Investigation on chip formation mechanism of high-aspect-ratio micro-milled structures

Abstract

Miniaturized components with High-Aspect-Ratio (HAR) have extensive applications in aerospace, biomedicine, and optical fields. However, the chip formation mechanism of HAR micro-structures is closely related to the machined surface quality and accuracy with insufficient attention at present. The minimum cutting thickness is changing in micro-milling, which leads to the transition from elastic deformation via elastic-plastic deformation to chip formation process. In this work, the chip formation mechanism of micro-structures with High-Aspect-Ratio is thoroughly studied considering the minimum cutting thickness, tool types and milling parameters from the theoretical and experimental perspective. Micro-milling experiments were carried out with single-edged PCD and two-fluted cemented carbide micro-milling cutters, and the chip characteristics and formation mechanism of HAR micro-grooves was further analyzed in detail. The quantitative evaluation of the top-burrs and comprehensive analysis of side-wall surface topography were conducted to investigate the influence of chip formation and chip removal on machined quality of HAR micro-grooves. The results suggest that the chip formation and characteristics of HAR micro-grooves has a significant relationship with the tool performance, milling parameters and side-wall limitation. The aspect-ratio has a negative impact on the effective chip removal which further promotes top-burr dimensions and reduces side-wall surface quality. Sharp micro-cutters with large chip space and exceptional wear-resistance are recommended for machining HAR micro-structures.