Investment precision casting industry develops rapidly

Investment casting uses the final product as a copy, presses paraffin materials into an accurate and smooth wax mold, and applies multi-layer refractory material to the wax mold. After the slurry is dried and hardened, the mold shell is formed. Then the wax mold solidified in the mold shell is melted and flows out. The mold shell is then burned to make it solid and dry. Finally, the melted liquid metal is poured into the mold shell. The liquid metal is cooled in the mold shell, and after solidification, it becomes an accurate and smooth casting. This casting process can produce precise and complex metal parts or exquisite handicrafts that are close to the final shape of the product, and can be directly used without processing or rarely processed. Therefore, it is a near-pure metal liquid forming process. Compared with the sand casting method, it has the following characteristics:

1.

The casting has high dimensional accuracy and low surface roughness value, so it can achieve less processing or no cutting processing;

2.

Thin-walled parts or lightweight castings can be cast; especially suitable for castings with patterns, text or grooves;

3.

Ability to cast particularly complex castings, or combine and weld numerous parts.

China is one of the birthplaces of investment casting technology. According to research, lost wax casting occurred in the Spring and Autumn Period 2,500 years ago. The Zunhe Pan of Zeng Houyi’s tomb unearthed in Suizhou, Hubei in 1978 was a representative work of early lost wax casting. Modern investment casting technology began to be formed in the early 20th century. During World War II, due to the needs of national defense and aviation development, the United States, Britain and other countries first used investment casting methods to produce jet turbine engine blades. Since the 1980s, the output, output value, and quality of investment casting around the world have increased and improved greatly. Current investment casting is developing in the direction of precision, large, complex, and whole casting.

my country's investment casting began to be used in industrial production in the 1950s. First, it gradually developed from the aerospace and aviation sectors to all industrial sectors and was widely used.

one.

Development status of fine casting industry in mainland China

1.

The scale of precision casting industry in mainland China

Although the fine casting industry in mainland China has been established in the mid-1950s and has been gradually promoted and applied, its real rapid development has been in the past ten years from the early 1990s to the present, especially in recent years. At present, China's investment casting has two levels of technology. The first type of enterprise uses medium-temperature mold molding and silicon sol or ethyl silicate binder shell-making investment casting technology, namely the internationally universal investment casting technology. The second type is the shell-making process using low-temperature molding and water glass binder shell-making technology. The dimensional accuracy and surface roughness of the casting are worse than that of the first type, and cannot reach the international investment casting level. According to the situation in the mainland, medium-temperature or low-temperature molding is also used.

The surface layer is made of silicon sol and the reinforcement layer is made of a composite process of water glass shell, which can reduce costs while ensuring high dimensional accuracy and surface quality. According to statistics, in 2001, more than 350 manufacturers of the first category were adopted, with an annual output of 75,000 tons and an annual output value of 3.28 billion yuan; the second category of process manufacturers (including composite processes) had an annual output of nearly 200,000 tons and an annual output value of 1.5 billion yuan. In 2002, the output reached 321,000 tons and an annual output value of 5.49 billion yuan. The output in 2002 was 6.4 times that in 1988. The output value was 16.6 times that of 330 million in 1988.

2.

Process level, casting quality and product category from the perspective of use and quality level

At present, the castings produced by precision casting in my country are mainly: castings for aviation and gas turbines produced by the first-class process, with a quality of 50 manufacturers, with an annual output of 5,000 tons and an annual output value of 400 million yuan; commercial precision castings produced by the first-class and composite processes have quality inspection items and standards lower than aviation parts, with an annual output of 70,000 tons and an annual output value of 2.88 billion yuan; investment precision casting blanks produced by the second-class process, with low dimensional accuracy and surface roughness requirements, including

There are about 1,350 companies with an annual output of nearly 200,000 tons and an annual output value of 1.5 billion yuan. From the proportion of castings of three mass levels, it can be seen that the output of high-level aviation precision castings is very small, accounting for only 1.8% of the total output, and general commercial precision castings account for 25.6%, and the quality does not meet the international standards, while water glass castings account for 72.6% of the total output. Overall, there is a clear gap compared with the market structure of investment castings in advanced countries and regions such as the United States, the United Kingdom, Europe and Japan, and the proportion of high-quality precision castings is still very low.

Despite this, there have been great progress in all aspects of China's investment casting process. There are many new materials, new processes and new equipment that have a great impact on the development of investment casting, such as water-soluble cores, ceramic cores, metal material improvements, large investment casting technology, titanium alloy investment casting, directional solidification and single crystal casting, filtration technology, thermal isostatic pressure, rapid molding technology, computer application in investment casting and mechanized automation and other technologies that have made investment casting not only produce small castings, but also large castings. The outline size of the largest investment casting is nearly 2m, while the minimum wall thickness is less than 2mm. At the same time, investment castings are more precise, and in addition to linear tolerances, parts can also achieve higher geometric tolerances. The surface roughness value of investment castings is also getting smaller and smaller, reaching Ra0.4um.

3.

Supporting business is gradually complete

Due to the rapid development of the fine casting industry, the rapid development of related supporting businesses has been driven by the rapid development of related supporting businesses. It is mainly reflected in mold processing, equipment manufacturing, and raw and auxiliary materials production. According to preliminary statistics, professional factories for manufacturing fine casting molds, mainly processing equipment, have been formed in areas where fine casting factories are concentrated, such as Guangdong, Shandong and Wuhan, and there are many manufacturers of special equipment; fine casting raw and auxiliary materials production plants and suppliers have developed to nearly 100, and because the mold materials, zircon powder, sand belts and other auxiliary materials required for the first-class fine casting process production cannot be produced domestically, thousands of tons of raw and auxiliary materials must be imported from abroad every year. However, since my country's basic industrial and resource conditions are much better than other developing countries, the fine casting service industry will also extend and develop their markets to Southeast Asian countries and even the world.

4.

The gap and advantages between industry and international level compared with international investment casting level

China's fine casting industry produces aviation fine castings that are produced by the first-class process in the production of aviation fine castings, and not many high-quality fine castings. Most of them produce pipe fittings, hardware, horse harness and auto parts with low precision requirements, and a single type of alloy, especially the proportion of high-temperature alloys and non-ferrous alloys is too small, so my country's fine casting level is still very backward.

However, China has low labor costs and rich raw materials, and has great advantages in product prices. As long as the product quality is improved, it will still have great competitiveness internationally. At the same time, with the rise of domestic high-tech industries, the development of the machinery industry towards precision and miniaturization, and some regulations and local regulations issued by the construction industry have successively issued, using cast copper and stainless steel castings instead of cast iron pipe fittings, providing unprecedented business opportunities for the fine casting industry.

At the same time, the franchise and rapid development of China's private fine casting industry has injected fresh vitality into China's fine casting industry and has become the strongest and most realistic competitor of the country's fine casting industry. From the 1980s to the early 1990s, this type of enterprise introduced silicon sol shell making technology from Taiwan, Japan and other places in the form of joint ventures and sole proprietorships, mainly distributed in coastal and surrounding areas. Most of its products are sold to the international market. At the same time, due to its advanced system, flexible mechanisms and efficient management, the benefits are very good. Although it has only developed for more than 20 years, it has become the new force for the fine casting industry in mainland China to undertake export business.

, Due to its high level of equipment and facilities, the process and quality level are advanced at home, and basically reaching the general level of foreign countries. There are direct export orders and market alliances, and the product value remains at a high level, which is basically in line with the international market. Whether in terms of technical level or marketing channels, they are strong competitors of state-owned fine casting enterprises. And some of the second and third types of process enterprises, represented by manufacturers such as Dongfeng Precision Casting Co., Ltd., have been accelerating in recent years, regardless of process technology level, product quality and labor productivity are being promoted to the international market, and will continue to actively work hard to improve the level of China's fine casting industry.

two.

Investment precision casting industry will continue to develop rapidly

At present, mainland China has formed a group of fine casting industries that are gradually embarking on the international business track in terms of technology and management and are familiar with the international market, which has driven the rapid development of the industry.

Since the last century, the annual output value of the fine casting industry in mainland China has grown from only 5.4% of the total global fine casting output value to 7.7% in 2001, and has shown an accelerated development trend. China's huge market has provided broad space for the development of the fine casting industry. It is reflected in:

1.

The domestic market continues to grow

The rapid development of China's economy has led to the expansion of the domestic fine casting market. For example, the rapid development of the automobile industry has driven the rapid increase in the output and brand of fine casting products for automobiles. The development of the housing construction industry has caused the demand for construction hardware to surge. Investment companies in China directly purchase parts from the region, and the original international market orders have become domestic market orders.

2.

Exports are growing year by year

After more than 10 years of hard work, some enterprises have been able to mass-produce machine parts with certain precision requirements and high-quality aviation precision castings. They have the ability to challenge commercial parts in terms of technology and cost-effectiveness, and their export volume has increased year by year. As shown in Figure 2, the annual export mass output value has increased from 157 million yuan in 1993 to 3.4 billion yuan in 2002, showing a rapid upward trend. With the deepening of global economic integration and global procurement, exports will continue to grow rapidly.

3.

The market for forgings is wide instead of sand castings

One of the advantages of precision casting is the ability to produce various alloys and very complex, thin-walled castings. The castings have high dimensional accuracy, low surface roughness, and can achieve less or no cutting processing, which is incomparable to sand castings and forgings. With the increase in requirements for parts, more and more sand castings or forgings will be replaced by fine castings.

three.

Investment fine casting industry must adhere to the path of sustainable development

Due to the high casting costs and environmental protection requirements, advanced countries such as Europe and the United States have gradually transferred heavily polluted sand casting to developing countries. Although the fine casting industry does not have the heavy pollution to the environment, it also has a large amount of wastewater and waste gas emissions. Therefore, China's fine casting industry must put some effort into environmental protection, product structure, management, etc., and adhere to the path of sustainable development.

1.

Environmental protection laws, regulations and standards are mandatory and the basis of sustainable development

Since pollution sources often occur during investment casting production processes such as molding, shell making, roasting, smelting, pouring, cleaning and cutting, my country has issued the "Environmental Protection Law of the People's Republic of China", "Environmental Protection Management Measures for Construction Projects" and "Environmental Protection Design Regulations" regulations on environmental protection. The current 3-level 5-category environmental protection standard system in my country has clear standards for environmental quality, pollutant emissions, and environmental monitoring.

2.

Essential, excellent, light, heavy, and green are the direction of product development

"Fine" means precision and accuracy; "Excellent" means defect-free; "Light" means lightweight of structure and material; "heavy" means important parts; "Green" means clean production and green casting. This is an important measurement indicator for fine casting enterprises to enhance their core competitiveness.

3.

Improving product structure and improving product quality is the common responsibility of China's fine casting enterprises

After joining the WTO, China's fine casting industry must comprehensively improve the quality of castings, improve product structure, and increase alloy types. First, improve metallurgical quality by introducing and developing alloy purification equipment and technology; second, pay attention to casting process design and improve the yield rate by applying solidification simulation software; third, strictly control the manufacturing process, increase investment in molding, shell making materials and process equipment, and strive for the effective operation of the quality system; fourth, establish and enrich casting correction, modification equipment and cleaning equipment that is not easy to damage castings, strengthen the post-treatment process to make castings more precise and beautiful; fifth, improve casting non-destructive testing equipment and improve quality assurance capabilities.

4.

"Three transformations" of fine casting products

That is, lean-to-create products that consume the least resources to create value-added products, and even make products into works of art; serialization-based-based products according to market layout, "do what to do, don't do what to do", divide existing products into series, and develop new products, systematically demonstrate, reflect the broad spectrum and corporate strategic development direction; modular-extend existing products horizontally to meet user needs and value, realize the transformation from product-based to process-based, and further enhance the market competitiveness of products.

5.

Vigorously promote the automation, intelligence and environmental protection of process equipment, and drive the environmental protection of process

At present, there is still a considerable gap in the manufacturing level of fine casting equipment in mainland China, including molding, shell making, smelting, finishing and other post-process equipment automation, the level of intelligence is significantly different from the international level. At the same time, including factory facilities, environmental protection methods from design to production processes are difficult to eliminate hazards. This is common in many different types of enterprises. It mainly includes a large amount of dust, toxic and harmful gases, waste slag, waste emissions, etc. In this regard, the country and industry have already had some standards, and there are two most active methods at present:

First, establish unified raw and auxiliary materials, equipment, facilities, and environmental protection standards in the entire industry, as mandatory industry regulations for entry into fine casting enterprises and industrial structure adjustment, and extend them to the industrial chain.

Second, the government has issued mandatory technical regulations and encouragement policies to guide enterprises to take positive actions and increase environmental protection investment and renewal. Enterprises that have not passed the environmental management system certification will rectify within a time limit and obtain certification qualifications. Appropriate fiscal and tax policy support will be provided to certified enterprises.

6.

Introduce computer information management to improve corporate management level

At present, in addition to technical problems, some companies often cause problems such as delaying delivery time, inventory backlog, loss of control of material consumption, and inefficiency. The introduction of computer management and lean ideas will help companies better play the efficiency of people, money and materials, thereby improving the quality of castings, reducing costs, maximizing customer requirements, and adapting to changes in market demand.

The application of computers in fine casting production, including ERP, CRM, CAD, PDM, CAE, etc., gradually realizes simulated design, manufacturing, online transactions and remote development. Chinese fine casting enterprises should accelerate the pace of informatization construction.

7.

Strive to explore the international and domestic markets

Due to the shortage of labor resources and changes in environmental protection, casting in developed countries is also shifting to developing countries. After China joins the WTO, the export situation of fine castings is relatively favorable. Judging from the current situation, foreign-funded enterprises have much more foreign orders than domestic orders, and are direct orders, which means that many domestic companies are still very unfamiliar with the international market, lack talents and investment in foreign market development, and do not understand the rules of international market operation. There is no substantial breakthrough at the beginning, nor is it bigger. Therefore, it is necessary to make good use of international media to promote themselves, understand others, and go abroad to participate in exhibitions and develop more direct customers. It is necessary to establish the concept of "lean and honest" to develop and expand business with customers.

8.

Domestic enterprises have the conditions and ability to develop domestic markets

First, we must strengthen unity, communicate information and regulate behavior; second, we must choose the company's product positioning and development positioning, and industry associations should also actively guide it. At present, we should not only avoid the expansion of the number of enterprises and rushing up, but also guide the orderly development of the fine casting industry chain, overall improve the level of China's fine casting industry and achieve sustainable development.
Chapter completed!