FA Krosno completed the installation of a Nitrex nitriding system at its manufacturing facility in southeastern Poland. The pit-type system has overall chamber dimensions of 86 inches (2,184 mm) in diameter x 136 inches (3,452 mm) high with a capacity to nitride an 8,400-pound (3,800-kg) load. The delivered solution includes Nitreg and ONC technologies. ONC is a post-nitriding oxidation process that further enhances the quality of the nitride layer, provides additional corrosion protection and similarly contributes to the aesthetic finish of piston rods. The system, which started production in December 2019, replaced a defunct gas nitrider that was phased out due to inconsistent results and high scrap losses.
FA Krosno manufactures gas springs for manufacturers of commercial vehicles and agricultural equipment. Over the last several years, FA Krosno and Nitrex have entered into a research and development initiative to improve the durability of piston rods in gas spring assemblies of passenger vehicles. The piston rod is the highest-stressed part of the assembly and is subject to buckling, which adversely impacts the service life of the gas spring. The challenge was to design a nitriding cycle that would achieve a high surface hardness for improved wear resistance and minimized friction and ultimately extend the service life of the gas spring.
According to Nitrex, results from various metallurgical and mechanical tests conducted on the nitrided piston rods confirmed that the desired thickness of the white layer, the oxide thickness of the white layer, corrosion resistance and the appropriate roughness were consistently obtained after Nitreg nitriding.