Production of castings for complex shaped components
Metal casting is used to form intricate shapes in 3-dimensions that would be difficult, expensive or time consuming to produce via other methods, and results in an integral component. There are many different variants of casting, but for the industries typically served by Langley Alloys, sand casting predominates.
1. The first stage of sand casting is creating a pattern. This is a replica of the outside of the desired part, with suitable allowances for thermal shrinkage. Patterns have traditional been formed from a combination of wood, plaster and metal, depending upon the size and detail.
2. If the casting is to be hollow, additional patterns (cores) are made to form these cavities in the finished product. Cores are typically made from sand (mixed with water and a binder), which are fired to form a strong, but able to be broken up and removed after casting.
3. Patterns and cores are combined to form a mold. Additional arrangements are made in the sand, such as runners (where the molten metal will flow) and reservoirs (to feed additional molten metal into the mold as it contracts) as well as chillers (blocks to encourage quick solidification in selective areas).
4. The desired alloy is melted and transferred by ladle to the mold. After sufficient time to allow cooling, the molds are ‘shaken out’ with the casting separated from the sand.
5. Finally, the casting is cleaned. Runners can be mechanically removed, whilst cores can usually be removed by compressed air if required. Non-destructive testing can be carried out, including dye penetration inspection on outer surfaces or radiography through the casting.
Langley Alloys history as an integrated manufacturer with in-house foundry means that we have retained expertise and links with partners able to undertake castings on our behalf.