Press  | 03/23/2015

What exactly is SDF® technology?

It can be assumed that even in pre-Christian times, it had been discovered that iron and steel could be hardened by repeatedly heating and forging them. For a long time, hardening was also an integral part of the manufacturing process during which a blacksmith carried out all necessary production steps. It was only with the onset of mass production and the related need for specialization that a separate industrial sector emerged which today plays an important role in the development of hardening processes.

Induction hardening
The classic hardening method is case-hardening in which the entire workpiece has to be heated for many hours in order for the hardening process to take place. This kind of hardening in particular has many disadvantages for industrial production such as high energy consumption and the fact that the process is more time-consuming, the impact on the entire workpiece and the related reworking which is more laborious, for example. Over the last few years, induction hardening has developed as the main alternative technology for machining gear wheels in particular, since only the teeth have to be hardened here. Inductive surface layer hardening is carried out by generating heat in a workpiece using induced eddy currents. This kind of heating avoids the abovementioned undesirable effects allowing only the areas to be heated that need heating thus reducing the machining time. This is brought about thanks to two important mechanisms: by precisely controlling the frequency at which the eddy currents are introduced, only a border area of a few millimeters deep is heated. In turn this means that the entire heating process takes less than 0.5 seconds – much too short a time for it to have thermal effects on the entire workpiece.

Induction Hardening using SDF®
eldec has developed the SDF® (Simultaneous Dual Frequency) process for special hardening requirements on gear wheels. Contour-true hardening of gear wheels in which an even contour is required on the teeth represents a huge challenge as regards hardening and the technologies used in this sector. The difficulty consists in uniformly heating both the base and tip of the gear tooth even though they are situated at different distances from the inductor. This is where the SDF® technology comes into play. By using two different frequencies and power ratings simultaneously, each of which are adapted to the base or tip of the gear tooth, the required thermal pattern is generated and thus the required hardening results along the contour of the tooth. eldec’s SDF® technology offers a hardening technology which can be used in a wide range of applications.

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