Production of the high quality investment castings is dependent on rational gating system design and proper castings structure.Modified equation for gating system was derived by altering parameters in empiric formula for gating system design and determining the applied scope and boundary conditions on the basis of analysis of data from conventional gating system design for investment castings with computer by mathematical statistics method

which can guide other gating system design with the similar working conditions.In addition

the quality of investment castings can be greatly improved by pertinentl application or combination application of above two ways based on castings structure

remarkably reducing shrinkage porosity（hole） and rising product rate and production yield rate.