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Sand Casting


Sand casting is a commonly used casting method that utilizes sand molds as casting molds to pour molten metal into the mold cavity, creating metal parts with the desired shape. The process involves mold preparation, pattern preparation, sand mold preparation, metal melting, pouring, solidification and cooling, as well as mold breakage and post-processing steps.

Mold preparation is the first step in sand casting. Typically, molds are made from materials such as aluminum alloys, copper alloys, etc. Detailed design and mold manufacturing processes are required to prepare the molds. The shape and size of the mold should match the final product.

Pattern preparation involves creating a model that represents the external shape of the sand mold. The pattern can be a physical sample, a 3D printed part, or a model made of wood, foam, or polystyrene.


Sand mold preparation is the core step in sand casting. Firstly, a layer of mold release agent is applied to the pattern surface to prevent it from sticking to the sand mold. Then, a flask is placed on the pattern and sand is poured into the flask to cover the entire pattern. The sand mixture usually consists of fine sand and a binder. The sand mold needs to undergo processes like squeezing, vibrating, and leveling to ensure a uniform and accurate mold.

The metal is melted by selecting an appropriate metal alloy and heating it to a liquid state. The molten metal is then poured into the sand mold to fill the entire cavity.

During pouring, the molten metal is slowly poured into the sand mold to ensure that it fills every detail of the mold. The pouring speed and pressure need to be controlled to avoid the formation of bubbles.

After pouring, the metal starts to cool and solidify gradually. During this process, the internal crystal structure of the metal gradually forms, ultimately affecting the mechanical properties and microstructure of the product.

Once the metal has solidified, the sand mold is broken, exposing the metal casting. The casting then undergoes post-processing such as removing burrs, polishing, and trimming to improve the surface finish and dimensional accuracy.

The advantages of sand casting include the ability to produce large and complex shaped castings, relatively low cost as sand is an economical material and mold preparation is relatively simple, short production cycle suitable for rapid production and short-term delivery demands, and the reusability of sand molds with a relatively long mold lifespan with proper maintenance.

The disadvantages of sand casting include relatively lower surface precision and quality, which may require subsequent machining, lower dimensional accuracy of the sand castings, and the generation of by-products such as waste sand and wastewater, causing certain environmental pollution.

In the future, sand casting still has development potential. Some trends include improving sand mold preparation technology to enhance surface quality and dimensional accuracy, exploring new sand mold materials and binders to improve casting performance and quality, optimizing sand casting processes through simulation technology to reduce defects, integrating other manufacturing technologies like 3D printing and CNC machining to enhance the precision and production efficiency of sand casting, and exploring sustainable sand casting methods to reduce environmental pollution and resource consumption.

In conclusion, sand casting is a mature casting method with wide application. Through continuous improvement and innovation, sand casting can still meet the demand for complex shaped and small to medium volume metal parts in various industries, achieving better quality and results in practice.


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