Learn About the Gravity Die Casting Process
1. What is gravity die casting?
gravity die casting, also known as permanent die casting, is a typical die casting technique used to manufacture high-quality metal parts with low melting points, such as aluminum and zinc alloys. During gravity die casting, molten metal is poured from a ladle into a mold, which then fills the mold cavity under the action of gravity and solidifies rapidly to make a metal part. Due to rapid solidification, the process of gravity die casting provides a better surface finish as well as better mechanical properties than sand casting.
Unlike other casting methods for example sodium silicate sand casting, gravity die casting is simply pouring molten metal into a mold without applying any additional pressure. Also, gravity die casting can use both metal and sand cores, called semi-permanent mold casting, for greater design complexity. For applications that require a solution between sand casting and high-pressure die casting including vacuum die casting, gravity die casting is a perfect choice. gravity die casting requires lower mold costs than high-pressure die casting, but is more durable than sand casting, which uses steel molds. A mold is a permanent form that consists of two halves.
2. Introduction of gravity die casting process
Compared with nuclear castings, gravity die casting is usually a manual process, using a ladle to add molten metal. However, for some high-volume applications, molten metal can also be poured using an automatic ladle. The speed and direction of filling can also be controlled by tilting the mold. The casting process is basically the same as sand casting except for the method of pouring molten metal into the cavity and the gravity mold material. The gravity die-casting process consists of four steps:
The mold is heated, then sprayed with a refractory coating, and then closed. The coating helps control the temperature of the mold during the manufacturing process and also aids in the removal of castings. The molten metal is then poured manually into the mold (although a machine can be used in some cases) and allowed to solidify. The mold is then opened and the casting is removed by hand or in some cases on a mechanized machine using an ejector pin. Finally, scrap, including gates, runners, and flash, is removed from the casting. Castings are then treated to remove sharp edges and excess material and then blast cleaned (if required) before being sent to the customer. Gravity die casting is a natural partner for sand casting, allowing us to provide our customers with the most cost-effective route to casting castings.