Iterative simulation-based techniques for control of laser powder bed fusion additive manufacturing

One of the challenges for process control of laser powder bed fusion additive manufacturing lies in thermal control. Excessively low laser power may lead to incomplete melting, while too high laser power can lead to keyholing, increasing the porosity of parts. Considering a thermal finite-element model from our prior work, a secant-based iterative method is proposed and implemented in this work to control the simulated laser power to attain a constant melt-pool size. Several experimental samples of Inconel 625 are designed and built with the EOSINT M280 system, and cross-sectioned to evaluate the effectiveness of the iterative simulation-based controller of laser power. Cross-sectional area statistics are collected near laser turnarounds, where the melt pool is most dynamic. The iterative simulation-based controller reduces the variation of melt pool size by between 13.4% and 48.8% compared to applying constant laser power for all configurations. With the extra iterations from the secant method, the controlled simulations take roughly 2.3 times longer than the simulations under constant laser power.