His CDH20.20 steel releases so little nickel that it cannot be allergenic. When it comes to sharing his knowledge of steelmaking, Henri Machwirth combines his specialist skills with a hefty dose of passion. Interview appeared in the Swiss watchmaking journal JSH, EPHJ 2022 edition.
Joël A. Grandjean, JSH Magazine & Swiss-Watch-Passport.ch’s Editor in chief & Publisher
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In iron country, every steelmaker has his own recipe and registers the name of his alloy. As if to mark his territory, to make a difference. The only problem is that by analysing their properties, the man who cut his teeth at Ugine Savoie, the cradle of European steelmaking, realised that the only thing left to do was to invent generics. A bit like a pharmaceutical group with a blockbuster product trying to make a tried and tested molecule more accessible.
Stamping and blanking, two generic steels
The result is two steels, SP360 and SP390D, dedicated to stamping and blanking respectively. The stamper, with his repeated strikes on recognisable plates that have to be bent and forced into the desired form, needs a special steel. A material that, once polished, can be used as a case, a middle, a bezel or even a calibre component. In short, a base material that meets the requirements of the striking process. The SP360 is specifically designed for this purpose.
As for those who practise stamping, they require a steel formulation that is optimally suited to deep-drawing, i.e. one that can be hardened by quenching to provide greater mechanical strength. FCDH Aciers SA, a Froidevaux Group company involved in the sale and development of fine steels, has the solution, in the form of SP390D.
Nickel-free approved by the major brands
So much for the introduction. The rest is virtually devoid of Nickel, that famous toxic metal tracked down by REACH standards or federal ordinances because of its allergic risks. It’s called CDH20.20. Protected as a registered trademark, it goes further than the standard tolerances that distinguish between steel that is permanently in contact with human skin (the case back of a timepiece, for example), and that which is in contact with it more occasionally (such as the case and its casing variations). The reason is that this balancing act comes from scrap metal selected for its purity. With maximum polishability, this ’20 out of 20′ of metallurgical science is a hero when it comes to corrosion resistance. In fact, the ‘cleaner’ the steel, the less likely it is to corrode, since corrosion uses the imperfections in the material to gain ground.
The lead-free era
Henri Machwirth speaks simply. He knows how to make even the most specialised concepts accessible to a layperson such as myself. You feel as if you’re touching the complexity of his profession. He also opens up when he talks about his current quest to eradicate lead. A dangerous lead, now banned worldwide. And yet lead is so highly prized in watchmaking for all the services it provides. Adding it to steel, sometimes mixed with sulphur, encourages the fragmentation of swarf. And when the swarf is less ‘sticky’, when it doesn’t clump around the tools, machining speeds are faster and yields are higher.
Henri Machwirth describes his quest to eradicate lead. A dangerous lead, now banned worldwide…
Will he find the formula his whole sector is looking for? There is hope. At the EPHJ 2022 trade exhibition, visiting professionals were no doubt trying to draw him out. So, to divert them from his well-kept secrets, he invited them to make use of his brand new analysis laboratory. Why not offer them a demonstration of his portable spectrometer right in the exhibition aisles?
