8 9 to cut the inclined cutting edge 9 is in itself straight and extends to the position 12 at the transition 18 in a straight configuration however the cutting edge 9 does not necessarily have to be configured as a straight line and could also be slightly arcuate the cutting edge 9 extends to the position 12 where a transition 18 is formed at the transition the cutting edge 9 at the position 12 is located higher in relation to the drawing plane of fig2 than the adjacent lower free edge 21 which does not perform a cutting action the cutting edges 8 9 and the free edge 21 form the boundaries of a chip removal face 6 which is located below the cutting edges 8 9 and which opens approximately conically outwardly from the position 16 between the lines 22 and 24 as seen in fig1 or 2 the free edge 21 ten continues at an angle into a line 24 which also forms the boundary of the chip removal face 6 is also seen in fig1 or 2 it is significant that a free edge 21 located on the control surface 5 is disposed adjacent to the inclined cutting edge 9 the control surface 5 does not performs a cutting action and is bounded on one hand on the side of the cutting edges 8 9 by the free edge 21 and on the other hand on the sides disposed opposite the cutting edges 8 9 along the periphery opposite the rotation direction 15 by the edge boundaries of a wedge 17 formed between the free surface 4 and the control surface 5 the wedge 17 is formed by a shoulder between the two side by side surfaces 4.