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Two ways of Induction hardening: Scanning Induction Hardening and Single Shot Induction Hardening
Two induction hardening methods are described below: conventional "scanning hardening" and less common "single shot hardening".
The artifact determines which method must be used. For example, long large diameter shafts need to be scanning hardening because the single shot hardening requires greater power. However, the presence of irregularly shaped or complex geometries makes the single shot the only viable alternative.

Scanning Hardening
Scanning hardening includes the relative movement between the workpiece and the inductor. Scanning is divided into vertical and horizontal quenching. In the former, the workpiece remains stationary in the vertical position, and the inductor moves over its length (sometimes the inductor is stationary and the workpiece moves). The inductor moves at various speeds, but it is usually in the range of 5-25 mm / sec. The main advantage of vertical scanning is that the inductor is relatively easy to manufacture because it is usually a single turn circular ring. Another advantage of vertical scanning is that the quench assembly is placed underneath the inductor. This means that the quenching medium flows down without interfering with heating. The depth of hardening in the different areas of the workpiece can be controlled by adjusting the speed of the sensor and the power fed thereto. By horizontal scanning quenching, the level of the workpiece is fed through the inductor and quenched. One of the benefits of horizontal scanning is that it can reduce distortion. This is achieved by maintaining the workpiece in a concentric position in the inductor and quenching, as this results in symmetrical heating and quenching. Another benefit of horizontal scanning is that it contributes to the hardening of large workpieces. For example, this method can be used to harden a six-meter long shaft tube.

Single-Shot Hardening
Single shot hardening means that the fully hardened zone is first heated and then quenched. This hardening can be achieved with a multi-turn coil surrounding the entire hardened zone. However, for workpieces with rotational symmetry, inductors that follow the contour of the workpiece and are combined with rotation are usually used. The inductor may be designed to introduce additional heat into an area such as a rounded corner on a flange shaft, where it is often difficult to obtain sufficient hardening depth. The advantages of single shot hardening include minimizing the deformation and best results of workpieces with complex geometries and / or large diameters. The relatively long heating time of the method (compared to scanning) is also beneficial for the microstructure and residual stresses of the workpiece. However, even if the individual heating time of each abrasive grain is longer than the scanning time, the total heating time is shorter because the entire heating zone is heated at the same time. Single shot hardening usually requires more power than scanning. Additional power is required to achieve the desired temperature rise in the fully hardened zone. In addition, the sensors used in the single shot hardening are more complex and expensive than the inductors used in the scanning. If the power demand changes somewhere on the workpiece, the inductor needs to be physically changed. By scanning, this change can usually be handled by adjusting the control program.

Hengjin Induction is professional in manufacturing induction hardening equipment, the selection of the appropriate parts of the induction hardening method, please consult Hengjin Induction professional technical staffs.

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