Sand Casting Process Sand casting is one of the oldest and most widely used metal casting processes, known for its simplicity, versatility, and cost-effectiveness. It involves pouring molten metal into a sand mold to create a desired shape. The process is suitable for producing both small and large components in various metals, including iron, aluminum, bronze, and steel. Key Steps in Sand Casting 1. Pattern Making A pattern, typically made of wood, plastic, or metal, is created in the shape of the final part. The pattern includes allowances for shrinkage and machining. 2. Mold Preparation The pattern is placed in a flask (a two-part box), and molding sand is packed around it. The sand mixture consists of silica sand, clay, and additives to improve strength and permeability. The mold is split into two halves (cope and drag) to remove the pattern. 3. Core Making (if required) For hollow or complex internal features, sand cores are inserted into the mold cavity. Cores are made from bonded sand and are placed in the mold before closing. 4. Mold Assembly The cope and drag are reassembled, ensuring proper alignment. Channels called gates and risers are added to allow molten metal to flow into the cavity and gases to escape. 5. Melting and Pouring The metal is melted in a furnace and poured into the mold through the gating system. The pouring temperature and rate are controlled to avoid defects. 6. Cooling and Solidification The molten metal cools and solidifies inside the mold. Cooling time depends on the metal type and part thickness. 7. Shakeout and Cleaning Once cooled, the sand mold is broken apart to retrieve the casting. Excess sand, cores, and gates are removed. 8. Finishing Operations The casting undergoes cleaning, grinding, and machining to achieve the final dimensions and surface quality. Advantages of Sand Casting - Low tooling cost compared to other casting methods. - Suitable for large and heavy parts. - Can produce complex geometries. - Works with a wide range of metals. Limitations - Lower dimensional accuracy compared to precision casting. - Surface finish may require additional machining. - Labor-intensive for high-volume production. Despite its limitations, sand casting remains a fundamental manufacturing process due to its flexibility and cost efficiency, making it ideal for prototypes, custom parts, and industrial applications.