Using Sensing for Process Improvement and Material Qualification in Metal Additive Manufacturing

Additive manufacturing (AM) can reduce lead times, facilitate affordable low quantity production, and enable complex geometries. These benefits can be realized in both direct metal part production and in tooling for conventional processes such as metal casting. The application of sensing along with AM processes is needed to realize the full benefits of AM and yield improvements in process efficiencies and quality. In this presentation, two applications are examined. First, a new approach for in-situ monitoring of laser processing during powder bed fusion of metal. Here, optical monitoring of laser powder bed fusion of the entire build bed with two high-speed cameras operating in stereovision. The primary goal of the monitoring system is to identify and track spatter particles that are ejected from the melt pool during laser processing. The effects of processing parameters on the formation of spatter (size and quantity) are studied, as well as the effects of scan strategy and airflow on directing spatter trajectory. Second, binder jetting AM technology is enabling new designs for sand casting molds including unparalleled geometric complexity and component consolidation. The inclusion of advanced wireless in-mold sensors has the potential to increase baseline quality control and to understand the behavior of highly complex binder jetting sand molds. These new sensors enable unprecedented monitoring of the casting process and allows early alerts to the manufacturer of process errors including misruns, core shifts, freeze-offs, and higher than acceptable flashing. Recent results will be reviewed including temperature, pressure, and motion sensing during the casting process. Challenges to mold sensorization such as sensor survivability, cost, and wired/wireless data transfer will also be discussed.