Film coated sand shell casting

Main process flow

Mold preparation: Heat the metal mold to a certain temperature (usually around 250-300 ° C).

Shell making: Injecting or pouring coated sand into a hot mold, the resin layer in contact with the mold is melted by heat, and the sand particles bond to form a solid sand shell with a controllable thickness (usually a few millimeters to tens of millimeters) on the surface of the mold.

Hardening and ejection: The sand shell continues to be heated on the mold to fully cure the resin, and then ejected to obtain half of the shell.

Shell combination: Two half shells (or combined with the core) are bonded together with adhesive to form a complete hollow thin shell cavity.

Pouring: Place the shell into a sand box, and support and fix it with dry sand or other materials around it to pour the molten metal.

Cleaning: After the casting cools down, the shell can be broken to obtain the casting, and the coated sand is usually not recyclable.

main advantages

High casting quality: high dimensional accuracy, good surface smoothness (up to Ra 6.3-12.5 μ m).

High production efficiency: The shell making process is fast, the shell strength is high, and it is convenient for mechanized and automated production.

Good flexibility: It can produce castings with complex shapes and thin wall thicknesses, especially suitable for manufacturing high-precision cores.

main drawback

High mold cost: requires heat-resistant metal molds, with a large initial investment.

Limited shell size: usually more suitable for producing small and medium-sized castings.

Environmental pollution: Resin will produce certain irritating gases during the heating process, which requires supporting environmental protection equipment.

Difficulty in regenerating old sand: The cost of recycling and reusing coated sand after use is relatively high.

Application field

Specially suitable for mass production of small and medium-sized cast iron and steel parts with high surface quality requirements and good dimensional accuracy. Typical products include:

The cylinder head, crankshaft, camshaft, and intake manifold of a car engine.

Various hydraulic components such as hydraulic valve blocks and pump bodies.

Various complex pipe joints, wear-resistant bushings, etc.

In summary, film coated sand shell casting is a casting method that pursues high precision and excellent surface quality. Although the mold cost is high, it has irreplaceable advantages in industrial mass production fields with strict requirements such as automobiles and hydraulics.