CompositesWorld
Issue link: https://cw.epubxp.com/i/532917
JULY 2015 28 CompositesWorld FEATURE / MOLDMAKING TECHNOLOGY The right tools for aircraft repair AM is signifcantly useful in aircraft repair and maintenance. Cottrell notes that AM technology has become invaluable for repair of legacy aircraft for which OEM spares are no longer avail- able. Te U.S. Department of Defense (DoD), for example, operates several repair depots around the US, and elsewhere in the world, to keep aging defense aircraft fying. Te Fleet Readiness Centers (FRC) of the US Naval Air Systems Command (NAVAIR) use AM tooling to mint spare parts that are otherwise hard to come by or are simply no longer available, says Robert "Yogi" Kestler, Science & Technology (S&T;) lead at FRC East located at Cherry Point, NC, US. FRC East is the maintenance, repair and overhaul center for all US Navy and Marine Corps vertical-lift aircraft. "Composites are a big part of what we do, day to day, and it's growing as older, metal-centric aircraft are retired," adds Robert Tompson, a materials engineer at Cherry Point. Douglas Greenwood, an aerospace engineer at the center, says that a typical legacy composite repair project used to require manual methods to capture part geometry, replicating those part features with a low-temperature fberglass splash, then making a reverse mold followed by a production tool for part layup. But, AM and digital tools are transforming that process. Today, a 3D scan captures part surfaces, either with a contact device like a FARO Arm (FARO, Lake Mary, FL, US) or noncontact laser scanning, and the scanned data are converted into a solid CAD model. From there, the data can be fed to a 3D printer to quickly make the tooling for a replacement part. Greenwood and Tompson say the group obtained its frst 3D printer in 2006, and began to investigate making parts for "ft and form" applications, that is, validating CAD fle information to ensure a part would ft properly, before undertaking conventional CNC machining and/or mold production. Later, in 2010, the group began more serious experiments, including direct 3D-printed tooling. Across the three industrial FRC installations, NAVAIR operates nine 3D printers, employing FDM and three other types: jetted binder, stereolithography (SLA) and selective laser sintering (SLS) technologies. Says Kestler, "Our AM eforts for composite tooling are still in their infancy, right now, but we're very inter- ested in moving forward." Greenwood echoes previously noted concerns about managing CTE issues and fnding AM materials able to withstand autoclave conditions. Given that, FRC East currently prefers the approach of using AM to print a master pattern with FDM polycarbonate, then Walton Process Technologies, Inc. Best Customer Service in The Industry www.autoclaves.com Mansfield TX 682-518-9002 Service/Repair Retrofit/Relocate Autoclaves Bond Presses Batch Process Controls Ovens Parts AM tooling is proving to be a cost-efective resource for molding replacement parts on aging DoD aircraft.