Precision Casting By Dewaxing Method

Features and Advantages
(1) The maximum limit length of the casting is 700mm, and the easy length is less than 200mm. The maximum weight of the cast is about 100 kg, usually less than 10 kg.
(2) The dimensional tolerance of the casting is 20mm ± 0.13mm, 100mm ± 0.30mm, 200mm ± 0.43mm, while the dimensional accuracy of the small piece is not easy to reach less than ± 0.10mm. The angle tolerance is ± 0.5~ ± 2.0 degrees, and the minimum thickness of the casting is 0.5~1.5mm. The surface thickness of the casting is about Rmax 4S~12S.
(3) Casting material is almost without any restrictions, such as aluminum alloy, magnesium alloy, titanium alloy, titanium alloy, copper alloy, all kinds of steel, cobalt-based and nickel-based heat-resistant alloy, hard materials.
(4) Production of workpieces with complex shapes, good size precision, less cutting and processing.
(5) Save material waste, and can be produced in bulk.
Dewaxed precision castings are widely used in jet engines, gas turbines, steam turbines, aircraft parts, vehicles, internal combustion engines, vehicles, food machinery, printing machinery, paper making machinery, compressors, valve parts, robots, meters, sewing machines, weapons, transaction machines, and other machine parts.
2-2 Process
There are two types of dewaxing casting method: solid mold (Solid Mold) method and ceramic shell mold (Ceramic Shell Mold) method, the latter is the improvement method of the former.
The solid die method makes molds similar to the final casting size after considering the condensation shrinkage of the cast mold and the condensation shrinkage of the molten metal. The melted wax is poured into the mold made of metal or silica gel. After removing the wax type, soak the powder refractory and binder. After dripping, sprinkle the coarse refractory and dry it. Put in the cast frame, fill the powder with binder, and then dry. Then heat it to melt the wax out of the mold. Heat the mold at high temperature, burn a small amount of residual wax and increase its strength, and then inject the metal flux.
The ceramic shell mold method until the wax type is the same as the solid mold method, but after a slurry and sand (or floating sand), not the mold operation, but repeatedly to the slurry and sand until the predetermined shell thickness is obtained. Dry, heating, melting out of wax, high temperature heating and then pouring, this method is widely used in the current dewaxing precision casting industry, because it has the following advantages:
(1) Good dimensional stability
(2) Less use of refractory materials
(3) Light weight, easy to carry, handle, and make large castings
(4) The manufacturing process can be partially automated to save manpower and improve the production rate
(5) Low production cost
(6) The ceramic shell mold is relatively thin, and the cooling rate of the casting after pouring is relatively high and uniform, so its mechanical properties are better.
(A) Master Model (Master Pattern)
The shape of the main model is similar to the final product. The condensation and shrinkage of the wax, and the heating and expansion and the condensation and shrinkage of the casting mold must be considered in the casting metal. For example, when the shrinkage rate of wax type is 1.2%, the thermal expansion rate of casting mold is 0.7%, and the shrinkage rate of casting metal is 1.7%, the size increase rate of the main model is 2.2%, and the commonly used materials are aluminum alloy and copper