Materials Science Forum Vols. 836-837

Abstract: Due to the weak rigidity of micro-drills and impulse effects, the micro-drill breakage is a common problem in printed circuit board micro-drilling. Traditional micro-drill breakage detection methods and principles, including vacuum-type, laser-type, and contact-type detection, were reviewed in this paper. The comparison of three detection methods showed that the contact-type detection can more satisfy the performance of CNC drilling machine. Three effective contact-detection circuits, including no transformer and rectifier circuit pulse-type, active-type, and trigger-type detection circuit, were introduced. And as a conclusion, differences of these detection methods were compared. Based on the characteristic of three effective micro-drill breakage contact detection circuits, the development trends and designs of innovative detection circuit were proposed to meet the challenges in micro-drill breakage measurement during PCB drilling.

Abstract: Thin-walled elements are widely used in aerospace engines, such as blisk,casing, blade etc. There are significant vibrations while machining because of thesmall thickness and the poor rigidity of thin-walled workpieces which will lead to lowsurface machining quality, low machining efficiency and even worse the huge damageto the workpieces and the tools. Nevertheless, the vibration during milling does nothappen frequently, as it is closely related to the position of the workpiece structureand the machining parameters. The stiffness of the workpiece varies due to thechanging of cutting position. Therefore, vibration only appears in some positionswhen milling thin-walled workpieces. This paper mainly focus on monitoring themachining process in order to analyze the vibration and the position where it occurs.Moreover, with confirming the vibrated position and analyzing the reason of vibration,the paper provides a valid reference to the machining vibration controlling, the qualityand effectiveness of workpiece surface.