Additive Manufacturing for Rapid Spares Replacement: AM Assisted Casting vs Direct Metal Printing

Longer than expected aircraft life cycles, corrosion, fatigue, and other related issues have led to the need for a number of replacement parts. Aircrafts on Ground (AoGs) situations while waiting for spare parts negatively impact fleet readiness for our armed forces. In many cases original part tooling is no longer available, further exacerbating the lead time and availability of spares. Disruptive Additive Manufacturing technologies in both the direct printing of metallic parts and the indirect printing of patterns for castings are now available and can be used to significantly reduce lead times for these critical components; with demonstrated lead time reduction from years to weeks.

This project demonstrated a significant lead time reduction in the design and manufacturing of F/A-18 C/D Gun Bay Door Louver spare parts, using both direct Additive Manufacturing (AM) and indirect AM Assisted Investment Casting methods. With both methods demonstrated, future spares efforts will be able to make use of the data obtained as well as the proven success of the manufacturing methods in order to meet part lead time requirements. For direct printing, an aluminum Laser Powder Bed Fusion (LPBF) machine was used. For indirect manufacturing, a Binderjet AM machine was used to produce the PMMA patterns for an aluminum investment casting.

Using AM for large, thin-walled, aluminum casting replacements without significant redesign has only recently become a possibility. Today, aluminum powder bed machines are available that can accommodate this large part for direct printing, and AM can assist in the investment casting process, due to advances in polymer pattern printing that have made thin wall patterns possible without the risk of cracking the ceramic shell.

In this presentation, we share cost and quality comparisons between these two additive manufacturing technology demonstrators, and how these lessons learned are being applied for current spares needs.