In spite of the care taken in the tinning of the regulated pads, the micrographic study shows that it is only possible to make by this process a deficient hooking of the regulator on the steel, because it always interposes a layer of oxide between tin and steel.

The researches carried out by the S. N. C. M. on the penetrations and diffusion of the metals between them made it possible to develop a particular cementation of the steel intended to receive the regulate. The regulate, diffusing in this cemented layer which itself penetrated inside the steel, is strongly hooked to the underlying metal.

Regulated specimens can indeed be subjected to pronounced twisting or flexing without taking off between the two layers.

Thanks to a development of the control operations, conducted in parallel with research on the hardening of steels under the influence of high frequency currents, S. N. C. M. has been able to produce bearings whose periphery presents a great hardness, while the bore retains the qualities of a perfectly adherent regulation.