Shell moulding is a metal casting process that uses a resin-coated sand mixture to form an expendable mould around a reusable metal pattern. This allows for higher production rates compared to sand casting, with better dimensional accuracy and precision for small to medium parts. The process involves heating metal patterns, coating them with sand and resin to form shell halves, assembling the shells to create the mould cavity, pouring molten metal, cooling and solidification, then removing the casting. It is commonly used for automotive and engine components that require precision dimensions.