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The development of smelting technology needs to be viewed from multiple perspectives.

1. Melting method

The development and improvement of melting technologies primarily focus on enhancing the quality of molten iron, increasing efficiency, reducing energy consumption, and improving environmental performance. Currently, casting enterprises mainly employ two major types of melting processes: one is the cupola furnace combined with induction furnaces (including core-type heat-preservation induction furnaces and coreless heat-preservation induction furnaces, etc.). Double-furnace melting Method two: medium-frequency induction furnace melting. Environmental protection concerns are one of the reasons why many companies choose electric furnace melting.

2. The characteristics of combined cupola-smelting and medium-frequency induction furnace smelting: The combined cupola-induction furnace smelting method offers advantages such as continuous supply of molten iron, high superheat temperatures for the molten iron, and effective elimination of inherited defects in the charge materials. However, cupolas emit large quantities of waste gases and smoke, causing environmental pollution. Therefore, this process requires advanced ventilation, dust removal, and desulfurization facilities to meet environmental protection standards. Developing high-temperature, long-range hot-air cupolas represents the trend in the development of combined smelting technology. For example, Weichai Foundry has introduced a 35 t/h oxygen-enriched hot-air cupola paired with an 80 t core-type holding induction furnace, placing it at the forefront of China’s casting industry. The molten iron exiting the cupola reaches temperatures of 1500~℃.

1550℃.

Melting cast iron in a medium-frequency induction furnace has several drawbacks, including long holding times for the molten iron, strong stirring action, severe oxidation of the molten iron, reduced availability of graphite nuclei, a high tendency toward white cast iron and shrinkage cavities, and poor fluidity of the molten iron. The overheating temperature typically used in medium-frequency induction furnace melting generally ranges from 1500 to...

At 1550℃, compared to the superheating temperatures of up to 1700℃ in cupola furnaces, induction furnaces are at a disadvantage when it comes to eliminating the coarse graphite structure typically found in newly produced pig iron. However, medium-frequency induction furnaces offer advantages such as simple operation, ease of switching material grades, and convenient adjustment of chemical composition. In production practice, by mastering the melting technology for medium-frequency induction furnaces, it is entirely possible to produce high-quality gray cast iron parts. Dongfeng Motor Corporation has accumulated extensive production experience in using electric furnace melting methods to manufacture high-quality castings and possesses mature medium-frequency induction furnace melting technologies and production processes.

3. The advancement of melting technology has driven improvements in casting quality. Regardless of the melting method employed, every casting enterprise needs to explore and master mature, effective melting technologies that are tailored to its own specific requirements, thereby ensuring the consistent performance of castings’ material properties. Our company’s melting processes have evolved from internal water-cooled cupola furnaces used in the 1950s and 1960s, through the dual-process melting system of external water-cooled cupola furnaces combined with induction furnaces in the 1980s and 1990s, to the current medium-frequency induction furnace melting technology. Each improvement in melting methodology has represented a step forward in the technology for melting gray cast iron. From producing low-grade castings (HT150, HT200) for crawler tractors, to manufacturing chassis components for high-horsepower wheeled tractors, and then to producing high-quality engine castings, melting technology has been refined and enhanced through practical exploration. To a certain extent, the development of melting technology at Konda Electric Furnace Equipment Company serves as a microcosm of the broader advancements in melting technology within the casting industry.