Capacitive Imaging applied for In-Situ Powder Topographic Characterization during Powder Bed Fusion

Capacitive imaging is proposed for topographic characterization of the surface of successive powder layers during powder bedfusion additive manufacturing. This capability enables new opportunities for early detection and, ultimately, prevention of defectiveconditions by using extensive capacitive sensor arrays integrated into the recoater unit. Finite element modeling was used to simulateindividual capacitive sensors in order to identify a suitable geometry for implementation in an array. A 12 sensors array wasdesigned and demonstrated while integrated with compact readout electronics instrumentation. Surface topographic irregularitieswere simulated by confining SS316 powder against a thin glass cylinder, on which various plastic structures were fabricated. Thesensors and associated electronics demonstrated the ability to detect cylindrical and linear voids with radii/widths as small as0.55 mm and depths of 0.1 mm.