The difference between cast valve and forged valve

The difference between cast valve and forged valve

Casting valves are valves made by casting. Generally, the pressure grades of cast valves are relatively low (such as PN16, PN25, PN40, but there are also high-pressure ones, which can reach 1500Lb, 2500Lb), and most of their calibers are above DN50. Forged valves are forged and are generally used in high-grade pipelines with relatively small diameters, generally below DN50.

Table of Contents hide Casting Forging The difference between cast valve and forged valve

Casting

1. Casting: It is the process of smelting metal into a liquid that meets certain requirements and pouring it into a mold, cooling, solidifying, and cleaning to obtain castings (parts or blanks) with predetermined shapes, sizes and properties. The basic technology of modern machinery manufacturing industry.

2. The cost of the blank produced by casting is low, and it can show its economical efficiency for parts with complex shapes, especially with complicated internal cavities; at the same time, it has a wide range of adaptability and better comprehensive mechanical properties.
3. Materials (such as metal, wood, fuel, modeling materials, etc.) and equipment (such as metallurgical furnaces, sand mixers, molding machines, core making machines, shakeout machines, shot blasting machines, cast iron plates, etc.) required for casting production ) Is more, and will produce dust, harmful gas and noise and pollute the environment.
4. Casting is a kind of metal thermal processing technology that humans have mastered earlier, with a history of about 6000 years. In 3200 BC, copper frog castings appeared in Mesopotamia. Between the 13th and 10th centuries BC, China has entered the heyday of bronze castings, and the craftsmanship has reached a very high level, such as the 875 kg Simuwu of the Shang Dynasty, the Zenghou Yizun plate of the Warring States Period and the Western Han Dynasty The translucent mirrors are all representative products of ancient casting. Early casting was greatly influenced by pottery. Most of the castings were tools or utensils used in agricultural production, religion, and life, with a strong artistic color. In 513 BC, China cast the world’s earliest cast iron found in written records—the Jin Kingdom cast tripod (approximately 270 kg). Around the 8th century, Europe began to produce iron castings. After the Industrial Revolution in the 18th century, castings entered a new era of serving large industries. In the 20th century, the rapid development of casting has been developed. Nodular cast iron, malleable cast iron, ultra-low carbon stainless steel, aluminum copper, aluminum silicon, aluminum-magnesium alloys, titanium-based, nickel-based alloys and other casting metal materials have been developed. A new process for inoculation of cast iron. After the 1950s, new technologies such as green sand high-pressure molding, chemical hardening sand molding and core making, negative pressure molding, and other special casting, shot blasting, etc. appeared.

5. There are many types of casting, which are divided into:

• ① Ordinary sand casting, including 3 types of green sand, dry sand and chemically hardened sand.

• ② Special casting, according to the modeling material, can be divided into special casting with natural mineral sand and gravel as the main modeling material (such as investment casting, clay casting, shell casting in the foundry, negative pressure casting, solid casting, ceramic casting Etc.) and special casting with metal as the main mold material (such as metal mold casting, pressure casting, continuous casting, low pressure casting, centrifugal casting, etc.).

6. The casting process usually includes:

• ① Preparation of casting molds (containers that make liquid metal into solid castings). Casting molds can be divided into sand, metal, ceramic, clay, graphite, etc. according to the materials used, and can be divided into disposable and semi-permanent types according to the number of uses And permanent mold, the pros and cons of mold preparation are the main factors affecting the quality of castings;

• ② Melting and pouring of cast metal, cast metal (cast alloy) mainly includes cast iron, cast steel and cast non-ferrous alloy;

• ③ Casting processing and inspection. Casting processing includes removing foreign bodies on the core and surface of castings, removing pouring risers, shoveling burrs and draping seams and other protrusions, as well as heat treatment, shaping, anti-rust treatment and rough machining.

Forging

1. Forging: It is a processing method that uses forging machinery to apply pressure to metal blanks to produce plastic deformation to obtain forgings with certain mechanical properties, certain shapes and sizes.

2. One of the two major components of forging. Through forging, the as-cast looseness of metal and welding holes can be eliminated, and the mechanical properties of forgings are generally better than those of castings of the same material. For the important parts of machinery with high load and severe working conditions, forgings are mostly used except for simpler shapes that can be rolled, profiles or welded parts.

3. Forging can be divided into forming methods:

• ① Open forging (free forging). Using impact or pressure to deform the metal between the upper and lower anvils (anvils) to obtain the required forgings, there are mainly manual forging and mechanical forging.

• ② Closed mode forging. The metal blank is compressed and deformed in a forging die with a certain shape to obtain forgings, which can be divided into die forging, cold heading, rotary forging, and extrusion. According to the deformation temperature, forging can be divided into hot forging (processing temperature higher than the recrystallization temperature of the blank metal), warm forging (below the recrystallization temperature) and cold forging (normal temperature).

4. Forging materials are mainly carbon steel and alloy steel with various compositions, followed by aluminum, magnesium, titanium, copper, etc. and their alloys. The original state of the material includes bar stock, ingot, metal powder and liquid metal. The ratio of the cross-sectional area of the metal before deformation to the die cross-sectional area after deformation is called the forging ratio. The correct selection of forging ratios has a great bearing on improving product quality and reducing costs.

The difference between cast valve and forged valve

Casting valve: the metal is smelted into a liquid that meets the requirements and poured into the specified valve mold. After cooling, solidification, and cleaning, a valve casting with a predetermined shape, size and performance can be obtained. This is the entire casting valve crafting process. The connection between casting and valves came after the 20th century. Casting developed rapidly, creating ductile cast iron, malleable cast iron, ultra-low carbon stainless steel, aluminum copper, aluminum silicon, aluminum-magnesium alloy, and titanium that are still often used in valve products. Cast metal materials such as base, nickel base alloy, etc. The main advantage of casting is that the cost of the blank produced by casting is low, and it can show its economy more for parts with complex shapes, especially with complex inner cavities. At the same time, it has wider adaptability and better comprehensive mechanical properties. However, many materials and equipment are required for casting production, and dust, harmful gases and noise will be generated to pollute the environment. Forged valve is a processing method that uses forging machinery to apply pressure to metal valve blanks to produce plastic deformation to obtain forgings with certain mechanical properties, certain shapes and sizes. Forging can be divided into open forging (free forging) and closed mode forging according to the forming method. According to the deformation temperature, forging can be divided into hot forging, warm forging and cold forging. Forging materials are mainly carbon steel and alloy steel with various compositions, followed by aluminum, magnesium, titanium, copper, etc. and their alloys. The original state of the material includes bar stock, ingot, metal powder and liquid metal. The ratio of the cross-sectional area of the metal before deformation to the die cross-sectional area after deformation is called the forging ratio. Through forging, the as-cast looseness of metal and welding holes can be eliminated, and the mechanical properties of forgings are generally better than those of castings of the same material. For the important parts of machinery with high load and severe working conditions, forgings are mostly used except for simpler shapes that can be rolled, profiles or welded parts. The correct selection of forging ratios has a great bearing on improving product quality and reducing costs. Casting valves are valves made by casting. Generally, the pressure ratings of cast valves are relatively low (such as PN16, PN25, PN40, but there are also high-pressure ones, which can reach 1500Lb, 2500Lb, and most of the calibers are above DN50. Forged valves are forged. They are generally used in pipelines with high pressure ratings. Forged valves are mainly of small diameter, generally below DN50.

Source: China Valves Manufacturer – Yaang Pipe Industry Co., Limited (www.ugsteelmill.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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