China Investment Casting Foundry

Investment casting (also known as lost-wax casting) is a high-precision process renowned for its casting accuracy and surface quality. It is uniquely suited for producing parts with complex shapes, precise dimensions, thin walls, and high strength requirements.

Through a controlled sequence of steps—from precise wax pattern creation to metal pouring and finishing—investment casting consistently produces components that meet the demanding specifications of the industrial machinery, automotive, and energy sectors.

Low melting point materials (like paraffin wax or plastic) are injected into a metal die and cooled. This forms a single, precise wax pattern replica of the final part.

Multiple individual wax patterns are attached to a wax runner system, creating a tree-like structure called a "wax tree." This assembly allows for multiple parts to be cast simultaneously.

The wax tree is repeatedly immersed in a refractory ceramic slurry. A layer of fine ceramic powder is coated onto the surface (typically 5 to 7 times). This process forms a robust refractory shell capable of withstanding the extreme heat and pressure of molten metal.

The completed ceramic shell is placed into a high-temperature steam kettle or oven (100–200°C). The internal wax melts and drains out, creating an empty cavity inside the shell. This step is why the process is often called "lost-wax."

The dewaxed ceramic shell is placed into a high-temperature furnace (800–1000°C). This firing process sinterizes the shell, increasing its mechanical strength, improving its refractory properties, and fully removing any residual wax or moisture.

The metal is melted to its required temperature (e.g., stainless steel at about 1600°C). The molten metal is then poured into the preheated ceramic mold, quickly filling the cavity to form the casting.

The filled mold assembly is allowed to cool gradually, enabling the molten metal to solidify fully within the ceramic shell. This controlled cooling process is crucial for minimizing internal stresses and ensuring the final component achieves the desired microstructure and material properties.

Once the metal has solidified, the ceramic mold is mechanically removed (knockout). Residual ceramic material is removed using vibration, impact, or chemical dissolution to fully expose the casting.

Final treatments are applied to optimize the part:

• Heat Treatment: Depending on the material and required performance, the casting undergoes necessary heat treatments (such as annealing, quenching, tempering, or solution treatment). This is done to improve the mechanical properties and corrosion resistance of the final part.

• Machining: Precision machining (like turning, milling, drilling, or tapping) is performed as required. This achieves the tightest dimensional tolerances needed for final assembly.

• Surface Treatment: A final surface finish (such as electroplating, oxidation, or painting) is applied if needed. This enhances the part's aesthetic appeal and provides additional corrosion resistance.