On Mechanics of Unsteady Cutting Process with Varying Undeformed Chip Thickness : 2nd Report, Some Phenomena in Aluminium Milling Process

Abstract

In order to study an unsteady cutting mechanics wity varying undeformed chip thickness using such a work material as aluminium, copper and others which has a comparatively low yield point and high work-hardening characteristic, up milling and down milling of a rolled aluminium workpiece and an annealed one are carried out. The distinctive features differed from a steel cutting are found out. Cutting force in down milling increases in spite of a decrease in undeformed chip thickness, and suddenly decreases at the later stage of cutting process. Two patterns of variation modes exist in the variational configurations of cutting force in down milling. It is considered that these phenomena are the general features when cutting these materials and that they result from the varying undeformed chip thickiness and work-hardening characteristic. This consideration is confirmed by calculating the varying depth of a work-hardened layer under a machined surface and by measuring the hardness of the machined workpiece.