Metal Cutting History
Release time:
2024-01-29
In ancient times, China, India, Babylon, Egypt, Greece and Rome had cut weapons, sacrificial objects, works of art and household utensils. Early castings were made of gold, silver, copper and their alloys. The Bronze Age is a glorious page in the history of human civilization; later cast iron pieces appeared. Iron castings were widely used in China as early as the Warring States period, and the technical tradition has a long history. Metallurgy and cutting are complementary processes, and the term "metallurgy" in ancient China reflects this fact. Although the cutting process has developed into a relatively independent branch of the mechanical manufacturing process, it is still inseparable from the metallurgical process.
In ancient times, China, India, Babylon, Egypt, Greece and Rome had cut weapons, sacrificial objects, works of art and household utensils. Early castings were made of gold, silver, copper and their alloys. The Bronze Age is a glorious page in the history of human civilization; later cast iron pieces appeared. Iron castings were widely used in China as early as the Warring States period, and the technical tradition has a long history. Metallurgy and cutting are complementary processes, and the term "metallurgy" in ancient China reflects this fact. Although the later cutting process has developed into a relatively independent branch of the mechanical manufacturing process, it is still inseparable from the metallurgical process.
Cast iron has a long history, but the development speed is slow. It was not until 1722 that Leomir created the "cupola" and began to study the structure and fracture of cast iron with a microscope. In 1734, Swedenberg (Svedenberg)'s "Cast Iron Science" (Deferro) was published, and he had a preliminary theoretical understanding of the cast iron process. Between 1765 and 1785, due to the emergence of steam engines, cast iron was widely used in the machine manufacturing industry since the 1860 s, and cast iron rails were also used in the transportation sector. In 1788, a 60-kilometer water-conveying cast iron pipe was produced for the Paris waterworks. The increase in the demand for cast iron has promoted the technological progress and theoretical research of cast iron.
The melting point of cast steel is high, and the composition control (such as deoxidation, etc.) is complicated. It was not until 1740 that the crucible method of steelmaking appeared and the process began to develop.
Cast aluminum 1886 invention of molten salt electrolytic aluminum. By the beginning of the 20th century, the cutting industry of aluminum and its alloys had developed rapidly and ranked first in the cutting of non-ferrous metals. However, the proportion of traditional copper alloy castings has gradually decreased.
Metal cutting methods have been developed to meet various needs and can economically produce castings of complex shapes and various sizes.
The cutting performance of metal includes: ① fluidity, the ability of liquid metal to fill the mold; ② shrinkage tendency, large volume shrinkage from liquid to solid, easy to produce defects such as shrinkage cavity, and large linear dimensional shrinkage, which affects the final dimensional accuracy of castings; ③ hot cracking tendency, some metals and alloys are prone to cracks and segregation tendency in the cutting process.
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The cutting performance of metal includes: ① fluidity, the ability of liquid metal to fill the mold; ② shrinkage tendency, large volume shrinkage from liquid to solid, easy to produce defects such as shrinkage cavity, and large linear dimensional shrinkage, which affects the final dimensional accuracy of castings; ③ hot cracking tendency, some metals and alloys are prone to cracks and segregation tendency in the cutting process.
Mold (liquid metal into a solid casting container) preparation, mold according to the materials used can be divided into sand, metal, ceramic, mud, graphite, etc., according to the number of use can be divided into one-time, semi-permanent and permanent, mold preparation is the main factor affecting the quality of castings
Gravity cutting
It is widely used in the production of various non-ferrous castings, but metal mold cutting also has the disadvantages of low metal utilization rate, difficult pouring of thin-walled complex castings, and low relative pressure cutting of casting tissue density.
When using metal type cutting, the following factors must be considered
When using metal type cutting, the following factors must be considered comprehensively: long manufacturing cycle, high cost, not suitable for single-piece and small-batch production; It is not suitable for cutting complex shapes (especially inner cavities), thin-walled and large castings (metal molds are limited by the size of mold materials and the ability of cavity processing equipment and cutting equipment, so metal molds are not suitable for the production of particularly large castings). The mold is more expensive than sand mold and cheaper than die casting.