Differentiating Defect Types in LENS (TM) Metal AM via In Situ Pyrometer Process Monitoring

In order for metallic additive manufacturing (AM) to find application in industrial production environments, methods for quality control need to be developed. Presently, even precisely calibrated process parameters cannot prevent the stochastic occurrence of defects resulting from elements in the AM process which are difficult to control. This study utilizes low framerate (10 Hz) pyrometry to record in situ temperature measurements of the molten pool and surrounding substrate in LENSTM AM. The data is statistically analyzed in search of anomalous behavior which is compared to the actual population of voids and inclusions found using Xray Computed Tomography. This statistical analysis technique was able to identify volumetric defects as small as 40 mu m in diameter aswell as inclusions such as powder contamination. This study shows that the thermal analysis parameters can be tuned specifically for detecting different anomalies in the build.