Buying the wrong furnace costs more than buying the right one. This step-by-step guide walks you through every decision — capacity, power, frequency, technology, lining, and site requirements — so you can specify with confidence.
Every furnace specification starts with two numbers: the type of metal and your required hourly output. Getting these right ensures your furnace is never the bottleneck in your production line — and that you are not paying for overcapacity you will never use.
Use these figures to estimate the power needed to achieve your target output. Actual values vary with scrap type, starting temperature, and lining condition.
| Metal | Melting Point | Energy (kWh/ton) | Typical Melt Cycle | Lining Type | Notes |
|---|---|---|---|---|---|
| Carbon Steel / Alloy Steel | 1,370–1,530°C | 480 – 560 | 45 – 90 min | Acid Silica | Most common application. Higher alloy content = higher energy. |
| Gray Cast Iron | 1,150–1,260°C | 450 – 530 | 40 – 75 min | Acid Silica | Lower melting point reduces energy vs. steel. High silicon content aids fluidity. |
| Ductile Iron (Nodular Iron) | 1,150–1,260°C | 460 – 540 | 45 – 80 min | Neutral / Acid | Similar to gray iron. Temperature control is critical for Mg treatment. |
| Pure Copper | 1,085°C | 450 – 520 | 30 – 60 min | Neutral | High conductivity means lower power factor — size power supply generously. |
| Brass (Cu-Zn) | 900–940°C | 420 – 500 | 30 – 55 min | Neutral | Zinc volatilizes above ~950°C. Temperature control essential to prevent zinc loss. |
| Bronze (Cu-Sn) | 850–1,000°C | 430 – 510 | 30 – 60 min | Neutral | Wide alloy range. Specify alloy composition for accurate frequency selection. |
| Pure Aluminum | 660°C | 340 – 420 | 25 – 50 min | Neutral / Basic | Lowest energy of common metals. Over-heating causes hydrogen pickup — monitor closely. |
| Al Alloys (ADC12, A380, etc.) | 550–660°C | 350 – 430 | 25 – 50 min | Neutral / Basic | Most common die casting alloys. Holding furnace strongly recommended. |
| Zinc / Zinc Alloys | 420°C | 160 – 220 | 15 – 30 min | Basic / Neutral | Very low energy. Often uses small, fast-cycling furnaces for die casting. |
| Gold / Silver | 961–1,064°C | — | 5 – 15 min | Graphite Crucible | Small capacity (1–50 kg). Use crucible furnace, not rammed lining. |
Power determines how fast you melt. More power = shorter melt cycles = higher hourly output. The formula is straightforward — but frequency selection requires understanding how electrical energy penetrates your specific metal.
Frequency affects the depth of electromagnetic penetration into the metal (skin depth). Higher frequency = shallower penetration = better for small or thin charges. Lower frequency = deeper penetration = better for large furnaces and stirring.
| Frequency | Capacity Range | Best For | Skin Depth (Steel) | Stirring Effect |
|---|---|---|---|---|
| 150 Hz | 3 T – 10 T | Large steel & iron foundries | ~60mm | Very strong — good for homogenization |
| 250 Hz | 1 T – 5 T | Medium steel, iron, copper | ~46mm | Strong stirring, good melt homogeneity |
| 500 Hz | 500 kg – 3 T | Most Common Steel, iron, copper, aluminum | ~33mm | Moderate — suitable for most metals |
| 1,000 Hz | 100 kg – 1 T | Aluminum, small copper, brass | ~23mm | Gentle — good for Al and low-density metals |
| 2,000+ Hz | 1 kg – 200 kg | Precious metals, jewelry, small alloys | ~16mm | Minimal — use crucible to contain melt |
💡 Modern IGBT furnaces automatically track the optimal operating frequency within their range — you do not need to select a fixed frequency manually. Just specify your capacity and metal type and the system adjusts accordingly.
This is the most consequential technology decision you will make. Both work — but they have very different total cost of ownership profiles. For the vast majority of new installations, IGBT is the right choice. Here is why.
IGBT (Insulated Gate Bipolar Transistor) is the current gold standard for induction furnace power supplies. Self-protecting modules, digital control, and near-unity power factor make it the most efficient and lowest-maintenance option available.
SCR (Silicon Controlled Rectifier / thyristor) technology has been used in induction furnaces for decades. It is robust, well-understood, and widely serviceable — but lags behind IGBT in energy efficiency and control precision.
Beyond the power supply, the physical configuration of your furnace determines how it integrates into your casting or foundry workflow. The right choice depends on your pouring method, metal type, and whether you run batch or continuous production.
The most common configuration. Fixed-body furnace with manual pouring ladle or bottom-pour system. Simple, reliable, and low-cost. Operator tilts or taps the furnace to pour.
Motorized hydraulic system tips the furnace body for precise, controlled pouring with minimal spatter. Essential for large capacities where manual pouring is unsafe or imprecise.
Maintains molten metal at a precise temperature between casting cycles. Not a melting furnace — used in conjunction with a melting furnace. Critical for die casting and semi-continuous operations.
Uses a removable graphite or silicon carbide crucible instead of a rammed lining. The crucible is lifted out for pouring. Ideal for precious metals and alloys that cannot contact refractory materials.
One power supply cabinet connected to two alternating furnace bodies. While one furnace melts, the other is being charged or tapped — maximizing power supply utilization and production throughput.
Enclosed furnace with vacuum or inert gas atmosphere. Prevents oxidation of reactive metals. Significantly higher cost and complexity. Requires specialized engineering and site infrastructure.
Lining and cooling are often treated as afterthoughts — but they directly determine furnace safety, energy efficiency, lining campaign life, and IGBT module lifespan. Select them as carefully as the power supply.
| Lining Type | Suitable Metals | Campaign Life |
|---|---|---|
| Acid Silica (SiO₂) | Carbon steel, alloy steel, gray iron, ductile iron | 80–200 heats |
| Neutral (Al₂O₃ / MgO blend) | Copper, brass, bronze, stainless steel, aluminum | 100–300 heats |
| Basic (MgO) | High-Mn steel, alloy steel with Mn or Cr, zinc alloys | 60–150 heats |
| Graphite Crucible | Gold, silver, platinum, small aluminum batches | 20–60 heats (replace crucible) |
| System Type | Best For | Notes |
|---|---|---|
| Recommended Closed-Loop Cooling Tower |
All IGBT furnaces, all climates | Process water never contacts air. No scale buildup. Extends IGBT life significantly. |
| Open Cooling Tower + Softener | Budget-constrained, mild climate | Must use water softener to prevent scale. Monitor water hardness monthly. Higher maintenance. |
| Industrial Chiller | Hot climates, indoor installations | Best temperature stability. Higher energy cost. Use where ambient temperature exceeds 35°C. |
| Municipal Water (once-through) | Not recommended | High water consumption, scale risk, environmental compliance issues. Avoid if alternatives exist. |
Enter your requirements below for an instant sizing recommendation. This is a guide — contact us for a precise engineering specification.
Before ordering, confirm your site can support the furnace. Electrical supply, water availability, and workshop height are the most common issues that delay commissioning.
| Requirement | 100–300 kW Furnace | 300–750 kW Furnace | 750 kW–2 MW Furnace | Notes |
|---|---|---|---|---|
| Power Supply Voltage | 3-phase 380V / 415V | 3-phase 380V / 415V | 3-phase 6kV / 10kV | Confirm local standard with YuRun — transformers available for all common voltages. |
| Incoming Circuit Breaker | 250–630A | 630–1600A | Consult engineer | Breaker must be sized for startup inrush current, not just running current. |
| Power Factor Correction | Not needed (IGBT: 0.95+) | Not needed (IGBT: 0.95+) | Not needed (IGBT) | SCR furnaces require capacitor bank compensation — consult your power utility. |
| Cooling Water Flow | 10–25 m³/hr | 25–60 m³/hr | 60–150 m³/hr | Closed-loop system strongly recommended. Confirm inlet water temp ≤ 35°C. |
| Cooling Water Pressure | 0.2 – 0.4 MPa (at furnace inlet) for all sizes | Too high pressure damages coil connections; too low causes overheating. | ||
| Workshop Floor Load | 5–10 T/m² | 10–20 T/m² | 20+ T/m² — civil engineer required | Include furnace weight + molten metal weight + platform. Tilting furnaces add lateral forces. |
| Workshop Ceiling Height | Min. 4m | Min. 5m | Min. 6–8m | Height needed for charging crane and overhead ladle movement. Check with YuRun for your specific model. |
| Ventilation / Fume Extraction | Basic ventilation | Canopy hood recommended | Dust extraction system required | Local environmental regulations vary. Consult your local authority before committing to exhaust system spec. |
| Floor Drainage | Cooling water drain required at furnace base for emergency and maintenance drainage | Water on the furnace floor is a serious safety hazard — drainage must be provided. | ||
The more information you provide, the more accurate your quote will be. Use this checklist to gather everything you need before contacting us.