A Numerical and Experimental Investigation into the Manufacturing Process of an Inconel 600 Superalloy Shell for Aerospace Ignition Systems

Jet engine spark plugs, which consist of a metal body, insulator, electrode, and adhesive, initiate combustion through an intermittent spark. This research focuses on the production of the plug's metal shell for the aircraft engine, which was specifically fabricated from the nickel-based superalloy Inconel 600. The manufacturing process was preceded by a numerical simulation in Abaqus to analyze the heat and stress distribution within the spark plug. The spark plug body was then fabricated through sequential CNC turning and electrical discharge machining (EDM) processes. The manufactured sample was evaluated for dimensional accuracy and quality through surface roughness measurement, SEM microstructure analysis, and hardness testing. The minimum achievable surface roughness was attained using distinct optimal parameters for each process. CNC machining required a feed rate of 0.06 mm/rev and a cutting speed of 60 m/min, whereas EDM required a pulse-on time of 5 μs, a pulse-off time of 4 μs, an electric current of 8 A, and purified dielectric fluid. The optimization of EDM parameters, notably a shorter pulse-on time and dielectric purification, successfully mitigated microstructural defects like globules, microcracks, and coarse carbides, thereby producing an excellent surface finish. The spark plug fabricated via CNC and EDM machining exhibits density and hardness values equivalent to those of the original Phantom F-5 spark plug.