An In-Situ Eddy Current Diagnostic for Temperature Monitoring in Metal Additive Manufacturing

We propose a novel, non-contact diagnostic for monitoring of sub-surface temperature in metal additive manufacturing (AM) using an eddy current (EC) system. An EC probe produces time-varying magnetic fields, that induce eddy currents in the sub-surface of a metal AM part. Variations in sub-surface temperatures lead to perturbation of the flow of the induced eddy currents and hence appear as localized magnetic anomalies. A controlled heat source is used to heat the metal surface, while the EC probe monitors the temperature from the opposite surface in a non-contact manner. The overall EC physics, a finite-element based numerical model and preliminary temperature monitoring experiments are presented.