Development of high intensity multibeam laser metal deposition system with blue diode lasers for additively manufacturing of copper rod

A 100 W blue diode laser with an optical fiber having a core diameter of 100 μm was developed and installed into a blue diode laser metal deposition system (B-LMD), achieving a laser intensity of 7.58 × 104 W/cm2, four times higher than that of the previous B-LMD system. The increase in laser intensity is expected to enable faster and more efficient 3D processing of pure copper. The authors conducted the rod formation experiment by varying the processing speed. The rod formation process is observed with a high-speed video camera to clarify the mechanism of copper rod formation. As a result of rod formation as a 3D modeling of pure copper, a 30 mm rod was formed in 1.5 s under the following conditions: a laser intensity of 1.27×106W/cm2, a powder feed rate of 220 mg/s, and a processing speed of 20 mm/s. It was found that the mode of rod forming changed depending on the processing speed. When the processing speed is high, the mode becomes molten layer type and the energy efficiency becomes high. In addition, the processing point became closer to the focal point at high speed, and the cross-sectional shape of the formed rod was closer to the circular ones.