Maintenance spare parts management: minimum stock and reorder point
- Minimum stock = average daily consumption × replenishment lead time (days) + safety stock.
- Classify spare parts by criticality and turnover: not all deserve the same stock.
- Deducting the part from the work order keeps the inventory reliable.
Maintenance spare parts management consists of having the necessary parts, in the right quantity and at the right time, without tying up money in stock that is not used. A missing spare part prolongs the stoppage; a surplus one costs money and space. The balance point is calculated with the minimum stock.
Minimum stock formula
Minimum stock = average daily consumption × replenishment lead time (days) + safety stock
Example: a filter is consumed at an average rate of 0.5 units a day, the supplier takes 10 days to deliver it and you want 2 units of safety stock. Minimum stock = 0.5 × 10 + 2 = 7 units. When stock drops below 7, you must order.
Classify before calculating
| Type of spare part | Criterion | Policy |
|---|---|---|
| Critical | Its absence stops a class A piece of equipment or it takes weeks to arrive | Always keep stock, even if it turns over slowly. |
| Rotating | Consumed regularly (filters, belts, gaskets) | Minimum stock with automatic or periodic replenishment. |
| Occasional | Rarely used and quickly obtained | Do not stock; order when needed. |
The classification depends on the criticality of the asset that the part serves.
How to keep the inventory reliable
- A single place to record receipts, issues and adjustments.
- Deduct from the work order: each consumption is linked to the machine and to the intervention, and the cost accumulates on the asset.
- Cycle counts: count part of the warehouse each month instead of stopping everything once a year.
- Review minimums when supplier lead times or consumption change.
- Link supplier orders and invoices with what was received.
Common mistakes
- Ordering “just in case” without looking at real consumption.
- Not recording small consumptions, which end up throwing the stock off.
- Treating all spare parts the same.
- Forgetting the delivery time when setting the minimum.
Spare parts linked to each work order
Mantenplan keeps stock per warehouse, records movements, manages supplier orders and deducts material from the orders that consume it.
Try MantenplanFrequently asked questions
What is the reorder point?
It is the stock level at which an order must be placed so that the spare part arrives before it runs out. It coincides with the minimum stock calculated from consumption, delivery time and safety margin.
How do I calculate safety stock?
It depends on how much consumption and the supplier’s lead time vary and on the cost of running out of the part. For critical spare parts it is usually higher than for normal-rotation ones.