Type 1, precision casting, ceramic precision is very high, only when the sintering of tiny deformation.If produce error in the process of manufacture, as long as improving sand box, ceramic slurry formula, sintering methods is roughly can achieve satisfactory results.So the deformation of the casting size is made up of solidification and cooling process of nodular cast iron volume changes.2, the accuracy of precision casting deviation according to the rotor shape and size.Thus in terms of tolerance, must first determine the benchmark, decided on the basis of consulting and user specific low in check the size, the decision to first base path for all products before delivery to centering on both ends of the rotor.