SBIR-STTR Award

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.

In Phase I of this project MLPC, WSU, and AFIT were successfully able to identify several optical data features that are indicative of the quality of components built with the selective laser melting additive manufacturing process. Four unique optical sensors were identified to collect this information and they include infrared and visible wavelength high-speed cameras and spectrometers. The sensors used in Phase I were very expensive, university developed, and produce very big data sets. In this phase II proposal MLPC and their collaborators will continue this work by developing a new low-cost sensor system to specifically track key data features identified in Phase I. This sensor system will then be used to perform in-process quality monitoring and qualification of manufactured parts. In Phase II this analysis will also be extended to electron beam freeform fabrication. To complete the project MLPC, WSU, and AFIT will continue analysis of the Phase I sensor data to identify more obscure process quality data, and develop process maps that correlate sensor output to part microstructure. Then MLPC and AFIT will design and build the low-cost sensor system to track all key data, and test it on MLPCs custom build additive manufacturing test cell. Next MLPC will perform the necessary programming and data processing to implement a process monitoring system that will show sensor data position on the process maps in real-time, thus enabling in-process quality assurance. MLPC will then study and report the cost savings NASA could gain with this technology. Finally, MLPC will test this concept on an electron beam system and determine its viability for that process. At the end of Phase II the TRL will be 5, and this product will be ready for licensing for commercial use in existing additive manufacturing machines, and the MLPC developed additive manufacturing system will be available for licensing as a package unit with the integrated sensor system.