Material Lot or Machine Zone? Cross-Tab Panel Failures
Cross two sheet IDs with two bed zones while holding file, setup, operator and inspection method constant. A failure that follows the sheet points toward material; one that follows the zone points toward support, focus, airflow or machine-area conditions.
A two-by-two test replaces blame
Production teams need to separate stock variation from a repeatable machine-zone symptom before changing settings or rejecting a lot.
Observation: failures appear on lot A near the rear of the bed. Controlled test: run identified coupons from lots A and B in rear zone 1 and control zone 2 with one file and setup. Interpretation: A1 fail, B1 fail, A2 pass, B2 pass means the symptom follows zone 1. Action: investigate support, focus, and airflow there before rejecting lot A.
Hold file and setup constant
| 2 × 2 result | Sheet A / Sheet B | Interpretation |
|---|---|---|
| Both fail in Zone 1 | Fail / Fail | Investigate zone |
| Sheet A fails in both | Fail / Fail across zones | Investigate lot A |
| Only A in Zone 1 fails | Interaction | Repeat and inspect both factors |
| No repeat failure | Pass / Pass | Original cause not reproduced |
Photograph every coupon beside its sheet and zone label. A 2 × 2 test without identity control becomes four anecdotes.
Worked outcome: failure follows Zone 1
- Choose small retained coupons from two identified lots.
- Choose two bed zones, one associated with the symptom and one control.
- Use the same file and verified settings without tuning between cells.
- Randomize order if heat or time could bias results.
- Repeat the critical cell before rejecting stock or servicing equipment.
A second filled result—A1 fail, B1 pass, A2 fail, B2 pass—makes the symptom follow lot A instead. If only A1 fails, the factors may interact and the decisive cell must be repeated. Settings remain locked until the cross-tab is complete.
Repeat the decisive cell
Photograph every coupon beside both labels. Without sheet identity and zone identity, four results cannot form a two-by-two experiment.
The X1S Pro page anchors current configuration facts. If the isolation run is interrupted, X1S Pro Unplanned Outage: Reassign Work Without Losing WIP protects coupon and panel state.
Questions about lots, zones, and repeat cells
Can I use two pieces cut from the same sheet?
That tests zones better than lots. To test lot effect, retain independent identified stock.
Should I adjust power after the first failure?
No. That breaks the controlled comparison.
Does one clean cross-tab prove the machine perfect?
No. It only reports the tested file, material, zones and conditions.
Let the two-by-two result choose the investigation
Zone-following failures move toward machine-area checks; lot-following failures move toward material review. An interaction requires repetition, not blame.
