Compared with the manufacturing processes of other institutions, the valve manufacturing process has the following characteristics: 

① The manufacturing process and inspection process of valve blanks are quite complex.

The casting blanks of valves are complex thin-walled shell components with a complicated structure. Their casting requires a smooth surface, clear casting characters, and especially a dense defect. To meet these requirements, a series of process measures should be adopted during casting, such as selecting high refractory casting materials and controlling the moisture content of the molding sand, layering and compacting the mold to ensure the hardness of the mold, using a reasonable pouring cap system and strictly controlling the pouring speed and temperature, etc. Due to the high technical requirements, the casting process of valve blanks is much more complex than that of ordinary castings.

In addition, in addition to checking the size, position accuracy and appearance of valve blanks, some also have to undergo various inspections such as metallographic structure, mechanical properties, corrosion resistance and non-destructive testing. Therefore, the inspection process of valves is also more complex.

② The installation of valve parts on the machine tool is rather difficult.

The structures and shapes of the main parts of valves are relatively complex. Some parts are thin-walled and slender, with poor rigidity. During machining on the machine tool, positioning and clamping are both very difficult, so often complex special fixtures are needed.

Some valve parts have a low precision of the positioning base surface and a high surface roughness. Sometimes even non-machined surfaces are used for positioning. However, the precision and surface roughness requirements of the machined sealing surfaces and other parts are very high, so it is difficult to ensure the processing quality. Therefore, to meet the requirements of the process, the precision of the positioning base surface and the surface roughness are often increased, or the positioning base surface is machined on the non-machined surface, which increases the complexity of the valve manufacturing process.

③ The mechanical processing is very difficult.

Due to the wide variety of valve materials, in addition to various cast irons and carbon steels, most high-strength, corrosion-resistant and hard materials have poor cutting performance, making it difficult for the parts to reach the specified processing accuracy and surface roughness. The geometric shape accuracy and surface roughness requirements of the valve sealing surfaces are very high, thus increasing the difficulty of valve mechanical processing. At the same time, the poor cutting performance of valve materials also brings many new problems to the processing methods, tool materials, cutting parameters, and process equipment of valves.