What Is Investment Casting？

Investment casting, as a precision casting process, plays a pivotal role in modern manufacturing. According to relevant statistical data, in the production field of high-end precision castings, the application proportion of investment casting exceeds 30% and shows an upward trend year by year, which fully demonstrates its irreplaceable role.

The origin of investment casting can be traced back thousands of years ago. In the early stage, it was used in a relatively simple form to produce some small and delicate metal products. With the continuous progress of industrial technology, today's investment casting has developed into a highly complex and precise technological system.

Usually, wax or other fusible materials are used. Based on the precise shape of the required casting, advanced means such as precision mold pressing or 3D printing are adopted to create models that are exactly the same as the final castings. This step can be regarded as the blueprint drawing stage of the entire process. Take the investment casting of aero-engine blades as an example. Its dimensional accuracy requirements are extremely high, and the tolerance is generally controlled within ±0.05 mm. Only through high-precision mold pressing combined with advanced 3D printing for mold repair technology can the要求 be met. This is an important part of answering “what is an investment casting” and shows “how investment casting is done” in the manufacturing of key components.

The made pattern is immersed into a special refractory material slurry, and then reinforcing materials such as sand grains are sprinkled on it repeatedly. The refractory material accumulates layer by layer on the surface of the pattern, forming a hard and high-temperature-resistant shell, just like putting a strong armor on the precise core. Generally, the shell-making process needs to be repeated 5 - 10 times to ensure that the the shell has sufficient strength and high-temperature resistance to withstand the subsequent pouring of high-temperature molten metal. This process is a key link in “what is investment casting in manufacturing process” and reflects “how to do investment casting” to achieve the required shell quality.

After the shell is dried and hardened to sufficient strength, the dewaxing step begins. By using heating or other methods, the internal pattern is melted and flows out. At this time, the hollow shell left becomes the cavity for pouring the molten metal. The heating temperature during dewaxing usually needs to be precisely controlled between 80 - 120 °C. If the temperature is too high, the shell may be damaged; if it is too low, the wax material cannot be completely melted and flow out. This step is crucial in understanding “what is investment casting process” as it affects the final casting quality.

The precisely proportioned and high-temperature-melted molten metal is carefully poured into the prepared cavity. The molten metal gradually cools and solidifies in the cavity, and finally forms a precision casting consistent with the initial pattern. For some high-end aluminum alloy castings, the pouring temperature needs to be controlled between 700 - 750 °C to ensure the fluidity of the molten metal and its performance after solidification, meeting the strict requirements of the aerospace field for material strength, toughness, etc. Through this series of steps, we can comprehensively understand “what are investment casting” and how they are produced.

Investment casting is highly favored because it has many advantages. On the one hand, it can achieve extremely high dimensional accuracy. For some fields with strict dimensional fit requirements, such as aerospace and medical devices, it can accurately meet the component design requirements, and its dimensional accuracy can reach ±0.1 mm or even higher. On the other hand, it can produce castings with extremely complex shapes. Those parts with fine holes, thin-walled structures, and irregular curved surfaces are difficult to achieve by conventional casting methods, but investment casting can handle them with ease.

In the aerospace field, key components such as engine blades often rely on investment casting to ensure performance and reliability. According to incomplete statistics, about 70% of global aero-engine blades are produced by investment casting technology. In the medical device field, such as precision dental implants and surgical instrument joints, investment casting guarantees their high precision and biocompatibility.

In conclusion, investment casting, with its unique technological charm, continuously promotes the development of high-end manufacturing and supplies high-quality precision castings for many fields. It is one of the essential key technologies in modern industry. It is also the core content when exploring “what is investment casting” and related processes.