Enhancing stability in thin-walled part production with L-DED wire using an adaptive controller

Abstract

Laser-based direct energy deposition (L-DED) with metal wire is an efficient additive manufacturing process known for its cleanliness, user-friendliness, and cost-effectiveness. Nonetheless, heat build-up, especially in thin-walled parts, leads to geometric deviations and process instabilities due to limited heat dissipation. Closed-loop control of deposition height and local temperature addresses this issue. However, traditional controllers like PID controllers with fixed dynamics cannot adequately handle the long-term drifts inherent in the system dynamics. This study introduces an adaptive controller that dynamically adjusts the parameters for effective L-DED control using optical coherence tomography for the measurement of the deposition height and a coaxial camera for the determination of the temperature from thermal radiation. The control variables include the feed speed of the wire for material input and the laser power to control the deposition height and temperature. Our approach reduces deviations of the wall’s height by a factor of 10 and enables defect-free fabrication of thin-walled parts. This underscores the efficacy of our control system in enhancing L-DED.