The common blanks of shaft parts are profiles (round bars) and forgings. Large and complex shafts can also be cast. Crankshafts in internal combustion engines are generally cast blanks. The profile blank is divided into hot-rolled or cold drawn bars, which are all suitable for smooth shafts or stepped shafts with little difference in diameter. After the forging blank is heated and forged, the fiber structure in the metal is distributed along the surface, so it has high tensile, bending and torsional strength, and is generally used for important shafts.