The typical situation
Rejection on the main line had drifted up over two years and every supervisor had a different explanation: the new ink supplier, the night shift, the humidity, a particular operator.
QC results were recorded on paper, then typed into a monthly summary that lost the batch-level detail.
What the data looked like
Eighteen months of batch records from the ERP, paper QC sheets digitised for a six-month sample, raw-material lot records and the machine settings log. Ambient humidity from the plant's own logger.
What we built
- A ranked list of rejection drivers: two raw-material lots and one machine-setting combination explained most of the variance; shift and operator explained almost none.
- A tablet-based QC entry form so batch-level results stopped disappearing into monthly summaries.
- Control limits on the two settings that mattered, shown on the operator screen.
Typical outcome
| Measure | Before | After | Period |
|---|---|---|---|
| Rejection rate | 4.8% | 2.9% | 3 months before vs 3 months after |
| Rework hours | ~160 / month | ~95 / month | same period |
What usually trips these projects up
The machine-learning model we built in week six added little over the control limits from week four. We kept the simpler system in production and said so to the client.