Scope of this guide
This senior guide covers the hard cases: combined variables, boundary conditions and the judgement calls that separate consistent lines from lucky ones.
Process: Mould Maintenance. 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 mould shop. Set by the card, verify by the control point column.
| Parameter | Typical range | Control point | Watch out |
|---|---|---|---|
| Try-out shot count | 20–50 shots per try | Dimensional first-article | Judge on stable shots only |
| Vent depth | 0.01–0.03 mm zinc | Vent impression check | Deep vents flash heavy |
| Polish direction | Along ejection | Ra reading at gates | Cross polish drags filling |
| Cooling flow | Turbulent, per circuit | Flow meter per circuit | Laminar flow warps parts |
| Slide clearance | Per die spec ±0.02 | Blue-check slides | Wear makes mismatch flash |
Push The Boundary: the senior view
Beyond the basic card, this is the layer that matters at your level:
| Hard case | Why it is hard | Method | Data to keep |
|---|---|---|---|
| Mixed-alloy loads | Different windows collide | Split by family or map positions | Per-family thickness trend |
| Seasonal humidity swings | Flash and dry times move | Season-set viscosities | Monthly setting log |
| Recesses at spec limit | Throwing power ceiling | Auxiliary anode trials | Before/after thickness maps |
| Repeat claim from one customer | Use conditions differ | Reproduce their test | Claim-vs-lab correlation |
Standard routine
- Clean cores with soft tools — steel scratches vent lands
- Blue-check slides at every service
- Log flow per cooling circuit at each pull
- Photograph vent lands after cleaning
- First-article dimension after every repair
Engineer notes
- Most flash is slide or parting-line wear, not clamp tonnage
- Vent maintenance beats injection-speed tuning for porosity
- Cooling balance decides warp; one clogged circuit hides in averages
- Polish marks copy onto castings — polish along ejection
- Spare cores for the two hottest cavities save the most downtime
Safety: Mould handling needs rated slings and clear floors. A dropped insert is a scrapped tool and a foot injury.
FAQ
Where should I look first when flash appears?
Parting line and slides with a blue check — wear shows before dimension drift.
How often should vents be cleaned?
Every 10–20k shots for zinc, sooner with hot runner gates.
Why does one cavity warp parts?
Its cooling circuit is partly blocked; flow-meter each circuit, not just the inlet.
How do I train juniors on this judgement?
Have them log the variable they changed and the measured result; review the log weekly against line outcomes.