Investment Casting: Process, Characteristics, Advantages, and Applications

Introduction

Investment casting is a precision metal casting method widely used by Vietnam die casting suppliers. Instead of adhesives, this technique uses polystyrol (expanded polystyrene) patterns and sand molds stabilized by vacuum aspiration. When molten metal is poured, it vaporizes the polystyrol pattern and gradually fills the cavity, forming the final casting. Because of its accuracy, this process is ideal for complex geometries, automotive parts, and engine components that demand both strength and design flexibility.

Characteristics of Investment Casting

Unlike traditional binder-based technologies, investment casting—also known as lost-foam casting or gasification casting—relies on disposable polystyrene resin patterns. Each component is manufactured individually and then assembled into a sprue system with runners and branches. The entire pattern receives a refractory coating, is dried, and placed into a sand-filled mold box. Vibration compacts the sand, and vacuum aspiration locks the mold in place, preparing it for pouring.

Investment Casting Process

The process involves several well-defined stages:

1. Fabricate individual patterns from polystyrol.

2. Let them air-dry for 5–7 days to stabilize dimensions.

3. Assemble multiple parts into a complete pattern.

4. Attach the gating and feeding system.

5. Apply a refractory coating and dry thoroughly.

6. Place the coated pattern inside a sand mold box and compact it by vibration.

7. Create a vacuum inside the mold box for stabilization.

8. Pour molten metal, which vaporizes the polystyrol and takes its shape.

9. Release the vacuum after solidification so the sand easily separates from the casting.

This sequence allows manufacturers to achieve both precision and repeatability in high-volume production.

Advantages of Investment Casting

Investment casting offers several notable benefits:

• Delivers smooth surface finishes, reducing post-machining work.

• Supports automation and lowers dependence on manual labor.

• Provides simple and repeatable foam pattern creation for consistent mass production.

• Improves workplace safety by reducing dust compared to traditional sand casting.

Disadvantages of Investment Casting

Despite its strengths, investment casting also presents some challenges:

• Requires high initial investment, especially for large or intricate parts.

• Foam patterns are fragile and can distort during handling.

• Pouring iron or steel produces large amounts of gas, sometimes leading to defects like wrinkles or indentations.

• Alloys with high carbon content, such as ductile iron, are more susceptible to lustrous carbon defects.

Applications of Investment Casting

Because of its precision and versatility, investment casting is widely used in automotive, aerospace, and machinery manufacturing. Common components include:

• Engine blocks and cylinder heads

• Crankshafts and camshafts

• Differential carriers

• Transmission housings and gearbox parts

Conclusion

Investment casting remains an essential process for producing complex, high-strength metal parts with superior surface quality. Although it comes with higher costs and technical limitations, its ability to deliver reliable results, reduce machining needs, and support automation makes it indispensable in industries where precision and performance are non-negotiable. For more casting method, you can read Low pressure casting