Scope of this guide
This intermediate guide goes into diagnosis: reading symptoms, isolating the variable that changed, and fixing it with data you can collect on the line.
Process: Quality & Testing. Figures in this guide are industry-standard starting ranges; confirm against your supplier TDS before locking settings.
Working ranges and control points
The table below is the daily reference for a QC lab. Set by the card, verify by the control point column.
| Test | Standard basis | Sample rate | Watch out |
|---|---|---|---|
| Salt spray (NSS) | ISO 9227 style hours by spec | Per lot, 3 parts | Bad edge prep lies low |
| Thickness (XRF) | Per spec layer stack | 3 points × 5 parts | Curved faces need stand-off |
| Adhesion | Bend or grid per spec | 2 parts per lot | Test after 24 h, not fresh |
| Colour | Standard card, D65 | Every batch | Viewer variation — one trained judge |
| Function (slider pull) | Per customer spec | AQL sample | Test rig wear drifts |
Diagnose It Fast: the intermediate view
Beyond the basic card, this is the layer that matters at your level:
| Symptom | Likely variable | Confirm by | First fix |
|---|---|---|---|
| Dull or hazy finish | Bath chemistry drift | Hull cell panel | Rebalance per test |
| Defects cluster on one rack position | Contact or current map | Position thickness map | Repair contact / re-map amps |
| Good-bad-good pattern | Loading or cycle drift | Time-stamped samples | Standardise load weight |
| Defect appears after maintenance | Work just done | Revert one change | Restore and re-verify |
Standard routine
- Prepare salt-spray edges exactly per spec
- Log chamber position for every sample
- Read thickness with calibrated foil check first
- Photograph every failure before handling
- Write claims with data: lot, hours, points, photos
Engineer notes
- Salt spray compares lots, not absolute field life
- Adhesion tested fresh reads better than 24-hour truth
- XRF needs geometry: flat, clean, right distance
- One colour judge or recorded light box — both is better
- Claim responses with photos settle faster than arguments
Safety: Salt spray chambers run hot, corrosive mist. Open with the exhaust on; wash skin after handling samples.
FAQ
How many parts per salt spray run?
Three parts per lot minimum, edges prepared exactly per the customer spec.
Why does adhesion fail in test but parts look fine?
Fresh-out-of-line plating reads better; test after 24 hours per spec.
What belongs in a customer claim pack?
Lot id, test hours, thickness points, photos of each failure mode.