The five most common casting methods are: sand casting, investment casting, metal mold casting, pressure casting (die casting), and centrifugal casting. These methods are widely used in industrial production, each with unique process characteristics and applicable scope.
1. Sand Casting
Principle: Sand is used as the primary molding material to create a mold. Molten metal is poured into the mold cavity, and the casting is obtained after cooling.
Characteristics: Low cost, high flexibility, suitable for the production of castings of various sizes and batches, especially suitable for single-piece or small-batch production.
Applications: Widely used in the manufacture of large or complex structural parts such as engine blocks, railway switches, and pump parts.
2. Investment Casting (Lost-Wax Casting)
Principle: A wax model is made, coated with refractory material to form a shell, heated to remove the wax, resulting in a hollow mold, which is then filled with metal.
Characteristics: High precision, smooth surface, can cast complex-shaped, thin-walled parts, and is a minimal or no-machining process. Applications: High-requirement castings such as aircraft engine blades, steam turbine parts, medical devices, and precision cutting tools.
3. Metal Mold Casting (Permanent Mold Casting)
Principle: Repeated pouring using a metal mold, relying on gravity to fill the cavity with molten metal.
Features: Molds can be reused; castings have a dense structure, high dimensional accuracy, and superior mechanical properties compared to sand casting.
Applications: Commonly used for mass production of automotive parts such as aluminum alloy pistons and cylinder heads.
4. Pressure Casting (Die Casting)
Principle: Molten metal is injected into a metal mold at high pressure and high speed, and solidified under pressure.
Features: High production efficiency; smooth casting surface; precise dimensions; suitable for thin-walled complex parts.
Applications: Mass production of small parts such as mobile phone frames, home appliance parts, and automotive components.
Caution: Die castings are prone to internal porosity and generally cannot be heat-treated; they are also unsuitable for applications subject to impact loads.
5. Centrifugal Casting
Principle: Molten metal is poured into a high-speed rotating mold, where it is formed under centrifugal force.
Characteristics: Castings have a dense structure, few defects, and good mechanical properties; hollow castings can be produced without a core.
Applications: Rotating castings such as water pipes, cylinder liners, rollers, and bushings.
