Shell Mold Casting

Shell Mold Casting

Shell moulding, also known as shell-mould casting, is an expendable mould casting process that uses resin covered sand to form the mould. As compared to sand casting, this process has better dimensional accuracy, a higher productivity rate, and lower labour requirements. It is used for small to medium parts that require high precision. Shell moulding was developed as a manufacturing process during the mid-20th century in Germany. It was invented by German engineer Johannes Croning. Shell mould casting is a metal casting process similar to sand casting, in that molten metal is poured into an expendable mould. However, in shell mould casting, the mould is a thin-walled shell created from applying a sand-resin mixture around a pattern. The pattern, a metal piece in the shape of the desired part, is reused to form multiple shell moulds. A reusable pattern allows for higher production rates, while the disposable moulds enable complex geometries to be cast. Shell mould casting requires the use of a metal pattern, oven, sand-resin mixture, dump box, and molten metal.

Shell mould casting allows the use of both ferrous and non-ferrous metals, most commonly using cast iron, carbon steel, alloy steel, stainless steel, aluminium alloys, and copper alloys. Typical parts are small-to-medium in size and require high accuracy, such as gear housings, cylinder heads, connecting rods, and lever arms.

Production Process

Moulding Line—Make Core—Melting—Pouring—Automatic Cutting—Heat Treatment—Shot Blast—CNC Machine

Inspection Center

Sand testing equipment—Metallurgical microscopy—Creaform 3D scanning machine—Impact test in low and room temperature—Spectrometer—CMM & Layout table—Magnetic powder inspection machine—Mechanical testing machine—Hardness tester—X-Ray inspection equipment—Ultrasonic  testing machine—NDT Level

Advantages of Shell mold casting

Shell mold casting  offers a number of important advantages.

    1. It permits the creation of very complex, detailed metal components. It offers an excellent way to produce small and medium-sized shapes, especially parts requiring accurate manufacturing.

    2. This form of casting today may occur in highly automated environments; production does not impose a high demand for labor following the creation of the metal pattern.

    3. Since Shell mold casting  generates intricate parts repetitively, manufacturers utilizing this process may avoid some manufacturing tooling costs required for other production processes. Fourth, depending upon the raw materials employed, Shell mold casting  may result in the creation of very attractive exterior surfaces. Parts may require a minimal investment in finishing, for instance.

    4. Shell mold casting  utilizes raw materials with a high degree of efficiency. Manufacturers who employ this process typically will conserve metals and metal alloys without wasting these assets. As with many other forms of casting, when a work piece fails to meet required specifications, a manufacturer can simply re-melt it and re-use the constituent raw materials.

    5. Since this casting process lends itself to automation in high volume production environments, it permits companies to generate large quantities of metal parts rapidly. The production of expendable shell molds may occur repetitively. While a manufacturer will eventually need to replace the metal pattern, that cost arises infrequently.