The difference between forged and cast valves

The difference between forged and cast valves: Forged valves are made by shaping heated metal into the desired form using compressive force, while cast valves are made by pouring molten metal into a mold to solidify into the desired shape.

Casting production of blanks at low cost, for the shape of complex parts, especially complex internal cavity is more economical; at the same time has a wide range of adaptability and good overall mechanical properties.

However, there are many materials (e.g., metal, wood, fuel, molding materials, etc.) and equipment (such as metallurgical furnace, sand mixer, molding machine, core making machine, sand falling machine, shot blasting machine, cast iron plate, etc.). Casting production required, will produce dust, harmful gases and noise pollution of the environment.

Casting is an early metal hot working process mastered by mankind, with a history of about 6,000 years. Copper frog castings appeared in Mesopotamia in 3200 BC. From the 13th century B.C. to the 10th century B.C., China entered the heyday of bronze casting, and the technology has reached a fairly high level. For example, the Simuwu square tripod of the Shang Dynasty, the Zenghouyi Zun disk of the Warring States period, and the transparent mirrors of the Western Han Dynasty are representative products of ancient casting. Early casting is influenced by pottery, casting most of the agricultural production, religion, life and other aspects of the tools or vessels, with a strong artistic color. In 513 BC, China cast the world's earliest recorded cast iron pieces, namely - gold tripod (about 270 kilograms). About the 8th century, Europe began to produce cast iron parts. 18th century after the industrial revolution, casting entered a new era for the service of big industry. 20th century, casting development is rapid, has developed ductile iron, malleable cast iron, ultra-low carbon stainless steel, aluminum-copper, aluminum-silicon, aluminum-magnesium alloy, titanium and nickel-based alloys, such as casting metal materials, the invention of the grey cast iron gestation treatment of the new technology. 20 century 50s, after the appearance of the After the 1950s, the emergence of wet sand high-pressure molding, chemical hardening sand molding core, negative pressure molding and other special casting and shot blasting cleaning and other new technologies.

There are many types of castings, customarily divided into: ordinary sand casting, including wet sand, dry sand, and chemical hardening sand. According to the molding material, special casting can be divided into two categories: special casting with natural mineral sand as the main molding material (such as investment casting, mud casting, foundry shell casting, negative pressure casting, full mold casting, ceramic casting, etc.). And special castings with metal as the main molding material (such as metal type casting, pressure casting, continuous casting, low-pressure casting, centrifugal casting, etc.).

铸造过程通常包括：铸型的准备（将液态金属倒入固体铸造容器中），可分为砂型、金属型、陶瓷型、泥型、石墨型。根据使用次数可分为一次性模具、半永久模具和永久模具，铸造准备的质量是影响铸件质量的主要因素；铸造金属的熔化和浇铸，铸造金属（铸造合金），包括铸铁、铸钢和铸造有色合金；铸造处理和检验。铸造处理包括去除芯和铸件表面的杂质，切断浇口，去除毛刺和缝隙，热处理，造型，防锈和粗加工。进口泵阀两，锻造成英文。

Forging: Forging machine is used to apply pressure to the metal blank, so that it undergoes plastic deformation, to obtain a certain mechanical properties, a certain shape and size of the forgings of the processing method.

One of the two main components of forging. Forging can eliminate the cast metal porosity and welding holes, the mechanical properties of forgings are generally better than the same material castings. In addition to simple rolled plates, profiles or weldments, forgings are mostly used in machinery for high loads, poor working conditions of important parts.

Forging can be divided into: open forging (free forging). Impact or pressure is used to deform the metal between the upper and lower counterweights (anvil seats) to obtain the desired forgings. There are two main types of forging: hand forging and mechanical forging. Closed die forging. Metal billet in a certain shape of the forging die chamber pressing deformation, get forging, can be divided into die forging, cold heading, rotary forging, extrusion, etc.. Forging according to the deformation temperature can be divided into hot forging (processing temperature higher than the recrystallization temperature of the blank metal), warm forging (lower than the recrystallization temperature) and cold forging (room temperature).

Forging materials are primarily composed of various carbon and alloy steels, followed by aluminum, magnesium, titanium, copper, and their alloys. The original state of the material includes bars, ingots, metal powders, and liquid metals. The ratio of the cross-sectional area of the metal before deformation to the area of the broken mold after deformation is referred to as the forging ratio. The correct selection of the forging ratio is closely related to improving product quality and reducing costs.

Cast valves are valves made by casting. General casting valves are relatively low pressure level (such as PN16, PN25, PN40, but there are also high pressure, up to 1500Lb, 2500Lb), most of them are above DN50. Forged valves are forged and generally used for high grade pipelines with smaller diameter than, generally below DN50.