How thick is hard chrome plating?

Usually 20–50 µm for wear surfaces such as piston rods, and up to 250 µm or more when a worn part is being built back to size. The drawing should give the thickness after grinding.

Why is hard chrome ground after plating?

Plating builds up unevenly, more at edges and less in recesses. Grinding after plating gives the exact diameter, roundness and surface finish.

Can worn shafts be rebuilt with hard chrome?

Yes. A worn journal or rod can be ground undersize, plated thick and ground back to the original size. For very large build-ups, metal spraying or welding may be cheaper.

Hard chrome plating job work: thickness, hardness, uses

Hard chrome plating deposits a thick layer of chromium on steel parts by electrolysis. The layer is very hard (about 800–1000 HV), slippery and wear resistant, so it is used on hydraulic piston rods, rolls, shafts and moulds. It is much thicker than decorative chrome and is usually ground or polished to size after plating.

Quick facts

Layer thickness: About 20–250 µm; more for rebuilding worn parts
Hardness: About 800–1000 HV (roughly 65–70 HRC)
Base materials: Steels, including hardened and induction-hardened steel; cast iron
Finish after plating: Ground, polished or superfinished to size
Corrosion resistance: Good when the layer is thick enough and crack-free enough
Usually priced: Per piece or per square decimetre, by thickness

How it is done

Parts are cleaned, degreased and areas that must stay bare are masked
The part is made the cathode in a chromic acid bath
Plating runs for hours; thickness grows by roughly 20–50 µm an hour
Parts are baked (about 190–220 °C) to remove hydrogen and prevent cracking of hard steels
The plated surface is ground or polished to the final size

Hard chrome or decorative chrome?

	Hard chrome	Decorative chrome
Thickness	20–250 µm and more	0.2–0.5 µm over nickel
Purpose	Wear, friction, corrosion, rebuilding size	Bright appearance
Typical parts	Piston rods, rolls, moulds	Taps, handles, trims
After plating	Ground to size	Ready as plated

What to tell the plater

Base material and its hardness
Areas to plate and areas to mask, marked on the drawing
Final plated thickness after grinding, and the grinding allowance
Final size and surface finish (Ra) after grinding
Whether hydrogen de-embrittlement baking is needed
Quantity and the length and weight of the longest part

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Questions

How thick is hard chrome plating?: Usually 20–50 µm for wear surfaces such as piston rods, and up to 250 µm or more when a worn part is being built back to size. The drawing should give the thickness after grinding.
Why is hard chrome ground after plating?: Plating builds up unevenly, more at edges and less in recesses. Grinding after plating gives the exact diameter, roundness and surface finish.
Can worn shafts be rebuilt with hard chrome?: Yes. A worn journal or rod can be ground undersize, plated thick and ground back to the original size. For very large build-ups, metal spraying or welding may be cheaper.

The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 16 October 2026.