Micro-milling tool mark removal mechanism by fluid jet polishing and its application for the precision manufacturing of micro-fluidic chip molds

The surface quality of micro-channels has a significant impact on their functional performance. Ultra-precision polishing of the micro-channel (mold) is essential to meet the requirements of the equipment. The tool marks resulting from the former manufacturing procedure such as micro-milling should be removed in the polishing process. Fluid jet polishing (FJP) is a promising method to achieve high surface quality as well as superior applicability to the small structure unit. However, the effect of the initial surface morphology and polishing parameters on the tool marks removal capacity in FJP is not clear. The manufacturing parameters are determined by trial and error approach, which is time-consuming and costly. In this paper, the tool mark removal capability of FJP was investigated theoretically and experimentally considering the effect of tool mark interval and abrasive size. Computational fluid dynamics (CFD) simulation of micro-channel polishing was conducted to investigate different abrasive impact angles with different abrasive sizes. The material removal characteristics at different stages were revealed to explain different polishing performance due to the variation of tool mark interval and abrasive size. This study can provide solid scientific basis for the ultra-precision finishing of micro-channel obtained by micro-milling and avoid invalid polishing due to the inappropriate initial surface.