The advantage of silica sol casting is high precision

Silica sol casting is a precision casting method using silica sol as a binder. Its product has complex characteristics and is an advanced near-net molding technology. In order to cast metal castings, textile castings, sewing castings, stainless steel castings, carbon steel castings and other fine products, we should start with the following points.

1. The metal materials of metal material foundry companies mainly come from the company's purchased materials, waste castings and risers. The metal materials purchased are usually in bulk and are rarely pressed into the cylinder, and different materials can be easily mixed. If 316 material is mixed with 304 or 430 material. Therefore, casting companies should try to choose to buy pressed tubular materials. Use spectral analysis method to analyze the chemical composition of each batch of purchased materials. If possible, the supplier shall consider on-site assessment of whether the materials are marked, protected and stored in isolation.

2. Mold material

The main performance indicators of the mold are: melting temperature, solidification temperature range, heat resistance, thermal expansion and shrinkage, strength, hardness, viscosity, fluidity, coating and ash content. It is difficult for general foundry companies to test these performance indicators one by one. Therefore, when selecting suppliers, we should try our best to choose some formal enterprises with perfect quality management system, and strictly evaluate and confirm the suppliers. As one of the important performance indicators of mold materials, shrinkage rate can be tested. The shrinkage directly affects the dimensional accuracy of the casting and the quality of the shell. At present, the linear shrinkage measurement method of circular cake sample adopted in our country does not consider the influence of wax mold structure on shrinkage rate. The stepped shrinkage measurement method adopted abroad is closer to the actual situation. 3. Silica sol

The physical and chemical parameters of silica sol mainly include SIO2 content, density, Na2o content, PH value, kinematic viscosity, colloidal particle size and so on. These physical and chemical parameters mainly affect the shell strength of the coating, the stability of the coating and the powder-to-liquid ratio of the coating. General foundry companies, because it is difficult to detect these physical and chemical parameters, on the one hand, strengthen the selection, supplier evaluation and confirmation, on the other hand, the surface layer should choose to use different specifications of silica sol, such as the surface layer Choose s-830 silica sol and s-1430 silica sol for the back layer.

4. Surface coating

Foundry companies generally choose zirconium powder as the surface coating. When the zirconium powder contains oxide impurities, the decomposition temperature decreases and amorphous Sio2 precipitates. Certain elements in the metal will undergo a chemical reaction, causing defects such as "pitting" on the surface of the casting, which will deteriorate the surface quality of the casting. The particle size and distribution of zircon powder directly affect the powder-to-liquid ratio. Therefore, the selection of suppliers should be strictly controlled. The application results show that the quality of Australian zircon powder is better.