Lost wax casting investment casting is known, is a little cutting or no cutting of the casting process, the casting industry in a superior technology, its application is very broad. It is not only applicable to all types, all kinds of alloy casting, casting and production of dimensional accuracy, surface quality is higher than other casting methods, or other casting methods were difficult to cast complex, high temperature, difficult in the casting process, can be cast by investment casting too.
Casting is in the ancient wax casting based on the developed. As ancient civilizations, China is using this technology one of the earlier, far in the centuries BC, in ancient China to create the working people of this lost wax casting technique, used with a variety of fine casting patterns and words bronze tripods and utensils, and other products, such as respect for the Spring and Autumn when the tomb site, etc.. Tomb respect to multiple base plate intertwining dragons, they end to end, staggered up and down to form a multi-layered hollow middle of moire patterns like these patterns is difficult with ordinary casting process produced, but with the lost wax casting technology, Can make use of paraffin is not strength, easy-to-carved features, with common tools and can be carved out of the tomb to receive the same respect paraffin plate material artifacts, and then additional gating system, paint, dewaxing, casting, they can respect by exquisite tomb site.
Modern investment casting method has been applied in industrial production in the twentieth century forties. At that time the development of jet engines, require manufacturers such as blades, impellers, nozzles and other complex shape, size, precision and smooth surface of the heat-resistant alloy parts. As the heat-resistant alloy machining difficult, complex shape parts, which can not or difficult to use other methods of manufacture, therefore, need to find a new precision in the molding process, so learn the ancient lost wax casting handed down through the material and process improved, modern investment casting method based on the ancient craft was an important development. Therefore, Promoted the development of the aviation industry the application of investment casting, investment casting and continuous improvement and perfection, but also further improve the performance of the aviation industry has created favorable conditions.
China is in the last century, the fifties and sixties began casting for industrial production. This advanced casting process was a tremendous development, one after another in the aerospace, automotive, machine tools, ships, internal combustion engines, gas turbine, telecommunications equipment, weapons, medical equipment and cutting tools and other manufacturing industries that are widely used, but also for process works of art manufacturing.
The so-called investment casting process, it simply is to use fusible materials (such as wax or plastic) can be fused model (referred to as investment casting or model), in its coated with some special fire-resistant coating layer, after drying and hardening After the formation of a whole shell, and then steam or hot water from the melting of the shell model, and then placed in sand box shell, filled with dry sand in the molding around it, and finally cast into the roaster in the high temperature baking (such as high strength shell, it can not form the shell after the stripping direct baking), mold, or after the shell by roasting, in which cast molten metal and get casting.
High dimensional accuracy of castings, generally up to CT4-6 (sand casting for the CT10 ~ 13, casting for the CT5 ~ 7), of course, the process as the process of casting complex factors that affect the accuracy of casting size larger, for example, Wax shrinkage, melting mold deformation, shell in the process of heating and cooling capacity in the line changes, the alloy solidification shrinkage and deformation of the casting process, so the size of ordinary investment castings precision are higher, but still need to improve their consistency (using the high temperature wax casting size to raise a lot of consistency).
Suppression of melting mode, the cavity surface finish using high-pressure type, therefore, melting mold surface finish is relatively high. In addition, a special shell from the high temperature binder and refractory material made into a fire-resistant coating Coating in Investment Scales and made direct contact with the molten metal surface finish cavity high. Therefore, Investment Castings Casting surface finish than the average high, generally up to Ra.1.6 ~ 3.2μm.
Casting of the biggest advantages is that because castings have a high dimensional accuracy and surface finish, it can reduce the machining work, only in part on the demanding part of machining allowance can stay a little, and even some of the cast only stay grinding, polishing margin, can be used without machining. This shows that the use of investment casting method can save a lot of machine tool equipment and processing time, a substantial savings of metal materials.
Another casting method of the advantages is that it can cast a variety of complex alloy castings, in particular, can be made into high-temperature alloy castings. Such as jet engine blades, its sleek profile and cooling outside the cavity, with the machining process almost impossible. With the production of investment casting process can be done not only to mass production, ensures consistency of the casting and machining to avoid the knife after the pattern of residual stress concentration.
The news come from: http://www.china-steel-casting.com/
