The first sets will be put to the skin with a Nitriding process for the second set leading to skin with Shot Peening, and the third, leading to skin with Nitriding and Shot Peening process.
The first series will bring to the skin by a process Nitriding second set, leading to skin with the Shot Peening and the third to the skin by a process Nitriding and Shot Peening.
The first set to the skin with the process Nitriding two sets of the skin with the process Shot Peening three series and the skin with the process. Nitriding Shot, and Peening