Feasibility study on ultraprecision micro-milling of the additively manufactured NiTi alloy for generating microstructure arrays

Abstract

Nickel-titanium (NiTi) alloy has unique functional properties in medical and microelectronics products. Recently, additive manufacturing has become an attractive way of fabricating NiTi alloy. However, the study of generating microstructure arrays on additively manufactured (AMed) NiTi alloy surfaces remains unclear. Motivated by this, this study proposes the ultraprecision micro-milling (UMM) process to generate microstructure arrays and perform a systematic investigation. First, selective laser melting, as a popular additive manufacturing way, was utilized to fabricate the AMed NiTi alloy. Then, the UMM process was carried out to machine these samples. After the machining experiments, a mirror surface with a surface roughness of 0.014 μm can be acquired, which demonstrates the good machinability of the AMed NiTi alloy. Moreover, the micro-groove array and micro-pillar array with low machining errors were machined on the AMed NiTi alloy surfaces, which verifies the effectiveness of the proposed machining process. The corresponding cutting forces, tool conditions, and chip morphologies were studied to fully understand the machining mechanism of the AMed NiTi alloy. Besides, the surface wettability of microstructure arrays was also quantitatively analyzed. Therefore, this study provides a facile and effective machining process for generating microstructure arrays on the AMed NiTi alloy surfaces.