With dispersed strengthening tin bronze as raw material,the pump body with high size precision,high water pressure was prepared by vacuum
investment casting process. The research suggests that inlet surface of the pump body prepared by shower gating system has many sand inclusions. After welding compensation,the result of 5 MPa water pressure test suggests that sweating phenomena appear at the pump inlet end and disk surface. Metallographic analysis suggests that there are dispersed shrinkages on the disk and the inlet end surface. The size of ingate was increased and the amount was decreased to 4,so that the water inlet face of pump can be compensated and the inclusions can float upward. The graphite pouring basin with 10mm of pelvicdiameter was applied to produce stable metal flow,which prevents sand cut,and the chills were put on the disc shell mould to prevent dispersed shrinkage. the casting passed the 5 MPa water pressure so it can be used under high pressure condition.