Milling shoe can be divided into three kind: flat-bottom(or concave-bottom) milling shoe, guide mill shoe and come mill shoe according to its structure and shape At the milling surface, the carbide particles are built up by welding, which plays a part of self-milling. It is used to mill the fallen substances, such as bolt, nut, tooth wheel, slip dog, fittings for deep-well pump, etc. The junk mill are designed to mill away metal objects, such as alloy-steel packers, squeeze tool, perforating guns, drill pipe, tool joints, reamers, reamer blades, and rock bits. The junk mills consists fo the body made from high-strength alloy steel and dressed with super tough sintered tungsten carbide.available in OD s from 3 3/4 to 18 1/2 with no blades or 3 to 6 blades in 10 to 36 lengths with convex, concave, flat bottom, or offset design.