Induction melting furnace

01

Compare energy use per tonne

A US Department of Energy best-practice study of metalcasting lists delivered energy for iron induction melting as 351.5 kWh per ton theoretical minimum, 796.3 kWh per ton industry average and 538.1 kWh per ton best-practice minimum. Citing an EPA background document, the same study notes that 95% of US induction melting furnaces were below 10 tons per hour melt capacity. [1]

Editorial calculation: the study uses US short tons (907 kg). Converting to metric tonnes, 538.1 ÷ 0.907 ≈ 593 kWh/t best practice and 796.3 ÷ 0.907 ≈ 878 kWh/t average. The gap is about 285 kWh per tonne, or about 2.85 GWh a year for a foundry melting 10,000 t. [1] Ask suppliers for guaranteed kWh/t at your metal, tapping temperature and duty.

Supplier ranges span small crucible furnaces to large foundry units; SEMC, for example, lists a 12 t, 8,000 kW medium-frequency induction furnace. [3]

Give the supplier the metal and grades, batch weight, melt rate, tapping temperature, charge materials, shifts and duty, energy guarantee basis, site power and harmonics limits, cooling water supply, tilt and pouring method, fume extraction and safety requirements.

02

Check cooling, interlocks and safe operation

Inductotherm's foundry safety fundamentals say any event that interferes with furnace cooling can quickly damage the coil and may cause a catastrophic explosion, so furnaces must have a backup cooling system and must not run without functioning water temperature and flow interlocks, which must not be bypassed; no induction melting equipment should run with any safety system jumpered or disabled. [2]

The same guidance says only dry spill pits can safely contain a run-out or emergency dump, furnaces must not run with ground probes disconnected or a faulty ground detection system, and the melt deck must be cleared on a ground-fault trip. All charge must be completely dry; wet charge, wet tools or additives, heavy charge dropped into the bath and sealed scrap are listed as primary causes of metal splash and furnace eruptions; people with pacemakers or metal implants must stay away from induction equipment, and Viton seals exposed to high temperature can form hydrofluoric acid. [2]

Ask the supplier which interlocks, backup cooling, ground and leak detection and lining-wear monitoring are included, and for operator training.

03

Relate furnace capacity, installed power and melt rate

OTTO JUNKER's induction melting brochure gives capacity and power pairs for coreless furnaces it has built: a Duomelt plant of 16 t capacity and 10 MW for melting up to 20 t of cast iron per hour; a standardised MFT JUPITER Line Duomelt plant of 8 t and 6 MW with IGBT converters; a medium-frequency coreless furnace of 12 t and 9 MW; and a medium-frequency furnace melting 1 t of aluminium in 80 minutes. The brochure lists furnaces for cast iron and steel, copper, aluminium, magnesium, silicon, silver, zinc and tin. Ajax TOCCO's coreless furnace page describes the parts such a furnace contains — a refractory-lined, insulated multi-turn copper coil, a steel shell or frame, silicon-steel yokes that return the magnetic flux, and top and bottom Faraday rings or flux plates that shield the steel structure — and lists shell, frame, box, lift-swing, lift-coil, rollover and high power density designs; its box furnace tilts a full 105° to empty the melt. [4] [5]

Editorial calculation: installed power per tonne of capacity is about 625 kW/t for the 16 t, 10 MW plant, 750 kW/t for 8 t and 6 MW, and 750 kW/t for 12 t and 9 MW, against about 667 kW/t for SEMC's 12 t, 8,000 kW furnace; 10 MW over 20 t an hour is 500 kWh of installed power per tonne, below the DOE's 593 kWh/t best-practice figure above, so ask for the guaranteed kWh per tonne at your tapping temperature rather than inferring it from power. [4] [3] [1]

04

Crucible units to multi-tonne furnaces, and the equipment each listed supplier sells beside them

SEMC lists induction melting furnaces up to multi-tonne units; Hengyang, Hongteng and Runxiang list induction melting furnaces with rolling mill or casting equipment; Hani lists induction melting furnaces with arc and refining furnaces; Yantong lists melting furnaces with heat treatment furnaces; Foco and HLQ list induction melting furnaces with induction heaters; Superbmelt lists induction melting furnaces including small precious-metal units.

05

Coil, lining, power supply, cooling, ground detection and tilt

Inductotherm's safety guidance covers five of the six rows — coil, lining, cooling, ground detection and tilt hydraulics; only the power supply row comes from a supplier listing. [2] [3]

06

Capacity, power, melt rate, kWh per tonne, cooling and tilt for an induction furnace

The 593 kWh/t row is the DOE best-practice figure converted from short tons; set it beside the supplier's guaranteed value at your tapping temperature. Maximum temperature, crucible volume, cooling water pressure and noise have no published figure here. [1]

07

Send the metal, energy and safety data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Metal: [type; grades; batch weight; melt rate; tapping temperature]
Charge: [scrap type; dryness; pre-heating]
Energy: [guaranteed kWh/t; basis]
Power: [supply; harmonics limits]
Cooling: [water supply; backup cooling; interlocks]
Safety: [ground detection; spill pit; training]
Plant: [tilt; fume hood; foundation]

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