​Silica sol investment casting shell

Plain carbon steel is mainly used to manufacture machine parts and various metal components with general strength requirements, and is widely used in all aspects of machinery manufacturing. In order to improve and enhance the performance of steel, other alloying elements are added to carbon steel. Alloy steel has different properties according to the addition of alloying elements, such as high wear resistance, corrosion resistance, low temperature resistance and other good special properties. 

Silica sol is a recognized mold shell binder. Compared with water glass and ethyl silicate, its main advantages are high temperature strength and creep resistance of the mold shell, easy coating preparation and use, no environmental pollution, and mold shell And the quality of castings is high, and the scrap rate and repair rate of castings are low.

The silica sol molding process is an advanced net molding process. The paste wax has good formability and copyability. Manual or pneumatic wax pressing equipment can be used to press wax molds for medium and small castings or extra large castings with a mass of 200kg. Wax molds are widely used.

Preparing silicone sol adhesive

The binder mainly plays a role in bonding and enhancing the strength of the investment casting shell. Its composition and characteristics are important factors affecting the slurry. Inorganic silica sol contains a large number of small (nano-scale) SiO2 particles with high surface energy, which can itself trigger gel aggregation; through the synergistic effect of silane coupling agent and organic alcohol, the organic materials and inorganic materials in the mixed gel can be Materials are joined together to further enhance material properties, increasing strength and breathability. In addition, the addition of silane coupling agent, surfactant, dispersant, and latex promotes the dispersion of nylon fibers, further improves the breathability uniformity of the adhesive, and results in better stability.

Add ingredients

(Inorganic silica sol, silane coupling agent, organic alcohol, wetting agent, polymethacrylic acid amine, latex)

Add the inorganic silica sol and these additives to the container, stir and mix evenly, then perform ultrasonic treatment for 20 minutes, then add the latex and stir for 10 minutes to obtain the silica sol adhesive

Refractory materials

Refractory materials mainly play a role in improving the comprehensive performance in precision casting shells. The refractory degree of white jade corundum is 2000°C, and the main chemical component is Al2O3, with a content of more than 98%. It can not only effectively enhance the fire resistance and corrosion resistance of the product It also ensures the smoothness of the surface of the casting, and is suitable for preparing products of various sizes and shapes; when silicon oxide, chromium oxide, and manganese oxide powder are added in a specific ratio, their filling effect can be fully exerted, helping The fluidity of the castable is enhanced, thereby reducing the usage of raw materials and improving the strength of the product.

Formulate coatings

Ultrasonic treatment: Ultrasonic oscillation moves and combines the molecules inside the silica sol. The reaction speed is fast and the effect is obvious.

Weigh 40 parts of 320-mesh white jade corundum powder, 5 parts of chromium oxide powder, 5 parts of manganese oxide powder, and 5 parts of silicon oxide powder respectively according to mass parts and mix them evenly to obtain a refractory material, and then bond the refractory material to the silica sol The agent is mixed according to the ratio of 4.2:1 to prepare the surface coating.

Mix 20 mesh Malay sand and silica sol adhesive in a ratio of 1.4:1 to prepare the back coating.

shell making

Blow the surface of the molded wax mold clean with gas, and then immerse the cleaned wax mold into the surface coating for coating. Then take out the soaked wax mold and use a rain shower sand spreader to spread refractory materials. Dry layer by layer. The drying temperature is controlled at 24°C and the relative air humidity is controlled at 60%. Repeat the above-mentioned film hanging, sand spreading and drying three times to obtain the shell surface layer.

Dip the surface layer of the mold shell into the back layer paint to hang the film. Then take out the soaked wax mold, use a rain shower sand spreader to spread Malay sand, and dry it layer by layer. The drying temperature is controlled to 24°C. , control the relative air humidity to 60%, repeat the above-mentioned film hanging, sanding and drying three times to obtain the wax model shell

Dewaxed sintering

Use hot water or low-pressure steam dewaxing to dewax the mold shell to obtain the mold shell blank

Put the shell blank into a high-temperature sintering furnace for sintering at 1000°C. The holding time is 60 minutes. The furnace is cooled to room temperature. The sintered shell is taken out and polished again to obtain the casting shell.

Precision casting castings are classified according to material:

Plain carbon steel precision castings, alloy steel precision castings, stainless steel precision castings and stainless iron precision castings

If classified according to application fields, it can be divided into:

Automobile castings, high-speed rail castings, motorcycle parts castings, ship castings, bathroom castings, lock castings, chemical machinery castings, engineering machinery castings, medical equipment castings, pneumatic tool castings, nail gun accessories castings, sewing machine parts castings