Spare Parts Management: The Maintenance Cost Lever Most Teams Underestimate

Spare parts management is one of those areas where the gap between good and average practice shows up clearly in the numbers, but it rarely gets the strategic attention it deserves.

In most asset-intensive operations, MRO inventory accounts for 40 to 50 per cent of the total maintenance budget. Industry data consistently shows that annual carrying costs, i.e. storage, insurance, obsolescence and tied-up capital, run at roughly 20 to 30 per cent of total inventory value. A facility holding half a million dollars in spare parts may spend over $100,000 a year simply to hold that stock, regardless of whether it gets used.

At the same time, a missing part can halt a production line for hours or days. The downtime cost almost always dwarfs the value of the part itself. The tension between overstocking and understocking is real. Resolving it well requires more than a spreadsheet and a gut feel for what to keep on the shelf.

After more than 20 years working with asset-intensive organisations, we have seen what strong spare parts management looks like in practice, and the operational and financial difference it makes when teams get it right.

What effective spare parts management actually delivers

Organisations that manage spare parts well share a few visible outcomes. Their maintenance teams spend less time waiting and more time working. Their storerooms hold less stock overall but experience fewer stockouts. Their maintenance costs become more predictable and easier to defend at budget time. Moreover, their asset reliability improves because technicians can complete planned work on schedule rather than deferring jobs when parts are unavailable.

Research from the manufacturing sector suggests organisations implementing strong spare parts management practices typically achieve 25 to 40 per cent improvements in equipment reliability. Those are significant numbers for a function that often receives far less attention than it deserves.

The two failure modes most operations fall into

Most maintenance teams land in one of two places with spare parts inventory.

Overstocking

Too many parts sit on the shelf, often ordered based on habit rather than data. Capital ties up in slow-moving stock. Storage space disappears. Parts degrade or go obsolete before anyone uses them. Industry estimates suggest 15 to 25 per cent of MRO inventory at many facilities is surplus or obsolete,  purchased with good intentions but never consumed.

Understocking

The opposite problem, but often more visible because its consequences hit immediately. A critical repair stalls because the required component is not on the shelf. An emergency purchase order goes out at a premium. A planned maintenance window extends while the team waits for parts. The downtime cost of a missing part almost always exceeds the cost of holding it in stock, which is why understocking tends to get fixed quickly, then overcorrected back into overstocking.

The goal is neither extreme. It is having the right parts, in the right quantities, connected to the right assets, managed confidently with data rather than reactively with guesswork.

What strong spare parts management looks like in practice

Parts classified by criticality, not just cost

Not all parts carry equal operational weight. A $15 seal that stops a production line for two days matters far more than a $2,000 motor available overnight from a local supplier. Strong spare parts management starts with classifying parts by their operational impact, i.e. the consequence of not having them when needed, rather than by unit cost alone.

ABC analysis provides a practical framework: Class A parts are critical and need to stay in stock. Class B parts warrant reasonable stock levels. Class C parts can generally be ordered when needed. This classification then shapes every other inventory decision that follows.

Stocking levels built on data, not habit

Reorder points and stock levels work best when teams calculate them rather than guess them. The relevant inputs are straightforward:

• Average usage rate, drawn from actual work order history
• Supplier lead time for each part
• A safety stock buffer based on criticality and lead time variability

When teams set stocking levels using real consumption data, inventory tends to get leaner and more accurate at the same time. The parts that matter carry appropriate stock. The parts held just in case start to get rationalised out of the storeroom.

Parts connected to assets and work orders

Connecting every part in the storeroom to the specific assets it serves and the work orders that consume it is one of the most powerful improvements a team can make. When this connection exists inside a CMMS or EAM system, several things happen:

• Technicians know which parts they need before they start a job
• Consumption patterns become visible and feed reorder logic automatically
• Part spend attributes to specific assets, making lifecycle cost analysis far more accurate
• PM schedules can pre-reserve parts ahead of a planned maintenance window, rather than discovering a shortage on the day

A storeroom that works for the people using it

Physical organisation matters more than it often gets credit for. Mislocation drives many perceived stockouts; parts are in the building, but nobody can find them, so someone orders a replacement anyway. Clear labelling, consistent bin locations recorded in the CMMS, and documented procedures for receiving, issuing and returning parts eliminate significant wasted time and duplicate purchasing.

Cycle counts rather than annual stocktakes

Annual physical stocktakes are a blunt instrument. By the time discrepancies surface, they have often been accumulating for months. Cycle counting, rotating through inventory continuously, prioritising critical parts most frequently, keeps records accurate in near real time. It also surfaces problems early, before a missing part becomes urgent during a breakdown.

Where the CMMS or EAM fits in

Strong spare parts management is achievable without sophisticated technology, but sustaining it at scale is significantly harder. A well-configured CMMS or EAM system provides the infrastructure that makes good practice stick:

• Automated reorder alerts trigger when stock drops below minimum levels, removing the dependency on someone remembering to check
• Parts link to assets and work orders so the system captures consumption without manual effort
• Consumption history and trends support data-driven stocking decisions over time
• Multi-site visibility gives organisations managing parts across multiple locations a single accurate picture
• Procurement integration means reorder processes flow without manual re-entry between systems

The key word is well-configured. A CMMS with an incomplete parts catalogue, no asset linkages and inconsistent transaction recording will not deliver these benefits. The system capability is there — but realising it requires the configuration work and ongoing data discipline that turns spare parts management from a reactive scramble into a reliable operational function.

That is exactly the kind of implementation and configuration support MCGlobal has been providing to asset-intensive organisations for more than 20 years. Whether you run an EAM or a CMMS, getting your spare parts module working properly is one of the highest-return configuration investments available.

A practical question worth asking your team

If a critical asset failed today, how confident are you that the required parts are on the shelf, correctly located and recorded in your system? If the honest answer is ‘not very’, spare parts management is worth looking at more closely.

The good news is that it does not require a system overhaul. It requires the right configuration, the right data discipline and a clear connection between your parts inventory and your asset register. That is a practical and achievable starting point for most operations.

Talk to us about getting more from your maintenance inventory.