A truly hybrid laser AM part for space exploration

Abstract

Additive Manufacturing (3D printing) is now an accepted form of manufacturing for a range of applications but in particular, laser AM for space exploration has become an exciting application. Additive processes including EBAM (Electron Beam Additive Manufacturing), WAAM (Wire Arc Additive Manufacturing) and laser hybrid arc have been demonstrated for fuel tanks, barrels and other structures but to really explore our solar system and beyond, we need to focus on better ways to print propulsion devices for launch vehicles. Laser powder bed fusion (also called Laser Metal Fusion – LMF) and laser DED (also called Laser Metal Deposition - LMD) are the tools to help us achieve these lofty goals. A method combining both LMF and LMD to create an additively manufactured rocket engine injector and nozzle, (example of a complicated propulsion device), was taken on by TRUMPF’s laser application lab in Plymouth, MI. We started this project work off with an injector designed to be printed in GR Cop 42, a copper alloy developed by NASA, that provides improved thermal conductivity with printability in laser metal fusion powder bed machines. A green laser optic was used for this powder bed process. We then utilized laser metal deposition process to print a wide-bell-shaped nozzle for the exhaust gases. The advantage of combining both processes gave us the intricate cooling channel design for fluid flow inside the injector chamber, along with thin wall features. The freeform nature of laser metal deposition allows a wide flared bell shape to be printed without the constraints of a powder bed.