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The silica sol process is developed on the basis of ancient wax casting, commonly known as investment casting precision casting. It is a casting process with little or no cutting, and is an excellent process technology in the casting industry. Its application is very wide.

The silica sol process is developed on the basis of ancient wax casting, commonly known as investment casting precision casting. It is a casting process with little or no cutting, and is an excellent process technology in the casting industry. Its application is very wide.

As an ancient civilization, China is one of the earliest countries to use this technology. As early as hundreds of years ago, the ancient Chinese laboring people created this lost wax casting technology to cast products such as bells, tripods, and vessels with various fine patterns and characters, such as the tomb tablet of Marquis Zeng Yi in the Spring and Autumn Period.

The practical application of modern investment casting methods in industrial production began in the 1940s. At that time, the development of aviation jet engines required the manufacture of heat-resistant alloy parts with complex shapes, precise dimensions, and smooth surfaces such as blades, impellers, and nozzles. Due to the difficulty in mechanical processing of heat-resistant alloy materials and the complexity of part shapes, it is not possible or difficult to manufacture them using other methods. Therefore, a new precise forming process needs to be found. Drawing on the lost wax casting that has been passed down from ancient times, and through improvements in materials and processes, modern investment casting methods have made important developments based on ancient processes. Therefore, the development of the aviation industry has promoted the application of investment casting, and the continuous improvement and perfection of investment casting have also created favorable conditions for the aviation industry to further enhance its performance.

The investment casting process, in simple terms, is to make a meltable model (referred to as an investment mold or model) from a fusible material (such as wax or plastic), coat it with several layers of special refractory coating, dry and harden it to form a whole shell, then melt the model from the shell with steam or hot water, and then place the shell in a sand box, fill it with dry sand for molding, and then put the mold into a baking furnace for high-temperature baking (if high-strength shells are used, the demolded shell can be directly baked without molding). After baking, the mold or shell is poured with molten metal to obtain the casting.

The major advantage of mold casting is that due to the high dimensional accuracy and surface smoothness of investment castings, it can reduce mechanical processing work. Only a small amount of machining allowance can be left in the parts with higher requirements, and even some castings only leave grinding and polishing allowance, which can be used without mechanical processing. From this, it can be seen that using investment casting method can greatly save machine tools and processing time, and significantly save metal raw materials.

Another advantage of investment casting method is that it can cast complex castings of various alloys, especially high-temperature alloy castings. The streamlined outer contour and cooling inner cavity of jet engine blades are almost impossible to form using mechanical processing technology. The use of investment casting technology not only enables mass production and ensures the consistency of castings, but also avoids stress concentration caused by residual tool lines after mechanical processing.