Integration of feedback and feedforward control in laser powder bed fusion

Abstract Laser powder bed fusion is among the most promising methods for fabricating metal parts with complex geometries; however, ensuring consistent melting remains challenging, as highly dynamic heat accumulation from previous layers and melt tracks alters the pre-melting surface temperature for the subsequent ones. Such a phenomenon will result in inconsistent melt pool behavior, leading to shape inaccuracies and porosities. Existing works have attempted to address this issue by regulating printing parameters, either via feedforward modeling or sensor-based feedback control. Yet, a practical framework for stabilizing multiscale heat variation remains missing. This work combines two control approaches by linking finite element modeling-based heuristic tuning with sensor-based feedback laser power control. Specifically, a photoresistor-based PD laser power control method is used to maintain consistent melting within each layer, and the control target for each layer is determined via feedforward tuning and calibration. The method is validated through a proof-of-concept case study with parts featuring geometries that exhibit high global and local heat-accumulation risks. The maximum interlayer temperature has been reduced from 182 °C to 158 °C with combined feedback and feedforward control. Comprehensive inspections demonstrated a significant improvement in geometric accuracy and porosity reduction. For fine features such as thin-wall structures, the thickness error is reduced from 0.36 mm to 0.08 mm. Porosity count improved from 1.36 counts/mm2 to almost 0 in the sub-inspection window at the heat-accumulated regions.