Electroplating
Electroplating deposits a thin layer of metal such as zinc, nickel, chrome, copper, tin or silver onto a part using an electric current. It is used to add corrosion protection, wear resistance, conductivity or a decorative finish to machined, pressed and fabricated components.
What it is
The part is cleaned, activated and placed in a plating bath as the cathode. When current flows, metal ions in the solution are reduced onto its surface, building up a coating a few microns to several tens of microns thick.
Parts are either hung on racks (for larger or cosmetic parts) or tumbled in barrels (for small parts in bulk such as fasteners, pins and washers). Coating thickness is controlled by current density and time.
Typical applications
- Corrosion protection of steel fasteners, brackets and pressings
- Wear-resistant or low-friction surfaces on shafts and sliding parts
- Electrical contacts and connectors (tin, silver, gold)
- Decorative finishes on consumer and architectural hardware
- Undercoats that improve adhesion of a following coating
Suitable materials
- Carbon and alloy steels
- Copper, brass and bronze
- Stainless steel (with special activation)
- Zinc die castings (with copper strike)
- Aluminium (with zincate pre-treatment)
Points to consider
- Coating builds up more on edges and corners and less in deep recesses and bores; critical internal surfaces may need electroless nickel instead.
- Plating adds thickness, so threads and close fits must allow for it or be masked.
- High-strength steels (roughly above 31 HRC, e.g. property class 10.9 and higher) can suffer hydrogen embrittlement and need baking after plating.
- Rack contact points leave small unplated marks; state which faces are cosmetic.
Frequently asked questions
Which plating is best for corrosion protection of steel?
For general steel parts, zinc plating with passivation is the most economical. Zinc-nickel gives much longer protection where parts see road salt or harsh outdoor exposure.
Will plating change my part dimensions?
Yes, by the coating thickness on each surface (so roughly double on a diameter). For tight fits or threads, specify the thickness or ask us to allow for it before machining.
What is the difference between rack and barrel plating?
Barrel plating tumbles many small parts together and is economical for fasteners and small components. Rack plating holds each part individually, which suits large, delicate or cosmetic parts.