Dual-path micro-holes process for 0Cr17Ni7Al stainless steel thin plate with picosecond laser

Abstract

Ultrafast laser is widely used in drilling micro-hole because of its excellent processing quality. However, when machining micro-holes with an aperture of fewer than 100 μm, the ultrafast laser drilling shows some drawbacks, such as poor roundness and taper of holes. This paper proposed a dual-path laser scanning strategy to solve the above-mentioned issues. A micro-hole with a diameter of about 90 μm was successfully fabricated on a stainless steel sheet with a thickness of 80 μm. In the dual-path laser scanning strategy, concentric circles were scanned layer-by-layer on the stainless steel sheet, quickly forming a through-hole. Then, a helical scanning path was conducted to reduce the taper of the hole. The effects of different laser ablation paths and angles of incidence (AOI) on micro-holes roundness, taper, and sidewall quality were illustrated. The experimental results showed that, through decreasing the AOI of the helical scanning path from 0° to −4°, the taper could be reduced to 2°, but the entrance diameter also increased. Furthermore, the radial ablation compensation was utilized to successfully reduce the hole-reaming phenomenon. The entrance and exit roundness error of the hole was between 0.2– 1.6 μm, and the taper could be reduced to 0.9°. In summary, the dual-path laser scanning strategy is an efficient and high-quality drilling method, providing a new laser drilling method for processing micro-holes in thin plates.