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Induction furnaces

Used Induction Furnaces Melting, Holding and Pouring Electrical Furnace Technology

The electromagnetic field generates heat directly within the metal.

Induction furnaces transfer electrical energy to the metallic charge material or existing molten bath through an electromagnetic field. Power, temperature and bath movement can therefore be adapted precisely to the relevant melting, holding or pouring process.

Furnace types Channel induction furnace and coreless induction furnace

Applications Melting, holding, pouring or processing metal chips

Metals Non-ferrous metals, copper alloys, cast iron and steel

System equipment Coil, power electronics, cooling and process control

From alternating current to molten metal

The inductive process combines electrical power, electromagnetic coupling and the heating of conductive metal. The specific configuration differs according to furnace design and application.

The heat is not generated first within the furnace chamber, but directly by electrical currents inside the metal.

Field

The induction coil generates a changing magnetic field The multi-turn copper coil is supplied with alternating current. Frequency, current, coil geometry and electrical tuning determine the electromagnetic coupling with the metal.

Current

Electrical currents are induced in the conductive material Within the system, the metal behaves similarly to the secondary side of a transformer. The induced currents flow through the charge material or molten bath.

Heat

Electrical resistance heats the metal The induced currents generate heat within the material. At the same time, electromagnetic forces can support controlled bath movement and mixing.

Two fundamental furnace designs

The decisive difference is whether the energy is transferred to the molten metal within a restricted channel or across almost the entire crucible contents.

Furnace Design 01

Channel Induction Furnace

In a channel induction furnace, electromagnetic energy is transferred within a channel connected to the main molten bath. The heated metal circulates between the inductor and the furnace vessel.

Typical duty Holding, pouring and, depending on the configuration, melting.

Typical metals Copper and copper alloys, aluminium and selected steel applications.

Central unit Inductor with copper coil, transformer core and molten-metal channel.

Key inspection Channel condition, inductor, refractory lining, circulation and minimum metal level.

Furnace Design 02

Coreless Induction Furnace

In a coreless induction furnace, the metal is contained within a ceramic-lined crucible surrounded by a cylindrical induction coil. Almost the entire crucible content is heated electromagnetically.

Typical duty Melting, holding, pouring and chip melting.

Typical industries Cast-iron foundries, the non-ferrous metal industry and selected steel applications.

Central unit Ceramic crucible, water-cooled coil and electrical power supply.

Key inspection Coil condition, refractory lining, cooling, earth-fault monitoring and tilting mechanism.

The application determines the required furnace configuration

An induction furnace can perform different duties. Metal demand, temperature, power, charging method and downstream metal flow must be considered together during technical selection.

Melting

Melt solid charge material under controlled conditions The batch size, initial temperature, piece geometry, bulk density, alloy and required melting time determine the necessary power range.

Power and batch time

Holding

Maintain molten metal within a stable process window Heat losses, metal withdrawal, replenishment and idle periods influence the required holding power and temperature control.

Stabilise temperature

Pouring

Transfer molten metal to a ladle or casting system The tilting angle, pouring height, spout geometry, dosing capability, ladle position and machine interface must match the system layout.

Measure metal transfer

Chips

Process lightweight material with a large surface area Drying, deoiling, compacting, controlled feeding, submersion and oxidation behaviour determine suitability for chip melting.

Prepare the material

Characteristic properties of induction furnace technology

The technical assessment should consider both the advantages of the electrical process and the requirements relating to power, cooling and refractory lining.

Precise power control and rapid response meet demanding electrical and thermal infrastructure.

Rapid response Depending on the converter and system concept, electrical power can be adjusted quickly. This allows targeted control of the temperature and melting process.

Reproducible process control Target power, temperature, batch programmes and process times can be stored within the control system and reused for recurring production sequences.

Controlled bath movement Electromagnetic forces can move and mix the molten metal. Their strength and effect depend on frequency, power, geometry and fill level.

Neutral furnace atmosphere Since no burner flame acts directly on the molten metal, energy is transferred without direct combustion gases within the melting chamber.

High cooling requirements The coil, busbars, converter and other electrical components require a controlled cooling-water supply with monitored flow, temperature and pressure.

The electrical system forms the actual energy path

All power components and connections of a used induction furnace must be documented completely. Missing assemblies can make reuse considerably more difficult.

Power supply

Check site capacity and voltage The connected load, mains voltage, transformer configuration, short-circuit capacity, cable cross-sections and existing power distribution must be compatible with the new location.

Converter

Convert mains frequency into the required operating frequency Power modules, semiconductors, the DC link, control boards, cooling and software version determine the usability of the frequency-converter system.

Tuning

Match the capacitors and resonant circuit Capacitor banks, contactors, busbars and connecting cables must be electrically and mechanically compatible with the coil and intended power range.

Coil

Generate the magnetic field within the furnace The copper tubing, insulation, winding spacing, connections, cooling-water flow and visible thermal or mechanical damage are central inspection points.

Monitoring

Protect the electrical and thermal condition Earth-fault monitoring, insulation monitoring, flow switches, temperature measurement, overcurrent protection and emergency shutdown must function completely.

The metal and refractory lining must be assessed as a material pair

The refractory lining provides the direct protective barrier between the molten metal, coil and supporting structure. Material selection, installation, drying and monitoring influence operational safety and service life.

Consider the alloy Cast iron, steel, aluminium, copper and other alloys place different requirements on the refractory material, operating temperature and chemical resistance.

Document the lining profile The material quality, layer thickness, crucible geometry, base, pouring zone, repair areas and previous service life should be documented as completely as possible.

Monitor the remaining wall thickness Wear, cracks and metal penetration can affect electrical and mechanical safety. Professional assessment is required before recommissioning.

Plan drying and heating New or repaired linings must be commissioned using an appropriate drying and sintering programme. The temperature curve and holding periods must be documented.

Inspect the inductor and channel carefully In channel furnaces, the channel geometry, deposits, minimum fill level and local lining condition directly affect circulation and energy transfer.

Which technical data determine suitability?

The manufacturer and year of manufacture are not sufficient for selecting a used induction furnace. Complete data relating to the metal process, furnace, electrical system, cooling circuit and scope of supply are required.

Furnace design

Channel or coreless induction furnace The design, vessel geometry, inductor, tilting mechanism and intended operating method form the basis of the technical assignment.

Application

Melting, holding, pouring or chip melting The main duty determines the required power reserve, charging sequence, temperature control, metal removal and peripheral equipment.

Metal

Alloy and operating temperature The metal type, composition, density, melting temperature and metallurgical requirements influence the lining, power and furnace size.

Capacity

Nominal content and usable metal quantity The total content, working bath, minimum fill level, residual metal and permissible maximum filling quantity should be documented separately.

Power

Electrical rated and operating power The furnace power, converter capacity, transformer, power stages and realistically achievable operating range must be compatible.

Frequency

Operating frequency of the induction system The frequency influences penetration depth, power coupling, bath movement and electrical tuning. It must be suitable for the metal and furnace geometry.

Melting rate

Metal quantity per unit of time The actual melting rate depends on the alloy, charge material, initial temperature, heel, charging sequence and heat losses.

Cooling

Water quantity, pressure and temperature The cooling capacity, pumps, heat exchangers, filters, cooling units, flow monitoring and water quality must be documented completely.

Tilting

Drive, angle and pouring height The hydraulic or electromechanical system, tilting axis, end positions, return movement, ladle position and safety area must be inspected.

Control system

PLC, operation and process data Document the power control, temperature, cooling circuit, tilting release, batch programmes, faults, data recording and interfaces.

Installation

Dimensions, weight and infrastructure Consider the foundation, furnace pit, steel structure, maintenance areas, cable routes, cooling system, switchgear and access route at the new location.

Power, temperature and safety are controlled together

The control system connects the electrical energy path with the metallurgical process. Reuse therefore requires both functional hardware and available programmes and parameters.

Power may be supplied to the coil only after the electrical system, cooling circuit and furnace condition have all been released.

System readiness The mains supply, converter, cooling-water circuit, earth-fault monitoring, doors, tilting position and other safety conditions must be confirmed.

Power setting The electrical power is controlled according to the process stage, temperature, fill level and selected batch programme.

Temperature control Measurements from the molten bath, furnace and cooling system are monitored and linked with target values, limits and release conditions.

Cooling-circuit monitoring Flow, supply temperature, return temperature, pressure and temperature must be monitored continuously. Deviations require a defined power reduction or shutdown.

Process data Power, energy consumption, temperature, batch time, fault messages and operating hours can be stored for analysis, maintenance planning and traceability.

Technical inspection of a used induction furnace

The condition assessment must include the furnace body, complete electrical system, cooling equipment, refractory lining, mechanical system, control system and all safety-related functions.

Inspection area Furnace housing and supporting structure Inspect the frame, vessel, cover, platforms, bearing points, enclosure and areas affected by corrosion, cracks or thermal deformation.

Inspection area Induction coil Inspect the copper tubing, insulation, connections, windings, spacers, visible leaks, discolouration and cooling-water flow.

Inspection area Refractory lining and crucible Document cracks, broken areas, metal penetration, remaining wall thickness, repair areas, the pouring zone and the previously processed alloy.

Inspection area Converter and power electronics Inspect the modules, capacitors, busbars, transformers, control boards, cooling, protective functions and spare-parts status.

Inspection area Cooling-water system Document the pumps, heat exchangers, cooling units, filters, hoses, manifolds, flow switches, leaks and water quality.

Inspection area Tilting mechanism and hydraulics Test the bearings, axis, cylinders, pumps, valves, end positions, interlocks and controlled return movement under suitable conditions.

Inspection area Monitoring and safety Inspect the earth-fault monitoring, insulation, overcurrent, overtemperature, cooling-water shortage, emergency stop and safe shutdown functions completely.

Inspection area Documentation and software Record circuit diagrams, cooling diagrams, programmes, parameters, operating instructions, lining data, spare-parts lists and data backups.

Plan relocation and recommissioning as one complete project

Induction furnaces combine heavy furnace mechanics with sensitive power electronics and extensive cooling equipment. Successful relocation therefore begins before dismantling.

Survey

Document the furnace and auxiliary equipment completely Record dimensions, weights, cables, busbars, cooling lines, transformers, converters, electrical cabinets, foundations and steel structures.

Shutdown

Remove metal and disconnect the energy supply safely Empty the furnace, shut down the cooling system in a controlled manner, discharge capacitors, secure electrical connections and remove residual materials professionally.

Dismantling

Label all electrical and mechanical units Clearly mark cables, busbars, hoses, sensors and assemblies. Package sensitive power-electronic equipment separately and securely for transport.

Installation

Coordinate the foundation, power supply and cooling system Integrate the furnace pit, load capacity, switchgear room, cable routes, cooling system, water treatment and safety areas into the new layout.

Commissioning

Release the lining, cooling and power step by step Perform leak testing, insulation measurement, dry runs, the sintering programme, the first melt, gradual power increase and safety testing under controlled conditions.

Used induction furnaces from various manufacturers

Depending on availability, individual furnaces, complete twin-furnace systems, converters, transformers, cooling systems and additional peripheral equipment may be offered. The actual scope of supply remains decisive.

Otto Junker · Inductotherm · ABP · ELZAMET · EGES

The manufacturer, year of manufacture, capacity, power, frequency, metal type, furnace design and scope of supply can change with the available machine inventory.

Additional furnace technology for foundries and metal supply

Depending on the alloy, melting rate and production concept, other furnace designs or combined systems may also be suitable for the project.

Used Furnaces Overview of melting, dosing, crucible, recycling, induction and special-purpose furnaces. View overview →

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Crucible Furnaces Compact melting and holding furnaces with a separate crucible in tilting or ladling configurations. View category →

Aluminium Recycling Furnaces Furnace systems for remelting scrap, chips, production returns and aluminium-containing residues. View category →

Dosing Furnaces Holding and reproducible dosing of aluminium or magnesium molten metal. View category →

Other Furnaces Heat-treatment, magnesium, recycling and other project-specific furnace systems. View category →

Furnace Reconditioning Technical inspection, repair, refractory relining and adaptation of used furnace systems. View service →

Buy or sell used induction furnaces

FISS supports the search for a suitable induction furnace and its technical assignment based on the furnace design, alloy, application, capacity, melting rate, frequency, electrical power, refractory lining, cooling system, tilting mechanism and available site infrastructure. If no suitable furnace is currently listed, FISS can conduct a targeted search through its international network for an appropriate solution.

When selling equipment, FISS supports condition assessment, technical documentation, dismantling planning and international marketing of individual induction furnaces and complete furnace and melting systems. In addition to brokerage and international marketing, direct purchase by FISS may also be an option depending on the project.

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