Cutter for drilling and reaming

A drill bit comprising:

• a drill bit body having a central axis;
• a first cutting flute having a first cutting edge disposed on the drill bit body at a first radial distance from the central axis as measured within a first plane normal to the central axis;
• a second cutting flute having a second cutting edge disposed on the drill bit body at a second radial distance from the central axis as measured from within a second plane normal to the central axis, the first radial distance being less than the second radial distance;
• the first cutting flute including a first insert forming the first cutting edge, and the second cutting flute including a second insert forming the second cutting edge;
• the first and second cutting edges each having a length extending along a combined direction of substantially perpendicular to the central axis and helically along the drill bit body;
• the length of the first cutting edge being longer than the length of the second cutting edge such that during orbital drilling, the first cutting edge removes a majority of material being machined;
• and
• the first insert is made of polycrystalline diamond (PCD) and the second insert is made of cubic boron nitride (CBN).

A cutting tool comprising:

• a shaft with a first end for engaging a tool holding system and a second end for engaging a part;
• a first cutting flute having a first cutting edge disposed on the shaft at a first radial distance from a shaft centerline;
• a second cutting flute having a second cutting edge disposed on the shaft at a second radial distance from the shaft centerline, the first radial distance being less than the second radial distance;
• the first and second cutting edges each having a length extending along a combined direction of substantially perpendicular to the shaft centerline and helically along the shaft;
• the length of the first cutting edge being longer than the length of the second cutting edge such that during orbital drilling, the first cutting edge removes a majority of material being machined;
• and
• the first cutting edge is treated with polycrystalline diamond (PCD) and the second cutting edge is treated with cubic boron nitride (CBN).

A method of drilling and/or reaming a hole in a part formed of at least one material, comprising the steps of:

• providing a cutting tool having a central axis and first and second cutting flutes including first and second cutting edges, the first and second cutting edges each having a length extending along a combined direction of substantially perpendicular to the central axis and helically along the cutting tool, the first cutting edge being longer than the second cutting edge;
• cutting, during orbital drilling, a majority of the material being removed with each pass of the first cutting edge at a first radius;
• cutting an outermost portion of material being removed with each pass of the second cutting edge at a second radius being larger than the first radius;
• performing at least one of the following:
• providing a first insert as the first cutting edge formed of polycrystalline diamond (PCD);
• and
• providing a second insert as the second cutting edge formed of cubic boron nitride (CBN).

An apparatus for forming a hole comprising:

• a drill bit adapted for orbital movement about an orbital center, and adapted for rotation about a drill bit central axis;
• a first cutting flute having a first cutting edge on the drill bit disposed at a first radial distance from the central axis as measured in a plane normal to the central axis;
• a second cutting flute having a second cutting edge on the drill bit disposed at a second radial distance from the central axis as measured in the plane, the first radial distance being less than the second radial distance;
• the first and second cutting edges each having a length extending along a combined direction of substantially perpendicular to the drill bit central axis and helically along the drill bit;
• the length of the first cutting edge being longer than the length of the second cutting edge such that during orbital drilling, the first cutting edge removes a majority of material being machined;
• and
• the first cutting edge includes or is made from polycrystalline diamond and the second cutting edge includes or is made from cubic boron nitride.