Observation of Non-Taylorian tool wear and machining parameter selection for miniature milling of Ti-6Al-4V on regular CNC machines

Abstract

ABSTRACT The nature of tool wear is analyzed for end milling the titanium alloy Ti-6Al-4 V using miniature solid carbide endmills. Established thermal and mechanical machining models are used to predict tool temperature and cutting forces. Model outputs are used as the basis for selecting machining parameters under constraints imposed by regular CNC machines lacking ultra-high-speed spindles. Chiploads of the order of a few microns put the application in the regime of micromachining. Tool wear of the principal peripheral has been examined, which distinguishes our tool wear study. Microscopic observations reveal tool wear to be non-Taylorian, i.e., abrasive flank wear is not the main mode of wear. Depth-of-cut notching, edge chipping, and corner crumbling are the dominant tool wear modes. Negative helix endmills are found to be advantageous in delaying corner crumbling. The machining parameter selection method developed has direct industrial relevance in miniature feature machining of Ti-6Al-4 V on regular CNC machines in which high-speed spindles are not used.