Pressure Die Casting vs Gravity Die Casting

Die casting is one of the most widely used metal casting processes — and at Surya Die Cast, we specialize in both Gravity Die Casting and Pressure Die Casting. While both methods use a metal mould to shape molten non-ferrous alloys such as aluminium, zinc, magnesium, lead, tin, or copper, the key difference lies in how the molten metal is introduced into the mould.

In Gravity Die Casting (also known as Permanent Mould Casting), molten metal is poured from above and flows into the mould cavity purely under the force of gravity. In contrast, Pressure Die Casting involves injecting the molten metal into the mould under high pressure — typically between 1,500 and 25,400 psi — and maintaining that pressure until the casting solidifies.

Because Pressure Die Casting uses high pressure and automation, it enables rapid filling, consistent quality, and high productivity with minimal human error. However, this complexity makes it costlier to set up. The tooling for Pressure Die Casting also tends to be more expensive, as the moulds must be made from hardened steel with internal cooling channels to handle the heat.

On the other hand, Gravity Die Casting is a simpler and more cost-effective process. Moulds can be made from cast iron, and sand cores can be used to create internal voids — something not possible with Pressure Die Casting. While slower and less suited to long production runs, Gravity Die Casting offers flexibility and is ideal for smaller batches or parts requiring heat treatment, as the slower filling rate reduces air entrapment and turbulence.

In terms of quality, Pressure Die Casting produces more precise, complex parts with thinner walls and smoother surfaces, often minimizing the need for secondary machining. Gravity Die Casting cannot achieve the same dimensional accuracy, but it yields castings with fewer trapped gases — advantageous for components that require subsequent heat treatment.

To summarize, Pressure Die Casting is best suited for high-volume, stable production runs where the goal is to achieve low unit costs and consistent precision. Gravity Die Casting, on the other hand, is more flexible and cost-effective for lower-volume production or when heat treatment is necessary.

At Surya Die Cast, we utilize both processes based on your project’s specific requirements — ensuring the right balance between precision, productivity, and cost-efficiency.