Scope of this guide
Senior version: the fix set with parameter windows, boundary cases and the discipline that keeps them fixed.
This series answers a top recurring question from finishing forums with platingclub line practice. Parameters are industry-standard starting ranges — confirm against your supplier TDS.
Triage: symptom → confirm → first move
| Observation | Likely cause | Confirm by | First move |
|---|---|---|---|
| Thickness below spec on time | Dose under-counted | Amp-min per kg log | Recalculate by weight, not barrel count |
| Outer parts thicker | Normal barrel gradient | Sample by position | Extend cycle; sample per spec points |
| Cycle drifting longer | Contact resistance rising | Dangler tips check | Clean/replace danglers |
| Burns after time extension | CD ceiling reached | Burn map by position | Split load or lower current |
| Thickness scatter widens | Load size variance | Weigh-in records | Standardise load weight |
The fix set
- Fix 1 — dose by weight — Amp-min per kg is the real dose: target = thickness × area per kg ÷ efficiency; log every load
- Fix 2 — sample plan — Thickness at 3 positions × 2 parts per 10 kg; outer-center-inner
- Fix 3 — contact health — Dangler tips dressed daily; contact resistance spot-check weekly
- Fix 4 — load discipline — Standard load cards by part family; flat parts get media to prevent nest
- Fix 5 — cycle chart — Publish thickness vs minutes curve per family; engineers adjust by data, not memory
Case method
A barrel line ran fixed 30-minute cycles 'because it always did'. Dose logging showed one family needed 38 minutes and another only 22 to hit spec. Publishing per-family curves cut average cycle 12% while thickness audit failures fell. (Method illustration: build your own curves from sample data.)
Engineer notes
- One variable per corrective action; verify by the confirm-by column.
- Records beat memory: log every trial on the tank card.
- Escalate when two consecutive actions fail — that is a senior call.
Safety: barrels, hoists and live bus bars share one line. Heat gloves for loads, lock-out before contact service, and never reach into a running barrel.
FAQ
Mixed families in one barrel — how to dose?
Don't. Split by family; mixed loads dose to the heaviest area part and burn the rest.
Efficiency drops late in bath life — where?
Usually organics and metal drift: Hull cell, then dose-curve re-verification before any time increase.
How tight should load weights be held?
±10% keeps the dose curve honest; beyond that, thickness scatter grows visibly.