Every manufacturing operator with a decade of floor experience has seen the same paradox at least once: a warehouse full of parts, and a line down for want of the one part that is not there. It is not a rare failure mode. It is a structural one — and it is what fragmented MRO management looks like at scale.
The costs are large enough to matter to a CFO, and the risks are large enough to matter to a plant manager. The problem sits in the middle of that, which is part of why it persists.
The headline numbers
Those four numbers are the entire argument. Too much inventory and too many stockouts. Both, at the same time, in most facilities.
The performance gap in plain dollars
Industry benchmarks measure MRO inventory as a percentage of Replacement Asset Value — essentially, "how much do you keep on shelves relative to how much your equipment cost to buy?" The numbers are less abstract when translated to dollars.
The gap becomes strategic, not tactical, when it multiplies across a multi-plant business unit. Which is where the next tool comes in — enter your own numbers.
Your MRO inventory would be:
Your MRO inventory would be:
Your MRO inventory would be:
Where the pain shows up — three different desks
| Production | 23 per cent of all unplanned downtime is spare-parts-driven. In heavy industry that translates to $10K–$100K+ per hour; on a high-throughput automotive line it can reach $2.3 million per hour. This is where the problem is most visible. |
| Operations | Emergency maintenance costs 3–5× planned maintenance for the same job. Emergency procurement premiums run 2–4× planned purchase cost. Neither figure appears on any dashboard until year-end. |
| Finance | Working capital tied up in inventory, obsolescence write-offs (15–25 per cent of MRO stock is typically obsolete in most enterprises), and annual carrying cost of 20–30 per cent of inventory value. This is where the problem shows up as a balance-sheet issue rather than a plant issue. |
The multi-site version of the problem
Single-plant MRO is a hard problem. Multi-site MRO is a categorically different one.
Each plant builds its inventory around its own risk profile, its own asset history, and its own procurement relationships. Over years, those inventories drift apart. A pump seal that sits in a bin at Plant A for four years may be exactly the part Plant B expedited via emergency freight last Tuesday. Neither plant sees the other's inventory. Neither is doing anything wrong at their own facility. But at the business-unit level, the same seal is being both carried and stocked-out at the same moment.
The published research on this is remarkably consistent. One cross-plant study evaluated 50,000 spare-part SKUs across a multi-site industrial network and found that 15,000 of them — 30 per cent — were suitable for central warehousing based on a combined ABC, XYZ, and criticality (VED) classification. Not all of them. Not none. About a third. That number is the actionable middle, and it does not appear until someone builds cross-plant visibility.
Too much inventory and too many stockouts, at the same time. That is not a paradox. It is what fragmentation looks like.
What "streamlined" actually looks like
There is no single answer. The right MRO model for a multi-site manufacturer is almost always a portfolio of the following, weighted differently for different part categories.
| Central warehouse + regional hubs | Best for medium- to high-value, low-frequency, non-time-critical parts. Published cases show inventory-cost reductions of up to 32 per cent when built with proper criticality analysis. Trade-off: longer lead times to distant sites. |
| Cross-plant CMMS / ERP visibility | The lowest-cost intervention with the highest ratio of insight per dollar. Not every plant needs to ship parts to every other plant; every plant needs to know what the others have. |
| Criticality-based stocking (ABC / XYZ / VED) | Not every part deserves the same policy. Criticality classification is the foundation everything else sits on — and it is the single most under-invested-in step at most facilities. |
| Vendor-managed inventory (VMI) | For high-turnover consumables where the vendor is closer to the demand signal than the plant is. Shifts working capital off the balance sheet and reduces obsolescence risk. |
| Additive manufacturing for low-volume parts | Emerging option for obsolete, discontinued, or long-lead-time components. Especially relevant where the OEM no longer supports the equipment. Not mainstream yet — worth watching. |
| Predictive maintenance reducing spares demand | The upstream fix. When failure prediction improves, safety-stock levels can come down without increasing stockout risk. This is where AI-driven maintenance and MRO strategy converge. |
Is your MRO inventory managed, or just accumulated?
A brief self-assessment. Nothing tracked, nothing saved.
What to watch next
The technology to solve this is not the bottleneck. It has not been for a decade. The bottleneck has always been organisational: who owns cross-plant MRO strategy, who has the authority to redistribute stock, and whose budget bears the transition cost. In multi-business-unit manufacturers, those questions rarely have clean answers — which is why so much inventory sits idle on so many shelves, and why so many lines still go down for want of a $200 part.
Sorting the MRO strategy from the MRO transactions in your own operation? Happy to compare notes.
Get in touch →Where these numbers come from
- Society for Maintenance & Reliability Professionals (SMRP), Business and Management Metric 1.4 — Stocked MRO inventory as percentage of Replacement Asset Value
- ReliaMag, MRO and Spare Parts Inventory Statistics — Stockouts, Accuracy, Costs
- F7i.ai, MRO Benchmarks for 2026 — Inventory Turnover Guide
- Plant Engineering 2025 Maintenance Survey — 23 per cent of unplanned downtime attributable to unavailable spare parts
- Verusen, Excess MRO Inventory Reduction — 2025 survey of 300 manufacturing executives
- Springer / Production Engineering, Criticality analysis of spare parts management — cross-plant central warehouse strategy (50,000-SKU case study)
- Innovapptive, Cost of Unplanned Downtime in Manufacturing
- Hero image: Pexels (free stock, commercial use)