Multi-sensing Process Monitoring and Control of Directed Energy AM Processes

A multi-sensor thermal imaging suite has been developed for process monitoring and to provide control signals for directed energy laser deposition. The multi-sensor suite includes a 2 wavelength imaging pyrometer for melt pool monitoring along the laser axis and IR thermal imaging sensor viewing the side of the larger deposit. A software feature has been developed to measure a variety of thermal metrics, TM, related to temperature levels in the deposit. The TM is used as a control set point and process parameter adjustments are communicated to the process computer from the instrument computer. The deposition process is therefore under partial control of the instrument computer. In one representation, the TM is designed to provide for component deposition with highly uniform microstructure and mechanical properties. Variation of the TM is shown to provide direct control of component microstructure and mechanical properties. Under repeated deposition of a statistical set of components, using a selected TM, a set of deposits have been built with precise microstructure and mechanical properties values, with tight statistical tolerances.