INFLUENCE OF EXIT ANGLE AND TOOL NOSE GEOMETRY ON BURR FORMATION IN FACE MILLING OPERATIONS

One of the more important burrs produced in a face milling operation i s the burr formed on the exit edge in the cutting direction. This burr is present over the full length of the exit edge, and under certain c utting conditions is relatively large in size, strongly attached to th e workpiece, and presents a strong configuration, features that make i t difficult to remove and consequently increases the cost of the compo nent. This paper is concerned with the influence of the exit angle and tool nose geometry on the formation of this burr for both finishing a nd roughing conditions (small and large depths of cut respectively), w ith a medium carbon steel. The results show that four different types of burr can be produced on the exit edge, namely the tear, curly, rubb ing and wavy burrs. The exit angle and the tool nose geometry have a s ignificant influence on the formation and characteristics of the burr formed on the exit edge. Under finishing conditions, exit angles great er than 90 degrees and large tool nose radii facilitate the formation of large primary burrs. Under roughing conditions, on the contrary, th e exit angle affects the type of burr produced on the exit edge, where as the tool nose geometry only influences the burr size. The formation of primary and secondary burrs is mainly determined by the chip how a ngle rho; primary (wavy) burrs usually form for rho > rho(t) (where th e transition chip flow angle rho(t) approximate to 42 degrees, in this case) and secondary (tear) burrs for rho < rho(t).