Lost wax casting, now called investment casting, is a casting process with little or no cutting. It is an excellent technology in the foundry industry and is widely used. It is not only suitable for casting of various types and alloys, but also produces castings with higher dimensional accuracy and surface quality than other casting methods, and even complex, high temperature resistant and difficult to process castings that are difficult to cast by other casting methods. All can be cast by investment casting.
Investment casting is developed on the basis of ancient wax casting. As an ancient civilization, China is one of the countries that used this technology earlier. As far back as hundreds of BC, the ancient working people of our country created this lost-wax casting technology, which was used to cast various fine patterns and characters. Zhong Ding and utensils and other products, such as the tomb plate of Zeng Houyi in the Spring and Autumn Period. The base of Zeng Hou Yi’s tomb is a number of intertwined dragons, which are connected end to end and staggered up and down, forming a hollowed-out multi-layer moiré pattern in the middle. These patterns are difficult to manufacture with ordinary casting techniques, but they are cast with lost wax method. The process can take advantage of the fact that paraffin wax has no strength and is easy to carve. With ordinary tools, you can carve out the same paraffin handicraft as the Zenghou Yi tomb plate, and then add a pouring system, coating, dewaxing, and pouring. Then you can get the exquisite Zenghouyi tomb plate.
The practical application of modern investment casting methods in industrial production was in the 1940s. At that time, the development of aviation jet engines required the manufacture of heat-resistant alloy parts with complex shapes, precise dimensions and smooth surfaces such as blades, impellers, and nozzles. Because the heat-resistant alloy material is difficult to machine and the shape of the parts is complicated, it is impossible or difficult to manufacture by other methods. Therefore, it is necessary to find a new precision molding process, so we learn from the lost wax casting handed down from ancient times. The improvement of modern investment casting method has obtained important development on the basis of ancient technology. Therefore, the development of the aviation industry has promoted the application of investment casting, and the continuous improvement and perfection of investment casting has also created favorable conditions for the aviation industry to further improve its performance.
- 1. It can cast complex castings of various alloys, especially high-temperature alloy castings. For example, the blades of jet engines, whose streamlined outline and inner cavity for cooling, can hardly be formed by mechanical processing technology. The investment casting process can not only achieve mass production, but also ensure the consistency of the castings, and avoid the stress concentration of the remaining knife lines after machining.
- 2. The dimensional accuracy of investment castings is high, generally up to ct4-6 (ct10~13 for sand casting, ct5~7 for die casting). Of course, due to the complexity of the steel investment casting process, there are many factors that affect the dimensional accuracy of castings. For example, the shrinkage of the mold material, the deformation of the investment mold, the change of the line amount of the shell during the heating and cooling process, the shrinkage rate of the alloy, and the deformation of the casting during the solidification process, etc., so although the dimensional accuracy of ordinary investment castings is high, But its consistency still needs to be improved (the dimensional consistency of castings using medium and high temperature waxes should be improved a lot).
- 3. When pressing the investment mold, the mold with a high surface finish of the cavity is used, so the surface finish of the investment mold is also relatively high. In addition, the mold shell is made of high temperature-resistant special binder and refractory paint prepared by refractory materials, which are hung on the investment mold, and the inner surface of the mold cavity that is in direct contact with the molten metal has a high finish. Therefore, the surface finish of investment castings is higher than that of general castings, generally up to ra.1.6~3.2μm.
- 4. The biggest advantage of investment casting is that due to the high dimensional accuracy and surface finish of investment castings, machining work can be reduced, and only a small amount of machining allowance can be left on parts with higher requirements, and even some Castings only have grinding and polishing allowances, and can be used without machining. It can be seen that the investment casting method can greatly save machine tool equipment and processing man-hours, and greatly save metal raw materials.
What Is Investment Casting Used For
What Is Investment Casting Used For？Investment casting is mainly used to cast accurate small parts with complex shapes. Batches of high-melting point alloy castings are used, which are mass-produced, small parts with complex shapes, and difficult to cut. Such as: blades, impellers, guides, guide wheels of steam turbines, gas turbines, water turbine engines, etc., and small parts on automobiles, tractors, pneumatic tools, machine tools, and handicrafts.
BE-CU Foundry Company
BE-CU is a manufacturer engaged in silica sol precision casting in China. Our professional production system has passed two quality management system certifications of ISO9001:2015 and IATF16949:2016. Fully capable of customizing all kinds of metal casting services you need. Our investment casting process can produce parts for you in the medical, military, aerospace, automotive and other industries.