June 8, 2017
GKN Aerospace and the U.S. Energy Department's Oak Ridge National Laboratory have signed a five-year research agreement focused on additive manufacturing (AM). Under the agreement, GKN is developing a large-scale AM process that could significantly improve the manufacture of large titanium aerospace components.
The process is called laser metal deposition with wire, or LMD-w. It uses a robot-mounted laser to melt the surface of a titanium substrate, creating a localized pool of molten titanium into which titanium wire is fed to form a bead. Advanced robotic controls manipulate this melt pool along a 3D path to fabricate a large near-net or net-shaped aerospace preform bead by bead as defined by a computer-assisted design (CAD) model.
Josh Crews, GKN's technology center manager for additive manufacturing in St. Louis, says LMD-w offers several advantages over other deposition processes through manipulation of widely tunable laser-energy and wire-feed rates. "These features enable a user-selectable deposition rate and control of material properties," he says. In addition, wire feedstock used in LMD-w is completely consumed in the melt pool. Powder-based deposition typically has powder incompletely consumed in the melt pool.
Current subtractive-manufacturing processes for these components use only a fraction of raw materials, leaving the rest as scrap. LMD-w can reduce costs by eliminating material waste. As an additive process, LMD-w puts material only where needed, reducing scrap generated by machining. LMD-w also enables designs not possible in subtractive processes.
"In the near future, additive manufacturing aims to extend beyond fabrication of preforms by unlocking new materials and design potential for future aircraft designs," says Project Manager Chris Allison, Crews' colleague. "These designs will enable lighter-weight, higher-performance aircraft."