The main advantage of casting is that the cost of casting blank is low, and it can show its economy for parts with complex shapes, especially parts with complex cavities. At the same time, it has wide adaptability and good comprehensive mechanical properties. However, casting production needs more materials and equipment, and it will produce dust, harmful gases and noise, which will pollute the environment.
Forging valve is a processing method that uses forging machinery to exert pressure on metal valve blank to make it produce plastic deformation, so as to obtain forgings with certain mechanical properties, shapes and sizes. According to the forming method, forging can be divided into open forging (free forging) and closed forging. Forging can be divided into hot forging, warm forging and cold forging according to deformation temperature. Forging materials are mainly carbon steel and alloy steel with various compositions, followed by aluminum, magnesium, titanium, copper and their alloys. The original state of materials includes rod, ingot, metal powder and liquid metal. The ratio of the cross-sectional area of a metal before deformation to the broken die area after deformation is called forging ratio.
Forging can eliminate the as-cast porosity and welding holes of metal, and the mechanical properties of forgings are generally better than those of castings of the same material. Forgings are mostly used for important parts with high load and bad working conditions in machinery, except for rolled plates, profiles or weldments with simple shapes. The correct selection of forging ratio has a great relationship with improving product quality and reducing cost.
Cast valves are valves made by casting. Generally, the pressure grade of casting valves is relatively low (such as PN 16, PN25 and PN40), but some valves have high pressure, which can reach 1500Lb and 2500Lb, and most of them are above DN50. Forged valves are forged and are generally used in pipelines with high pressure grade. Forged valves are mainly small caliber, generally below DN50.