Development Status and Trend of Stainless Steel Precision Casting

Barinder
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Stainless steel precision casting has broad prospects for development Stainless steel investment casting is also called investment casting. This process minimizes or does not cut at all in the casting process. It is a casting process with little or no cutting, and is an excellent process technology in the casting industry. Its application range is very wide, 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. At the same time, investment casting can be used for castings that are resistant to high temperature and difficult to process. Since this casting method is not in an ultra-high temperature state during the casting process, it is more suitable for casting components in high-precision industries such as aerospace and national defense.
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The earliest stainless steel precision casting can be traced back to the 1930s and 1940s. The United States was the first to use the stainless steel precision casting method to cast turbine blades in aero-engines with leading technology at that time. be promoted. my country's research and development and use of stainless steel precision casting began after the founding of New China. With the development of my country's national defense industry, stainless steel precision casting research institutes or foundries have been opened in Liaoning, Guizhou, Beijing, Shaanxi, Hunan and other places.

At present, there are many mature technologies and processes in stainless steel precision casting. Silica sol shell process. The silica sol shell-making process is widely used in the more advanced foundry industry of internal combustion engine parts. The coating used in this method has good stability, does not require a chemical hardening process, is resistant to high temperature, and has better resistance to deformation. However, the disadvantage of this technology is that the wettability of the wax mold is poor. Although it can be improved by adding surfactants, it will increase the investment to a certain extent.

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Water glass shell process. The water glass shell process was invented very early, and my country also introduced this technology from the Soviet Union in the 1950s and 1960s. The technology has low cost, relatively simple operation, and low requirements on raw materials, so it is widely used in stainless steel precision casting. However, the biggest problem of this technology compared to the silica sol shell making process is that the surface quality of the resulting castings is general and the dimensional accuracy is low. However, due to its cost advantage, my country still uses this technology in some civilian or low-precision internal combustion engines. Since the introduction of this technology, Chinese researchers have made great improvements to it, mainly in improving shell coatings, optimizing hardeners, and using composite shells.

The main improvement of improving the shell coating is to add a certain amount of refractory clay to the back coating of the shell, which greatly improves the strength of the shell and realizes single shell baking and injection. In terms of optimizing the hardener, ammonium chloride is often used for traditional hardeners, but this material releases a large amount of ammonia and nitrogen oxides during the casting process, causing pollution to the atmosphere. Therefore, the hardener is changed to aluminum chloride solution, and the aluminum chloride crystal is further used. The effect of this hardener is similar to that of ammonium chloride.

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In the future development direction, the intersection and integration of stainless steel precision casting technology will become more and more obvious. The development direction of the new round of science and technology and industrial revolution will not only depend on one or two disciplines or a single technology, but multidisciplinary , the high degree of intersection and deep integration of multi-technology fields. Therefore, stainless steel precision casting should also be integrated and developed with related technologies. Cross-use with rapid prototyping technology. The intersection of science and technology is mostly to complement each other. The design and mold making in the wax mold making process of stainless steel precision casting are more complicated and take a lot of time. Rapid prototyping technology can make up for this shortcoming. However, due to material limitations, rapid prototyping technology alone cannot meet the requirements. Therefore, in recent years, many workers first used polymer technology to obtain casting prototypes, and then made wax molds, which were then put into use in the stainless steel precision casting industry.

For example, Stereolithography (SLA) and Selective Laser Sintering (SLS) are relatively mature technologies currently used in conjunction with investment casting. SLA techno