In Situ Melt Pool Monitoring and the Correlation to Part Density of Inconel® 718 for Quality Assurance in Selective Laser Melting

Additive Manufacturing looks back on a history of about two decades and today SLM® technology keeps moving as an integral element in industrial production environments. Sensitive markets such as energy, medical or aerospace have the highest quality standards for complex, safety-related and highly stressed components which are to be met at competitive costs for each build job and single part. In this context process monitoring is necessary for documentation, qualification and at the same time it is expected to be able to detect process anomalies during the process. In addition to surface roughness, part density which mostly depends on volume energy, changing with laser power, scan velocity etc., is a distinctive quality feature of every component. This paper presents a method for a real time melt pool monitoring system based on photodiodes and the correlation between thermal emission and part density of Inconel® 718 with respect to volume energy deviation.