Below are a series of photos describing the aluminium casting process.
Aluminium Casting Cores
Depending on the complexity of the aluminium casting – such as engine mounts and gear boxes used in boats – certain parts of the castings may need to be hollowed or of more intricate shapes that are simply not possible from a pattern board, resulting in the need for sand cores.
Sand cores are hand made sand mouldings that are shaped to be placed inside the casting box after the associated pattern has been removed.
After a core has been completed, it is covered in a liquid mix of Refractory coating and Isopropanol and then set alight. This ensures that when the molten metal is poured into the casting box, it does not break through the sand and cause a pimple effect against the sand core, making sure that the castings is of highest quality.
The green sand needs to be packed around the shape of the wooden pattern and to do so it needs a specific casing to hold it, known as a moulding box. These are designed to withstand the heat of the molten metal and not allow the green sand to expand or adjust in any way. The cores are placed within the green sand and the moulding boxes to allow the metal to shape around it.
Once the metal has been melted and has settled to the appropriate temperature, it is then poured into the moulding boxes using a specially designed ladle. If the metal is too cold, it will begin to solidify and not fill the space within the sand.
Fettling is the process of smoothing the surface of the metal so there are no imperfections, ensuring the quality and strength of the product.
Completed aluminium castings