Investigation of geometric groove accuracy in micro end milling (1^st Report)

—Groove position error and groove warp in tool-width milling—

Abstract

Square end mills of a small diameter are often used in micro end milling for making rectangular micro grooves. However, they are inevitably very flexible during milling, and it brings about poor machined accuracy on workpieces. In this paper, “groove warp” on a workpiece is discussed experimentally according to analyze the high frequency cutting force measured during tool-width milling with square end mills of 0.1mm in diameter. As a result, it is made clear that the resultant cutting force compels to deflect cutting edges even when they are situated at a rotating angle θ=0 or 180 deg., where position accuracy of both side walls are decided respectively, although the depth of cut on each cutting edge is negligible small. Therefore, the tool axis is deviated during transient milling from a contact start to the feed inside a tool radius, and the tool gets starting elastic recovery in the distance inside a tool radius from the end face of a workpiece. Therefore, the larger normal cutting force increases, the poorer groove accuracy deteriorates.