Research on high-speed laser micro-machining and micro-hole arrays based on polygon mirror scanner

Abstract

With the development of laser technology, laser drilling has been widely used in industrial processing, especially the manufacture of micro-hole arrays on metal or non-metal surfaces to improve the surface properties of materials. The manufacture of laser micro-hole arrays depends on high-frequency laser and high-speed scanning devices. Compared with the traditional galvanometer scanning device, the scanning speed of the polygon mirror scanner can reach 1000 m/s, which is dozens or even hundreds of times that of the galvanometer. Polygon mirror scanner combined with the high repetition rate nanosecond laser can realize the ultra-high-speed two-dimensional plane precision micro-hole arrays. High-speed laser precision drilling, especially micro-hole manufacturing, has become the core technology of high-speed laser micro-machining. Based on the FPGA control system, the scanning speed of the polygon mirror scanner can be synchronized with the pulse repetition rate of the nanosecond laser, and the dot-arrays drilling can be effectively realized. There is only one laser pulse injection at each scanning position. This paper mainly studies the effects of average laser power, laser pulse repetition rate, laser pulse width, and working defocus on laser drilling. Including hole diameter, the conical degree of each hole, and drilling efficiency. The hole diameter and the threshold energy density of material burning under different laser pulse widths were tested and compared. The changes of laser drilling aperture and taper were observed with increased laser power and single pulse energy. While the laser pulse width is 120 ns, the material burning threshold is 4.59 J/cm², and the maximum hole radius is 50 μm. The minimum taper is 0.36. The optimized processing technology is proposed. Under the same other conditions, the hole depth and hole morphology of 0.3 mm stainless steel dot-arrays arrangement drilling, dot-arrays dislocation arrangement drilling, and dot-arrays dislocation arrangement drilling under zoom were experimentally studied. While the number of scan times is 40, the maximum hole depth of the dot-arrays staggered arrangement zoom drilling can reach 161 μm.