Process Features and Machining Process of Chrome Plating on Piston Rods

Hard chrome plating on piston rods involves applying a thick chrome coating to the surface of the steel substrate, typically exceeding 10-30μm in thickness. This process utilizes the properties of chrome to enhance the hardness, wear resistance, temperature resistance, and corrosion resistance of the parts.
The process characteristics of hard chrome plating on piston rods:
1) The cathodic current efficiency reaches 25% to 35%, with a rapid deposition rate.
2) The coating boasts high hardness (900-1200HV), featuring a uniform and dense network of cracks, with excellent wear resistance. It can produce micro-cracks, with up to 800-2000 cracks per centimeter (adjustable as needed), enhancing corrosion resistance. The piston rod can withstand salt spray for over 500 hours. The shock absorber rod can also endure salt spray for over 500 hours.
3) Excellent dispersion ability of the plating solution, even coating thickness, and minimal occurrence of rough blisters; the chrome layer has a bright, smooth, and blue appearance.
4) The coating has a strong bonding with the substrate, the pretreatment is similar to traditional processes, and the operation is easier than traditional methods.
5) The trivalent chromium content in the electrolyte solution has a wide allowable range, usually requiring no shutdown for electrolytic treatment of trivalent chromium.
6) The dipping solution is free of fluorides and rare earth elements, resulting in no corrosion in the low-voltage areas of the workpiece.
Process Flow
Hydraulic Piston Rod Machining Process
The connecting rod is made of 35# steel, with processing techniques including: cold drawing forming, turning, continuous medium-frequency induction hardening, pre-grinding of the outer diameter, pre-finishing of the outer diameter, finishing of the outer diameter, ultra-fine processing, electro-chromic plating, dehydrogenation and tempering, and ultra-fine grinding. To enhance the surface quality and corrosion resistance of the piston rod, an ultra-fine processing step is added before electro-chromic plating.