Spare Parts Inventory Management for Maintenance Teams

Key takeaways

• Spare parts inventory management is one trade-off: the cost of holding a part against the cost of not having it when a machine is down. The right answer is different for every part.
• What you stock should be driven by asset criticality, not by what is cheap or easy to order. A low-cost part for a critical machine can be worth holding; an expensive part for a redundant one may not.
• Stock levels come from reorder point and min-max settings, which depend on lead time, demand, and how much variability you can tolerate.
• The two failure modes are mirror images: stocking everything (cash tied up, dead stock, obsolescence) and stocking too little (a cheap part causes an expensive line-down wait).

The core trade-off

Every spare part carries two opposing costs. Holding it costs money: cash tied up, storage, and the risk it expires or becomes obsolete. Not holding it also costs money: when a critical machine fails and the part is not on the shelf, the line waits for a delivery, and that downtime can dwarf the part's price. Good spare parts management is simply deciding, part by part, which cost is larger.

That decision is not uniform. A two-dollar seal for a bottleneck machine with a two-week lead time is worth stocking; a costly motor for a machine with a standby twin may not be.

Let criticality drive what you stock

The single most useful input is asset criticality. Parts for critical assets, especially long-lead-time parts whose failure would stop production, are the ones to hold. Parts for low-criticality, redundant, or quickly-sourced assets can be ordered as needed. This is why spare parts strategy follows directly from asset criticality analysis: the critical-asset list is most of your stocking list.

Setting stock levels

For each stocked part, a few settings control the inventory:

• Reorder point: the level at which you reorder, set so stock lasts through the supplier lead time.
• Minimum (safety stock): the buffer that absorbs demand spikes and late deliveries.
• Maximum: the cap that stops over-ordering and dead stock.

The longer and less reliable the lead time, and the more critical the part, the higher the safety stock. Consumption data from past work orders is what makes these settings accurate rather than guessed.

Common mistakes

• Stocking everything "to be safe." This ties up cash and fills shelves with parts that expire unused. Safety has a carrying cost.
• No link to criticality. Stocking by part cost or order frequency, rather than by the consequence of a stockout, protects the wrong machines.
• Dead stock nobody reviews. Parts for retired equipment sit for years. An annual review reclaims that cash.
• Guessed levels. Min-max settings pulled from intuition rather than consumption history are usually wrong in both directions at once.

How Fabrico fits

Fabrico links parts to the assets and work orders that consume them, so consumption is recorded rather than estimated and stock levels can be set from real usage. Because it also holds each asset's criticality and downtime impact, the stocking decision connects directly to which failures actually hurt, instead of treating every part the same. Fabrico is built and hosted in the EU with data residency in mind and is ISO 27001 certified. To base your spares on real consumption, book a demo.

Related reading

• Asset criticality analysis
• Work order management systems
• Preventive maintenance schedule
• Manufacturing KPIs

To turn this into a tool decision, see our overview of the affordable CMMS software.

Many manufacturers pair these methods with the tool crib management software.

Frequently asked questions

How do I decide which spare parts to stock?

Start from asset criticality. Stock parts whose absence would stop a critical machine, especially long-lead-time parts. Parts for redundant or quickly-sourced assets can usually be ordered on demand rather than held.

What is a reorder point?

The inventory level at which you place a new order, set high enough that remaining stock lasts through the supplier's lead time plus a safety buffer. It prevents running out while a replacement is in transit.

How much safety stock should we hold?

It scales with lead time, demand variability, and the part's criticality. A critical part with a long, unreliable lead time needs more buffer; a commodity part available next-day needs little or none.

How do we avoid dead stock?

Review inventory at least annually against the current asset list, and base min-max levels on actual consumption history rather than intuition. Parts for retired equipment and parts that never move are the first to remove.