3, precision casting of the rotor blank has quite high accuracy.But still need mechanical processing.So rough play with more than rabbit machining allowance in advance how much and decided to tolerance, to the full decided to between the parties.Casting surface is too little machining allowance is not jump even if it's bright and clean, but on the surface of casting blank tend to produce steel small defects.And when processing if centering slightly partial color more than more than rabbit is workpieces with scale.And ordinary cast iron casting surface machining is poor, machining allowance too less likely to cause the tool after the skid and make.So machining allowance is not far too little in general machining allowance deliser more than for the whole casting machining allowance is the same.In formulating process close these standard must be taken into account.