How To Manufacture Metal Parts in Investment Casting?

Investment casting, also known as wax loss casting, is an ancient and exquisite manufacturing process for metal parts, especially suitable for producing metal products with complex shapes, high dimensional accuracy, and strict surface smoothness requirements. This technology combines the essence of art and engineering, making the manufacturing of metal parts both precise and aesthetically pleasing. The following is a detailed process for manufacturing metal parts through investment casting:

The first step in investment casting is to create one or more wax molds using specialized wax materials based on the design drawings of the required metal parts. These wax molds must accurately replicate every detail of the parts, including complex internal structures and surface textures. The production of wax molds usually relies on fine craftsmanship, and modern technologies such as CAD/CAM (computer-aided design/manufacturing) systems are also widely used to improve efficiency and accuracy.

Once the wax mold is ready, the next step is to make a refractory shell. This step involves repeatedly immersing the wax mold into a special refractory slurry, usually a silicone or ceramic based slurry, and then sprinkling a layer of refractory sand particles after each immersion coating. This process may need to be repeated multiple times until the shell reaches sufficient thickness and strength. The number of layers and thickness of the shell directly affect the quality of the final metal parts, so careful control is necessary.

After completing the shell preparation, the wax mold needs to be melted and removed. This process is usually carried out in a high-temperature furnace, where the wax mold inside the shell gradually melts and is discharged, leaving a cavity that is exactly the same shape as the original wax mold. Subsequently, the shell needs to undergo further high-temperature treatment to enhance its structural stability and high-temperature resistance, in preparation for the next step of metal casting.

After the shell is completely hardened, the next step is to pour the molten metal into the cavity of the shell. The choice of metal depends on the material of the required parts, which can be copper, aluminum, steel, or various alloys. The metal liquid rapidly cools and solidifies within the shell mold, forming metal parts that are consistent with the original wax mold shape. This process requires precise control of the temperature and casting speed of the metal to avoid defects such as porosity and shrinkage.

After the metal parts are completely cooled, the shell shape needs to be removed. This is usually achieved through physical fragmentation, exposing the internal metal parts. Subsequently, the parts may require a series of post-treatments, such as cleaning, polishing, heat treatment, etc., to remove residual shell materials, improve the mechanical properties of the parts, and achieve the final dimensional accuracy and surface smoothness requirements. Finally, all finished parts will undergo strict quality inspection to ensure they meet design specifications and performance standards.

Investment casting is a complex and precise manufacturing process for metal parts, which combines traditional techniques with modern technology to produce complex and high-precision metal parts.