Overview
Features
Industry solutions
By: Tanya Goncalves
Reviewed by: Nitin Joseph
Fact-checked by: Jason Afara
Published on: June 12, 2023
Last revised on: February 2, 2026
If you searched for MRO, chances are you're not looking for a textbook definition. You're probably in one of these situations:
All three are stressful, and none are solved by a glossary-style explanation of MRO. The truth is: MRO is inherently imperfect. There is no such thing as a flawless storeroom or perfectly calm MRO operation. What does exist is an ideal state, one that reliability and maintenance teams continuously work toward.
This article goes deeper than a definition. It reframes MRO as a system, exposes the traps that create chaos, and outlines what modern, strategic MRO actually looks like in practice.
Most definitions will tell you something like:
MRO refers to the supplies, equipment, and activities used to maintain and repair assets.
That's technically correct but not the most useful; a more accurate definition would be:
MRO is the system that ensures the right labor and materials are available when asset demand must be satisfied.
This framing and distinction matters. MRO isn't just a storeroom. It's not just spare parts. And it's not just purchasing. It sits at the intersection of:
When MRO isn't aligned to asset demand, everything downstream breaks. From forecasting, uptime, wrench time, team morale, and cost control.
MRO feels chaotic because it operates under constant uncertainty:
The goal of modern MRO isn't really about perfection; it's about controlled responsiveness. Yet most organizations struggle with the same recurring problem patterns.
According to MacInnes and Pearce (2003), most MRO problems that teams are dealing with fall into the following categories.
The system says four bearings are in stock. The bin is empty. The result?
The ghost inventory problem duels maverick buying and destroys any chance of accurate forecasting.
Fiix insight
The ghost inventory can occur for several reasons. People don't have time for a work order or to write down what they took. People will hoard parts in their toolbox due to a lack of trust that the part will be there when they need it; or because previous leaders had to be tight with the budget and stopped buying parts.
Industry studies consistently show technicians spend up to a quarter of their day searching for parts, driving to suppliers or calling vendors. That's time not spent fixing equipment. The downstream effects of that include:
Procurement is measured on cost savings. Maintenance is measured on uptime and reliability. When procurement buys the cheapest parts available for cost savings, it causes a massive maintenance expense down the road. Maintenance will need to replace the parts in a few weeks, downtime increases, and total cost of ownership goes up. In other words, maintenance decisions live inside a cost-quality-time tradeoff, not a unit price spreadsheet.
There is a triangle for maintenance that includes cost, quality and time. How much is the repair, how long will it take, and how long will it last.
MRO teams manage thousands of low-value items like filters, PPE, and lubricants. Each SKU is cheap. Managing them is not. Processing a $15 purchase order can cost $100 or more in administrative labor, making tail spend one of the most expensive parts of MRO. Without structure, tail spend quietly drain time, money, and focus.
These traps don't look like mistakes at first, but they compound over time.
When teams forecast based only on consumption:
When technicians don't trust the system they use, they protect themselves. That leads to:
The system fails, so people work around it.
In summary, this is the "let's buy more to save more." In reality it goes like this:
Bulk buying often increases total cost, even when the unit price drops.
Parts also have a shelf life. So, we may be installing a part on a major repair that is near the end of its life, making maintenance look bad if the machine goes down again after the repair.
Fast delivery feels good, even when it's unnecessary. For slow-moving parts, this habit:
Speed without strategy creates a lot of bloat.
A rare failure happens, maybe even on a new asset. It's unexpected. Stock levels have increased. The event never happens again, but inventory stays permanently higher. Over time, these reactions create silent, irreversible inventory growth.
Modern MRO treats spare parts as strategic assets, not just supplies.
Parts intelligence is critical for modern MRO, that's where MRO starts working with reliability. According to Cato and Keith Mobley (2002), asset-level bills for materials (BOMs) allow maintenance planners to build repeatable job plans and pull required parts directly into work orders.
Where-used data helps teams identify interchangeable parts, locate any borrowable inventory during emergencies, and reduce stock when assets are retired. It also ensures something even more important: preventing duplicate SKUs across similar equipment.
Where-used analysis is one of the fastest ways to reduce inventory without increasing any risks.
High-performing reliability teams use MRO data to do the following things:
The diagram below shows the flow that prevents ghost inventory, reduces maverick buying, and aligns materials with asset demand, which is the core objective of strategic MRO.
This shows how reliability analytics turn into BOM accuracy, kitting success, and fewer stockouts.
A deeper understanding of what the diagram shows:
Actively lower and tune safety stock. Most organizations only ever raise safety stock. Very few systematically lower it.
MRO driven teams monitor service levels and stockouts and adjust their safety stock based on real performance not just what they think.
If you never experience stockouts, you are almost certain to have excessive inventory. The solution: controlled risk is healthier than permanent bloat.
MRO will never be perfectly calm. But with the right systems, data, and discipline, it can move from reactive and distrusted to planned and reliable.
Regular maintenance and the use of MRO parts not only keep equipment operational but also contribute to increased efficiency and productivity. Well-maintained machinery minimizes downtime, reducing the loss of productivity and revenue associated with equipment failures.
MacInnes, R.L. and Pearce, S.L. (2003) Strategic MRO powered by DSC: A roadmap for transforming assets into strategic advantage. New York: Productivity Press.
Cato, W.W. and R Keith Mobley (2002) Computer-managed maintenance systems: a step-by-step guide to effective management of maintenance, labor, and inventory. Butterworth-Heinemann.
Maintenance, repair, and operations (MRO) is the process of maintaining and repairing equipment. MRO is also known as maintenance, repair, and overhauling. MRO can be used to ensure everything is working correctly and to prevent future equipment problems. It can also help extend the lifespan of your items if they are correctly maintained. MRO is not part of the final product or production materials; that includes the labor that is used when a product is being manufactured.
An example of MRO in maintenance is replacing an industrial machine's faulty component. Let's say a production line in a manufacturing facility is experiencing issues due to a malfunctioning motor. The maintenance team identifies the problem and determines that the motor needs to be replaced.
Organizations can align their procurement and maintenance incentives by using governance tools and shared KPIs that reflect operational impact, such as downtime cost (TOC-based) and critical spares fill rate, rather than unit price alone. This ensures procurement decisions to protect asset availability and throughput, not just short-term cost savings.
The difference between VMI and JIT is that VMI places responsibility on the supplier to maintain agreed inventory levels, reducing downtime risk for critical or fast-moving spares. JIT minimizes inventory by ordering only when needed, which works for planned, non-critical maintenance but carries higher risk in unplanned failures.
Leverage the cloud to work together, better in the new connected age of maintenance and asset management.