Milling Shoe can be divided into three kinds: Flat-bottom(or concave-bottom)milling shoe, guide milling shoe and cone milling 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.