Application of the CAD and the rapid prototyping (RP) technology in investment casting has increasingly demanded on the accurate modeling of the casting process. A single good casting from the only casting trial must be secured with the numerically optimized casting process. Therefore an approach to integrating numerical simulation and rapid prototyping into investment casting was proposed, and examined on an automobile manifold prototype and dental castings. Geometric models of the casting objects were constructed by CAD program, or digitized by 3D laser scanning, then processed and converted to a standard STL format, which is acceptable by most RP systems and required by many numerical simulation software. MAGMASOFT was used to simulate the mold filling and solidification. A feeding criterion was employed to predict the shrinkage porosity. The riser and gating system and the casting parameters was optimized by means of the repeated computer 'pours'. Polystyrene or paraffin models, which replace the traditional wax patterns being melt and burnt out in the de-waxing and firing program, were 'laser sintered' or 'printed' out directly on RP systems. Following the rest of the investment casting process, sound automobile manifold prototype and dental prostheses with excellent functional details were made at the first casting trial. This study indicated that the potential of applying RP in investment casting can be brought into more effect with the aid of the integrated numerical mode/ing. Numerical optimization of the casting parameters aids in minimizing the risk of the casting failure and ensuring the casting quality.
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