A cast valve is a valve that is formed by pouring the material into a mold as a whole. Generally, the pressure rating of the cast stop valve is relatively low (such as PN16, PN25, PN40, PN64, but there are also high-pressure ones, which can reach 1500Lb, 2500Lb), and most of the diameters are DN15 or above.
Forged globe valves are forged and are generally used in high-grade pipelines, with a relatively small diameter, usually below DN50. But there are also some imported valves with large forged diameters.
1. Casting: refers to the process of melting metal into a liquid that meets certain requirements and pouring it into a mold. After cooling, solidification, and cleaning treatment, a casting (part or blank) with predetermined shape, size, and performance is obtained. The basic technology of modern mechanical manufacturing industry.
2. The cost of casting produced blanks is low, and for parts with complex shapes, especially those with complex inner cavities, it can better demonstrate its economy; At the same time, it has a wide adaptability and good comprehensive mechanical performance.
3. However, there are many materials and equipment required for casting production (such as metal, wood, fuel, molding materials, etc.) and equipment (such as metallurgical furnaces, sand mixers, molding machines, core making machines, sand shakers, shot blasting machines, cast iron flat plates, etc.), which can produce dust, harmful gases, and noise, polluting the environment
4. Casting is an early metal hot working process that humans have mastered, with a history of approximately 6000 years. In 3200 BC, copper frog castings appeared in Mesopotamia. Between the 13th and 10th centuries BC, China had entered the heyday of bronze casting, and its craftsmanship had reached a considerable level. Representative products of ancient casting, such as the 875 kilogram Simu Wu Fang Ding from the Shang Dynasty, the Zun Pan of Zeng Hou Yi from the Warring States period, and the translucent mirror from the Western Han Dynasty, were all representative products. Early casting was greatly influenced by pottery, with most of the castings being tools or utensils for agricultural production, religion, and daily life, with a strong artistic color. In 513 BC, China produced the earliest recorded iron casting in the world - the Jin Dynasty Ding (weighing approximately 270 kilograms). Around the 8th century AD, Europe began producing iron castings. After the Industrial Revolution of the 18th century, castings entered a new era of service for large industries. In the 20th century, the development speed of casting was very fast, with the development of ductile iron, malleable iron, ultra-low carbon stainless steel, as well as cast metal materials such as aluminum copper, aluminum silicon, aluminum magnesium alloys, titanium based, nickel based alloys, and the invention of new processes for inoculation treatment of gray cast iron. After the 1950s, new technologies such as wet sand high-pressure molding, chemical hardening sand molding, core making, negative pressure molding, and other special casting and shot blasting cleaning emerged.
5. There are many types of casting, which are customarily divided into: ① ordinary sand mold casting, including wet sand mold, dry sand mold, and chemically hardened sand mold. ② Special casting can be divided into special casting with natural mineral sand and stone as the main molding material according to the molding material (such as investment casting, mud casting, shell casting in casting workshops, negative pressure casting, full mold casting, ceramic mold casting, etc.) and metal as the main molding material.