In most factories, nobody decides to waste material. It just happens, a little at each step: a cutting setup, a changeover, a batch that failed inspection, a roll damaged in handling. Each loss is small and goes in the bin without a record. At the end of the month, the stock is short, and the explanation is "process loss" — a number nobody can break down.
Where scrap hides
- In stock adjustments, written off at the count.
- In BOM allowances nobody checks against reality.
- In good output figures that don't mention what was rejected.
- Across shifts, so no one shift owns it.
Record scrap where it happens
Each scrap entry should say:
- Which production order it belongs to.
- Which step of the routing.
- What and how much was scrapped.
- Why — from a short list: setup, operator, material quality, machine, handling, inspection.
The numbers to watch
| Measure | Calculation |
|---|---|
| Scrap rate | Scrap ÷ material issued |
| Yield | Good output ÷ planned output |
| Scrap by reason | Share of scrap from each cause |
| Unexplained loss | Issued − consumed − scrap, as recorded |
Worked example
A unit issues 3,950 kg of material for an order planned at 3,700 kg, records 120 kg of scrap, and finds:
| Reason | Scrap | Share |
|---|---|---|
| Setup and changeover | 54 kg | 45% |
| Material defect | 36 kg | 30% |
| Handling | 18 kg | 15% |
| Operator | 12 kg | 10% |
Nearly half the scrap comes from changeovers — an argument for longer runs or a better setup procedure, not for blaming operators. Without recording reasons, the factory would only know it lost 120 kg.
How Zaqnet records scrap
- Scrap logs against production orders, alongside material issues, consumption and outputs — see production orders.
- Routings with steps at work centres, so losses can be tied to where they happen.
- BOMs to compare planned against actual material — see getting BOMs right.
The calculator below was built for textile mills, where defects on fabric are the main loss; the same thinking applies to any material you cut, mix or shape.
You cannot reduce scrap you do not write down.