For the rail industry, relative difficulty is the body of main components for bogies, hollow shaft and other locomotive and diesel engine components. Locomotive diesel engine main parts of complex, precision manufacturing, high geometrical tolerances and surface quality (mostly in 5~7 's accuracy level, surface roughness Ra=0.4 μ m or so), requires good interchangeability, such as crankshafts, connecting rods, cylinder head and body, in high speed, the main objective is to ensure the locomotive reliability, long life, high safety factor. To key parts of a diesel engine, many parts dimension precision in Micron, it is difficult to imagine, can't do that. If a crank: 4m in length, weighing about 2 500kg, main 250-0-0.029mm long runout 0.06mm; shape and position tolerances, surface roughness requirements are very strict. Main difficulty table now blank extrusion requirements are high, forming non-work surface sizes higher crankshaft balance block welding requirement was originally not used; balance block welding structure, machining equipment turning radius increases, tolerances of form and position high normalizing + final surface spray cooling heat treatment, have great difficulty on deformation control.