Calibration of galvanometric scan heads for additive manufacturing with machine assembly defects consideration

The calibration of additive manufacturing machines using scanning heads in processes such as Laser Powder Bed Fusion (LPBF) and vat photopolymerization is an iterative and time-consuming process often based on limited physical models. Indeed, the relationship between the laser spot position in the work plane and the actuators position (galvanometers) is achieved by interpolating correction tables experimentally determined. In this paper, representative geometrical models of the real system are established in order to reduce the time required to obtain the final correction tables. For this purpose, a geometrical model is developed with assembly defects consideration. This model is used in a process of defects identification to obtain a virtual machine representative of the real system and thus directly generates the final correction tables. The geometrical model thereby developed is used to quantify the impact of assembly defects on the laser spot position, to compensate them and to reduce the calibration time of an additive manufacturing machine.