What Is Induction Hardening?

Induction hardening (induction hardening or inductive hardening) is the use of electromagnetic induction to generate eddy currents in the workpiece to heat the workpiece.

Induction hardening

1. The heat source is on the surface of the workpiece, and the heating speed is fast and the thermal efficiency is high.

2. Because the workpiece is not heated overall, the deformation is small

3. The workpiece has a short heating time and a small amount of surface oxidation and decarburization

4. The workpiece has high surface hardness, small notch sensitivity, and greatly improved impact toughness, fatigue strength and wear resistance. Conducive to realizing the potential of materials, saving material consumption and increasing the service life of parts

5. Compact equipment, easy to use and good working conditions

6. Easy to mechanize and automate

7. Not only for surface hardening, but also for penetration heating and chemical heat treatment.

Induction hardening equipment is generally an induction hardening machine, which consists of induction power, load lines, capacitors, transformers, inductors, and machine tools.

Types of induction hardening are divided into: power frequency, low frequency, intermediate frequency, super audio, high frequency, ultra high frequency. Select the appropriate frequency according to the hardening depth. The greater the depth of the hardened layer, the lower the required frequency, and vice versa.

Induction hardening is mainly based on intermediate frequency, super audio, high frequency and ultra high frequency.

Intermediate frequency is generally thyristor. At present, domestic IGBT induction power supplies are used for IF, which is more energy-efficient than thyristor, but the price is higher than thyristor. Relatively speaking, IGBT is a development trend, because of its high conversion efficiency and stable performance, the internal implementation of soft switching is not easy to fail.

Super audio and high frequency are IGBT induction power supplies. At present, the domestic IGBT induction power supply has gone through three generations. The first generation was a prominent feature of the narrow frequency multi motherboard. The second generation is a wide frequency range, with a single motherboard as its main feature. The third generation has made a revolutionary change in the technical structure, realized digital control, and can transmit and store energy monitoring data to facilitate standardized management.

Ultra-high frequency is generally based on electronic tubes, and MOSFETs have also developed to a certain extent. At present, IGBTs are used in China. The environmental pollution of high-frequency devices for electronic tubes is well known, but its replacement has a higher MOSFET failure rate, and its reference range is limited. IGBT is relatively stable and is currently the core device commonly used in high frequency and intermediate frequency fields