what is investment casting

Lost wax casting method now known as the Investment Casting, a little cutting or cutting the die casting process, the foundry industry is a superior technology, its application is very extensive. It is not only applicable to all types, all kinds of alloy casting, casting and production of dimensional accuracy, surface quality than other methods of casting is higher, or even other methods of casting difficult to cast a complex, high temperature, difficult in the casting process, Can be used Investment Casting a cast.

Investment Casting in the ancient wax casting on the basis of developed. As countries with ancient civilizations, China is using the technology of the earlier one, about a few hundred years before Christ, ancient China to working people to create this kind of lost wax casting technique, used with a variety of fine casting patterns and text Zhong Ding and products such as containers, such as the Spring and Autumn when the statue of the tomb site, and so on. Tomb sites chassis respect for each other more than the winding-long, they both connected, staggered up and down to form a multi-layer in the middle of the hollowing-like moire patterns, the general pattern casting process is difficult to manufacture, use and lost wax casting method Technology can not use paraffin strength, easy-to-carved features, you can use common tools and carving out to be the tomb site, like the wax statue of the craft materials, and then pouring additional systems, paint, dewaxing, Casting, you can be beautiful statue tomb site.

Modern methods of investment casting in industrial production in the practical application of the twentieth century in the 1940s. At that time, aviation jet engine development, manufacturing requirements such as leaves, impeller, the complex shape of the nozzle, and so on, as well as the exact size of the smooth surface of heat-resistant alloy parts. As the heat-resistant alloy machining difficult, complex shape parts, or can not be so difficult to use other methods of manufacture, therefore, need to find a new precision of the molding process, they have been handed down from ancient lost wax casting, through to the materials and processes Improvement of modern methods in the investment casting process on the basis of ancient times was an important development. Therefore, the development of the aviation industry to promote the application of investment casting, investment casting and continuous improvement and perfection, but also for the aviation industry to further improve performance and create favorable conditions.

Our country is in the last century in the 1950s and 1960s to the beginning of investment casting used in industrial production. Later this advanced technology has been casting a huge development, one after another in the aerospace, automotive, machine tools, ships, internal combustion engines, gas turbine, telecommunications equipment, weapons, medical equipment and cutting tools, such as manufacturing that are widely used in industry, but also for the process Art manufacturing.

The so-called investment casting process, it is simple to use fusible materials (such as wax or plastic material) can be made of fused model (referred to as casting or model), in its coating on a number of tailor-made fire-resistant coating layer, after drying and hardening A whole-shell, and then steam or hot water from the melting of shell-out model, and then placed in the shell-sand box, filled with dry sand around its shape, will be cast into the final after a high temperature in the roaster Roasting (such as high-strength shell, the shape and will not have to be after the release of the direct-shell roasting), or mold-shell by roasting after pouring molten metal which has been cast.

aluminum die Casting and sand casting or iron casting  a higher dimensional accuracy, usually ranging from CT4-6 (sand casting for the CT10 ~ 13, for the die-casting CT5 ~ 7), Investment Casting, of course, because of the complexity of the process, the impact of dimensional accuracy of casting many factors, such as The module is expected to contract, deformation of the casting, shell-type heating and cooling in the course of the line changes, alloys, as well as shrinkage in the solidification of the casting process, such as deformation, the General Casting although the size of high precision, but Still needs to improve its consistency (used in high-temperature wax casting material to improve the lot size consistency).

Suppression of casting, the cavity surface finish using high-pressure, the casting of the relatively high surface finish. In addition, the type shell from the special high temperature refractory material and adhesive preparation of fire-resistant paint coating hung on the casting and made direct contact with the molten metal of the high-cavity surface finish. Therefore, the Investment Casting surface finish than the average high-castings, usually ranging from Ra.1.6 ~ 3.2μm.

Casting of the biggest advantages is that because of Casting a very high dimensional accuracy and surface finish, it can reduce the machining work, but in the higher parts of the site can stay a little allowance, or even just some of the casting Stay grinding, polishing margin, do not have to use the machine. This shows that the use of investment casting method can save a large number of machine tools and processing equipment, working hours, a substantial saving of metal raw materials.

Casting another advantage of the method is that it can cast a variety of complex alloy castings, in particular, can cast high-temperature alloy castings. Such as jet engine blades, with its streamlined profile outside the cooling cavity, the mechanical process is almost impossible to form. To use investment casting process can produce not only do mass production to ensure the consistency of the casting and machining to avoid the knife after the pattern of residual stress concentration.