01How the process works
Parts are cleaned, activated and plated in electrolytic baths, either on racks or in barrels for small parts. Zinc coatings are passivated and often sealed; high strength steel parts must be baked after plating to relieve hydrogen.
Thickness distribution (thin in recesses, thick on edges), corrosion resistance in salt spray, adhesion and hydrogen embrittlement relief are the main checks. Bath analysis records show whether the process is controlled.
- Pretreatment. Degreasing, pickling, activation.
- Plating. Rack or barrel plating.
- Passivation and sealing. Conversion coating and sealer.
- Baking. Hydrogen relief for high strength steel.
- Testing. Thickness, salt spray, adhesion.
02What typically goes wrong
| Defect | Typical cause | How it is found |
|---|---|---|
| Low thickness in recesses | Throwing power, racking | XRF, magnetic gauge |
| Poor adhesion and blistering | Cleaning | Bend or thermal shock test |
| Early white or red rust | Thin coating, passivation | Salt spray test |
| Hydrogen embrittlement | No or late baking | Baking records, sustained load test |
| Burning on edges | Current density | Visual |
| Stains | Rinsing | Visual |
03Where an inspector should look
01
Before production
- Coating specification and thickness
- Baking requirement for parts ≥ 320 HV
- Salt spray requirement
02
During production
- Bath analysis records
- Baking start time and duration
03
After production
- Thickness by XRF
- Salt spray samples
- Visual
04Standards and references
ISO 2081 (zinc), ISO 19598 (zinc alloy), ISO 1456 (nickel and chrome), ISO 9227 (salt spray), ISO 4042 (fasteners).
Standards are named for orientation. The applicable edition and acceptance criteria are those in your contract and specification.
05How we support buyers of electroplating parts
Manufacturing and Special Process AuditsProcess audits of casting, machining, welding, heat treatment, plating and moulding, with VDA 6.3 style evaluation.
Coating, Painting and Galvanizing InspectionSurface preparation, paint application, DFT, adhesion and hot-dip galvanizing inspection against the coating specification.