Vacuum induction melting furnace (VIM furnace) is a high-end metallurgical equipment that uses the principle of electromagnetic induction heating to melt metals under high vacuum or controlled atmosphere conditions.
Vacuum induciton melting furnace has fast heating speed, less oxidation and decarburization, good process repeatability and high degree of automation, which can realize fully automatic unmanned operation and improve labor productivity.
The vacuum induction melting furnace combines two core technologies:
Electromagnetic induction heating:
Medium or high-frequency alternating current passes through a water-cooled copper induction coil, generating eddy currents in the metal material within the crucible, causing it to heat up and melt.
Vacuum environment:
The entire melting process takes place in a sealed vacuum chamber, with a vacuum level typically reaching 10⁻² to 10⁻⁴ Pa (or even higher), effectively removing gases (such as O₂, N₂, H₂) and volatile impurities, preventing oxidation, and promoting degassing and the flotation of inclusions.
Vacuum System
Composed of a mechanical pump (pre-pumping), Roots pump, diffusion pump or molecular pump, achieving high vacuum.
Equipped with vacuum gauges, valves, and safety interlock devices.
Induction Power Supply System
Typically uses medium frequency (150 Hz–10 kHz) or high frequency (>10 kHz) power supplies, with power ranging from tens of kilowatts to several megawatts.
Modern equipment mostly uses IGBT inverter technology, offering high efficiency, fast response, and low harmonics.
Melting Chamber and Crucible System
The melting chamber is a double-layered stainless steel water-cooled structure, resistant to high temperatures and high vacuum.
Crucible material is selected according to the metal being melted:
Aluminum oxide (Al₂O₃) – used for nickel-based and iron-based alloys
Magnesium oxide (MgO), calcium oxide (CaO) – used for reactive metals
Graphite crucible – requires an inert atmosphere (such as argon) to avoid carbon contamination
Casting System
Can achieve tilt pouring, bottom pouring, or pneumatic/centrifugal casting, suitable for different molds (such as ceramic shells, metal molds).
High-end equipment supports in-furnace refining + casting, reducing secondary pollution.
Control System
Fully automatic PLC or industrial computer control, integrating parameters such as vacuum level, temperature, power, and casting time.
Supports process curve programming, data storage and traceability, complying with quality system requirements of industries such as aerospace and medical (e.g., AS9100, ISO 13485).
Cooling and Safety System
The induction coil, furnace body, and power supply all require forced water cooling.
Equipped with multiple protections against overvoltage, overcurrent, water failure, and vacuum failure.
