To prevent problems caused by burrs in machining, reduction and control of burr size is desirable. This paper presents a basic framework Sor and conceptual understanding of the burr formation process based upon the material properties of the, workpiece. In order to verify this framework and explain the basic phenomena in the burr formation process, the deformation at the edge of the workpiece was analyzed using a finite element method (FEM). Micro-machining tests under an optical microscope and a scanning electron microscope using Al-2024-O material were also done to observe the burr formation process. The Seen rate and tool edge radius were varied and the resulting burr formation observed. FEM analysis of burr formation in the 2024 material and observation of the deformation at the workpiece edge in the micromachining tests verified the proposed conceptual understanding of the burr formation process. For the experimental conditions examined, all of the burrs in Al-2024-O were ''negative'' burps, that is, edge breakout As the Seed was increased two effects were observed. One effect was an increase in the resulting burr thickness. Another effect, which was observed during the burr initiation stage while machining with a sharp tool, was an increase in both the distance and depth of the initial pivoting point of the burr from the tool edge.
