How does the pressure die casting process differ from the gravity die casting process

Metal casting is a fundamental manufacturing process that enables the creation of intricate components for various industries.

Among the array of casting techniques available, pressure die casting and gravity die casting stand out as two prominent methods, each possessing distinct characteristics and applications.

Pressure Die Casting: Precision Through Forceful Injection

Pressure die casting is a sophisticated metal casting procedure that involves injecting molten metal into a precisely crafted mould cavity under substantial pressure.

This process is executed using a specialized machine called a die-casting machine. The critical steps of pressure die casting are as follows:

Pressure Die Casting Machine

Mould Preparation

Utilizing a two-part steel mould or die, the cavity is meticulously shaped to mirror the desired end product.


Molten metal is forcefully injected into the mould cavity at high pressures, typically 1,500 to 25,000 psi. This ensures thorough mould filling and the replication of intricate details.


Rapid cooling and solidification of the metal occur due to the efficient heat transfer brought about by the high-pressure injection.


Following solidification, the mould halves are separated, and the casting is ejected using ejector pins.


The short cycle times of pressure die casting make it suitable for mass production of parts featuring complex shapes and intricate details.

Gravity Die Casting: A Process Driven by Nature

Gravity dies casting, or permanent mould casting employs gravity as the primary force to fill a mould cavity with molten metal. This technique offers its own set of procedures and characteristics:

Gravity Die Casting Machine

Mould Preparation

Similar to pressure die casting, gravity die casting employs a reusable permanent mould, often constructed from durable materials like steel.


Molten metal is poured into the mould cavity from a spoon, and the force of gravity is responsible for distributing the metal throughout the mould.


The cooling process is relatively slower due to the absence of high-pressure injection, resulting in more extended solidification times.


After solidification, the mould is opened, and the casting is extracted using ejector pins or tilting the mould.


Gravity die casting is better suited for simpler shapes and parts lacking intricate details. It might encounter challenges in maintaining consistent wall thickness in complex components.

Key Differences and Considerations:

Process Dynamics

Pressure die casting relies on high-pressure injection, while gravity die casting solely relies on gravity for metal distribution.

Cycle Time

The rapid injection and cooling of pressure die casting result in shorter cycles, whereas gravity die casting involves longer cycles due to slower cooling.


Pressure die casting excels in producing complex shapes with refined details, while gravity die casting suits simpler designs.

Surface Finish

Pressure die casting often yields a smoother surface finish compared to the surface finish of gravity die casting.


Pressure die casting and gravity die casting represent two distinct paths in the world of metal casting.

While pressure die casting harnesses controlled injection for precision and rapid production, gravity die casting capitalizes on gravity for simpler shapes.

Understanding these techniques’ unique characteristics and applications empowers manufacturers to make informed decisions, ensuring optimal results in their casting endeavours.

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