Abstract

Process parameters, including deposition direction, are crucial in direct metal deposition (DMD) for microstructure formation and mechanical properties of the final part. Multi-directional deposition along with in-situ deposition control can minimize deposition anisotropy and improve dimensional accuracy. In this paper, a DMD system is developed to achieve multi-directional metal deposition by using 6 degree-of-freedom (DOF) motion of the workpiece platform rather the laser head for a highly compact design. An in-situ control strategy with two independent loops of laser focus and power is developed to control the printing process based on the feedback from real-time melt pool geometry and intensity. Experimental results have shown that the laser focus and power control can significantly improve geometrical accuracy and reduce heat accumulation. In addition, system kinematics are derived and verified for the 6-DOF hexapod to achieve multi-directional deposition. Oblique structures have been successfully printed to demonstrate the effect of optimized build direction.

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