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Powder Bed Fusion (PBF) is a type of Additive Manufacturing (AM) technology that builds parts in a layer-by-layer fashion out of a bed of metal powder via the selective melting action of a laser or electron beam heat source. The technology has become widespread, however the demand is growing for closed loop process monitoring and control in PBF systems to replace the open loop architectures that exist today. This paper demonstrates the simulated efficacy of applying closed-loop state estimation to the problem of monitoring temperature fields within parts during the PBF build process. A simplified LTI model of PBF thermal physics with the properties of stability, controllability and observability is presented. An Ensemble Kalman Filter is applied to the model. The accuracy of this filters’ predictions are assessed in simulation studies of the temperature evolution of various test parts when subjected to simulated laser heat input. The significant result of this study is that the filter supplied predictions that were about 2.5x more accurate than the open loop model in these simulation studies. 

This work reports on the measurement of the internal temperature distributions of parts being manufactured via the Powder Bed Fusion (PBF) process. Eight test coupons were machined from a piece of wrought 304 stainless steel (SS). Thermocouples were inserted into the test coupon interiors to sample internal thermal history. The coupons were then placed into the open architecture laser PBF machine housed at EWI and covered to their uppermost surfaces with 316 SS powder.Three tests were executed: First, the laser rastered over the coupons without inducing melting.Second, the laser rastered over the coupons while melting the exposed faces. Lastly, five layers of316 SS were built atop the coupons. The main result is a comprehensive data set of a multitude of measured physical inputs and outputs under typical build conditions: embedded thermocouple temperatures, laser centroid, laser power, and infrared imagery of the exposed coupon faces.