Development of blue diode laser for additive manufacturing

Abstract

We developed several blue diode lasers and applied laser metal deposition one of the additive manufacturing technologies. This system has two laser modules, a focusing head, a powder feeder and a XYZ stage. Fiber couple direct diode laser module was guided to focusing head by optical fiber, which core diameter is 400 μm. In case pure copper layer formation with blue diode laser, the laser output power is 80 W, a scanning speed is 10 mm/s. A powder feed rate was varied from 14 to 80 mg/s. The stage was moved to the X direction. And In case pure copper rod formation with blue diode laser, the laser output power is 80 W and a scanning speed is 4 mm/s. A powder feed rate was varied from 14 to 80 mg/s. The stage was moved to the Z direction. Layer thickness was linearly increased to 40ms in all powder feed rate and the layer formation rate was gradually decreased over 40ms. An average slope Δspeed = 4 mm/s at 40 ms is obtained. From this, it is considered that pure copper rod can be formed by pulling upward at 4 mm/s. Based on the results obtained from copper layer, pure copper was stacked upward (direction Z) to form a pure copper wire. The result as expected was obtained by raising the speed at 4 mm/s. And since a thin molten pool was formed only in a limited area, it was observed that the molten pool was piled up without melting. It was confirmed that the flying powder adhered without melting. And thereafter, it was melted to form a rod. It was confirmed that there were no pore in pure copper rod.