Precision casting (also known as investment casting or lost wax casting) is a manufacturing process for high-precision, complex-shaped parts. Its core process includes the following key steps:
1. Mold design and manufacturing
Design a profiled mold (usually metal or 3D printed mold) based on the part drawing to produce a wax mold.
2. Wax mold forming
Inject melted wax (such as paraffin, beeswax, or synthetic wax) into a mold, and after cooling, a wax mold consistent with the shape of the final part is formed.
3. Wax mold assembly
Weld or bond multiple wax molds onto a wax casting system (such as sprue bars and runners) to form a wax mold tree (mold assembly).
4. Shell making (mold shell preparation)
Coating: Immerse the wax pattern tree in refractory slurry (such as a mixture of silica sol or water glass with zircon sand).
Sanding: Sprinkle refractory sand (such as zircon sand, corundum sand) on the wet coating to form a shell that thickens layer by layer.
Drying and hardening: Each coating layer needs to be dried and solidified, and this process is repeated multiple times (usually 5-9 layers) until the mold shell reaches the required strength.
5. Dewaxing
Place the shell mold into a steam or high-temperature furnace (approximately 150°C) to melt and flow out the wax pattern, forming a hollow cavity.
6. Shell baking
High-temperature baking (typically at 800-1100°C) is conducted to eliminate residual wax and enhance the strength and permeability of the shell mold.
7. Melting and pouring
Melt metals (such as stainless steel, aluminum alloy, titanium alloy) until they become liquid, and then pour them into preheated molds.
8. Cooling and shelling
After the metal solidifies, the mold shell is removed through mechanical vibration or high-pressure water jetting, resulting in a metal casting tree.
9. Cutting and cleaning
Cut individual castings from the pouring system, and perform post-processing such as sandblasting and grinding to remove residual shell and burrs.
10. Inspection and finishing
Defects are detected through means such as X-ray inspection and dimensional measurement, and if necessary, thermal treatment, machining, or surface treatment (such as electroplating and polishing) is carried out.
