Study on additive and subtractive manufacturing of high-quality surface parts enabled by picosecond laser

Abstract

Low dimensional accuracy and high surface roughness induced by the inherent powder adhesion and staircase effect are the critical challenges for the application of parts fabricated by laser powder bed fusion (LPBF). In this study, an innovative hybrid additive manufacturing process by adding the ultrafast laser machining to the LPBF process was proposed. After LPBF process, the additively manufactured samples were micromachined using a picosecond laser. The effects of parameters (i.e., laser frequency, and scanning speed) of the ultrafast laser machining on the surface morphology were investigated by the single-pass ablation experiments. The impact of the scan counts on the cutting depth was analyzed by the large-area cutting experiments. Subsequently, samples with different tilt angles were fabricated by a hybrid additive manufacturing process with alternating processing of LPBF and the ultrafast laser machining. The side surface roughness (4.98 ± 0.44 µm) of the samples fabricated by hybrid additive manufacturing process was lower than that of as-built LPBF samples. The processing characteristics and the ablation morphology of the picosecond laser were investigated. The factors affecting the quality of hybrid manufacturing were systematically discussed. This work may provide a new way to manufacture parts with high dimensional accuracy and low surface roughness by LPBF.