Controlling grain structure in metallic additive manufacturing using a versatile, inexpensive process control system

Additive manufacturing (AM), commonly termed 3D printing, is a revolutionary manufacturing technology with great industrial relevance in the aerospace, medical and automotive sectors. Metallic AM allows creation of complex intricate parts and repair of large components; however, certification is currently a concern due to lack of process consistency. A versatile, inexpensive process control system was developed and integrated, reducing variability in melt pool fluctuation and improving microstructural homogeneity of components. Remnant microstructural variation can be explained by the change in heat flow mechanism with geometry. The grain area variability was reduced by up to 94% at a fraction of the cost of a typical thermal camera, with control software written in-house and made publically available. This decreases the barrier to implementation for process feedback control, which can be implemented in many manufacturing processes, from polymer AM to injection moulding to inert-gas heat treatment.