How Should Melting Be Performed in Induction Furnaces?

A Step-by-Step Guide to Efficient and Safe Smelting

Melting—also known as smelting or refining—is the process of transforming metal ores or scrap into liquid form to achieve the desired alloy composition. Among modern melting methods, induction furnaces stand out as one of the most efficient, clean, and controllable systems, especially for the production of steel, cast iron, and ferrous alloys.

However, to ensure these systems operate safely, sustainably, and at maximum efficiency, melting must follow a well-planned, technically grounded procedure. In this guide, we break down each phase of the induction melting process, key safety points, and performance-enhancing best practices.

How Induction Melting Works

Induction furnaces melt metal through a high-frequency electromagnetic field generated by a coil surrounding a graphite or ceramic crucible. This induces eddy currents inside the metal, causing internal molecular friction and heat buildup. The result: fast, uniform internal heating from the inside out.

Advantages of Induction Melting:

High energy efficiency
Rapid temperature rise
Minimal oxidation and alloy loss
Clean, compact, and environmentally friendly operation

Step-by-Step Melting Procedure

1. Crucible and Refractory Inspection

Check for cracks, wear, and any signs of metal leakage
Ensure sintering has been completed if newly lined
Do not proceed with melting if leakage is suspected

2. Scrap & Charge Material Preparation

All scrap (HMS, DKP, castings, chips) must be clean, dry, and free of oil or paint
Moisture in the charge can cause explosions and refractory damage
Scrap composition must align with target steel chemistry

e.g., DKP + HMS blend for low-carbon steel
If using recycled returns, alloy balancing is essential

3. Charging the Furnace

Charge progressively based on furnace power and crucible capacity
Start with large, dense pieces; then add finer scrap as melting progresses
Avoid charging the full load at once—staggered feeding supports stability
Increase power gradually; metal typically liquefies within minutes
Monitor temperature frequently and maintain 1500–1600°C
Use mixing/stirring to ensure uniform temperature and alloy distribution

4. Slag (Sludge) Management

Surface slag must be removed regularly to:
- Prevent alloy imbalance
- Protect the refractory lining
- Maintain casting quality
A clean crucible improves heat transfer and flow behavior

5. Chemical Sampling & Alloy Adjustment

Once metal is fully molten, collect samples for analysis
Add carbon, manganese, silicon, or chromium as needed
Alloy additions should be precisely calculated

Overdosing raises costs; underdosing reduces quality

6. Final Temperature & Casting Readiness

Maintain casting temperature between 1550–1600°C
This ensures optimal fluidity, homogeneity, and pourability

7. Pouring Process

Pour molten metal into the tundish or mold slowly and steadily
Prevent overflow and spillage—liquid metal should only contact lined surfaces
After casting, allow the furnace to cool gradually and reinspect the lining

Critical Melting Precautions

Do not charge wet, painted, or contaminated scrap
Always follow a gradual and controlled charging process
Remove slag regularly to prevent contamination
Avoid over-mixing, which may cause temperature fluctuations
Only make alloy adjustments after verified analysis
Overheating can crack refractories or shorten lining life
Power failure during melting may cause the metal to freeze and damage equipment

Advantages of Induction Melting

Fast heat-up and short melt times
Exceptional energy efficiency
Low oxidation and material loss
Precise temperature and chemistry control
High throughput with compact furnace systems
Low carbon emissions and cleaner operation

How Alpha Refractory LLC Supports Your Melting Operations

Successful melting depends on more than just furnace power—it requires engineering insight, process control, and refractory expertise.
At Alpha Refractory LLC, we provide: