Learn about electroplating for sheet metal parts. Discover plating types, process steps, thickness standards, and applications for corrosion and wear resistance.
Why Electroplating Sheet Metal Gets Specified
Electroplating deposits a thin metal layer on a substrate through electrolysis. At Fulei Metal, electroplating is routed to audited applicators that we specify and inspect: the plating system, the thickness and the passivation colour are set on the drawing and verified on receipt.
What is Electroplating?
The part is immersed in an electrolyte solution containing metal ions. An electric current causes metal ions to deposit on the part (cathode). The anode supplies metal ions. The result is a thin, uniform metal coating.
Common Plating Types
Zinc Plating
Most common for steel parts. Corrosion protection. Can be clear (blue), yellow, or black passivated. Thickness: 5-15 microns. Cost-effective. Used for fasteners, brackets, and general hardware.
Nickel Plating
Excellent corrosion resistance. Attractive appearance. Can be decorative or functional. Thickness: 5-25 microns. Used for decorative parts, food equipment, and wear surfaces.
Chrome Plating
Hard chrome for wear resistance. Decorative chrome for appearance. Thickness: 0.5-25 microns (decorative), 25-250 microns (hard chrome). Used for hydraulic cylinders, molds, and decorative trim.
Copper Plating
Often used as undercoat for other plating. Good electrical conductivity. Thickness: 2-10 microns. Used for electronics and as a base for nickel-chrome.
Tin Plating
Food-safe and non-toxic. Good solderability. Corrosion resistant. Thickness: 2-10 microns. Used for food equipment, electrical contacts, and soldering surfaces.
Process Steps
Surface Preparation for Electroplating Sheet Metal
Degreasing: remove oils and grease. Electrocleaning: remove fine contamination. Acid activation: remove oxide layer. Surface must be perfectly clean for good adhesion.
Plating
Immersion in plating bath. Electric current applied. Duration determines thickness. Temperature and chemistry controlled. Agitation for uniform deposition.
Post-Treatment
Rinsing between steps. Passivation (zinc). Neutralization. Drying. Optional topcoat or sealer.
Design Points for Electroplating Sheet Metal
Recessed Areas
Recesses may not plate adequately. Electric field is weaker in recesses. Consider design modifications. Use barrel plating for small parts.
Sharp Edges
Plating builds up on edges and points. May be thinner on flat surfaces. Round edges for more uniform coating.
Blind Holes
Solution may not circulate properly. May have thin or no plating. Provide drain holes if possible.
Material Compatibility
Some materials are difficult to plate. Aluminum requires special pre-treatment. Stainless steel requires activation. Cast iron may have porosity issues.
Thickness Standards
ISO 2081: zinc plating thickness. ISO 1456: nickel-chromium plating. ASTM B633: zinc plating. Typical: 5-8 microns for indoor, 12-25 microns for outdoor.
How Electroplating Sheet Metal Is Tested
Thickness: X-ray fluorescence, magnetic gauge. Adhesion: bend test, tape test. Salt spray: corrosion resistance. Appearance: visual inspection. Porosity: ferroxyl test.
Where Electroplating Sheet Metal Gets Used
At Fulei Metal, we electroplate: fasteners and hardware, brackets, electrical components, food equipment, and decorative elements.
Environmental Considerations
Plating baths contain chemicals. Hexavalent chromium being phased out. Trivalent chromium alternatives. Wastewater treatment required. Compliance with environmental regulations.
Closing Notes on Electroplating Sheet Metal
Electroplating provides specific surface properties for sheet metal parts. At Fulei Metal, our plating capabilities ensure components meet functional and aesthetic requirements.
Plating Type, Thickness and the Limits Behind the Salt Spray Number
Electroplated finishes are usually bought against a salt spray figure. That figure is only meaningful alongside the plating type, the thickness and the passivation, and it predicts corrosion behaviour but not wear or appearance life.
| Plating | Typical thickness | What it provides | Limits to respect |
|---|---|---|---|
| Zinc, acid or alkaline | 5-25 µm | Sacrificial protection for steel; the baseline for indoor and mild outdoor duty | Limited abrasion resistance; white rust forms in humid storage without good passivation |
| Zinc-nickel | 8-15 µm | Substantially better corrosion performance than plain zinc at similar thickness | Higher cost and tighter process control |
| Zinc with passivation | Conversion layer over 5-25 µm zinc | Delays white rust; available in clear, blue, yellow and black | Passivation appearance varies by supplier; specify the colour and the standard |
| Nickel | 5-20 µm | Barrier protection and wear resistance, often as an underlayer | Not sacrificial; any pore exposes the substrate and corrosion spreads underneath |
| Electroless nickel | 5-50 µm | Uniform thickness even in recesses and on complex geometry, with good wear and corrosion behaviour | Cost, and bath life management |
| Hard chrome | 20-100 µm | Wear and low-friction surfaces on tools and moving parts | Not a corrosion finish on its own; micro-cracking means it needs an underlayer |
| Tin | 5-15 µm | Solderability and food-contact suitability | Soft, and whisker formation is a consideration on fine-pitch electronics |
One metallurgical risk outranks the rest on plated steel. Hydrogen generated during pickling and plating can be absorbed into high-strength steel and cause delayed brittle failure. The control is baking soon after plating, typically in the 190-230 C range for a defined duration, and it is mandatory rather than optional on hardened parts. If a drawing specifies both a plated finish and a high-strength or hardened fastener, the baking requirement needs to be on the drawing as well.
Geometry matters more in plating than in almost any other finish, because current distribution is not uniform. Recesses, deep holes and internal corners receive less deposit than exposed faces, and sharp external corners receive more. Where a minimum thickness in a recess is required, say so on the drawing, because the thickness on the flat face will not be the thickness in the recess.
Short Answers on Electroplating Sheet Metal
What does 1,000 hours salt spray actually mean?
It means the sample reached 1,000 hours in a continuous neutral salt spray cabinet to a defined acceptance criterion, usually hours to white rust and to red rust. It does not convert into a number of years outdoors, and it says nothing about UV resistance or wear.
Is zinc-nickel worth the extra cost?
Where the part is safety-related, hard to replace, or exposed to road salt or marine air, usually yes, because it delivers much longer protection at a similar thickness. On an indoor bracket it is rarely justified.
Why do plated parts fail after assembly rather than before?
Often because the plating was damaged at assembly, or because the part was bent or crimped after plating and the coating cracked. Where a part will be formed after plating, specify a ductile deposit and test the formed sample rather than the flat panel.
Questions about a specific part are usually faster to answer against the drawing — send it through the route below.
If you are still comparing options before requesting a quote, coating thickness standards covers the decision in more depth. When you are ready, send drawings through surface finishing service — we check them against real tooling and flag anything that would raise cost. See also send the drawing for review and corrosion protection methods compared.
What stands behind this quotation
- Manufacturing since 20162,500 m² Ningbo plant — 3 laser cutting machines (including newer TRUMPF), 4 CNC press brakes and 10 welding stations.
- Shipped to more than 30 export marketsEnclosures, cabinets and formed parts supplied to OEM buyers across Europe, North America and Asia.
- 123 documented product casesMedical device housings, HVAC and heat pump enclosures, agricultural and livestock equipment, industrial hydraulics, material handling trolleys and EV charging cabinets.
- Factory evidence you can checkTUV Rheinland audit reference MIC-ASI243729 and Bureau Veritas reference MIC-ASR263630 available for buyer review on request.
Before you send drawings: project confidentiality is default · first-article inspection is carried out before a batch continues · pricing is staged from prototype quantity to repeat volume · pre-shipment photos and packing records are prepared when the project needs them.