Understanding the different casting processes is essential when sourcing custom metal parts. Each method has unique strengths in terms of cost, precision, surface finish, and production volume. Below we break down the six most common casting techniques used in industrial manufacturing.

1. Sand Casting
Sand casting is the most versatile and widely used process. A pattern creates a cavity in sand, molten metal is poured in, and after solidification, the sand mold is broken to remove the casting. It accepts almost all metals, including iron and steel, and works for both small batches and high volumes. While cost-effective, surface finish and dimensional accuracy are moderate.

2. Investment Casting (Lost-Wax)
This process uses a wax pattern coated with ceramic slurry. Once the shell hardens, the wax is melted out, leaving a precision cavity. Investment casting delivers excellent surface finish and tight tolerances, ideal for complex shapes like turbine blades. It is more expensive and best suited for smaller, high-value parts.

3. Die Casting
Molten metal is injected under high pressure into a steel mold (die). This is the fastest casting method, producing parts with excellent dimensional consistency and smooth surfaces. It is limited to non-ferrous metals like aluminum, zinc, and magnesium and requires high tooling investment, making it viable for mass production.

4. Permanent Mold Casting
Uses reusable metal molds (usually iron or steel) without high-pressure injection. Metal flows by gravity or low pressure. This process offers better mechanical properties and surface finish than sand casting, with lower cost than die casting. It suits medium-to-high volumes of aluminum, copper, and magnesium alloys.

5. Centrifugal Casting
Metal is poured into a rotating mold, and centrifugal force distributes the liquid metal against the mold wall. This produces dense, defect-free parts with excellent directional solidification. It is the go-to method for cylindrical parts like pipes, tubes, and cylinder liners.

6. Low-Pressure Casting
Molten metal is pushed upward into a graphite or metal mold using low gas pressure (0.1–0.8 bar). The controlled fill reduces turbulence and porosity, yielding sound castings with good strength. It is commonly used for automotive wheels and structural components.

Choosing the Right Process
When selecting a casting method, consider these four factors:

• Production quantity (low, medium, or mass)

• Dimensional tolerance and surface finish required

• Alloy type (ferrous vs. non-ferrous)

• Part geometry complexity

For projects that demand both complex shapes and critical dimensions, combining casting with secondary CNC machining is a proven strategy.

Contact our engineering team for a process recommendation tailored to your part drawings.