Casting is one of the most important methods of metal forming and it is the basis of thermal processing. The history of casting is as old as the history of the Chinese civilization. Our ancestors cast the exquisite bronzes of the “Sanxingdui†more than 4,000 years ago. The technical level is amazing, but in modern times, as the world's largest producer of castings, China The level of casting is behind the developed countries. An overview of China's foundry industry China's casting production has surpassed the United States since 2000 and has ranked first in the world for six consecutive years, including 22.42 million tons in 2004, an estimated 26 million tons in 2005, and an annual output value of more than 250 billion yuan. The output of castings accounts for the world's total output. As much as 1/4, it has become the world's foundry production base. According to the 2004 production statistics of the major casting producing countries in the world, it can be seen that the top ten casting producing countries can be divided into two categories. The first category is developing countries. Although the output is large, the added value of castings is low, there are many small enterprises, the number of employees is huge, and the proportion of ferrous metals is significant. The other is developed countries, such as Japan, the United States and Europe, which use high technology to produce high value-added castings. In developed countries, casting technology is advanced, product quality is good, production efficiency is high, environmental pollution is small, and raw and auxiliary materials have been serialized. Europe has established a multinational service system, and its production is mechanized, automated and intelligent. The production process strictly enforces technical standards, and the casting scrap rate is about 2%-5%. Emphasis on using information technology to improve the design level of casting process, universal application software for filling solidification process simulation and process optimization design. From the perspective of batch and labor productivity, Europe, the United States and Japan have great advantages. Japan's labor productivity is 140 tons of casting per capita per year, and China's estimated is about 20 tons, a difference of 7 times. China's labor cost is less than 1 US dollar / hour, which is several times different from that of developed countries, so export castings have advantages. However, in recent years, the price of materials has soared, making the advantages of China's export castings in terms of material costs disappear. In terms of product quality and grade, we lag far behind developed countries. In recent years, although China's casting exports have increased, exports account for only 97% of China's total output, accounting for less than 8% of the world's castings market. The overall growth rate is slow, showing poor quality and low prices. For a long time, the exported castings are mainly medium and low-grade products, and all kinds of pipe fittings, radiators, kitchen utensils and bathing utensils accounted for 36%. Although some export castings can meet international standards, there is still a distance to meet European and American customer standards. In China, the foundry industry is an important industry related to the national economy and the people's livelihood. It is the foundation of the pillar industries such as automobile, petrochemical, steel, electric power, shipbuilding, textile and equipment manufacturing, and is an important part of the manufacturing industry. In mechanical equipment, castings account for a high proportion of the weight of the whole machine, 80% of internal combustion engines, 50%-80% of tractors, and 50%-60% of hydraulic parts and pumps. Almost all the key components in the automobile are cast; major equipment such as metallurgy, mines and power stations are dependent on large castings and forgings, and the quality of the castings directly affects the quality and performance of the machine. China's foundry production enterprises are mainly distributed in the east, with less production in the west. At present, there are about 24,000 foundry companies and more than 1.2 million employees. From the perspective of industrial structure, there are casting factories or workshops that are subordinate to the main production plants, professional foundries, and a large number of township foundries. In terms of scale and level, there are large-scale foundries with advanced technology, high degree of mechanization and annual output of tens of thousands of tons of castings, such as some advanced foundries in the heavy industry, automobile industry and aviation industry, as well as backward technology and poor equipment. Hand-operated, small-scale foundry with an annual output of more than 100 tons of castings. Second, the problems in China's foundry industry The technical level of China's foundry industry is about 20 years behind that of developed countries and cannot meet the needs of the rapid development of the national economy. The backwardness of technology, outdated equipment, high consumption of energy and raw materials, serious environmental pollution and poor working environment of workers have become the consensus of the industry. Specifically in: (1) Low process level and poor casting quality 1 castings have a large processing margin. Due to the lack of scientific design guidance, it is difficult for process designers to control the deformation problem based on experience. The machining allowance for casting is generally 1-3 times larger than that of foreign countries. The processing allowance is large, the energy consumption of the castings and the consumption of raw materials are serious, the processing cycle is long, and the production efficiency is low, which has become a bottleneck restricting the development of the industry. 2 Large casting segregation and inclusion defects are serious. After the solidification of large steel castings and large steel ingots, macroscopic segregation and coarse grain problems exist in the thick section of the riser and the casting. 3 The casting crack problem is serious. 4 The design of the gating system is unreasonable. Due to improper design, there are defects such as gas and inclusions, resulting in low casting yield and yield. 5 simulation software applications are not popular. Casting process simulation is a necessary part of casting production. In foreign countries, if there is no computer simulation technology, orders will not be available. China's foundry computer simulation started earlier. Although the core computing part has strong development capabilities, the overall software packaging capability is poor, resulting in mature commercial software development far behind developed countries. A considerable number of foundry companies are discouraged from computer simulation technology. lack of trust. Although this situation has improved, the companies that have purchased casting simulation software are still rare in their role, and they need to train software applications for their employees. 6 The production capacity of ordinary castings is excessive, the manufacture of high-precision castings is still difficult, and core technologies and key products are still dependent on imports. (2) High energy consumption and raw material consumption The energy consumption of China's foundry industry accounts for 25%-30% of the total energy consumption of the machinery industry, the average energy utilization rate is 17%, and the energy consumption is about twice that of developed countries. The energy consumption per ton of qualified cast iron produced in China is 550-700 kg of standard coal, and that of foreign countries is 300-400 kg of standard coal. The energy consumption per ton of qualified steel castings produced in China is 800-1000 kg of standard coal. 500-800 kg of standard coal. According to statistics, the input of materials and energy in the production process of castings accounts for about 55%-70% of the output value. The gross weight of Chinese castings is 10%-20% higher than that of foreign countries. The average production rate of steel castings is 55%, and foreign countries can reach 70%. (3) Serious environmental pollution and poor working environment In addition to a few large enterprises such as FAW, Second Automobile, Daqi Dazhong, Shenyang Liming Company, such as sophisticated production equipment, advanced casting technology, and environmental protection measures are in place, most foundry production equipment is outdated, backward technology, and rarely considered. Environmental issues. In the 1980s, the government made special adjustments to enterprises with small scale, low technical level and serious pollution, which increased the degree of intensification of enterprises, but the extensive characteristics of foundry production have not been fundamentally changed. More than 90% of foundry companies with poor production environment, poor operating conditions, backward technology and extensive production; the Environmental Protection Award was presented at the 63rd World Foundry Conference held in Hungary in 1998. None of the award-winning foundries in China This is extremely incompatible with China's status as a founding power. The environmental problems in China's foundry industry are also reflected in the excessive consumption of natural resources. In the production of foundry, the crucible is mainly made of pig iron, scrap steel, coke, limestone, etc., sand, core sand, mainly raw sand, clay, coal powder, resin and other binders, curing agents, old sand, etc. Transportation, sand mixing, modeling Processes such as core making, baking, melting, pouring, cooling, falling sand, cleaning and post-treatment are carried out in mechanical vibration and noise, and some work in high temperature, such as melting and pouring. Some produce irritating odors, and the dust working environment is even worse. In China's foundry, for every ton of castings produced, about 50 kilograms of dust is emitted. The smelting and pouring process discharges 200 kilograms of waste residue, 20 cubic meters of waste gas, and shapes and cleans waste sand by about 13-15 tons. With an annual output of 22 million tons of castings, the total amount of pollutants discharged each year is: 4.4 million tons of waste slag, nearly 16.5 million tons of waste sand, and 400 million cubic meters of waste gas. These data are sufficient to illustrate the seriousness of environmental problems in China's foundry industry. The use of high technology to achieve green casting is a key issue that needs to be addressed at present. Next page Insulated Composite Insulation Air Duct Insulated Composite Insulation Air Duct,Fabric Air Duct Colling Systems,Fabric Duct,Fabric Ductwork Jiangsu Buna Technology Development Co. , Ltd. , https://www.bunaduct.com
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