Gauge-Correlated Asymmetry in Polymer Cooling
Cooling symmetry is admissible only if downstream product artifacts remain invariant under controlled variation of cooling time. Reproducible, gauge-correlated defects invalidate the symmetry assumption for operational use.
A process symmetry assumption is admissible only if controlled parameter variation does not produce reproducible, product-correlated asymmetry. Otherwise, the assumption is operationally void.
No reproducible artifact trend appears across cooling-time variation.
A monotonic or directional defect signature correlates with cooling time.
Product-correlated artifact response to controlled cooling variation.
Cooling suppresses operational asymmetry
Standard cooling times are assumed to suppress internal thermal asymmetry such that no reproducible downstream defect emerges under nominal conditions.
Throughput and invisibility
- Fixed cooling times maximize throughput
- Internal gradients are not directly observable
- Downstream defects are averaged within tolerance
- Low scrap rates are misinterpreted as validation
Minimal plant-ready experiment
- Standard PP part (~4 mm wall)
- All parameters fixed except cooling time
- Three conditions: nominal, −20%, +20%
- 30 parts per condition
No sensors. No tooling changes. No instrumentation dependency.
One artifact, consistently measured
- Warpage magnitude/direction
- Sink depth
- Shrink differential
- Optical banding
Multiple metrics are not admissible. One signal must carry the test.
PASS
No systematic trend across cooling-time variation.
FAIL
Reproducible defect shifts with cooling time.
What can be shifted by control is not suppressed by assumption.
If a process parameter produces reproducible product asymmetry, the symmetry assumption is no longer admissible for control decisions.
Part of the Edge of Practice short-cycle experiment index