Norsk Titanium (client registration required) recently announced that Boeing has ordered titanium structural components for the 787 made using Norsk’s additive manufacturing process. Norsk received FAA approval for the components in question in February 2017 after more than a year of testing by Boeing. Its printing process, Rapid Plasma Deposition (RPD), combines additive and subtractive steps: first building up a part using plasma arc deposition from a wire feedstock, then CNC machining the part to the final specifications. Compared to conventional titanium manufacturing, the RPD process can reduce cost by up to 70%, primarily from its comparatively low buy-to-fly ratio of 1.5:1. At the same time, compared to powder-based 3D printing processes (which can sometimes achieve even lower 1.1:1 buy-to-fly ratios), RPD is faster and can produce larger parts, up to 2 m across. Other wire-based metal 3D printers, such as those from Sciaky, achieve similar speed and part size to RPD but do not incorporate subtractive machining in a single production tool. To meet the increased production demand from Boeing’s purchase order, Norsk plans to move production from Norway to a facility in Plattsburgh, NY, which will have nine printers operating by the end of 2017. Ultimately, the company claims it will be producing several tons of titanium components for each 787, which would reduce the Boeing’s material cost per plane by as much as $2 million to $3 million.
While 3D printing has been extensively used in aircraft for years for nonstructural polymer parts and some metal 3D printed functional parts, such as GE’s LEAP engine fuel nozzles (client registration required), this announcement is the first use of printed metal structural parts in a commercial aircraft. Norsk Titanium aims to build on its recent success to achieve FAA approval for its RPD process, certifying that RPD in general can produce materials and parts with certain minimum performance characteristics. Such approval would make it much easier to begin printing additional components in the future without having to go through the same extensive testing process each time.
Norsk Titanium and Boeing’s announcement also highlights the ongoing maturation of metal 3D printing, as companies and organizations like the American Society for Testing and Materials (ASTM), America Makes, the American National Standards Institute (ANSI), and Lawrence Livermore National Laboratory’s Accelerated Certification of Additively Manufactured Metals project (LLNL ACAMM) aim to develop material and process standards that will enable them to guarantee an adequate level of quality that is currently still difficult to achieve for most users. The U.S. Federal Aviation Administration (FAA) itself has highlighted this challenge, noting that while some metal additive manufacturing systems match or exceed the performance of cast or wrought counterparts, there are over 100 adjustable process parameters. The effects of varying those parameters remain poorly understood and hard to predict, as is the extent of part-to-part and printer-to-printer variation with the same nominal parameters.
As new standards are developed, the FAA will be able to develop a more effective additive manufacturing regulatory framework the way it has for traditional manufacturing methods. Currently, for example, Boeing has only two approved suppliers for Electron Beam Melting (EBM) printed metal parts. One of those two is Addaero Manufacturing (client registration required), a printed part manufacturer founded by former Pratt and Whitney employees with a similar strong focus on having a consistent, reliable process to hit aerospace OEM specifications. Readers should expect that in the next few years, better open standards will enable other companies to adopt metal printing for their own purposes without the extensive testing timelines and budgets that aerospace can devote to part development.
By: Anthony Vicari