The dimensional accuracy of investment casting can usually reach CT4-6 level, and the surface finish is Ra1.6-3.2μm.
Precision and surface finish
Dimensional accuracy: The dimensional accuracy of ordinary investment castings is about 5-7 tolerance levels higher than that of sand castings (CT4-6 vs CT10-13), but due to factors such as mold shrinkage and shell deformation, the consistency of high-precision castings still needs to be improved.
Surface finish: The shell is made of refractory materials with high surface finish. The surface roughness of ordinary investment castings can reach Ra1.6-3.2μm, which is close to the surface quality after machining.
Influencing factors
Process complexity: Investment casting needs to go through wax mold making, shell sintering, pouring and other processes. There are variables such as mold shrinkage and shell deformation in the process, which leads to large fluctuations in dimensional accuracy in actual production.
Material properties: Complex materials such as high-temperature alloys may further affect precision control.
How to ensure the precision of investment casting?
The precision of investment casting is mainly achieved through the following process links:
Process flow control
Investment casting adopts wax mold precision molding technology, and forms a refractory shell through processes such as wax mold pressing, shell coating, and baking and dewaxing. The shell needs to be baked at a high temperature of about 1000℃ for 1-2 hours to ensure that the wax mold is completely melted and the residual moisture is discharged to form a dense shell structure.
Dimensional accuracy advantage
The dimensional accuracy of the casting can reach CT4-6 level (sand casting is CT10-13 level), and the surface roughness Ra can reach about 1.3μm. High-temperature wax materials and precision molds can significantly improve dimensional consistency and reduce machining allowances.
Process parameter optimization
By controlling parameters such as mold shrinkage, shell deformation, and alloy shrinkage, medium and high temperature wax materials are used to further optimize dimensional accuracy. For example, high-temperature wax materials (such as rosin 50%, ceresin 20%, and polystyrene 30%) can improve the dimensional stability of castings.
Subsequent processing guarantee
After pouring, a vibrating sheller is used to separate the shell and the casting, and residual stress is eliminated through polishing, machining and other processes to ensure the final dimensional accuracy.
The precision guarantee of investment casting is mainly achieved through the following process links:
Process flow control
Investment casting uses wax mold precision molding technology to form a refractory shell through wax mold pressing, shell coating, roasting and dewaxing. The shell needs to be roasted at a high temperature of about 1000℃ for 1-2 hours to ensure that the wax mold is completely melted and the residual moisture is discharged to form a dense shell structure.
Dimensional accuracy advantage
The dimensional accuracy of the casting can reach CT4-6 level (sand casting is CT10-13 level), and the surface roughness Ra can reach about 1.3μm. High-temperature wax and precision molds can significantly improve dimensional consistency and reduce machining allowances.
Process parameter optimization
By controlling parameters such as mold shrinkage, shell deformation, and alloy shrinkage, medium and high temperature wax is used to further optimize dimensional accuracy. For example, high-temperature wax materials (such as rosin 50%, ozokerite 20%, polystyrene 30%) can improve the dimensional stability of castings.
Subsequent processing guarantee
After pouring, a vibrating sheller is used to separate the shell and the casting, and residual stress is eliminated through polishing, machining and other processes to ensure the final dimensional accuracy.
Of course, if there is a large demand for customized investment casting, you can choose Mulan Metal to cooperate. Mulan Metal has 12 years of experience in metal casting and processing, helping customers in more than 30 countries to complete customized casting work, and has received consistent recognition and long-term cooperation opportunities. Looking forward to your cooperation consultation.
Here is our Custom metal Castings Display：
