A gravity casting mold is a permanent casting process. The process pours molten metal into a cavity inside the permanent mold. Once the molten metal has filled the cavity, it is allowed to cool and solidify inside the mold. After the cooling process, excess metal is removed and the casting is ready for use. Here's how gravity die casting works. During this process, metal is poured into a permanent mold using a runner system.

Gravity-pour permanent mold casting uses the force of gravity to pour molten metal into a mold. The mold is usually made from iron or steel and is an exact replica of the part. A runner, or large vertical cavity above the mold, provides a reservoir for the molten metal. As the metal cools, the volume in the cavity diminishes because of thermal contraction and solidification shrinkage. A gravity pour mold is a great choice for parts made from lightweight alloys.

Before pouring metal into a gravity casting mold, hot metal is coated with a refractory material. This coating protects the casting and prolongs its life. The mold is then clamped shut. The liquid metal then flows into the mold cavity under gravity. Once solidified, the casting is removed from the mold and a riser is installed to compensate for shrinkage, which limits the yield to 60 percent or less. When coatings fail to provide adequate protection, mechanical ejector pins are often used. The pins are placed throughout the mold and usually leave small round impressions on the casting.

In this process, a heat-resistant steel mold is used. The molds are durable and have a long lifespan. In contrast to sand casting, gravity die casting requires a more expensive die. It is suitable for medium to high-volume production runs and for parts that have intricate shapes. In addition, gravity casting molds can be reused multiple times, which reduces the cost of making new dies. A gravity casting mold also produces quality casts with minimal finishing.

A gravity casting mold is also versatile because it can be reused for similar parts. This can be particularly useful for repetitive production runs of the same part. Because the metal is poured at a low temperature, the mold can be reused multiple times. The mold can even be reused if it is made of durable constituents, such as stainless steel or graphite. The molds are also durable enough to endure multiple casting processes.