Shell Mold Casting

Shell mold casting is a sand-like metal building system in which condensed steel is placed into an expendable mold. The mold, however, is a thin-walled shell produced by adding a sand-resin combination around a motif in shell mold casting. The model is utilized to create various shell molds, a metal element in the shape of the required portion. A reusable model enables greater manufacturing prices, while the disposable molds allow the casting of complicated geometries. Shell mold casting needs a metal model, furnace, combination of sand-resin, dump tank, and molten metal to be used.

Shell mold casting enables both ferrous and non-ferrous metals to be used, most frequently using cast iron, coal steel, alloy steel, stainless steel, aluminum alloys and metal alloys. Typical components are small to medium in size and involve elevated precision such as equipment housings, heads of the cylinder, linking wires and arms of the lever.

The shell mold casting process consists of the following steps:

1. Pattern creation - A two-piece metal pattern is created in the shape of the desired part, typically from iron or steel. Other materials are sometimes used, such as aluminum for low volume production or graphite for casting reactive materials.
2. Mold creation - First, each pattern half is heated to 175-370°C (350-700°F) and coated with a lubricant to facilitate removal. Next, the heated pattern is clamped to a dump box, which contains a mixture of sand and a resin binder. The dump box is inverted, allowing this sand-resin mixture to coat the pattern. The heated pattern partially cures the mixture, which now forms a shell around the pattern. Each pattern half and surrounding shell is cured to completion in an oven and then the shell is ejected from the pattern.
3. Mold assembly - The two shell halves are joined together and securely clamped to form the complete shell mold. If any cores are required, they are inserted prior to closing the mold. The shell mold is then placed into a flask and supported by a backing material.
4. Pouring - The mold is securely clamped together while the molten metal is poured from a ladle into the gating system and fills the mold cavity.
5. Cooling - After the mold has been filled, the molten metal is allowed to cool and solidify into the shape of the final casting.
6. Casting removal - After the molten metal has cooled, the mold can be broken and the casting removed. Trimming and cleaning processes are required to remove any excess metal from the feed system and any sand from the mold.