1600℃ Medium Frequency Melting Furnace

— 1600°C Medium Frequency Melting Furnace

A 1600°C medium frequency melting furnace is a heavy-duty industrial induction melting system engineered for high-temperature metals and specialist alloys that demand intense, sustained thermal energy. It pairs medium-frequency electromagnetic induction with refractory engineering specified for the duty, and it delivers melting that is rapid, clean and closely controlled all the way up to 1600°C. That working ceiling places the machine above ordinary non-ferrous melting practice, in the range where stainless and alloy steels, high-purity copper and the higher-melting precious metals are handled, and it is why the machine is built around a refractory crucible rather than a metal pot.This page documents the medium-frequency, 1600°C-class machine: its working envelope metal by metal, the charge forms and loading practice that decide whether a heat reaches temperature at all, the crucible and lining selection that follows from the melt chemistry, the batch formats and tilting drives it is built in.

Product Overview

A 1600°C medium frequency melting furnace heats metal by induced current rather than by combustion. A water-cooled copper coil surrounds the crucible; alternating current in the coil drives a reversing magnetic field into the charge; the field induces eddy currents inside the metal; and the metal’s own electrical resistance turns that current into heat released within the charge itself. The charge therefore heats from the inside out, which is why an induction melt reaches temperature faster than a fuel-fired crucible furnace and why the whole bath holds one temperature instead of a hot top over a cold base. Medium frequency is the band used for this duty because it heats a heavy charge through rather than only at its surface and stirs the bath while it heats it, so the pour temperature is a number the operator can hold. The 1600°C figure is the rated working ceiling, and what has to fit beneath it is the metal’s melting point plus the superheat the pour requires — a thin-section casting or an intricate investment mould needs more superheat than a heavy open ingot mould, which is why the same machine is comfortable on stainless steel at approximately 1510°C and tight on palladium at 1555°C. How that ceiling is engineered — refractory and crucible grades, the insulation stack, the atmosphere and the sensor ranges — is documented on the companion page for the 1600°C induction heating furnace; this page stays on the melting duty.

A melting furnace is defined as much by what it accepts as by what it reaches. Bars, slabs, refinery doré, sponge, cement, dried reduced powder, briquetted powder, swarf, granules and off-cuts all melt in the same crucible, but they do not load the same way: a dense bar sinks and melts from the bottom upward, while light swarf and loose powder sit high, bridge, and oxidise before they reach the bath. Pieces sized so that the stack descends as it melts keep the charge inside the active coil length, and pieces that bridge sit above the coil — the most common reason a melting furnace does not reach temperature. Bulk density decides what the crucible actually holds, because a crucible is a volume and not a weight, and melting down from cold is a different operation from charging into a standing bath: a cold charge builds its molten pool progressively from the coil-active zone, whereas charging into a bath melts each addition almost as it lands. Wet, coated, sealed and non-conductive items each change what the machine does, and section 04 lists them with the reason. This is why the machine is quoted against a charge description — form, piece size, bulk density and grade — rather than against a metal name alone.

Three terms are routinely confused. Melting is what this machine does: nothing is added but the metallic charge, the output is molten metal and then an ingot, and the metal’s grade is preserved rather than raised. Smelting adds flux and reductant and produces metal plus slag, separating metal from gangue or from oxide. Refining adds reagents, electric current or both and raises grade — to 99.99% and beyond. A medium frequency melting furnace melts and homogenises. If your feed is an ore, a concentrate, a sulphide, a slag, a salt or a wet slime, melting is the wrong unit operation, and the smelting furnace page carries the terminology boundary and the furnace types used upstream.

The machine is built as a stationary furnace, in which the crucible is lifted out or the melt is transferred by a separate pouring device, or as a tilting furnace, in which the whole body rotates about a trunnion and pours directly into a mould — the standard format for ingot-making and for precious-metal work where every gram of metal has to be accounted for. Tilting is driven by a manual lever on small batches, a chain drive at mid-size, and a motor or hydraulic drive where batch weight or safety distance makes hand pouring unacceptable, with hydraulic units operated from a remote panel. Within the four-machine YuSai family, this page is the charge-and-heat-making machine; the high-frequency induction smelting furnace serves very small gold and non-ferrous batches where speed matters more than batch weight, the 1600°C induction heating furnace is the small-scale tabletop or vertical configuration for laboratories, schools, jewellery stores and research institutes, and the smelting furnace is the family entry page covering the model range and the selection logic. For casting the melt under vacuum or inert gas rather than in air, the matching unit is the vacuum ingot casting machine.

Application Scenarios

Precious metal refineries and minting rooms. The furnace melts doré bars, sponge, precipitated powder after drying, anode scraps and recycled jewellery into a single homogeneous heat before it is poured into ingots, bars or anodes. Where the downstream step is electrolytic, the ingot produced here becomes the anode the refining cell consumes; where the downstream step is sale, it becomes the finished bar.

Gold and silver alloy and karat work. Colour golds, karat golds, sterling and silver-copper alloys are melted and stirred into a composition that is uniform through the whole batch, which is the precondition for a representative assay. Melting point is not the constraint here — homogeneity is.

Palladium and palladium-bearing alloy melting. Palladium melts at approximately 1555°C, inside the 1600°C class, so palladium sponge and palladium alloy scrap can be consolidated and cast in this furnace. This is the point at which the machine’s temperature class starts to matter: the same furnace is running close to its ceiling, and the lining, crucible and pyrometer chain have to be specified for it.

Copper, brass and bronze melting and ingot casting. High-purity copper, copper scrap, brass and bronze are melted for ingot casting, for alloy blending, or for producing anodes for downstream copper electrolytic refining. The medium-frequency stirring is what keeps zinc from segregating in brass heats.

Stainless steel, alloy steel, tool steel and special steel melting. Small and medium foundries use the medium-frequency crucible furnace as the melting unit for stainless and alloy steel heats, where the 1600°C class provides the superheat needed for thin-section and intricate castings. Because the melt is stirred electromagnetically rather than by a lance, the result is a uniform bath with a low gas content.

Nickel- and cobalt-base superalloy melting. Nickel-base superalloys sit in the same temperature class and are usually melted under a protective cover because their reactive elements are sensitive to oxidation. Stirring helps bring reactive additions into solution quickly, shortening the time the bath spends at temperature.

Electronic scrap and PCB-derived metal concentrates. After mechanical separation and a metallurgical enrichment step, the metal-bearing fraction from waste circuit board recycling equipment arrives as a metal-state concentrate that is melted, homogenised and cast into an ingot before it goes to hydrometallurgical or electrolytic refining. The furnace does not extract metal from the board; it consolidates what the upstream process has already concentrated.

Spent catalyst and anode slime derived metal. Metal produced by a precious metal hydrometallurgical refining system — reduced powder, cemented metal, calcined residue that has been reduced to metal — is dried, melted and cast in this furnace so the metal can be weighed, sampled and delivered as a solid.

Investment casting and lost-wax foundries. Rapid, repeatable melts of small to medium lots where the melt has to be delivered to the mould at a defined temperature and with a composition that matches the master heat.

Jewellery manufacturing and repair. Alloying, recycling bench sweeps and off-cuts, and remelting customer metal in front of the customer where the shop needs the melt to be quick, clean and precisely weighted.

Dental and medical alloy melting. Precious and base dental alloys, and small medical-device alloy lots, where contamination control and repeatability matter more than tonnage.

Assay laboratories, universities and research institutes. Sample fusion for assay, small alloy development heats, and teaching melts, where the temperature ceiling, the stirring and the ability to log every heat are the reasons the machine is chosen.

Banks, mints and secure vault operations. Remelting and re-casting of standard bars and coins in a controlled room, where metal accountability across the batch is the primary requirement.

Foundries and machine shops using the furnace as a satellite melter. Precision casters, die casters and forging shops that need a small, fast, independent melting unit alongside a larger melting operation.

Secondary and recycled metal traders. Consolidating mixed metal scrap into saleable ingots of a declared composition.

Applicable Raw Materials

This furnace melts metal-state solid charge. In practice that means the following feed classes.

Refinery doré and intermediate bars. Partially refined bullion containing gold, silver and base-metal impurities, produced by an upstream smelting or cementation step. Input: solid bars or slabs, in the 1600°C class, cleaned of loose slag and refractory before charging.

Gold and silver sponge, cement and dried reduced powder. Metal recovered by precipitation, cementation or reduction with a precious metal hydrometallurgical refining system. Input: solid metal powder or sponge, dried and briquetted where necessary to limit dusting and to control the initial charge position in the crucible.

Gold, silver and precious-metal alloy scrap. Bench sweeps after burn-off, jewellery scrap, watch cases, silverware, coin blanks, dental scrap and process off-cut. Input: solid metal pieces, sorted by declared grade and by melting envelope before charging.

Palladium sponge and palladium-bearing alloy scrap. Reduced palladium powder, palladium alloy strip and palladium-bearing dental or catalyst-derived metal. Input: solid metal, melted close to the ceiling of the class, with the crucible and lining specified for palladium chemistry.

High-purity copper, copper scrap and copper alloy. Wire, busbar off-cuts, sheet, shavings and briquetted turnings, plus brass and bronze returns. Input: solid metal, de-oiled and with free iron and steel removed.

Stainless steel, alloy steel, tool steel and other ferrous charge. Foundry returns, machining scrap, bar ends and cropping, sorted so the resulting heat matches the target grade. Input: solid metal, dry, with no entrained coolant, oil or water.

Nickel- and cobalt-base superalloy charge. Clean scrap, returns and master alloy additions. Input: solid metal, charged with the cover-gas option selected where reactive elements are present.

Metal concentrate from e-waste, PCB and solar-panel processing. The metal-rich fraction produced after mechanical separation, carbonisation and metallurgical enrichment. Input: solid metal-state concentrate, dry, with the non-metallic fraction already removed upstream.

Metal recovered from spent catalysts and anode slime. Reduced metal, desulphurised metal and calcined-then-reduced residue. Input: solid, dry, metal-state material after the hydrometallurgical route.

Master alloys and alloying additions. Pre-alloyed grain refiners, hardeners and colouring additions charged into the bath to bring the heat to the target composition. Input: solid, sized to melt within the bath rather than floating on it.

Granulated metal and shot. Previously granulated metal returned for remelting. Input: solid granules, charged with the geometry checked against the crucible bore so the bed does not bridge.

Not accepted. The furnace is a melting unit and its envelope is finite. It is not designed for the following, and we do not propose it for them.

Ores, concentrates, sulphides, mine feed. These require reduction, fluxing and slagging — a smelting furnace, not a melting furnace.
Cyanide solutions, leach liquors, plating baths and any wet feed. These belong in a hydrometallurgical or electrowinning circuit.
Wet anode slime and undried filter cake. Water in a crucible at 1600°C flashes to steam and ejects metal.
Metals and alloys whose melting point exceeds 1600°C — platinum and platinum alloys, rhodium, iridium, ruthenium, tungsten, molybdenum, tantalum and titanium, among others. See the envelope table in section 09. These require a higher temperature class, not a larger power supply.
Slag, dross, ash, dust and baghouse catch. The metal content has to be recovered and put into metal state first.
Mirror-finish reactive metals and magnesium. Oxidation and ignition risk.
Sealed or closed containers, aerosol bodies, gas cylinders, sealed tubes, batteries and electronic assemblies. Pressure build-up inside a closed body inside a 1600°C crucible is a burst hazard.
Zinc-coated, lead-coated or cadmium-coated steel and wet galvanised scrap. Coatings fume heavily; without a properly designed extraction and filtration train this must not be charged.
Free liquids, oil-soaked scrap, water-trap components and hydraulic assemblies.
Fine, dry, easily airborne powders charged without briquetting. They either blow out of the crucible or bridge over the coil.
Non-conductive materials. Induction heating requires an electrically conductive charge. Ceramics, glass, polymers and refractory rubble cannot be melted directly by this furnace.

Finished Products

One homogeneous heat of molten metal. The immediate product of the furnace is not an ingot but a bath: a single, stirred, uniform-temperature, uniform-composition pool of liquid metal that can be sampled, adjusted and poured. Every downstream product below inherits its quality from this bath.

Precious metal ingots and bars. Gold, silver, palladium and their alloys cast into standard or customer-specified bar weights. Output: solid cast ingots with the as-melted composition of the charge, stamped or marked for identification.

Anodes for electrolytic refining. Cast anode plates for a downstream precious metal electrolytic refining cell, made to a defined thickness, flatness and lug geometry. Output: cast anodes ready for the cell, with the metal balance of the heat carried forward to the refining step.

Copper, brass and bronze ingots. Cast ingots for sale or for further working, and copper anodes for a copper electrolytic refining plant. Output: cast ingots or anodes at the chemistry of the heat.

Steel and superalloy castings and electrodes. Molten metal delivered straight to an investment-casting or lost-wax line, or cast as an electrode billet. Output: cast components and cast electrode stock.

Alloy ingots at a controlled composition. Brass, bronze, karat gold, sterling silver, and custom alloy heats where the whole point of the operation is to hit a specification rather than to change one. Output: alloy ingots whose assay matches the heat sheet.

Metal granules and shot. Where the furnace is paired with a granulator or a shotting device, output is metal granules classified by sieve. Output: dry, free-flowing granules or shot for sampling, for dissolution or for sale.

Metal consolidated from scrap and residues. Mixed metal scrap, e-waste derived concentrate and catalyst-derived metal consolidated into a single weighed, sampled, saleable ingot rather than a variable heap. Output: ingots with a declared weight and a declared assay.

Master alloy and addition blocks. Small heats of an alloying addition cast into blocks for later use in larger heats. Output: pre-weighed addition blocks at a known composition.

A documented heat record. Every batch carries a record of charge weight, charge assay, melt temperature, holding time, pour temperature and cast weight. Output: an audit trail that reconciles the incoming metal against the outgoing metal — the number a refinery or a bank actually audits.

Not a product of this machine: a purity upgrade. A melting furnace melts. It does not reject impurities to a slag, it does not partition metals into an electrolyte, and it does not raise grade. If the charge leaves the process as 99.5% metal, the ingot leaves the process as 99.5% metal — correctly homogenised, correctly cast, and correctly weighed. Grade is raised upstream in smelting and hydrometallurgy, or downstream in refining and electrolysis, not here.

1600℃ Medium Frequency Melting Furnace Process Flow

The nine stages below describe one melting campaign: from a sorted charge to a reset furnace. Each stage states its own output, so the sequence can be audited step by step.

Steps 1 — Charge Sorting and Melting Envelope Verification. The charge is sorted by declared grade, weighed, and checked against the machine’s temperature envelope before anything is loaded. This is the stage that prevents the two most expensive mistakes in induction melting: charging a metal whose melting point is above the class ceiling, and mixing a grade into a heat that cannot then be separated. Anything wet, sealed, coated or non-conductive is removed here. Output: a verified charge list with weights, grades and an envelope decision for every item.

Steps 2 — Crucible Setting and Hot-Zone Inspection. The crucible is seated in the furnace bore, sintered or pre-fired according to its type, and checked for concentricity with the coil. The working lining, the backing insulation, the coil insulation and the coil water connections are inspected at the same time. Poor crucible centring is the single most common cause of a short lining campaign, so it is verified rather than assumed. Output: a centred crucible in an inspected hot zone, with the inspection recorded.

Steps 3 — Cold Charge Loading and Coil Alignment. The cold charge is loaded to a defined fill pattern: heavier pieces to the base where the induced field is strongest, sized so that the stack does not bridge across the crucible, and positioned so that the charge mass sits inside the active coil length rather than above it. Output: a loaded crucible with the charge mass aligned to the coil and the initial power schedule set from the known charge weight.

Steps 4 — Power Staging and Medium-Frequency Ramp-Up. Power is raised in stages rather than switched straight to full output. The first stage establishes a conductive path and a molten pool at the base; the intermediate stages raise bath temperature at a controlled rate that the crucible and lining can tolerate; the final stage hands over to the melting schedule. Output: a stable ramp to melting power with no thermal shock to the crucible.

Steps 5 — Full-Power Melting and Electromagnetic Stirring. At full power the bath melts down and the induced electromagnetic stirring circulates it continuously. This is where alloy homogeneity and bath temperature uniformity are actually created — reactive additions and master alloys are introduced into a moving bath so they dissolve quickly and distribute through the whole heat instead of stratifying. Output: a fully molten, stirred, compositionally uniform bath.

Steps 6 — Superheat Setting and Temperature Verification. With the charge molten, power is trimmed to hold the bath at the pour temperature required by the downstream step: a defined superheat above the alloy’s melting range, high enough to fill a thin section or an intricate mould, low enough to limit oxidation, gas pickup and lining wear. Temperature is read from the melt — immersion noble-metal thermocouple for a spot check, optical pyrometer tied into the PID loop for control — and the melt is sampled for the heat record. Output: a bath at the specified pour temperature, with a recorded temperature trace and a retained sample.

Steps 7 — Tilting, Pouring and Ingot Mould Filling. The furnace body is tilted — by lever, chain, motor or hydraulic drive depending on the batch weight — and the melt is poured into preheated, coated and dried ingot moulds. Pour rate is held steady so that the mould fills from the bottom up without lapping, turbulence or trapped gas, and so the last of the melt does not carry surface dross into the mould. Output: filled moulds, with the pour temperature and pour sequence logged against each mould.

Steps 8 — Cooling, De-Moulding and Weight Reconciliation. The ingots are cooled under controlled conditions, stripped from the moulds, cleaned, weighed and marked. Cast weight is reconciled against charge weight and the difference is booked as melting loss rather than absorbed as an unexplained gap. Output: cooled de-moulded ingots — or bars, anodes or granules — with individual weights, an identification mark and a reconciled mass balance for the campaign.

Steps 9 — Crucible Change-Out, Coil Cleaning and Reset. The crucible is inspected against its wear indicators and either retained for the next campaign or changed out. Splash and metal spatter are cleaned from the coil, the coil cooling passages are checked, the hot-zone insulation is repaired or renewed, and the machine is returned to the start of the cycle with its maintenance record updated. Output: a furnace ready for the next campaign, with crucible life and lining condition recorded for planning.

Product Structure (Main Equipment)

Medium-frequency power supply cabinet. The IGBT rectifier and inverter stage that converts three-phase mains power into medium-frequency current at a controlled output. It carries the power control loop, the start-up and protection logic, and the metering the operator works from. Where the site supply characteristics call for it, the supply is configured with harmonic mitigation so the furnace does not degrade the plant’s power quality.

Capacitor and compensation cabinet. The tank capacitor bank that resonates with the induction coil at the working frequency and supplies the reactive power the coil needs. Capacitors are water-cooled and are matched to the coil on each machine; frequency is set by this combination, which is why coil and capacitor bank are specified together.

Furnace body — steel shell or aluminium shell. The structural housing that carries the coil, the magnetic yokes and the crucible. Two configurations are built: an aluminium shell body, which is light and simple to service, and a steel shell body, which adds a magnetic-field shielding system that contains stray flux and protects both structure and surroundings.

Water-cooled copper induction coil. The heating element: a heavy-wall copper tube wound around the crucible bore, carrying both the medium-frequency current and its own cooling water. Coil turn count, tube section and bore are matched to the crucible size and to the required melting rate.

Magnetic yokes and shielding. Laminated silicon-steel yokes arranged around the outside of the coil to close the magnetic circuit, cut stray leakage flux and strengthen the field inside the crucible. Yokes also act as mechanical support for the coil, and are cooled on both faces where the design calls for it.

Crucible. The vessel the charge is actually melted in, seated inside the coil. Crucible material — graphite, clay-graphite or silicon carbide based — is selected for the metal being melted, the operating temperature and the required service life. Crucible size sets the batch weight.

Dry vibratable working lining and backing insulation. A rammed or vibrated refractory lining formed in place inside the furnace body, backed by high-density ceramic fibre board or vacuum-formed blanket. The lining carries the thermal load; the fibre package limits heat flow to the coil and protects the surrounding structure. Alumina-based grades are standard for this temperature class, with zirconia or magnesia grades where the charge chemistry demands them.

Tilting system. The trunnion-mounted drive that rotates the furnace body for pouring. Available as a manual lever, a chain drive, a motorised drive or a hydraulic drive, selected against batch weight, pour rate control requirements and the operator-safety distance the installation requires. Hydraulic units are operated from a remote panel.

Control cabinet and human-machine interface. The operator station: a touch screen or panel HMI carrying the power setpoints, the melting recipe, the temperature loop, the alarm list and the batch log, plus the PLC that sequences start-up, ramp, holding and shutdown.

Temperature measurement chain. A dual measurement arrangement: an optical (infrared) pyrometer aimed at the melt surface for continuous control, closed into a PID loop that trims power, and an immersion noble-metal thermocouple for verifying the reading and for recording the pour temperature. The pyrometer is the working instrument at this temperature class because contact sensors do not survive repeated cycling.

Closed-loop water cooling system. The cooling train that serves the coil, the capacitors and the power supply: circulating pumps, a heat exchanger or chiller, a reservoir, flow and temperature instrumentation, and the interlock wiring that shuts the power down if flow or temperature goes out of range. Water quality and inlet temperature are part of the machine specification, not an afterthought.

Fume capture hood and exhaust connection. A hood over the crucible mouth and a duct connection sized for the plant’s extraction system, so that metal fume, oxidation products and any coating burn-off are captured at source rather than released into the melt shop. The furnace is supplied with the capture geometry; the extraction and filtration train is specified against the charge chemistry.

Ingot moulds, granulation and pouring accessories. Moulds sized to the target ingot weight, with preheat and coating consumables; and, where granulation rather than casting is required, a granulation or shotting device matched to the furnace discharge.

Emergency and safety devices. Over-voltage, over-current, over-temperature, phase-loss and water-flow protection on the electrical side; an emergency stop at the operator station; and, where specified, an earth-leakage detection system that warns the operator when molten metal has penetrated the lining and approached the coil — the failure mode that destroys an induction furnace body fastest.

Heat record and batch documentation. The pyrometer trace, the power log, the charge and cast weights and the sample reference, retained per heat so a delivered ingot can be traced back to the heat that produced it.

Product Features

Medium-frequency heating for deep penetration. The medium-frequency band is chosen so the induced field reaches through a heavy charge instead of heating only its surface, which is what allows a single heat to be brought to a uniform temperature rather than a hot shell around a cold core.
Electromagnetic stirring built into the process. The same field that heats the bath circulates it. Alloy additions dissolve into a moving bath, composition evens out through the heat, and the sample taken at the end represents the whole batch rather than the top of it.
1600°C temperature class. Rated to a working temperature of 1600°C, which places gold, silver, copper and copper alloys, palladium, stainless and alloy steels, tool steels and nickel-base superalloys inside the machine’s envelope.
Hot zone engineered for the class. High-purity dry vibratable refractory working lining, high-density ceramic fibre backing insulation, and a heavy-wall water-cooled copper coil with magnetic yokes around it — the three-part hot-zone package that makes 1600°C a sustainable working temperature rather than a peak figure.
Pyrometer-based temperature control. An optical pyrometer read into a PID loop controls power output continuously, with an immersion noble-metal thermocouple for verification — a measurement chain designed for a temperature at which ordinary base-metal contact sensors fail.
IGBT medium-frequency power supply. Solid-state power conversion with precise output control, fast arc-free start-up, and controlled ramp behaviour that protects the crucible from thermal shock and the lining from premature wear.
Rapid melt from cold. Because heat is generated inside the charge, cold start to first pour is short, so a melting campaign can be run in a working day rather than booked around a furnace that has to stay hot.
Low bath oxidation and low metal loss. There is no combustion gas passing through the melt, no flame impingement on the bath, and rapid melting means the metal spends less time at temperature — all of which reduce oxidation loss and dross formation compared with fuel-fired crucible melting.
Tilting pour with a controlled rate. Furnace bodies are trunnion-mounted and poured by lever, chain, motor or hydraulic drive, so pour rate can be held steady and the operator can stand clear of the mould on hydraulic units.
Batch traceability as standard. Charge weight, charge assay, melt temperature trace, holding time, pour temperature and cast weight are logged per heat, so every delivered ingot can be traced back to the melt that produced it.
Modular construction. The machine is built from the power cabinet, capacitor cabinet, furnace body, coil, crucible assembly, cooling unit and control cabinet as modules, which reduces assembly time, simplifies shipment and makes individual units serviceable or replaceable in place.
Interlocked protection. Over-voltage, over-current, over-temperature, phase-loss and water-flow protection are interlocked into the power control loop, with emergency stop at the operator station and, where specified, earth-leakage detection that warns of lining penetration before it reaches the coil.
Configurable rather than fixed. Power rating, batch capacity, furnace format, tilting drive, crucible type, lining grade, control interface and cooling configuration are set against the client’s actual charge chemistry and batch schedule instead of being sold as a catalogue compromise.
Cover-gas option for reactive alloys. A protective atmosphere can be arranged for alloys whose reactive elements would oxidise in open air, so the same furnace platform can serve both ordinary and sensitive heats.
Matched downstream interface. The machine is specified with the pour geometry, ingot mould sizes and discharge method that suit what comes next — anodes for an electrolytic cell, bars for sale, or a granulation stream.

Technical Parameters And Specifications

Table 1 — Furnace specification

Parameter	Specification
Machine type	Crucible-type coreless medium frequency induction melting furnace
Rated working temperature	1600 °C
Temperature class rule	The charge’s melting point plus the superheat required for pouring must sit below the rated working temperature
Working frequency	Medium-frequency band, conventionally 1–10 kHz; the coil and capacitor combination is matched to the crucible size
Power supply type	IGBT medium-frequency power supply, three-phase input
Rated power	Configured per project against charge weight, charge metal and required melting time
Batch capacity	Configured per project; stated as molten metal weight at the specified charge density for the metal being melted
Batch definition	A charge description — form, piece size, bulk density and grade — not a metal name alone
Melting time	Configured per project; at a hot furnace a batch is a matter of minutes, at cold start the first heat is longer
Temperature control	Optical (infrared) pyrometer in a closed PID power loop, verified by immersion noble-metal thermocouple
Crucible	Graphite, clay-graphite or silicon-carbide based, selected for the metal, the temperature and the required service life
Working lining	High-purity dry vibratable refractory; alumina base as standard, zirconia or magnesia grades where charge chemistry requires it
Backing insulation	High-density ceramic fibre board or vacuum-formed blanket between coil and crucible
Induction coil	Water-cooled heavy-wall copper tube, matched to crucible bore and melting rate
Magnetic circuit	Laminated silicon-steel magnetic yokes around the coil; steel-shell body with a magnetic shielding system available
Furnace format	Stationary, or trunnion-mounted tilting
Tilting drive	Manual lever, chain, motorised or hydraulic, selected against batch weight and required pour control
Cooling	Closed-loop water system serving coil, capacitors and power supply, with flow and temperature protection interlocked
Atmosphere	Open air as standard; protective cover gas optional for reactive alloys
Fume control	Capture hood over the crucible mouth with an exhaust duct connection for the plant extraction system
Electrical protection	Over-voltage, over-current, over-temperature, phase loss and water-flow protection, with emergency stop
Optional protection	Earth-leakage detection to warn of lining penetration approaching the coil
Power input	Three-phase; voltage and transformer rating matched to the site supply
Documentation	Heat record per batch: charge weight and assay, temperature trace, holding time, pour temperature, cast weight

Values in the table describe the machine class. Final ratings — power, batch capacity, melting time, cooling water duty and electrical supply — are confirmed at engineering stage against the client’s charge assay, batch weight, pour temperature and working schedule. Working voltage, frequency setting and control interface can be customised.

Table 2 — Working temperature envelope

The envelope below is what the 1600°C rating actually buys. Melting points are stated for the pure metal; alloys melt over a range and the range is what has to fit inside the class.

Metal	Typical melting point / range (°C)	Position against the 1600 °C class
Silver (pure)	961	Inside, with wide superheat margin
Red brass	990–1025	Inside, with wide superheat margin
Gold (pure)	1064	Inside, with wide superheat margin
Copper	1085	Inside, with wide superheat margin
Steel	1371–1593, grade dependent	Inside; the upper end of the range needs the margin checked case by case
Stainless steel	approx. 1510	Inside, with a working margin
Palladium	1555	Inside, but close to the ceiling — lining, crucible and pyrometer chain are specified for it
Platinum	1768	Outside the class. Requires a higher-temperature furnace, not a larger power supply
Rhodium, iridium, ruthenium, tungsten, molybdenum, tantalum, titanium	Above the class ceiling	Outside the class. Not proposed for this machine

Nickel- and cobalt-base superalloys melt over grade-dependent ranges that sit below the class ceiling and are routinely melted in this furnace; the exact margin is checked against the specific grade before a configuration is quoted. Most non-ferrous metals — aluminium, zinc, lead, tin and their alloys — sit far below the ceiling and are limited by crucible material and alloying practice rather than by temperature.

Table 3 — Information needed to configure the machine

Item	Why it determines the configuration
Charge metal and grade	Sets the melting range, the superheat, the crucible material and the lining grade
Batch weight in metal	Sets the crucible size, the power rating and the coil geometry
Required melting time	Sets the power rating together with the batch weight
Pour temperature and downstream product	Sets the superheat and the pour geometry — ingot, anode, bar or granulation
Working schedule	Sets the duty cycle and therefore the cooling and power-supply specification
Site supply and utilities	Sets the input voltage, transformer rating, cooling water duty and the foundation and floor-loading requirements
Site environment	Sets the extraction requirement and the level of fume and emission control needed for the charge chemistry

Temperature Sensors Against a 1,600 °C Set Point

Published type ranges for the thermocouple families and for non-contact instruments. At 1,600 °C the common base-metal couple is more than 200 K past its own limit and the noble-metal types are at theirs, so the sensor is a design decision rather than a purchase.

Sensor	Published range	Use at a 1,600 °C set point
Type K (base metal)	About −200 to 1,372 °C	Out of range; about 230 K short of the set point
Type N (base metal)	About −200 to 1,300 °C	Out of range
Type S (platinum-rhodium)	0 to about 1,600 °C, short term to about 1,700 °C	At its own limit; usable only with a stated short-term basis and a suitable sheath
Type R (platinum-rhodium)	0 to about 1,600 °C, short term to about 1,700 °C	At its own limit; same restriction as type S
Type B (platinum-rhodium)	About 600 to 1,700 °C, short term to about 1,800 °C	Usable with margin and without cold-junction compensation; the usual permanent-installation choice
Type C (tungsten-rhenium)	0 to about 2,320 °C	Usable and required above the platinum types; oxidises in air, so it belongs in vacuum or inert service
Type D (tungsten-rhenium)	0 to about 2,320 °C	Usable; same atmosphere restriction as type C
Optical, infrared or two-colour pyrometer	Non-contact, above the couple range	Used where the charge can be sighted; needs a declared emissivity, a clean window and a sight path that does not look at a wall

Technical Advantages

The machine is quoted against a charge, not against a metal name. Most melting-furnace disappointments start at the quotation stage, when a furnace is sold against a metal and a weight without anyone asking about the form the metal arrives in. We ask for the charge form, the piece size, the bulk density and the grade, because those four answers decide the crucible, the loading pattern and the melting schedule — and because a machine specified without them is a machine that gets argued about on site afterwards.

Charging practice is treated as part of the process, not as the operator’s problem. How the solid charge is built inside the crucible decides whether the machine reaches temperature at all. Fill pattern, piece sizing and charging sequence are agreed with you and written into the operating procedure, so the machine performs the same in month twelve as it did in the first week instead of drifting into bridging, dusting and short heats.

Stirring is treated as a quality function, not a side effect. In precious metal and superalloy melting, the value of a heat is decided by whether one sample represents the whole batch. The electromagnetic stirring that comes with induction heating is what makes that true: it dissolves additions quickly, evens out composition, and removes the temperature stratification that otherwise forces the operator to overheat the bath to guarantee a minimum pour temperature everywhere.

The crucible is specified against your melt chemistry, not against the temperature alone. At this temperature class the crucible is usually the element that decides how well the machine performs and what it costs to run. The grade is chosen for the metal and the campaign length and quoted as part of the configuration, because an incompatible crucible does more than wear out — it contaminates the heat, and the contamination is only discovered at assay.

The machine’s limits are stated up front. Platinum melts at 1768°C and will not melt in a 1600°C furnace, however much power it is fitted with. Ores, sulphides, slags and wet slimes need smelting or hydrometallurgy, not melting. We say so on the specification sheet rather than after the purchase order, because a furnace used outside its envelope fails in the crucible, and the failure is expensive and dangerous.

Rapid, low-loss melting. Heating generated inside the charge, with no flame impingement and no combustion gas in contact with the bath, means less oxidation loss, less dross, and less time spent at temperature. For precious metal work, where a fraction of a percent of metal loss is a real number on the P&L, that is the advantage that pays for itself.

Pour control and operator safety by design. Trunnion-mounted tilting with a drive selected against batch weight, steady pour rate so moulds fill without turbulence, and hydraulic units operated from a remote panel so the operator is not exposed over the mould. Preheated, coated, dry moulds are specified with the machine rather than discovered later.

Metal accountability across the whole campaign. Charge weight, charge assay, temperature trace, holding time, pour temperature and cast weight are recorded per heat. Melting loss is booked as a measured figure rather than absorbed as an unexplained difference — which is exactly what a refinery, a mint or a bank needs from a melting room.

Modular build, serviceable in place. Power cabinet, capacitor cabinet, furnace body, coil, crucible assembly, cooling unit and control cabinet are separate modules. Assembly from components to finished machine is short, shipment is straightforward, and a failed module is replaced rather than rebuilding the furnace.

Layered protection, including the failure mode that bankrupts furnaces. Electrical protection covers over-voltage, over-current, over-temperature, phase loss and water flow. Where specified, earth-leakage detection warns when molten metal has penetrated the lining and is approaching the coil — the single failure that destroys an induction furnace body fastest, and the one most often left unmonitored.

Configured against your charge, and re-configurable as your feed changes. Crucible size, tilting drive, control interface, cooling arrangement and cover-gas option are selected for your process. When the feed changes from doré to palladium sponge or from jewellery scrap to e-waste concentrate, the change is met by re-specifying crucible and lining rather than by replacing the machine.

One supplier for the upstream and downstream steps. The melting furnace is specified by the same engineering team that builds the hydrometallurgical refining system, the electrolytic refining cells and the vacuum ingot casting machine that sit either side of it, so the pour geometry, the anode size and the metal balance are continuous from feed to finished bar instead of being negotiated between three vendors.

Service Process

1. Requirement review and envelope check. We start from your feed, not from a catalogue. Send the charge metal and grade, the batch weight, the required melting time, the pour temperature and the downstream product, and we check the process against the machine’s temperature envelope and process boundary before anything is quoted. If your feed needs smelting or hydrometallurgy rather than melting, we tell you at this stage and point you at the right unit operation.

2. Process and configuration proposal. We return a configuration proposal: furnace format and tilting drive, crucible type and size, lining grade, power rating, temperature control chain, cooling duty, cover-gas requirement if any, ingot mould or granulation arrangement, and the electrical and utilities interface the site has to provide. Where the feed is unusual, we propose a trial melt to confirm behaviour before the furnace is specified.

3. Quotation and technical clarification. A quotation is issued against the agreed configuration, together with the site interface list — power supply and transformer requirement, cooling water duty, floor loading, extraction requirement and the layout drawing the civil and electrical works are built from. Anything in the scope that is not the furnace itself is named explicitly so that nothing is discovered on site.

4. Manufacture and factory assembly. The machine is built modularly: power cabinet, capacitor cabinet, furnace body, coil and crucible assembly, cooling unit and control cabinet are manufactured and assembled together, and the completed machine is powered up in the factory so that the frequency match, the protection interlocks and the temperature control chain are proven before shipment. Modular manufacture keeps assembly time from components to finished machine to approximately one week.

5. Shipment and documentation. The machine ships with its packing list, layout and foundation drawings, electrical and piping interface drawings, the operating and maintenance manual, the crucible and lining installation procedure, and the recommended spare parts list.

6. Site installation and commissioning. Our engineers supervise installation and carry out commissioning on site: foundation and levelling, power and cooling connections, coil and crucible setting, lining installation, protection and interlock testing, and the first melt. Commissioning is not complete until the machine has produced an on-specification heat at the specified pour temperature.

7. Operator training and handover. Your operators are trained on the machine they will actually run: start-up and ramp, temperature control and pyrometer handling, alloying and sampling, pouring and mould handling, crucible and lining condition checks, routine maintenance, and the alarm and fault response list. Training is delivered at the machine, with a written procedure left with the plant.

8. Trial production support. Where the client wants it, our technical staff stay on site to support the first production campaigns — the first heats, the first ingots, and the first metal balance reconciliation — so the plant reaches its specified yield and its documented procedures before we hand over.

9. Ongoing technical service. After handover we remain the technical contact for the furnace: melt behaviour questions, crucible and lining selection as the feed changes, control and protection settings, spare parts, and process advice on the steps either side of melting.

Warranty And After-Sales Service

What the warranty covers

The warranty covers the machine’s manufactured assemblies — the medium-frequency power supply, the capacitor and compensation cabinet, the furnace body, the induction coil, the tilting mechanism, the control system and the closed-loop cooling unit — against defects in materials and workmanship arising under normal operation and correct maintenance. The warranty period and its exact scope are confirmed in the supply contract and restated on the quotation, so the terms on paper are the terms you hold.

What is excluded

Consumables and wear items are excluded, because their life is set by the charge chemistry and the operating practice rather than by the machine: crucibles, working linings and backing insulation, refractory cements and coatings, seals, and ingot moulds and mould coatings. Damage arising from use outside the machine’s temperature envelope, from charging material the specification does not accept, from operation without cooling water or extraction, or from unauthorised modification is likewise outside warranty scope. We state these boundaries plainly because they are the same boundaries that determine whether the machine gives you years of service or months.

Spare parts

A recommended spare parts list is issued with the machine and priced with the order so that it can be bought as part of the project rather than sourced in an emergency. Critical items — pyrometer, control modules, protection relays, cooling-circuit components, coil insulation materials and crucible and lining consumables — are held for repeat customers, and consumable supply is planned around your production schedule.

Remote support

Fault diagnosis and parameter advice are provided remotely from the heat records and alarm logs the machine produces. The control system logs the temperature trace, the power profile and every protection trip per batch, so a fault can usually be identified from the record rather than by a site visit. Remote support also covers re-tuning the melting recipe when the feed or the batch weight changes.

Field service

Where a fault cannot be resolved remotely, field service is dispatched with the agreed response priority for your region. The service scope at handover, and the terms and response commitments of ongoing field service, are set out in the contract so that expectations are documented in advance on both sides. Site work is supported with commissioning-quality procedures, and the machine record travels with the case so a field engineer arrives with the relevant history.

Maintenance and operating support

The manual issued with the machine sets out the routine maintenance schedule: coil and hot-zone inspection intervals, crucible and lining wear checks, cooling water quality and flow verification, insulation resistance checks on the coil, pyrometer verification, and the protection interlock test routine. Crucible life and lining condition are recorded per campaign so replacement can be planned rather than reacted to.

Upgrade and re-configuration

Because the machine is built modularly, changes in your feed or your batch schedule are met by re-specifying rather than replacing: a different crucible and lining grade for a new metal, a different ingot mould set for a new product form, a granulation device where the output moves from ingots to shot, a cover-gas arrangement where reactive alloys enter the feed, or additional instrumentation where tighter heat records are required.

Frequently Asked Questions

What is a 1600°C medium frequency melting furnace?

A 1600°C medium frequency melting furnace is a crucible-type induction melting machine that converts three-phase mains power into a medium-frequency current, conventionally in the 1 kHz to 10 kHz band, and melts a metallic charge inside a refractory crucible at a rated working temperature of up to 1600°C. It consists of a medium-frequency power supply, a capacitor cabinet, a water-cooled copper coil around a crucible, a lined furnace body, a tilting or stationary frame, a cooling unit and a control system with pyrometer-based temperature control. It takes metal in and delivers a homogeneous molten bath out, which is then poured into ingots, bars, anodes or a granulation stream.

Which metals can a 1600°C melting furnace melt?

Metals and alloys whose melting and pouring temperatures sit below the 1600°C ceiling: gold at 1064°C, silver at 961°C, copper at 1085°C, red brass at about 990–1025°C, stainless steel at approximately 1510°C, steel across a range of roughly 1371–1593°C depending on grade, and palladium at 1555°C. Nickel- and cobalt-base superalloys also melt in this class, at grade-dependent temperatures below the ceiling. The practical rule is that the metal’s melting point plus the superheat needed for pouring has to fit under 1600°C with a working margin.

Can a 1600°C furnace melt platinum?

No. Platinum melts at 1768°C, which is above the working ceiling of a 1600°C furnace, and platinum group metals with higher melting points — rhodium, iridium and ruthenium — are further out of range. Adding power does not change this: the limitation is the temperature class of the hot zone, meaning the refractory lining, the crucible and the coil insulation, not the size of the power supply. Platinum and its alloys require a higher-temperature furnace, and we will say so rather than sell into the envelope.

What is the difference between a melting furnace and a smelting furnace?

A melting furnace is fed a charge that is already metallic and produces molten metal plus an ingot. A smelting furnace is fed a charge containing metal in combined or oxidised form — ore, concentrate, sulphide, calcine, slag or residue — and is operated with flux and reductant to produce metal plus a slag. The dividing question is whether a slag is produced: melting produces no slag, smelting does. Smelting also separates metal from gangue; melting only liquefies and homogenises. If your feed is not already metal, you need a smelting furnace or a hydrometallurgical route rather than a melting furnace.

Medium frequency or high frequency — which melting furnace should I choose?

Choose medium frequency when batch weight is significant and melt quality depends on heating the whole charge through and stirring it uniformly. Medium-frequency fields penetrate deeper into a large crucible and produce the moderate, useful stirring that homogenises alloy composition. Choose high frequency when the batches are small and the priority is speed in a compact unit — the classic case being a few kilograms of precious metal melted in minutes at a bench or in a small workshop. As a working rule: a few kilograms per batch points to high frequency, tens of kilograms and upward points to medium frequency.

What crucible should be used at 1600°C?

Crucible material is selected for the metal, the temperature and the required service life. Silicon-carbide based crucibles are used for non-ferrous and precious metal melting and are rated around 1600°C in air. Graphite crucibles tolerate higher temperatures but oxidise in air, so they are used with a protective or reducing atmosphere, and they are widely used for precious metal work where contamination by the crucible must be minimal. Clay-graphite crucibles are a cost-effective choice for smaller non-ferrous melts. Crucible grade also has to be compatible with the melt chemistry, because an incompatible crucible contaminates the heat; and crucible centring in the coil matters as much as the material choice, since poor centring is the most common cause of a short lining campaign.

How is the melt temperature measured and controlled at 1600°C?

By an optical, or infrared, pyrometer aimed at the melt surface and connected into a closed PID loop that trims the power supply output. Contact thermocouples of base-metal type degrade rapidly at this temperature, so they are not used as the working instrument. An immersion noble-metal thermocouple is used to verify the pyrometer reading and to certify the pour temperature on the heat record. The combination gives continuous control from the pyrometer and periodic verification from the contact measurement, which is what a batch record needs in order to be defensible.

Why does electromagnetic stirring matter in a melting furnace?

The same alternating field that induces heating currents also exerts a force on the liquid metal and drives a continuous stirring flow through the bath. That stirring dissolves alloy additions rapidly, evens out composition through the whole heat, and removes temperature stratification so that the bath has one temperature rather than a hot top and a cold bottom. In precious metal and superalloy work this is the difference between a sample that represents the batch and a sample that represents only the top of the crucible. Stirring intensity rises as frequency falls, which is one reason medium frequency is preferred for larger heats; it can also be moderated by power and frequency settings where a sensitive alloy would otherwise pick up gas or entrain its own surface oxide.

How long does one melt take?

At a hot furnace, one batch is a matter of minutes, measured from charging the next lot into the standing bath to pouring it. At a cold start the first heat of a campaign takes longer, because the crucible and the lining are being brought up to temperature as well as the charge. The exact figure depends on the batch weight, the metal’s specific heat and melting point, the power rating fitted and the required pour temperature, so melting time is quoted as a configuration result rather than as a catalogue number. The practical planning figure is how many batches the machine can complete in a working day on your charge, and that is what we calculate when we configure it.

What batch sizes are available?

Batch capacity is set by the crucible, and crucibles are selected against the metal, the required melting time and the pour geometry, so the machine is built to the batch rather than offered only in fixed sizes. The relevant range for this class covers the tens-of-kilograms span typical of refinery, foundry, mint and e-waste melting rooms. Note that capacity is stated as molten metal weight at the charge density of the metal being melted, because the same crucible holds different weights of copper, steel and aluminium. Give us the batch weight in metal and the metal itself, and the crucible and power rating follow from that.

What utilities and site works does the furnace need?

Three-phase electrical supply with the voltage and transformer rating to suit the fitted power rating; a closed-loop cooling water circuit with the specified flow, inlet temperature and water quality; a foundation and floor loading to suit the machine and its tilting load; an extraction connection for the fume capture hood over the crucible mouth, sized against the charge chemistry; and sufficient working space around the tilting arc for moulds and for the operator to stand clear during a pour. Where the site supply is weak or harmonics are a concern, the electrical interface is engineered accordingly. The full interface list — power, water, foundation, extraction and layout — is issued with the quotation so that civil and electrical works are built to the right numbers the first time.

Does melting a metal increase its purity or grade?

No. Melting liquefies and homogenises metal; it does not separate impurities from it. A charge that goes in at 99.5% metal produces an ingot at 99.5% metal — correctly homogenised, correctly cast and correctly weighed, but not upgraded. Raising grade happens upstream in smelting and hydrometallurgy, where impurities report to a slag or to solution, or downstream in refining and electrolysis, where metals are partitioned. Buying a melting furnace to improve purity is a common and expensive misunderstanding: the melting furnace’s job is to turn an assayed charge into a uniform, traceable, saleable solid, and it does that job well only when the grade was established before it.