The process of melting metal into a liquid that meets certain requirements and pouring it into a mold, and obtaining a casting (part or blank) with predetermined shape, size and performance after cooling, solidification and cleaning. Basic technology of modern machinery manufacturing industry. The cost of the blank produced by casting is low, and it is more economical for parts with complex shapes, especially parts with complex cavities. At the same time, it has wide adaptability and good comprehensive mechanical properties. However, there are many materials (such as metal, wood, fuel, molding materials, etc. ) and equipment (such as metallurgical furnace, sand mixer, molding machine, core making machine, sanding machine, shot blasting machine, etc.). ) casting production will produce dust, harmful gases and noise, polluting the environment.

Casting is an early metal hot working process mastered by human beings, with a history of about 6000 years. In 3200 BC, bronze frog castings appeared in Mesopotamia. During the period from BC 13 to BC 10, China entered the heyday of bronze casting, and its technological level reached a fairly high level. For example, Simuwu Fang Ding, weighing 875 kg in Shang Dynasty, Zunpan in Ceng Houyi in Warring States and transparent mirror in Western Han Dynasty are all representative products of ancient casting. Early casting was greatly influenced by pottery, and most of the castings were tools or utensils for agricultural production, religion and life, with strong artistic color. In 5 13 BC, China cast the earliest recorded iron castings in the world-Jin Guoding (about 270kg). Around the 8th century, Europe began to produce iron castings. /kloc-after the industrial revolution in the 0/8th century, castings entered a new era of serving large industries. In the 20th century, casting developed very rapidly. Foundry metal materials such as nodular cast iron, malleable cast iron, ultra-low carbon stainless steel, Al-Cu, Al-Si, Al-Mg alloy, Ti-based alloy and Ni-based alloy have been developed successively, and a new technology of inoculation treatment for gray cast iron has been invented. After 1950s, new technologies such as green sand high pressure molding, chemically hardened sand molding and core making, negative pressure molding, other special casting and shot blasting cleaning appeared.

There are many kinds of casting, which are customarily divided into: ① ordinary sand casting, including wet sand mold, dry sand mold and chemically hardened sand mold. ② Special casting, according to the molding materials, can be divided into special casting with natural ore as the main molding material (such as investment casting, clay casting, shell casting in casting workshop, negative pressure casting, full mold casting, ceramic mold 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. ). The casting process usually includes: ① Preparing molds (containers for making solid castings from liquid metal), which can be divided into sand molds, metal molds, ceramic molds, clay molds, graphite molds, etc. According to the times of use, it can be divided into disposable mold, semi-permanent mold and permanent mold, and the quality of mold making is the main factor affecting the quality of castings. (2) Melting and pouring of casting metals, casting metals (casting alloys) mainly include cast iron, cast steel and casting nonferrous alloys; (3) Casting processing and inspection. Casting treatment includes removing foreign bodies from the core and the surface of the casting, cutting off the riser, shoveling off burrs, overlapping seams and other protrusions, as well as heat treatment, shaping, rust prevention and rough machining.

forge

A processing method of applying pressure to metal blank by forging press to make it plastically deform, so as to obtain forgings with certain mechanical properties, shapes and sizes. One of the two major elements of forging. 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. Forging can be divided into: ① free forging (free forging). The metal is deformed between the upper and lower supports (anvil) by impact or pressure to obtain the required forgings. There are two main methods: manual forging and mechanical forging. ② Closed forging. Forgings are obtained by pressure deformation of metal blanks in a forging die chamber with a certain shape, which can be divided into die forging, cold heading, rotary forging, extrusion and so on. According to the deformation temperature, forging can be divided into hot forging (the processing temperature is higher than the recrystallization temperature of the blank metal), warm forging (lower than the recrystallization temperature) and cold forging (normal 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. The correct selection of forging ratio has a great relationship with improving product quality and reducing cost.