Milling cutter, cutting insert, and milling method

A milling method comprising the steps of:

• providing a plurality of cutting edges at an outer peripheral part of a front end of a tool body that is configured to rotate about an axis with intervals provided between one another in a circumferential direction around the axis;
• performing milling on the work material by moving the tool body to the work material in a radial direction that perpendicularly intersects the axis while the tool body is rotated in the circumferential direction;
• forming a flat face on the work material by using a flat face machining cutting edge that extends along a virtual plane that is perpendicular to the axis among the plurality of cutting edges;
• and
• forming a recessed groove with a V-shaped section recessed from the flat face on the work material by using a recessed groove machining cutting edge that projects further toward a front end side in the axial direction than the flat face machining cutting edge among the plurality of cutting edges wherein the milling method further comprising:
• when the milling is performed on the work material, for which a width of a face to be machined is smaller than a diameter of a rotation locus formed by rotating the recessed groove machining cutting edge in the circumferential direction,
• after arranging the tool body to face the face to be machined in the axial direction, moving the tool body closer to the work material in the axial direction while the tool body is moved in the radial direction, and performing milling, making transition to facing;
• and
• after completing the facing on the entire face to be machined, moving the tool body away from the work material in the axial direction while the tool body is moved in the radial direction, at a position that overlaps a position where the transition to the facing is made.