Maintenance and Repairs: Definition and KPIs

What Is Maintenance and Repairs?

In industrial operations, maintenance and repairs represents one of the largest controllable cost categories and one of the most direct determinants of production uptime. The distinction between the two terms reflects their relationship to failure: maintenance is what organizations do to reduce the probability of failure; repair is what they do in response to failure when it occurs. Well-managed maintenance programs do not eliminate repair work entirely, but they change its character: failures become less frequent, more predictable, and easier to address because deterioration has been detected before it progresses into major secondary damage.

The economic case for investing in maintenance over repair is well established. Emergency repairs consistently cost more than equivalent planned maintenance because parts must be procured urgently at premium prices, technicians work overtime, production is interrupted at the worst time, and secondary damage from run-to-failure events often multiplies the original repair cost. A bearing that could have been replaced for $200 during a planned shutdown may require a $4,000 repair including shaft damage, housing damage, and emergency labor when it fails catastrophically during production.

The aggregate of maintenance and repair activity in a facility is typically measured through the Maintenance and Repair Ratio: total maintenance and repair costs expressed as a percentage of the replacement asset value (RAV) of the plant. Industry benchmarks typically range from 2 to 8 percent of RAV annually, varying by industry, asset age, and maintenance program maturity. Facilities at the high end of this range often have excessive reactive maintenance; those at the low end may be under-maintaining assets, deferring costs that will eventually manifest as accelerated deterioration and early replacement.

Maintenance vs. Repair: Core Differences

Types of Maintenance in an M&R Program

Reactive Maintenance

Reactive maintenance addresses failures after they occur, with no prior planning or scheduled work. It is appropriate for low-criticality assets where the consequences of failure are minimal and the cost of prevention exceeds the cost of repair. In most industrial facilities, reactive maintenance consumes a disproportionate share of the maintenance budget because emergency conditions are inherently inefficient: technicians are diverted from planned work, parts are expedited, and production is interrupted. Systematically reducing reactive maintenance, measured by Planned Maintenance Percentage, is a primary objective of maintenance program improvement initiatives.

Preventive Maintenance

Preventive maintenance performs scheduled tasks at fixed time or usage intervals to prevent failures from occurring. It converts reactive repairs into planned maintenance events by addressing the deterioration mechanisms that cause failures before they reach the failure threshold. Preventive maintenance is appropriate for failure modes with reasonably consistent wear-out patterns where the interval can be set based on component service life. It is less appropriate for random failure modes where failures occur at statistically unpredictable intervals regardless of age or usage.

Corrective Maintenance

Corrective maintenance addresses a deficiency or substandard condition identified during an inspection or monitoring activity before it has caused a functional failure. Unlike emergency repair, corrective maintenance can be planned: the deficiency is documented, parts and labor are arranged, and the repair is scheduled for the most appropriate time. Corrective maintenance initiated by condition findings from inspection or predictive maintenance is a critical pathway for converting potential emergency repairs into planned work.

Predictive Maintenance

Predictive maintenance uses condition monitoring data to detect developing faults and schedule corrective action before failure occurs. Vibration analysis, thermography, oil analysis, and acoustic monitoring provide leading indicators of equipment deterioration that allow maintenance teams to intervene with advance planning. Predictive maintenance programs systematically reduce emergency repair by identifying failures in their early stages, when they can be addressed with planned corrective work rather than emergency response.

MRO: Maintenance, Repair, and Operations Materials

MRO refers to the materials, parts, tools, and supplies consumed in maintaining and repairing assets and facilities. Unlike production materials (which become part of the finished product), MRO items support the maintenance function itself: spare parts, lubricants, fasteners, cleaning supplies, safety equipment, and indirect materials. Managing MRO inventory effectively is a significant operational challenge because:

• MRO demand is often unpredictable (especially for reactive repair parts), making traditional inventory optimization methods difficult to apply.
• MRO parts range from very fast-moving consumables (filters, belts, lubricants) to very slow-moving insurance spares (critical spare motors, gearboxes) that may sit for years before use.
• Stockouts directly extend repair time and production downtime, while excess stock ties up working capital in non-productive inventory.
• MRO categories span thousands of part numbers, requiring systematic classification and stocking policies to manage effectively.

A CMMS typically manages MRO inventory alongside work orders and asset records, tracking parts consumption, setting reorder points, and providing visibility into parts availability before work orders are issued.

The Maintenance and Repair Workflow

In a well-structured facility, maintenance and repair activities follow a defined workflow that ensures work is properly authorized, resourced, executed, and recorded:

1. Identification and notification: A maintenance need is identified, either by a scheduled trigger (PM due), an operator observation (unusual noise, vibration, leak), or an automated alert from a condition monitoring system. A work request is raised.
2. Planning: The maintenance or repair requirement is assessed. Required labor, parts, tools, access, and safety procedures are identified. Parts availability is confirmed. For complex repairs, a detailed job plan is developed.
3. Scheduling: The work is assigned to a technician and scheduled for a time that minimizes production impact, considering equipment criticality, parts availability, and the maintenance team's workload.
4. Execution: The work is performed following documented procedures, with time and materials recorded against the work order.
5. Close-out: The work order is closed with completion notes, actual time and materials recorded, and any findings documented. The asset's maintenance history is updated.
6. Analysis: Work order data is reviewed periodically to identify recurring failures, excessive repair times, high-cost assets, and opportunities to improve maintenance strategy or equipment design.

This workflow is managed within a CMMS. Facilities that manage maintenance and repair work outside a CMMS, using paper work orders or spreadsheets, consistently struggle to achieve the planning discipline, history visibility, and data quality needed to improve maintenance performance.

Key Performance Indicators for Maintenance and Repairs

The effectiveness of a maintenance and repairs program is measured through a set of KPIs that together provide a comprehensive view of program performance:

• Planned Maintenance Percentage (PMP): Planned maintenance hours ÷ total maintenance hours. Measures what proportion of maintenance work is executed on a planned basis. Target: 80 percent or above for a mature program.
• Mean Time Between Failures (MTBF): Average time between unplanned failures on a given asset. Measures the effectiveness of the preventive maintenance program.
• Mean Time to Repair (MTTR): Average elapsed time from failure detection to restoration of working condition. Measures maintenance responsiveness and repair efficiency.
• Asset Availability: Proportion of scheduled time the asset is in a condition to perform its function. The net operational outcome of MTBF and MTTR combined.
• Maintenance Backlog: The volume of maintenance work that has been identified but not yet executed, measured in work orders or labor hours. A maintenance backlog that grows over time indicates the maintenance team is falling behind on planned work, which is a leading indicator of increasing reactive maintenance.
• Maintenance Cost per Unit / per RAV: Total maintenance spend relative to production output or plant replacement value, measuring the economic efficiency of the maintenance function.

The Bottom Line

Maintenance and repairs represent the core execution activity of every industrial maintenance organization. How effectively this work is planned, prioritized, and executed determines equipment availability, maintenance cost per unit of output, and the long-term reliability of the asset base.

The shift from reactive repairs to planned maintenance requires both process discipline and data infrastructure. A CMMS that captures every work order, failure code, and cost provides the foundation for measuring maintenance performance and identifying where improvement will have the greatest impact. Organizations that close this loop between maintenance execution and performance data are the ones that make sustained, measurable progress in reducing unplanned failures and controlling total maintenance cost.

Frequently Asked Questions