Induction Hardening

Induction hardening offers excellent hardness distribution with minimal deformations

Induction hardening offers considerable advantages over conventional methods for heat-treating steel, alloy, and other metal parts. It is suited for metal with a carbon content of more than 0.3%, particularly hardened steel with a low alloy content (C34, C35, C60, etc.), as described in the DIN EN 100083 industry norm. Shafts, gears, armatures, sprockets and other components can all be hardened using this induction process.

The process also places high demands on the equipment and the inductor used. Ideal hardening results can only be achieved by perfectly matching a precisely controlled energy source with an optimum inductor design. eldec's experienced engineers custom design the induction coils to meet customer specifications, including single turn, two-turn, face-heating, clamshell, and clamp inductors. Every machine is fully inspected and tested to ensure optimum power and heat settings.

Heating directly with induction hardening

Induction hardening is a process in which the heat is generated directly in the workpiece. The principal advantage of this type of heat treatment is that the material quickly attains the desired temperature to produce hardened metal parts. In conventional heat treatments such as flames, ovens, or by convection, heat is applied to the part by heating up the surface layer. These methods take considerably longer and require significantly more energy to produce the desired hardness. Induction hardening, by contrast, offers extremely short heating times. It is a very effectiveattractive method in the manufacturing of steel shafts, components, and other metal parts across a range of industries. Moreover, induction heating can be controlled very precisely via the power, frequency, and the inductor geometry. This minimizes deformities in the workpiece and ensures that the process is highly efficient.

How induction hardening works

The induction method's primary application is hardening steel. One or many induction coils are used to generate and target an alternating magnetic field. This magnetic field produces eddy currents in the metal, which heat the workpiece up to the desired temperature. Immediately after heating, the component then goes through a quenching process using water, oil, or an emulsion. This cools the metal until martensitic transformation occurs, producing a hardened surface that is tougher than the base metal.

After quenching, the steel undergoes tempering, a low-temperature heat treatment process, to reach the desired hardness / toughness ratio. The maximum hardness of a steel grade obtained through the hardening process gives the material a low toughness. Treating the steel through tempering reduces the hardness in the material and increases its toughness.

The hardening depth in the workpiece is precisely controlled by adjusting the electrical power output of the induction machine and the frequency of the inductor / coil current. The thickness of the heated layer from the surface of the metal to some point below the surface is inversely proportional to the frequency of the applied alternating current. Higher frequencies produce thinner skins. Case hardening the surface of steel increases the wear resistance of the component without reducing the ductility of the bulk of the material. eldec offers energy sources with the latest converter technology in three frequency ranges:

  • Low: 1 – 7 kHz
  • Medium: 8 – 40 kHz
  • High: 60 – 500 kHz

Induction hardening with SDF

With Simultaneous Dual Frequency, also known as SDF, eldec offers a further method that is used especially for workpieces with complex shapes. A medium frequency is overlaid with a high one so that both act upon the material simultaneously at a uniform depth. This ensures the component is heated at a consistent temperature across the whole of the part to ensure even surface hardness. Applications suitable for SDF include cogs and gears. Even though the top and bottom of the gear teeth are at different distances from the inductor, a smooth and precise hardness layer can be achieved.

Induction Hardening

What are the advantages of induction hardening?

Induction hardening offers outstanding control of the hardening process. This safe heating method enjoys a multitude of applications, including the manufacture of steel shafts and axels, and can be used across a range of industries. Induction heating machines have minimal space requirements and can easily be integrated into manufacturing processes and production lines. Furthermore, they do not have to be kept running when not in use, unlike surface hardening furnaces.

The use of induction is highly energy efficient since. as only a small proportion of the material is heated. Typically, less than 5% of the mass needs be targeted to accomplish the required properties. The results are outstanding, achieving accurate hardening results even on complex pieces with contours. The number of rejected or deformed parts is kept to a minimum.

Why eldec?
eldec offers a wide range of generators for induction hardening. The machines offer high-quality performance in a compact form. Thanks to precision frequency adjustment, even the most demanding job can be completed with ease. The MIND range of machines are specially designed and manufactured to meet customer requirements, ensuring the right solution for any application. As well as hardening systems, eldec also offers a wide range of generators, brazing and heating systems and tools.




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