In-Process Monitoring of Additive Manufacturing

The key innovation in this project is the implementation of an Imaging Fourier Transform Spectrometer (IFTS) for in situ metal additive manufacturing process monitoring. In this Phase I STTR project, Mound Laser & Photonics Center, a developer of laser based additive manufacturing processing, will collaborate with the Air Force Institute of Technology, with expertise and innovative hardware for spectroscopy, to implement the IFTS in a Selective Laser Melting (SLM) R&D test bed to demonstrate advanced strategies for process control and in situ quality assurance such as: (1) automatic detection of the molten area in various layers, (2) in situ release of stresses induced by temperature gradients, and (3) real-time control of alloy composition and minimization of contaminants. These capabilities with facilitate the manufacture of parts with complex geometries with improved microstructures and properties. In Phase I we intend to: (1) prove the utility of the IFTS for monitoring SLM processing of metals and alloys, (2) determine surface temperatures with a statistical accuracy of better than 4 oC, systematic accuracy of better than 10 oC and a dynamic range of up to 2000 oC, and provide rapid (1 kHz), automatic identification of the molten area, (3) track changes in chemical composition due to evaporation, oxidation, and melt expulsion, (4) reduce data dimensionality and correlate these IFTS sensor features with manufacture quality metrics, and (5) design the concept for a Phase II prototype sensor suite that focuses on key aspects of the IFTS datascape to inexpensively emulate the IFTS. In Phase II, a prototype optical sensor will be developed for process control of metallic additive manufacture of lightweight, reliable, low cost structures.