The variety of milling cutters available helps make milling a versatile machining process. Cutters are made in a large range of sizes. Milling cutters are made from High Speed Steel (HSS), others are carbide tipped and many are replaceable or indexable inserts.
Solid end mills — Solid end mills have two, three, four, or more flutes and cutting edges on the end and the periphery. Two flute end mills can be fed directly along their longitudinal axis into solid material because the cutting faces on the end meet. Three and four fluted cutters with one end cutting edge that extends past the center of the cutter can also be fed directly into solid material.
Solid end mills are double or single ended, with straight or tapered shanks. The end mill can be of the stub type, with short cutting flutes, or of the extra long type for reaching into deep cavities. On end mills designed for effective cutting of aluminum, the helix angle is increased for improved shearing action and chip removal, and the flutes may be polished.
Special end mills — Ball end mills are available in diameters ranging from 1/32 to 2-1/2 in., in single and double-ended types. Single purpose end mills such as Woodruff key-seat cutters, corner rounding cutters, and dovetail cutters are used on both vertical and horizontal milling machines. They are usually made of high-speed steel and may have straight or tapered shanks.
Milling cutter nomenclature — As far as metal cutting action is concerned, the pertinent angles on the tooth are those that define the configuration of the cutting edge, the orientation of the tooth face, and the relief to prevent rubbing on the land.
Outside diameter — The diameter of a circle passing through the peripheral cutting edges. It is the dimension used in conjunction with the spindle speed to find the cutting speed (SFPM).
Root diameter — This diameter is measured on a circle passing through the bottom of the fillets of the teeth.
Tooth — The tooth is the part of the cutter starting at the body and ending with the peripheral cutting edge. Replaceable teeth are called inserts.
Tooth face — The tooth face is the surface between the fillet and the cutting edge, where the chip slides during its formation.
Land — The area behind the cutting edge on the tooth that is relieved to avoid interference is called the land.
Flute — The flute is the space provided for chip flow between the teeth.
Gash angle — The gash angle is measured between the tooth face and the back of the tooth immediately ahead.
Fillet — The fillet is the radius at the bottom of the flute, provided to allow chip flow and chip curling.