Improving Manufacturing Readiness of Additive Friction Stir Deposition for Ferrous and Nickel-based Materials

Additive friction stir deposition (AFSD) is a near net shape, solid-state additive process capable of printing numerous metals at high deposition rates. While AFSD has seen increasing success at printing titanium and aluminum alloys of varying alloys, printing of ferrous and nickel-based products has lagged in the development due to complexities associated with tooling. Traditionally, these materials would use super-abrasive tools like poly crystalline cubic boron nitride (PCBN); however, the heat and stress associated with the process has significantly limited tool life in previous studies. Using a modified liquid-cooled tool holder often deployed for high temperature friction stir welding, improvements were made in cooling systems of a MELD L-3, 3-axis, discrete feed AFSD machine. Measurements of the cooling changes were quantified to understand the magnitude of the changes on cooling the tool, spindle and the print deck. Furthermore, the addition of the liquid-cooled tool holder enabled the cooling system to undergo additional changes that allowed greater flow of cooling water, which further enabled long-term printing of these high melting temperature materials, both from a tool life and machine perspective. A detailed layout of the tool-holder integration, novel PCBN tooling, and printing of 316L stainless steel is presented as a means of quantifying and demonstrating the value of the machine and tool updates.