Metal casting is a manufacturing process where molten metal is poured into a mold to form a desired shape. There are several types of metal casting, broadly classified into expendable mold casting and permanent mold casting methods. Here's an overview of the major types:
1. Sand Casting (Expendable Mold)
Description: Uses sand as the mold material.
Applications: Automotive parts, engine blocks, pump housings.
Advantages: Low cost, suitable for large and complex shapes, and wide material compatibility.
Drawbacks: Rough surface finish, lower dimensional accuracy.
2. Investment Casting (Lost Wax Casting)
Description: A wax pattern is coated with ceramic, then melted out and replaced by molten metal.
Applications: Aerospace, jewelry, medical instruments.
Advantages: High precision and surface finish, suitable for complex geometries.
Drawbacks: More expensive, limited to smaller parts.
3. Die Casting (Permanent Mold)
Description: Molten metal is injected into a metal mold (die) under high pressure.
Subtypes: Hot chamber and cold chamber die casting.
Applications: Mass production of aluminum, zinc, and magnesium components (e.g., housings, enclosures).
Advantages: Excellent dimensional accuracy, high production rates, smooth finish.
Drawbacks: High tooling costs, limited to non-ferrous metals.
4. Gravity Die Casting (Permanent Mold Casting)
Description: Molten metal is poured into a permanent mold using gravity.
Applications: Automotive parts, engine components.
Advantages: Better mechanical properties than sand casting, reusable molds.
Drawbacks: Less complex geometries, higher mold cost than sand casting.
5. Centrifugal Casting
Description: Molten metal is poured into a rotating mold, using centrifugal force to distribute the metal.
Applications: Pipes, bushings, rings.
Advantages: High density and strength, reduced porosity.
Drawbacks: Limited to symmetrical shapes.
6. Shell Mold Casting
Description: Uses a resin-coated sand mold formed over a heated metal pattern.
Applications: Gear housings, valve bodies.
Advantages: Better surface finish and accuracy than traditional sand casting.
Drawbacks: Higher cost than sand casting.
7. Lost Foam Casting
Description: Similar to investment casting, but uses a foam pattern instead of wax.
Applications: Complex aluminum parts, engine blocks.
Advantages: No parting lines, suitable for complex shapes.
Drawbacks: Higher pattern cost, slower production cycle.
8. Vacuum Casting
Description: A vacuum is used to draw molten metal into the mold.
Applications: Thin-walled, precision parts in aerospace and defense.
Advantages: Reduces air entrapment, ideal for reactive alloys.
Drawbacks: More complex and expensive setup.
Metal Casting Methods Comparison Chart
| Casting Type | Mold Type | Key Features | Advantages | Drawbacks | Typical Applications |
|---|---|---|---|---|---|
| Sand Casting | Expendable | Uses sand molds; flexible and widely used | Low cost, handles large parts, widely adaptable | Rough finish, lower accuracy | Engine blocks, pump housings, brackets |
| Investment Casting | Expendable | Wax model, ceramic shell; high-precision process | Excellent detail, smooth surface, complex shapes | Higher cost, limited part size | Aerospace parts, jewelry, surgical tools |
| Die Casting | Permanent | High-pressure metal injection into steel molds | High accuracy, fast production, good surface finish | High tooling cost, limited to non-ferrous metals | Housings, gears, electronic enclosures |
| Gravity Die Casting | Permanent | Uses gravity to fill metal mold | Better than sand casting in strength, reusable mold | Higher mold cost, simpler shapes | Automotive parts, wheels, engine components |
| Centrifugal Casting | Permanent | Spun mold, forces metal outward | High strength, low porosity, dense structure | Only for cylindrical/symmetrical parts | Pipes, bushings, cylinder liners |
| Shell Mold Casting | Expendable | Resin-coated sand mold made on a heated pattern | Smoother finish and better precision than sand casting | More expensive than sand casting | Gear housings, valve bodies |
| Lost Foam Casting | Expendable | Foam pattern evaporates during pouring | Great for complex shapes, no parting lines | High pattern cost, slow setup | Complex aluminum castings, engine parts |
| Vacuum Casting | Permanent/Expendable | Vacuum draws molten metal into mold | Reduces defects, good for reactive metals | Costly equipment, slower production | Thin-walled aerospace parts, prototypes |
Quick Selection Guide
| Need | Best Option |
|---|---|
| Low-cost and flexible | Sand Casting |
| High precision and detail | Investment Casting |
| Fast, mass production | Die Casting |
| Strong, dense, cylindrical parts | Centrifugal Casting |
| UV/heat-resistant industrial components | Shell Mold Casting |
| Complex, seamless parts | Lost Foam Casting |
| Aerospace-grade, clean castings | Vacuum Casting |
Conclusion:
Each casting method serves different purposes based on complexity, volume, material, and required tolerances. Choosing the right type depends on the application needs, production scale, and material properties.
Dongrun Casting has 20000 square meters of facility space and 200 production & test equipment. From quotation and tooling design to casting and finished machining, we can work with you at every stage. We serve a wide range of industries-from Fortune 500 corporations to small and midsize OEMs. Our products include Automotive & Trucking, Electric Utility & Communications, Metering Systems, the Hydraulic Industry, Medical Devices, Lighting, Fuel and Gas Pressure, and Furniture parts.
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