Classification is the foundation of spare-parts management. Without it, every decision about what to stock, what to buy and what to scrap is made anecdotally, and the warehouse slowly fills with the wrong things.
Classify by failure consequence
- Critical — failure stops production, affects safety, or carries a lead time longer than the plant can tolerate. Hold stock.
- Essential — causes disruption but has a workaround or a short lead time. Hold on consignment or with a supplier.
- Desirable — can wait for the next planned shutdown. Buy on demand.
Classify by movement
ABC analysis on consumption value separates the few parts that account for most of the spend from the long tail. Combine it with the criticality class: a cheap part with a long lead time and high criticality deserves stock, while an expensive part with a short lead time may not.
Classify by source
- Standard, multi-source — competitive, low risk.
- Single-source or OEM-only — higher risk, longer lead times.
- Obsolete or near-obsolescence — requires a decision now: stock up, qualify an equivalent, or plan a redesign.
What good management looks like
- Stocking levels derived from lead time and demand variability, reviewed regularly.
- A single, consistent part record with a photograph and the machine it fits.
- Documented substitutions with the basis of approval.
- Obsolescence reviews on a fixed cycle rather than after a failure.
- Measured service level, dead stock and emergency-buy premium.
The practical test
Ask of any stocked item: if it were not on the shelf, what would happen? If the honest answer is “nothing for weeks”, it belongs on the list. If the answer is “we would buy it locally tomorrow”, it does not.
References we have recently quoted in this category
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Related reading
- Obsolete PLC, Sensor & Motor Parts: A Cross-Reference Workflow
- MRO Spare Parts Management
- Spare Parts Management: Principles and Practice