EXCURSION TO CARL MERTENS & GEBR. HARTKOPF
A Cutlery Manufacturer & Drop Forge in Solingen – 2.4.2019
Carl Mertens is a company with a long tradition which, for almost 100 years now, in addition to the production of cutlery, has paid special attention to the manufacture of high-quality kitchen knives.
Carl Mertens cutlery is punched out and cold formed. The knives, however, are produced by so-called drop forging. A steel with an alloy of chrome, molybdenum and vanadium is used as the basic material for the knife production process. Due to this special alloy, the tool has a long service life, remains sharp for a long time and does not rust. This basic material is therefore delivered in long plates and then cut into small pieces corresponding to the workpiece in a press. These so-called split pieces are then heated to 1060 to 1200 degrees Celsius in a blast furnace.
The split piece is then forged with a die into a first rough shape. Depending on the thickness of the knife, up to five strokes are required. Since the material is so hard after forging that it would simply break under load, it must now be annealed again. This serves calming the blank, i.e. to make it cutable again. The next step is to remove the excess material from the knives and punch them into their actual shape. The knives are then perforated, ground and hardened in an oil bath. Now the knife is cooled down to minus eighty degrees Celsius and then quenched and tempered at two hundred and twenty degrees Celsius. In the final step, the knife is ground and polished on all sides, giving it its own long-lasting sharpness.
Thanks to Christian Darmann for the insights and guided tour
text: Milan Behrens & Parinati Tamboli