An accurate and real-time melt pool dimension measurement method for laser direct metal deposition

Laser direct metal deposition (LDMD), as a type of additive manufacturing (AM) technology, has gained broad applications across many industries. However, producing high-quality and accurate geometric workpieces remains a challenge without controlling the fabrication process. A visual-based process monitoring system provides information about melt pool dimensions as vital process parameters for controlling the LDMD process. As the result, the accuracy of the measurement determines the performance of the control system. This paper proposes a method that includes an efficient approach for obtaining the melt pool dimensions in real time and a novel melt pool boundary calibration for finding a suitable threshold to achieve high measurement accuracy. The proposed method is verified on an LDMD system, and the experimental results show that the proposed approach has provided accurate measurements of the melt pool widths that can be used for process quality control.