How a Hard Chrome Plated Hydraulic Piston Rod Is Manufactured
A hydraulic piston rod has to be straight, dimensionally accurate, hard on the surface and tough underneath. Each of those properties comes from a different stage of manufacturing.
Base material selection
Rods are usually made from medium carbon steels such as EN8, EN8D or EN9 (C45 / CK45 equivalents). The grade sets the core strength and how the surface responds to plating; induction hardened rods are used where impact and denting are a concern.
Machining and grinding
- Straightening of the bar to bring runout within limits before machining.
- Turning to near-net diameter, leaving grinding stock.
- Centreless or cylindrical grinding to the final tolerance, typically f7.
- Polishing to prepare a surface that plating can bond to uniformly.
Hard chrome plating
The rod is electroplated with hard chrome, usually 20–40 microns thick depending on service conditions, giving surface hardness in the 850–1000 HV range. Plating thickness must be uniform — thin patches corrode first and thick build-up requires excessive final polishing.
After plating the rod is polished again to the final surface finish, then inspected for adhesion, porosity, straightness and diameter before rust preventive coating and packing.
What to inspect on delivery
- Diameter across the length, not just at the ends.
- Straightness over the full rod length.
- Surface finish and freedom from plating cracks or pinholes.
- Protective wrapping intact — plated rods are easily damaged in transit.
Frequently asked questions
What chrome plating thickness do you supply?
Standard hard chrome plating is 20–25 microns, and thicker layers can be supplied where the application demands additional corrosion or wear resistance.
Which steel grades do you offer for piston rods?
We commonly supply EN8, EN8D and EN9 grades, with induction hardened and chrome plated options on request.