Hard Chrome Plating
Hard chrome plating deposits a thick, very hard chromium layer, typically 10–250 µm at around 800–1,000 HV, for wear resistance, low friction and rebuilding worn parts. It is standard on hydraulic piston rods, rollers, dies and shafts, and is often ground to size after plating.
What it is
Unlike decorative chrome, which is a fraction of a micron, hard (industrial) chrome is plated directly onto the part and built up thick enough to be ground or honed to a precise final size.
The coating is extremely hard, has a low coefficient of friction and resists galling. The same process restores worn or undersized components to their original dimensions.
Typical applications
- Hydraulic and pneumatic cylinder piston rods
- Printing, textile and paper-mill rollers
- Moulds, dies and punches
- Shafts, plungers and valve stems
- Rebuilding worn journals and bearing seats
Suitable materials
- Carbon and alloy steels
- Hardened and tool steels
- Stainless steel
- Cast iron (limited)
Points to consider
- Allow grinding stock: plate oversize and grind to the finished diameter for precision fits.
- Hard chrome has a network of micro-cracks; for severe corrosion, use a thicker coat, an undercoat of nickel, or crack-free chrome.
- High-strength steels need hydrogen embrittlement relief baking after plating.
- Hexavalent chromium is tightly regulated, so work goes only to platers with proper effluent control.
Frequently asked questions
How thick should hard chrome be for a hydraulic rod?
Hydraulic rods commonly use about 20–30 µm of hard chrome after grinding and polishing. Heavier-duty or corrosive environments may call for more, or a nickel undercoat.
Can hard chrome repair a worn shaft?
Yes. Worn areas are ground clean, plated oversize and then ground back to the original dimension, often much cheaper than making a new shaft.
What is the difference between hard chrome and decorative chrome?
Hard chrome is thick (tens to hundreds of microns) and functional. Decorative chrome is a very thin layer over nickel, mainly for appearance and tarnish resistance.