The so-called investment casting process , it is simply said that use fusible material fusible model covered with several layers of special refractory coating in the model surface, after drying and hardening to form a whole body shell, then steam or hot water from type shell model melt away , and then placed in the shell sand box , after filling the dry sand molding around it , and finally it is cast into the roaster in the high-temperature roasting, mold or shell after roasting, in which pouring molten metal and casting finally obtained.
The biggest advantage of investment casting is that due to the investment casting with high dimensional accuracy and surface finish, so it can reduce mechanical processing work, just in the component parts of the high demand for a little machining allowance, and even some castings only grinding, polishing allowance, don’t need to machining can be used. Using investment casting method, therefore, can save a lot of machine tool equipment and processing time, and greatly save metal materials. Another advantage of the method of investment casting is that it may be cast complex castings of various alloys, particularly may be cast super alloy castings. Such as jet engine blades, with the machining process its sleek outline and cooling cavity is almost impossible to form. Investmentto produce not only mass production can be done to ensure the consistency of the casting, and avoid stress concentration of residual knife pattern after machining.
The available investment casting production of alloy types include carbon steel, alloy steel, heat-resistant alloy, stainless steel, precision alloy, permanent magnet alloy, bearing alloy, copper alloy, aluminum alloy, titanium alloy and nodular cast iron etc.. Investment casting process is complicated, and not easy to control, use and consumption of material is expensive, so it is suitable for production of complex shape, high precision, or difficult to other processing of small parts, such as turbine engine.