Gravity Die Casting is a permanent mould casting process, where the molten metal is poured from a vessel or ladle into the mould. The cavity fills with no force other than gravity, filling can be controlled by tilting the die. As with the low pressure process, undercuts can be incorporated into the component form with the use if separate sand cores. This process gives a better surface finish than sand casting as well as better mechanical properties, both due to rapid solidification.
Additionally, this process has a higher casting rate than sand casting, however, the metal moulds are higher cost than sand. Advantages of this process include the possibility of low gas porosity and fine grain sizes can be achieved. Compared to sand casting, this process requires less finishing and fetling and gravity die casting tends to produce the highest quality product, but the accuracy achievable is limited with minimum wall of thickness of 3 to 5mm. The Gravity die casting production method is more cost effective in the manufacture of tooling compared with high pressure die casting with the flexibility of manufacturing complex internal shapes. What is more, castings can be heat treated to improve their physical properties by approximately 30%.