End Mill Anatomy 101
End Mill Definitions
Cutting Diameter
The size measured as a straight line across the center of a theoretical circle formed by the cutting edges as the end mill rotates.
Cutting Edge (Tooth)
The sharp edge of the end mill tooth
Flute
The deep spiral grooves behind each cutting edge that allow for chip formation and evacuation
Length of Cut (LOC)
The total measurement of the functional (sharp) cutting depth, this excludes any Flute Washout
Flute Length
Length of flutes, usually the same as Length of Cut, but can be different
Flute Washout
The amount of non-cutting flute area past the cutting edges
Overall Length (OAL)
The total measurement from one end of the end mill to the other, from the top (cutting end) to the bottom of the shank
Shank
The end of the end mill that is held in the work holder
Shank Diameter
The size measured as a straight line across the center of the shank circle
Shank Flat
A flat area ground on the shank used with a set screw to prevent pull out in certain types of holders. This could be referred to a weldon flat, long flat, or tapered flat
Helix Angle
The cutting edge angle measured from the centerline of the end mill to a straight line tangent along the cutting edge. See images
End Teeth
The teeth or cutting edges at the very top of the end mill, also known as axial teeth.
Side (Peripheral) Teeth
The teeth or the cutting edges on the side of the end mill, also known as radial teeth.
End Gash
The pockets on the end of the end mill that create the axial (end) teeth
