Due to the rapid development of modern mechanical manufacturing and metallurgical industries, castings are now required to meet three major criteria: high quality, precision, and energy efficiency. To satisfy these requirements, current trends in induction furnace development are as follows:
(1) Increasing adoption of medium-frequency induction furnaces
Advantages of medium-frequency induction furnaces include:
① High power density, fast melting speed, easy start-up, and suitability for energy-efficient batch melting methods. The specific energy consumption for melting in a medium-frequency induction furnace of the same capacity is lower than that of a power-frequency (line-frequency) induction furnace.
② Flexible and convenient operation, making them well-suited for applications where the type of metal being melted frequently changes.
③ Adjustable power supply frequency, which makes medium-frequency induction furnaces more suitable for melting light metals.
④ Due to their high power density, absence of phase-balancing equipment, and reduced civil construction costs, the initial investment for a medium-frequency induction furnace with equivalent productivity is 10%–15% lower than that of a power-frequency induction furnace.
Because of these advantages, medium-frequency induction furnaces have largely replaced power-frequency induction furnaces abroad (except for channel-type induction furnaces) and are also increasingly replacing them in domestic applications.
(2) Expanded use of crucible-type induction furnaces in cast iron holding applications
Crucible-type induction furnaces—including short-coil and medium-frequency crucible furnaces—offer flexible operation, adjustable electromagnetic stirring, convenient control of molten iron composition and temperature, and easy replacement of refractory lining materials. These benefits have led to their growing adoption as holding furnaces for cast iron.
(3) Rapid expansion in the use of pouring furnaces equipped with induction heating systems
Precise and highly efficient pouring temperature control is essential for producing high-quality castings. Pouring furnaces capable of storing a certain amount of molten metal facilitate production organization. Consequently, over recent decades, countries have developed various types of holding and pouring furnaces—such as air-pressure, stopper-rod, combined air-pressure/stopper-rod, and electromagnetic-pump types—which have significantly modernized casting pouring operations, improved casting quality, reduced scrap rates, and delivered substantial economic benefits.
(4) Development of new types of induction furnaces
To meet the demands of advanced technologies for super-precision alloys, new furnace types—including plasma induction furnaces, vacuum induction furnaces, water-cooled copper crucible induction furnaces without refractory linings, and levitation (magnetic float) induction furnaces—have been continuously researched and developed. These innovative technologies and equipment have played important roles in high-end industrial fields.
(5) Growing application of computers in induction furnace systems
Computers are being increasingly used for furnace operation control, fault diagnosis, real-time monitoring of furnace conditions, and even integrated process control of entire melting and pouring workshops.
