Novel Process Approach for Additive Manufacturing Using Inductive Wire Melting by Forced Droplet Detachment

Abstract

To date, no AM technology for large-volume metallic components has been established on an industrial scale like Laser Powder Bed Fusion (LPBF). This contribution presents a new process approach to fabricate larger metallic structures from steel by inductive melting of a continuously fed wire. The presented method is characterized by the comparatively low energy input in contrast to comparable processes for AM, such as arc, laser, or electron beam. Previously published work is based on the principle of a melt reservoir of low-melting alloys and droplet delivery using gas pressure or vibration. In contrast, the approach described here is to transfer the material directly from the end of the wire to the substrate by continuous drop deposition. However, to avoid a stochastic material transition, a suitable process strategy has to be chosen. This challenge is met by a pulsed coil current and the resulting periodically varying Lorentz forces in order to achieve regular and forced droplet detachment. Tests confirm the principle of controlled droplet detachment and reveal the great potential of this technological approach.