Summary Of Knowledge Of Precision Casting Processing Process

Precision casting processing is one of the methods of casting. Precision casting is a special casting method compared to the traditional casting process. It can obtain relatively accurate shapes and high casting accuracy. The more common practice is: firstly, according to the product requirements to design and manufacture (the margin can be very small or no margin) mold, with the casting method to cast wax, to obtain the original wax model; Repeat the coating and sanding process on the wax mold, harden the shell and dry; Then the internal wax mold is dissolved to remove the wax and obtain the cavity; Roasted shells for sufficient strength and breathability; Metal materials required for pouring; The sand is removed after hulling, so as to obtain a high-precision finished product. According to the needs of precision casting products, heat treatment and cold working are carried out.

 

1. What is precision casting of stainless steel

In the production of stainless steel products, when some products have strange shapes and cannot be produced by bending pipes and other processes, in order to produce such irregularly shaped products (hollow or solid inside), a process of using wax molds → to make sand molds → liquid materials is used.

Advantages: It is possible to make products with different styles according to different wax patterns.

Disadvantages: the accuracy of the forming blank is not high, and the surface roughness is large.

 

2. Precision casting process
1. Make molds according to different shapes of products. The mold is divided into upper and lower concave mold methods, which are completed through comprehensive processes such as turning, planing, milling, etching, and electric sparking. The shape and size of the pit are the same as half of the product. Because the wax die is mainly used for industrial wax pressing, the aluminum alloy material with low melting point, low hardness, low requirements, cheaper price and light weight is selected as the mold.

2. Use aluminum alloy molds to produce a large number of industrial wax solid core models. Under normal circumstances, an industrial wax solid core model can only correspond to one blank product.

3. The peripheral margin of the wax mold is refined, and a plurality of single wax patterns are glued to the pre-prepared die (also known as the group tree) after deburring, and this die is also an industrial wax solid core model produced by wax molds. (Looks like a tree)

4. A plurality of wax molds that have been fixed on the die are coated with industrial glue and evenly sprayed with a layer of fine sand (a kind of refractory sand, high temperature resistance, usually silica sand). The sand particles are small and fine, which ensures that the surface of the blank is as smooth as possible.

5. Let the wax mold sprayed with a layer of fine sand dry naturally at the set room temperature (or constant temperature), but it can not affect the change of the internal wax mold, and the natural air-drying time depends on the complexity of the product itself, and the general air-drying time of precision castings is about 5-8 hours. 10. Baking sand shell In order to make the sand shell of the waxed sand more solid and stable, before pouring stainless steel water, the sand shell should be baked, usually in a very high temperature (the temperature is about 1000 ゚) in the oven.

Stainless steel water, which has been dissolved into a liquid state at high temperature, is poured into the dewaxed sand shell, and the liquid stainless steel water fills the space where the wax mold was formed until it is completely filled, including the middle die part.

Because there will be materials of different compositions mixed in the boiler of dissolved stainless steel, the factory needs to check the percentage of materials. It is then adjusted according to the desired proportions, such as adding those aspects of the elements to achieve the desired effect.

After the liquid stainless steel water is cooled and solidified, the outer layer of sand shell is broken with the help of mechanical tools or manpower, and the solid stainless steel product is exposed, which is the shape of the original wax model, that is, the required blank. They are then cut and separated one by one and then coarsely ground to become a single blank

Inspection blank: The blank with sand hole and porosity on the surface should be repaired with argon arc welding, and the waste product should be returned to the furnace after cleaning.

Cleaning blanks: Blanks that have passed the inspection must go through the cleaning process.