Scrap and Rework: Factory Calculation and Cause Log
Calculate first-pass yield, rework and scrap from consistent denominators, then connect the result to a cause log, owner and verified corrective action.
A useful scrap and rework review separates first-pass good, reworked-good and scrapped quantities. Consistent denominators and a cause log show whether an action changed the process instead of merely moving losses between categories.
A shift can report 980 good units and still hide a rework problem. The team needs to know how many passed first time, how many needed another operation and how many became scrap.
Calculate the shift result correctly
Illustrative shift: 1,000 units processed, 930 passed first time, 50 became good after rework and 20 were scrapped.
| Metric | Calculation | Result |
|---|---|---|
| First-pass yield | 930 ÷ 1,000 | 93.0% |
| Rework rate | 50 ÷ 1,000 | 5.0% |
| Scrap rate | 20 ÷ 1,000 | 2.0% |
| Final good yield | (930 + 50) ÷ 1,000 | 98.0% |
Do not count the 50 reworked-good units as first-pass good. If failed rework later becomes scrap, record that later disposition without adding another original unit to the denominator.
Use a cause log that supports action
| Time / job | Defect | Quantity | Observed condition | Owner | Next check |
|---|---|---|---|---|---|
| 10:20 / WO-210 | Burr above limit | 18 rework | Tool at life limit | Production engineer | After tool change |
| 13:10 / WO-214 | Hole position | 12 scrap | Fixture stop loose | Maintenance | First 5 parts after repair |
| 15:40 / WO-219 | Surface mark | 9 rework | Handling tray damaged | Supervisor | Next tray batch |
The log records an observed condition, not a guessed root cause. Confirm the cause through the planned check.
Connect quality and production in Optiwise
Optiwise links production quantities, process entries, inspection requests, rejection, rework and stock movements. Quality parameters and disposition keep accepted, held, rework and rejected material distinguishable. Machine and IoT context can support the investigation when the relevant signal is available.
Review production in Optiwise production and inspection in Optiwise quality. The work-order documentation is a primary reference for relating manufacturing quantities to the work record.
Questions from manufacturing teams
What is the difference between scrap and rework?
Scrap cannot continue as the intended product under the approved disposition. Rework receives additional authorised processing to meet requirements.
What denominator should scrap rate use?
State the denominator explicitly. For this shift example, scrap units are divided by total units processed.
Does a cause code prove the root cause?
No. A cause code records the working classification. Confirm the cause through evidence and a follow-up check.
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