Chromite Sand AFS45-55 for Foundry Mining Equipment Castings Parts
In the production of heavy-duty mining equipment castings parts, the choice of foundry sand plays a critical role in casting quality. Chromite sand AFS45-55, due to its unique properties, is an ideal choice for these applications.
1. High refractoriness for high-temperature environments.
During the pouring process of heavy-duty mining equipment castings, the molten metal temperature is extremely high. Chromite sand AFS45-55 boasts a refractoriness of 1770-2000°C, capable of withstanding the impact of hot molten steel without softening or melting. This ensures sand mold stability at high temperatures and prevents defects such as sand erosion and pinholes in the casting.
For example, when casting thick castings such as jaw plates for large crushers, the highly refractory chrome ore sand maintains the integrity of the sand mold, ensuring high-quality castings.
2. Excellent anti-sand sticking performance ensures casting surface quality.
During the solidification process of heavy castings, intense thermal, mechanical, and chemical reactions occur between the molten metal and the sand mold, easily leading to metal penetration and sand sticking, which affects the dimensional stability and surface quality of the casting. The chemical composition of chromite sand AFS45-55 (e.g., Cr₂O₃ content ≥46.0%, SiO₂ content ≤1.0%) gives it excellent anti-sand sticking performance. For example, a large foundry, producing the upper, middle, and lower frames and crossbeam steel castings for a gyratory crusher (maximum gross weight 75t), used chromite furan resin sand in all sand core fillets and hot spots. After cleaning, the casting, except for a few hot spots, remained smooth and clean, effectively preventing sand sticking, reducing subsequent cleaning work, and improving production efficiency.
3. Moderate particle size distribution meets process requirements.
AFS45-55 indicates a particle size distribution within a specific range of 0.25-0.35mm. This particle size ensures sufficient air permeability in the molding sand, allowing gases generated during pouring to escape smoothly and preventing porosity in the casting. It also provides suitable bonding strength between the sand particles, preventing mold collapse during handling, assembly, and pouring. In actual production, some companies, such as those producing large steel castings, use chromium ore sand of this particle size, combined with appropriate binders, to achieve excellent overall molding sand properties.
4. High thermal conductivity promotes sequential solidification of castings.
The high thermal conductivity of chrome ore sand AFS45-55 enables rapid cooling of castings, facilitating sequential solidification. In heavy-duty castings for mining equipment, such as large gears and shafts, sequential solidification can densify the casting’s internal structure, reduce defects such as shrinkage cavities and porosity, and improve the casting’s mechanical properties and service life. For example, when casting high-impact and high-wear components like bucket teeth for large excavators, the sequential solidification promoted by chromite sand ensures better internal quality and enhances wear and impact resistance.
5. Low thermal expansion coefficient reduces casting defects.
During the pouring and solidification process of heavy castings, large temperature differences occur between different parts of the sand mold. Chromite sand AFS45/55 exhibits minimal thermal expansion, preventing defects such as dimensional deviation and cracking in the casting caused by sand mold expansion. When producing castings requiring high dimensional accuracy, such as large motor casings, chromium ore sand with a low thermal expansion coefficient can better ensure dimensional accuracy and reduce scrap rates.
6. Strong chemical stability.
Chromite sand is chemically stable and does not readily react with the molten metal during the casting process. This avoids defects such as slag inclusions and pores caused by chemical reactions, ensuring the purity and consistent quality of the casting. The chemical stability of chromium ore sand is particularly prominent for mining equipment castings requiring high material purity, such as corrosion-resistant pump bodies.
In summary, chromite sand AFS45-55, with its high refractoriness, anti-sand sticking, suitable particle size, high thermal conductivity, low expansion coefficient and chemical stability, can effectively meet the casting requirements of heavy castings of mining equipment, improve casting quality and production efficiency, and is therefore widely used as foundry sand.
