Difference between cast parts and forged parts


Definition of casting: The process of smelting a metal into a liquid that meets certain requirements and pouring it into a mold. After cooling and solidifying and finishing, a casting (part or blank) with a predetermined shape, size and performance is obtained.

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

1.  Ordinary sand casting, including wet sand, dry sand and chemically hardened sand.
2.  Special casting, according to the molding materials, can be divided into special castings with natural mineral sand and gravel as the main molding materials (such as investment casting, mud casting, shell casting in foundry, negative pressure casting, solid casting, ceramic casting) Etc.) and special castings (such as metal casting, pressure casting, continuous casting, low pressure casting, centrifugal casting, etc.) with metal as the main mold material.

The casting process usually includes:

1.  Preparation of casting molds (containers for making 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 according to the number of uses And permanent mold, the quality of the mold preparation is the main factor affecting the quality of the casting;

2.  Melting and pouring of cast metals. Cast metals (cast alloys) are mainly cast iron, cast steel and non-ferrous alloys;

3.  Casting processing and inspection. Casting processing includes removing foreign matters from the core and casting surface, cutting out the riser, shovel and burr, and other protrusions, as well as heat treatment, shaping, rust prevention and rough processing.


Definition of forging: A method of forging a metal blank by using forging machinery to plastically deform it to obtain a forging piece with certain mechanical properties, a certain shape and size.

One of the two major components of forging. Forging can eliminate metal as-looseness, weld holes, and mechanical properties of forgings are generally better than castings of the same material. For the important parts with high load and severe working conditions in the machinery, in addition to the simpler shapes that can be rolled plates, profiles or welded parts, forgings are mostly used.

Forging can be divided into:

1.  Open forging (free forging). The impact force or pressure is used to deform the metal between the upper and lower resisting irons (anvils) to obtain the required forgings. There are mainly manual forging and mechanical forging.

2.  Closed mode forging. Metal blanks are deformed by compression in a forging die cavity with a certain shape to obtain forgings, which can be divided into die forging, cold heading, rotary forging, and extrusion.

Forging according to the deformation temperature can be divided into hot forging (the processing temperature is higher than the recrystallization temperature of the billet metal), warm forging (below the recrystallization temperature), and cold forging (normal temperature). Forging materials are mainly carbon steel and alloy steel with various components, followed by aluminum, magnesium, titanium, copper, and their alloys. The original state of the material is bar, ingot, metal powder and liquid metal. The ratio of the cross-sectional area of ​​the metal before deformation to the die area after deformation is called the forging ratio. The correct selection of forging ratio has a lot to do with improving product quality and reducing costs.
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