subject: The Concept Of Precision Casting [print this page] The precision casting is compared with the traditional casting a foundry method. It can get relatively accurate shape and high precision casting. A common approach is needed to make the blank: firstly, and then using electrodes electrode, corrosion mode formed cavity. The method with casting, the original casting wax wax models. In the wax models layers of liquid brush high-temperature sand. To obtain enough thickness after dry, warm, make interior wax pattern, and melting consistent die-cavity. Required blank In the molten iron casting, curing cavity after shelling shell, can obtain precise manufacturing finished!
Lost wax casting method is called revestment precision casting, is a little or no cutting cutting of casting process, is one of the foundry industry outstanding technology, its application is very extensive. It not only applicable to all types, various alloy casting, and produce the precision and surface quality of castings than other casting method to high, even other casting method to cast the complex, high temperature resistant, not easy machining castings, all can use revestment precision casting casting.
Revestment precision casting is in ancient wax casting developed on the basis of. As the ancient civilizations, China is using this technique, one of the early centuries BC, in ancient China's labor created the lost wax casting technique, with various fine decorative pattern and casting of the text ZhongDing and vessels products, such as spring when zenghou yi tomb honour plate etc. Zenghou yi tomb honour for multiple disk base of each coil dragon, end to end, fluctuation, forming hollow tubular multi-layer moire among these patterns using common patterns, casting, and to make with lost wax casting method, can use without strength, easy to carving wax, use common tools can be carved by the zenghou yi tomb of paraffin wax statue plate material handicraft, then add gating system, coating, dewaxing, pouring, can get fine zenghou yi tomb honour.
Modern investment casting method in practical application in industrial production in the 1930's. When air jet engine development, manufacture, impeller blades as complex shape and nozzle, etc, and the surface is bright and clean the size precise meritett papir parts. Due to the heat resistant alloy material, hard machining parts, that cannot be complex shape or difficult to use other methods, therefore, need for manufacturing a new precision molding process, so the handed down from ancient times and the lost wax casting process improvement, materials and modern investment casting method in ancient process on the basis of the development of important gain. Therefore, the aviation industry development promoted application of investment casting and casting of continuous improvement and perfection, and further enhance the performance for the aviation industry created favorable conditions.
Our country is in the 1950s and 1960s began casting will be applied to industrial production. Subsequently the advanced foundry technology gets huge development, successively in aviation, automotive, machine tool, ship, internal combustion engines, gas, telecommunications equipment, weapons, medical equipment and tools etc widely used in manufacturing industry, also used in arts and crafts.
So-called investment casting process, is a simple fusible materials can melt in the sexual model, some special coating layer of refractory coating, after drying and forming an integrated shell, reoccupy steam or hot melt away from the shell, then the model of sand box shell in filling in the round, modelling, finally will dry sand casting has been put in high-temperature roasting, casting or shell after roasting, in which the pouring molten metal and casting.
Investment casting dimension precision, generally can reach CT4-6, of course, due to the investment casting process complex, the influence factors of the dimension precision casting mould material, such as shrinkage, the deformation and introduced.technology shell in heating and cooling process line changes, the shrinkage and alloy casting during solidification process of deformation etc., so ordinary revestment precision castings, but its consistency, although still need to improve.
When pressing revestment by cavity surface finish high pressure, therefore, is introduced.technology of surface finish is high. In addition, the shell by high temperature resistant special binder and refractory materials preparation of refractory coatings introduced.technology hanging in the molten metal, and made the cavity in direct contact with high surface finish. Therefore, the investment casting surface finish than general casting high, can reach Ra. 1.6 ~ 3.2 muon m.
Casting the biggest advantage is due to the investment casting with high precision and surface finish, so can reduce machining parts in the work, but a higher requirement of the position, and even some limits.but can only leave buffing and casting, machining allowance can be used. Thus, the welding casting method can save machine equipment and processing of metal materials, greatly saves.
Investment casting method of another advantage is that it can be cast all kinds of alloy castings, especially the complex of high temperature alloy castings can cast. As the jet engine blades, the streamline the contour and cooling with inner cavity machining process, with almost can't form. In investment casting process not only can batch production, to ensure the consistency of casting, machining and avoid the grain after the residual stress concentration.
