Drilling milling tool and methods for producing a through-hole

A method for producing a through-going bore in a metallic workpiece using a combination drilling and milling tool having a drilling and milling shank which has at least two front-end cutter tips, at a leading end of the shank, such that at least one of the front-end cutter tips at the end is, at a same time, a circumferentially-cutting cutter tip having a radially outermost cutting point or cutting edge section that projects beyond a plurality of circumferentially-cutting cutter tips in a radial direction,

• the circumferentially-cutting cutter tips are made with straight cutting edges, and, together the straight cutting edges, produce a cylindrical cut contour,
• the circumferentially-cutting cutter tips being arranged on at least two helical chip flutes such that the circumferentially-cutting cutter tips on each helical chip flute has the same orbit as an opposed circumferentially-cutting cutter tip so that in each case two opposed circumferentially-cutting cutter tips on opposed helical chip flutes form a cutter pair, the method comprising the following which are carried out in one working operation:
• drilling through the workpiece by a forward-feed movement of the drilling and milling tool with the at least two front-end cutter tips;
• stopping the forward-feed movement of the drilling and milling tool as soon as the circumferentially-cutting cutter tips, on the drilling and milling tool, are located inside the bore just produced;
• and
• orbital milling of an inside surface of the bore with the plurality of circumferentially-cutting cutter tips.

A method of producing a through-going bore in a metallic workpiece using a combination drilling and milling tool having a drilling and milling shank which at least two front-end cutter tips, at a leading end of the shank, such that at least one of the front-end cutter tips at the end is, at a same time, a circumferentially-cutting cutter tip having a radially outermost cutting point or cutting edge section that projects beyond a plurality of circumferentially-cutting cutter tips in a radial direction,

• the circumferentially-cutting cutter tips are made with straight cutting edges, and, together the straight cutting edges, produce a cylindrical cut contour,
• the method comprising the following carried out during one working operation:
• drilling through the workpiece by forward-feed movement of the drilling and milling tool with the at least two front-end cutter tips;
• either face-milling or flat countersinking an edge of the bore at an end of the forward-feed movement with a flat cutter tip;
• withdrawing the drilling and milling tool and stopping the withdrawing movement as soon as the circumferentially-cutting cutter tips are located inside the bore just produced;
• and
• orbital milling of the inside surface of the bore with the plurality of circumferentially-cutting cutter tips.