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: Die-Casting. 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 die-cast cell. Set by the card, verify by the control point column.
| Parameter | Typical range | Control point | Watch out |
|---|---|---|---|
| Mould temperature | 180–220 °C zinc | Thermocouple per cavity | Cold moulds cold-flake |
| Injection speed | High-speed switch position | Shot profile log | Speed too high traps air |
| Porosity target | No blisters after 200 °C bake | Bake test per lot | Hidden porosity blows in plating |
| Trim die flash | ≤ 0.1 mm remaining | First-article check | Flash lines show after polishing |
| Alloy lot control | One supplier lot per run | Lot tag on tote | Mixed alloys vary plating |
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
- Bake-test first articles before release to plating
- Weigh shots; drift means sleeve wear
- Tag totes by alloy lot
- Check flash at trim, not after packing
- Log cavity temps at start, mid, end
Engineer notes
- Plating bake at 200 °C is the honest porosity test
- Vent plugs wear — rising porosity often means vent maintenance
- Gate marks polish out easier than solder marks; fix die lube first
- Alloy lead content poisons nickel baths — keep lots separate
- Weigh every shot: weight drift predicts porosity
Safety: Molten zinc splash risk at the shot sleeve. Full face shield, no water near the cell, and dry tools only.
FAQ
Why do blisters appear after plating, not before?
Sub-surface porosity expands during plating bake. Bake-test castings before releasing them.
What causes solder on the die?
Die lube failure or local overheat. Re-check release agent coverage at that feature.
How is alloy lot control linked to plating?
Trace elements vary with each lot and change deposit colour and adhesion.