Rotary cutting tool with enhanced coolant delivery

A rotary cutting tool, comprising:

• a tool body including a shank portion proximate a rearward end of the rotary cutting tool, a flute portion integral and adjacent the shank portion in an axial direction of the tool body, and a pocket portion proximate a forward end of the rotary cutting tool, the flute portion having a plurality of flutes separated by lobes;
• a replaceable cutting insert mounted in the pocket portion of the tool body, the replaceable cutting insert has an outer peripheral surface interrupted by a plurality of flutes that continuously merge into the plurality of flutes of the flute portion of the tool body;
• a central fluid hole extending along a central, rotational axis, RA, from the rearward end, entirely through the shank portion of the tool body, entirely through the flute portion of the tool body, and partially into the cutting insert, the central fluid hole terminating in the cutting insert at a predetermined distance, DB, from a base surface of the cutting insert;
• one or more connecting fluid holes in fluid communication with the central fluid hole, the one or more connecting fluid holes extending from the central fluid hole at the predetermined distance, DB, from the base of the cutting insert and terminating in a first opening in a flank of the cutting insert for supplying fluid to one or more cutting edges of the cutting insert;
• and
• one or more twisted fluid holes extending from the rearward end of the tool body, entirely through the shank portion, entirely through a lobe in the flute portion, entirely through the cutting insert, and terminating in a second opening in the flank of the cutting insert for supplying fluid to one or more cutting edges of the cutting insert,
• wherein at least a portion of the central fluid hole has a triangular cross-sectional shape when viewed in a plane perpendicular to the central, rotational axis, RA, and wherein the one or more twisted fluid holes has a different cross-sectional shape than the central fluid hole.