Boeing and ORNL Collaborate on Massive Metal Mould Using Wire-Arc Additive Manufacturing
Oak Ridge National Laboratory (ORNL) and Boeing have collaborated on an innovative project to create a massive metal mould using wire-arc additive manufacturing (WAAM). The result is a 2-ton Stamp Form Die (SFD) mould, measuring 6 feet by 4 feet, printed in steel. This enormous tool will be used in NASA's Hi-Rate Composite Aircraft Manufacturing (HiCAM) project to increase the production rate of composite aircraft parts.
The Boeing SFD mould was designed for the manufacture of thermoplastic aircraft doors. Traditionally, these moulds are produced through machining, casting, forging, and drilling. However, the team at ORNL and Boeing wanted to explore whether 3D printing could be a faster, less costly alternative.
ORNL's Arc-1 WAAM system was used to print the massive tool. This robotic system melts wire and builds metal parts layer by layer, allowing for multi-material printing with greater design flexibility. The mould combines mild steel in structural regions for strength and stiffness with stainless steel on the surface for corrosion resistance and dimensional stability.
The biggest challenge of applying 3D printing was warping due to residual stresses as the deposited metal cooled. To minimize this issue, temporary ribs were added to the back of the mould, and computer simulations were used to refine the design. After 32 simulation iterations, a mould within a few millimeters of the intended shape was produced.
The SFD mould was sent to Baker Industries in Michigan for annealing to remove internal stress and then finished with remaining fabrication operations to meet Boeing's requirements.