare parts, especially parts that normally have long lead times if ordered and manufactured using more traditional methods. The parts are produced faster, with equal to better detail, and at a greater savings.”

For years, engineers at Bell Helicopter’s XworX facility in Arlington, Texas, have been using laser sintering (LS), stereolithography (SL), and fused deposition modeling (FDM) equipment to fabricate prototypes, create part models that check fit, build conceptual models, and create temporary tooling. In 2006, significant advancements in LS thermal controls and the release of a new nylon powder with improved mechanical properties allowed Bell Helicopter engineers to begin the process of evaluating, and qualifying, AM for production.

Bell Helicopter was the first aerospace company to approve a new nylon material for the production of flight worthy parts using the AM processes, receiving the first production parts in July 2007. Today, Bell Helicopter uses additive manufacturing for final products for three of its aircraft – the Bell 429, Bell 412, and Bell 525 Relentless, the world’s first commercial fly-by-wire helicopter.

For the Bell 429, AM is instrumental in producing the aircraft’s environmental control system ducting – the system that directs airflow through the aircraft. For the Bell 412, it’s used for the defog system. The newly designed Bell 525 Relentless uses AM parts both in the environmental control system ducting and the wiring conduits. The parts range from as small as 3" x 2" x 1" up to 7" x 10" x 18".
 

Excellence in design

To design and produce final products, such as environmental control system ducting, Bell’s engineers use a CAD-optimization program, CATIA, which uploads to the AM system. Depending on the process, the additive machine creates several layers of material and then a laser or electron beam (EB), following the design's intricate details, shapes and essentially grows the desired geometry. The printer is made by 3D Systems and EOS. Within a couple of days, engineers have a hardened, strong duct printed in one piece rather than several separate parts that then must be assembled.

“The process is truly amazing,” Ferrie says. “The part accuracy is comparable to traditional manufactured thermoplastic parts like blow molding and rotational molding.”

Bell initially focused on nonstructural thermoplastic parts and nonmetallic spare parts, but recently has qualified EB for metal. The 3D printing process is ideal for certain composites and injection molding applications, metallic castings, some machined parts, customized interior parts, and legacy plastic metal parts. Because 3D printing allows for replication on the spot, Bell and other companies can forgo long lead times and large minimum purchases, saving time and money. According to Ferrie, the savings from using additive manufacturing in place of traditional methods varies but can range from 30% all the way to 80%.
 

Collaboration throughout the business

Bell Helicopter is so pleased with the benefits of 3D printing that its Canadian subsidiary (BHTCL) – together with its partners in the Consortium for Research and Innovation in Aerospace in Quebec (CRIAQ) – is exploring the possibility of creating a local supply chain of AM parts. The result will be a world-class supply base in Quebec. Along with Bombardier and Pratt & Whitney, Bell Helicopter recently signed an agreement with CRIAQ, which will initially prepare an inventory of available additive manufacturing resources in the Montreal area. These proposals were done in close collaboration with Bell Helicopter engineers in Ft. Worth.

“The goal is to ensure additive manufacturing is a collaborative effort across the entire business,” Ferrie says. “In the end, we all benefit, especially our customers.”

Bell Helicopter
www.bellhelicopter.com

About the authors: Kathleen Oldham is head of Bell Helicopter's manufacturing R&D laboratory. Chris Gravelle represents the engineering group. Both can be contacted via Brian Bianco, communications manager, at bbianco@bh.com or 817.280.4588.