Stringer 3 Tension Excursion · 14:32–15:08

Cluster cluster_stringer3_1432_excursion

← Back to mod_showcase_crack_001

Modules affected

10 Scrap · 2 B · 1 C · 1 clean

Defect rate

93%

across the cluster

Avg signature match

76%

coherence 93%

Net impact

$1,890

risk $2,380 − salvage $490

Root cause: Operator-1 raised Stringer 3 tension from 4.2 → 4.8 N at 14:32 to compensate for an alignment drift. CUSUM warning crossed at 14:35; recommendation declined; tension reverted only at 15:08 after action threshold. All 14 modules processed by Stringer 3 in the 36-minute window are members of this cluster.

Excursion timeline · 14:32 → 15:08 · 36 min

String Tension · Stringer 3

CUSUM chart

warn 4.5 · action 4.8 N

Operator raised tension from 4.2 → 4.8 N at 14:32. CUSUM warning crossed at 14:35 and action threshold at 15:08. This module passed through Stringer 3 at 14:42, in the middle of the excursion.· Green dashed: If recommendation accepted at 14:38.

Soldering Temperature · Stringer 3

I-MR chart

warn 250 · action 260 °C

Soldering iron held nominal throughout the shift; no thermal contribution to the defect.

Cell Microcrack Rate · Stringer 3

p-chart

warn 0.02 · action 0.04 proportion

Per-lot crack rate from EL screening of cells exiting Stringer 3 spiked from 0.5% to 3.8% during the tension excursion before recovering once tension reverted.

Scrap with defect B/C-tier UnaffectedEach tick = one cluster module's processing time

Affected modules · 14 total

sort

mod_showcase_crack_001

Branching crack adjacent busbar — classic signature.

mod_cluster_stringer3_002

Crack overlaps inter-cell wire — hard scrap.

mod_cluster_stringer3_003

Branching pattern matches predicted high-tension crack.

mod_cluster_stringer3_004

Multi-finger crack, very strong signature match.

mod_cluster_stringer3_005

Smaller crack but overlaps wire — Scrap.

mod_cluster_stringer3_006

Branching pattern, busbar adjacent.

mod_cluster_stringer3_007

Crack outside wire but A-tier limit exceeded.

mod_cluster_stringer3_008

mod_cluster_stringer3_009

Outside-wire crack, similar tension signature.

mod_cluster_stringer3_010

Mild outside-wire crack.

mod_cluster_stringer3_011

Below A-tier limit — B-tier with note.

mod_cluster_stringer3_012

Small crack, marginal — B-tier.

mod_cluster_stringer3_013

Small branching crack — C-tier on wire-overlap reduction rule.

mod_cluster_stringer3_014

Escaped — passed through after CUSUM warning but before crack initiation threshold.

Cluster Bayesian coherence — is this one cluster or many?

Confidence that all 14 modules share a single causal root:93%

Predicted signature

Branching crack near busbar on cells passing through Stringer 3 at ≥4.5 N tension

Observed signature

Branching crack patterns observed on 13 of 14 affected modules, 1 unaffected

Average signature match across affected modules: 76%. High coherence means the defects look like the same phenomenon — strong evidence of a common cause.

Economic impact

Total modules affected14

Scrap10

B-tier2

C-tier1

Unaffected (A-tier)1

Revenue at risk$2,380

Salvage realised$490

Net impact$1,890

If the platform's recommendation had been accepted at the right moment, projected savings:~$1,607 across this cluster.

Cluster-wide recommendations

Re-train Operator-1 on stringer tension SPC thresholds

shift

Recommendation declined twice in this shift across different modules.

→ Faster acceptance of CUSUM-driven recommendations.

Implement automatic tension hold when CUSUM warning crosses for ≥5 min

process

Would have prevented this 36-minute excursion regardless of operator decision.

→ Estimated 13/14 cluster outcomes prevented in similar future events.

Add 'cluster forecast' tile to operator UI showing real-time blast radius

station

Operator could not see the projected impact of declining the 14:38 recommendation.

→ Better-informed real-time decisions.

This cluster page shows how a single upstream excursion produces a coherent pattern across many modules. In production, every excursion that exceeds SPC thresholds is automatically grouped into a cluster, and cluster-level analysis runs continuously.