Hard chrome plating on piston rods is a relatively thick chromium coating on the surface of steel substrates, with a thickness generally above 10-30 μ m. It utilizes the characteristics of chromium to improve the hardness, wear resistance, temperature resistance, and corrosion resistance of the parts.
The process characteristics of hard chrome plating on piston rods:
1) The cathode current efficiency is as high as 25% to 35%, and the deposition rate is very fast;
2) The coating has high hardness (900-1200HV), presents uniform and dense network cracks, and has good wear resistance; It can generate microcracks, with the number of microcracks reaching 800-2000 per centimeter (adjusted as needed), improving corrosion resistance. The
Piston Rod can withstand salt spray for more than 500 hours. The shock absorber rod can withstand salt spray for more than 500 hours.
3) The dispersion ability of the plating solution is good, the thickness of the coating is uniform, and it is not easy to produce rough blisters. The appearance of the chromium layer is shiny and smooth;
4) The adhesion between the coating and the substrate is strong, and the pre-treatment is similar to traditional processes, making the operation easier than traditional processes;
5) The allowable range of trivalent chromium content in the plating solution is wide, and it is usually not necessary to stop electrolytic treatment of trivalent chromium;
6) The plating solution does not contain fluoride or rare earth elements, and there is no corrosion in the low electric zone of the workpiece.
2、 Process flow
1. Processing process of hydraulic piston rod
The connecting rod is made of 35 steel, and the processing technology is: cold drawing forming, turning, continuous medium frequency induction quenching, pre grinding outer circle, pre precision grinding outer circle, precision grinding outer circle, ultra precision machining, chrome plating, dehydrogenation tempering, ultra precision grinding. In order to improve the relationship between the surface quality and corrosion resistance of the piston rod, an ultra precision machining process is added before chrome plating.
2. Electroplating process flow of piston rod
Pre plating inspection - mounting fixtures - chemical degreasing - electrolytic degreasing - water washing - activated acid washing - water washing - reverse etching treatment - chrome plating on piston rod - recycled water washing - water washing - unloading fixtures - inspection
