Induction Forging & Hot Forming: Billet, Bar and End Heating

Quick Answer

Induction forging and hot forming use induction heating to bring a metal billet, bar or block to a temperature at which its resistance to deformation is weak, so it can be forged, bent or shaped. Approximate hot forming temperatures are 1200 °C for steel, 750 °C for brass and 550 °C for aluminium. Parts can be heated completely (billets, bars, brass and titanium blocks) or only at the forming zone (pipe ends, axle ends, automotive parts and bar ends). Compared with conventional furnaces, induction gives much shorter heating times with less scaling and oxidation, accurate temperature control, no furnace ramp-up, automated operation and greater thermal efficiency.

Table of Contents

• What is Induction Forging & Hot Forming?
• Key Applications
• Suitable Materials
• Working Principle
• Technical Specifications
• Recommended Model Selection
• Process Workflow
• Common Problems and Solutions
• Engineering Selection Guide
• Advantages and Limitations
• Why Choose HLQ?
• 10 Core FAQs

What is Induction Forging & Hot Forming?

Forging and hot forming are methods of plastically deforming metal. Industrial forging and hot forming processes bend or shape a metal billet or bloom after it has been heated to a temperature at which its resistance to deformation is weak. Induction heating is an excellent way to reach that temperature: the heat is generated in the part itself, so it does not need to be produced in a large chamber. Blocks of non-ferrous materials can also be used, and induction forging solutions have been installed in many countries, mainly in the metal and foundry sector.

Key Applications

Total Forging / Hot Forming Applications

Induction heating machines are commonly used to heat steel billets, bars, brass blocks and titanium blocks to the proper temperature for forging and hot forming.

Ends Forging / Hot Forming Applications

Induction heating is also used to heat parts such as pipe ends, axle ends, automotive parts and bar ends for partial forming and forging. An HLQ example is induction forging steel rod ends.

Suitable Materials

Materials processed with induction forging and hot forming include aluminium, brass, copper, steel, iron and stainless steel; titanium blocks are also heated. Typical heating ranges come from the HLQ induction forging billet heating guide.

Working Principle

The power supply drives alternating current through a water-cooled, multi-turn helical copper coil. The magnetic field induces eddy currents in the billet, which heats from the inside of the part rather than from a furnace chamber. In through heating, billets are pushed through the coil and leave at forging temperature. In end heating, only the bar, pipe or axle end that will be formed sits inside the coil.

The heated layer depth follows the skin effect. Calculation (δ = 503·√(ρ/f), hot steel above the Curie point, ρ ≈ 1.2×10⁻⁶ Ω·m, µr = 1): δ ≈ 17 mm at 1 kHz and ≈ 5.5 mm at 10 kHz. Lower frequency gives deeper heating, so larger billets use lower frequencies.

Technical Specifications

HLQ forge furnace data by system size (steel billets):

Source: HLQ induction forge furnaces for hot forming steel billets.

Recommended Model Selection

DW-MF induction heating rod forging furnaces, from the HLQ induction heating device model table:

Larger units from the induction forging bar and billet furnace page:

DW-MF-200 to 600: 3 phases 380/410/440 V, 50/60 Hz; oscillating frequency 0.5–20 kHz, customized to the part size; 100% duty, 24 h continuous work; cooling water 0.1–0.3 MPa, hardness < 50. Small rods and bar ends in HLQ cases used DW-HF units (DW-HF-45kW and DW-HF-60kW, 50–70 kHz).

Process Workflow

1. Bar stock – billets, bars or blocks are loaded.
2. Cut – cut to forging length.
3. Feed – roller or pusher feed into the coil.
4. Heat – the induction coil heats the part to forging temperature.
5. Check – a pyrometer checks temperature; parts outside specifications are detected and removed.
6. Transfer – automatic transfer to the press.
7. Forge – forging or hot forming.

Common Problems and Solutions

Engineering Selection Guide

• Total or end heating: billets and bars heated through, or only the end that is formed.
• Material: it sets the temperature (steel ≈ 1200 °C, brass ≈ 750 °C, aluminium ≈ 550 °C).
• Billet size: it sets the frequency. Larger billets use lower frequency (see the system tables).
• Output: kg/hr or parts per hour sets the power, from 80–250 kW (100–300 kg/hr of steel) to 500–1000 kW (800–2500 kg/hr).
• Utilities: confirm the supply voltage and cooling water capacity.

Advantages and Limitations

Why Choose HLQ?

• DW-MF rod forging furnaces from 45 to 160 kW, DW-MF-200 to 600 for larger lines, and DW-HF units for small rods and ends.
• Published forging and hot forming cases in steel, titanium, Inconel and copper.
• Complete lines: feeder, coil line, pyrometer sorting and closed-loop cooling.
• Induction forging solutions installed in many countries, mainly in the metal and foundry sector.

10 Core FAQs

1. What is induction forging and hot forming?

Heating a metal billet, bar or block by induction to a temperature at which its resistance to deformation is weak, before it is forged, bent or shaped.

2. Which materials can be forged with induction heating?

Aluminium, brass, copper, steel, iron and stainless steel; titanium blocks and other non-ferrous blocks can also be heated.

3. What are typical hot forming temperatures?

Approximately 1200 °C for steel, 750 °C for brass and 550 °C for aluminium.

4. What is the difference between total and end heating?

Total heating brings the whole billet or bar to temperature; end heating heats only pipe ends, axle ends, automotive parts or bar ends for partial forming.

5. Why use induction instead of a fuel furnace?

Shorter heating times, less scaling and oxidation, accurate temperature control, no ramp-up, minimal manual labour, higher thermal efficiency and better working conditions.

6. Which HLQ machines are used for forging?

DW-MF induction heating rod forging furnaces (45–160 kW, 1–20 kHz) and DW-MF-200 to DW-MF-600 (0.5–20 kHz) for larger lines.

7. How is the frequency chosen?

By billet size: lower frequency heats deeper. HLQ steel billet systems use 500–3000 Hz for Ø30–100 mm and 150–600 Hz for Ø150–300 mm.

8. What output can an induction forge furnace reach?

For steel billets, 100–300 kg/hr with 80–250 kW systems and up to 800–2500 kg/hr with 500–1000 kW systems.

9. How fast can small bars be heated?

In HLQ cases, steel rod ends reached 1800 °F in under 5 seconds, and a 13″ section of steel strip reached 1800 °F in 10 seconds.

10. What information is needed for a quotation?

The material, billet or bar diameter and length, forging temperature, total or end heating, output, and available power supply and cooling water.

 

HLQ-Induction-Forging-Hot-Forming-Brochure