Comprehensive reference for 60+ essential maintenance, CMMS, and equipment reliability terms. Master the language of modern asset management.
The systematic approach to managing physical assets throughout their lifecycle—from acquisition to disposal—to maximize value and minimize cost. In manufacturing, this includes tracking equipment condition, scheduling maintenance, managing spare parts, and optimizing replacement decisions based on total cost of ownership and reliability metrics.
The percentage of time an asset or system is capable of performing its intended function without unplanned interruptions. Calculated as: (Total Time − Downtime) / Total Time × 100%. High availability is critical for production facilities targeting 95%+ uptime and is directly impacted by maintenance strategy and execution.
The accumulated queue of planned maintenance work orders that have not yet been scheduled or completed. A growing backlog indicates maintenance resources are insufficient relative to demand, typically resulting in deferred maintenance, increased breakdowns, and rising costs. Healthy maintenance operations maintain a backlog of 1–3 weeks of planned work.
Unplanned repair work performed after equipment fails or begins to malfunction. This reactive approach is costly—typically 3–5× more expensive than preventive maintenance—due to lost production, emergency labor costs, and potential secondary damage. Modern facilities minimize breakdown maintenance by shifting to planned preventive and predictive strategies.
A structured list of all components, parts, and materials required to manufacture, assemble, or repair a product or piece of equipment. In maintenance, BOMs are critical for spare parts planning, ensuring technicians have the correct parts on hand and enabling accurate inventory forecasting for critical equipment.
Related:
The process of comparing an instrument or measurement device against a known standard to ensure accuracy and verify it meets specified tolerances. Regular calibration of sensors, gauges, and test equipment is essential for reliable condition monitoring, diagnostic accuracy, and regulatory compliance in regulated industries.
Software platform that centralizes maintenance data, work order management, asset tracking, and scheduling. A robust CMMS enables data-driven decisions, tracks equipment history, calculates KPIs like MTBF and MTTR, and coordinates preventive, predictive, and corrective maintenance across complex operations.
Maintenance triggered by real-time equipment condition data rather than fixed schedules. Using vibration, temperature, ultrasound, or other sensors, technicians repair or replace equipment only when condition thresholds indicate degradation is imminent. This approach reduces unnecessary maintenance while preventing catastrophic failures.
Planned repairs performed to address identified equipment defects or degradation before failure occurs. Unlike reactive breakdown maintenance, corrective work is scheduled based on inspection findings or condition data, allowing technicians to prepare resources, plan downtime, and execute repairs methodically.
A high-priority replacement part for equipment that would cause significant production loss if unavailable during a failure. Critical spares should be stocked on-site or with guaranteed rapid delivery. Identifying critical spares through failure mode analysis and RCA prevents extended downtime and prioritizes procurement budgets.
Related:
A structured assessment ranking equipment based on the business impact of failure (production loss, safety risk, quality impact, cost). Results guide maintenance strategy—critical equipment receives more rigorous preventive and predictive programs, while less critical assets may use run-to-failure approaches. Criticality drives resource allocation.
The total time an asset or production line is unable to perform its intended function due to failure, maintenance, or other causes. Planned downtime (scheduled maintenance) is controlled and budgeted; unplanned downtime (failures) is costly and unpredictable. Minimizing unplanned downtime is a core maintenance objective.
Related:
Comprehensive business software that integrates maintenance management with financial, inventory, and operational systems across an entire organization. EAM systems provide visibility into total asset value, lifecycle costs, capital planning, and strategic depreciation while coordinating maintenance across multiple facilities and locations.
Related:
The ability of equipment to perform its intended function consistently over a specified time period without failure. Measured through metrics like MTBF and availability, reliability is improved through preventive maintenance, condition monitoring, spare parts availability, and operator training. Reliability-focused strategies directly impact profitability.
The connection between a CMMS and broader enterprise resource planning systems (finance, procurement, HR), enabling seamless data flow for cost tracking, purchase orders, and capital planning. Integrated systems eliminate manual data entry, improve accuracy, and provide complete visibility into total maintenance cost and ROI.
Related:
The specific way an asset fails or malfunctions—for example, bearing seizure, seal leakage, belt slippage, or electronics failure. Identifying failure modes enables technicians to understand root causes and implement targeted prevention strategies. Each failure mode may have distinct symptoms, detection methods, and remedies.
A systematic methodology for identifying potential failure modes of equipment, analyzing their causes and effects, and prioritizing prevention and mitigation strategies. FMEA scores failure modes by severity, occurrence likelihood, and detection difficulty, focusing maintenance resources on high-impact risks.
The percentage of maintenance work orders that are resolved completely on the first visit without requiring follow-up repairs (target: >90%). High first-time fix rates indicate strong diagnostic skills, adequate spare parts availability, and effective planning. Low rates signal chronic part shortages, knowledge gaps, or underlying asset problems.
Related:
A visual project planning tool displaying tasks, durations, dependencies, and timelines on a horizontal bar chart. Gantt charts are invaluable for scheduling complex maintenance shutdowns, coordinating multiple crews, and communicating timelines to operations and management.
Related:
A formal process identifying potential safety risks associated with equipment operation and maintenance activities. Analysis results drive hazard mitigation—lockout/tagout procedures, personal protective equipment requirements, and training programs. Hazard analysis is foundational to OSHA compliance and safe maintenance practices.
Related:
A standardized list of conditions, measurements, and visual indicators that technicians verify during routine equipment inspections. Well-designed checklists ensure consistency, catch early warning signs, and create historical data for trend analysis. Digital checklists feed directly into CMMS for traceability and analytics.
The practice of maintaining optimal stock levels of spare parts and materials to support maintenance operations without excessive carrying costs. Effective inventory management balances critical part availability against cash flow, warehouse space, and obsolescence risk using demand forecasting and ABC classification.
Related:
Connected devices that continuously measure equipment parameters (vibration, temperature, pressure, sound) and transmit data to central systems for real-time monitoring. IoT sensors enable condition-based maintenance, allow early detection of degradation, and provide the foundation for AI-driven predictive analytics.
An inventory strategy where spare parts and materials arrive exactly when needed for maintenance work, minimizing storage space and carrying costs. JIT requires reliable suppliers, accurate demand forecasting, and strong vendor relationships. While efficient, JIT increases risk if critical equipment fails unexpectedly.
Related:
A measurable metric tracking maintenance performance toward business objectives—including MTBF, MTTR, availability, first-time fix rate, and maintenance cost per unit produced. Effective KPIs provide early warning of problems, justify investment in preventive programs, and enable data-driven decision-making.
Application of lean principles (eliminate waste, optimize flow, continuous improvement) to maintenance operations. Lean maintenance minimizes unnecessary downtime, reduces inventory waste, streamlines work order processes, and empowers technicians to identify and eliminate inefficiencies.
Related:
The total cost of owning and operating an asset from acquisition through disposal, including purchase price, maintenance, energy, spare parts, and eventual replacement. Lifecycle cost analysis reveals the true cost of equipment choices and justifies investment in high-reliability designs and preventive maintenance programs.
Related:
Safety procedures isolating energy sources (electrical, hydraulic, pneumatic) and preventing accidental startup during maintenance work. LOTO compliance is a legal requirement (OSHA 1910.147) and essential for preventing serious injuries. Technicians must be trained and certified in facility-specific LOTO procedures.
Related:
The average time elapsed between consecutive failures of an asset under normal operating conditions. MTBF is a key reliability metric—higher values indicate better equipment performance. Tracking MTBF trends reveals whether maintenance strategies are improving reliability or if equipment is degrading.
The average duration from the moment equipment failure is reported until it is fully repaired and returned to service. MTTR includes diagnostic time, parts procurement, repair execution, and testing. Reducing MTTR through training, spare parts availability, and efficient troubleshooting directly decreases total downtime and production loss.
A comprehensive strategy documenting the maintenance approach for equipment—including preventive schedules, condition monitoring parameters, spare parts requirements, safety procedures, and resource needs. Maintenance plans ensure consistency, guide technicians, and provide the foundation for budgeting and resource allocation.
A calendar of planned maintenance tasks assigned to specific dates, frequencies, or meter readings for each equipment item. Schedules balance workload across teams, coordinate maintenance downtime with production, and ensure nothing is overlooked. Digital scheduling integrates with CMMS for real-time visibility and adjustments.
The category of supplies—parts, lubricants, cleaning materials, consumables—required to maintain and operate equipment. MRO procurement is often overlooked but represents significant cost; optimizing MRO sourcing, standardization, and inventory can yield 10–20% savings without compromising reliability.
Related:
Adherence to standards from the National Fire Protection Association covering electrical safety, hazardous materials, emergency procedures, and equipment protection. NFPA-compliant maintenance practices reduce fire risk, electrical hazards, and accident liability in industrial facilities.
Related:
A comprehensive productivity metric: (Availability × Performance × Quality) × 100. OEE identifies losses from downtime, speed loss, and defects, benchmarking against industry targets (85%+ is world-class). OEE directly reflects maintenance quality—planned maintenance, rapid repairs, and reliability improvements all boost OEE.
A maintenance philosophy that empowers equipment operators to perform basic maintenance tasks (lubrication, cleaning, bolt tightening, inspections) alongside their primary duties. Operator involvement catches problems early, reduces specialist technician workload, and builds ownership and awareness of equipment health.
Scheduled maintenance tasks performed at regular intervals (time or usage-based) to prevent failures before they occur—includes lubrication, filter changes, inspections, and component replacement at predetermined life limits. Effective PM extends asset life, reduces emergency repairs, and improves uptime by 20–30% compared to breakdown maintenance.
Any maintenance activity scheduled in advance with prepared resources, spare parts, and technician assignments. Planned maintenance (preventive, corrective, or condition-based) is far more efficient than unplanned repairs—reducing costs by up to 50%, minimizing downtime, and improving safety.
Maintenance triggered by equipment condition signals—measured through vibration, temperature, ultrasound, oil analysis, or thermal imaging—indicating degradation is progressing. Predictive approaches maximize asset utilization by repairing only when necessary while preventing catastrophic failures. Implementation requires condition monitoring systems and data analytics expertise.
Advanced analytics that not only predict failures (predictive) but also recommend the optimal timing, approach, and resources for repairs. Prescriptive maintenance maximizes value by accounting for production schedules, spare parts availability, technician workload, and business impact—enabling smarter maintenance decisions.
The percentage of scheduled preventive maintenance tasks completed on time (target: 95%+). High PM compliance indicates commitment to planned maintenance discipline and strong organizational execution. Low compliance signals resource constraints, competing priorities, or insufficient prioritization of preventive work.
Related:
A systematic investigation methodology identifying the underlying reasons why equipment failed, rather than just treating symptoms. RCA uses structured techniques (5 Why, fishbone diagrams) and uncovers systemic issues—design flaws, operator error, maintenance gaps, environmental factors—enabling permanent solutions and preventing recurrence.
A strategic framework determining the most cost-effective maintenance approach for each asset by analyzing failure modes, consequences, and prevention methods. RCM optimally combines preventive, predictive, corrective, and run-to-failure strategies based on criticality and failure patterns, improving reliability while reducing unnecessary maintenance.
Unplanned repairs performed after equipment failure occurs. Reactive approaches are expensive (3–5× costlier than planned maintenance), disrupt production schedules, risk secondary damage, and strain technician resources. Modern facilities minimize reactive maintenance by shifting to preventive and predictive strategies.
The engineering discipline focused on designing, operating, and maintaining equipment to achieve target reliability and availability metrics. Reliability engineers conduct failure analysis, optimize maintenance strategies, select high-reliability components, and implement systemic improvements to reduce downtime and extend asset life.
Related:
A maintenance strategy that allows non-critical equipment to operate until failure rather than performing preventive maintenance. Run-to-failure is cost-effective for low-criticality assets where failure impact is minimal, but inappropriate for critical equipment where failure would cause significant production loss, safety risk, or secondary damage.
Related:
A work order initiated to address identified safety hazards or non-compliance issues—lockout/tagout deficiencies, guarding problems, hazardous conditions. Safety work orders receive priority prioritization and must be tracked and closed separately to ensure hazards are eliminated and compliance is maintained.
Related:
A contractual commitment between maintenance and operations defining response times, resolution targets, and availability guarantees for different priority levels. SLAs provide clarity, accountability, and enable trade-off discussions between maintenance resource investment and production reliability targets.
Related:
Detailed written instructions documenting the step-by-step process for performing specific maintenance tasks, troubleshooting procedures, or equipment operation. Well-written SOPs ensure consistency, reduce errors, accelerate technician training, and provide critical documentation for audits and compliance verification.
The strategic practice of identifying critical parts, forecasting demand, maintaining optimal inventory levels, and managing supplier relationships. Effective spare parts management prevents extended downtime due to part unavailability while avoiding excess inventory carrying costs. ABC classification and demand forecasting drive smart inventory decisions.
Related:
A comprehensive maintenance philosophy that emphasizes operator involvement, equipment design optimization, maintenance team coordination, and continuous improvement. TPM aims to achieve zero unplanned downtime through preventive maintenance, rapid problem-solving, and a culture where all employees take responsibility for equipment reliability.
Related:
Undocumented expertise and insights held by experienced technicians—often critical to equipment troubleshooting and long-term maintenance strategy. Relying on tribal knowledge creates vulnerability if experts leave. Smart organizations capture this knowledge through documentation, training programs, and knowledge management systems.
Related:
A structured reference document guiding technicians through diagnostic processes for common failures—listing symptoms, probable causes, testing procedures, and remedies. Digital troubleshooting guides integrated with CMMS accelerate diagnosis, improve first-time fix rates, and enable less experienced technicians to resolve problems effectively.
Intensive, planned maintenance performed during scheduled production shutdowns—often annually or every several years—addressing deferred work, major overhauls, capital upgrades, and intrusive inspections. Turnarounds are expensive but prevent extended unplanned downtime and extend equipment life by addressing deep issues.
Related:
Production loss due to unexpected equipment failure or emergency maintenance. Unplanned downtime is costly (lost revenue, overtime labor, expedited parts, customer impact) and disruptive to schedules. Reducing unplanned downtime through preventive and predictive maintenance is a primary maintenance objective.
The percentage or duration of time equipment is operational and capable of producing (complement of downtime). High uptime directly drives revenue and customer satisfaction. Uptime is impacted by maintenance strategy, technician capability, spare parts availability, and equipment design reliability.
Related:
A condition monitoring technique measuring equipment vibration signatures to detect degradation in bearings, gears, misalignment, and imbalance. Abnormal vibration patterns provide early warning of developing problems, enabling predictive maintenance decisions before catastrophic failure. Vibration analysis is especially valuable for rotating equipment.
A fundamental condition assessment technique where technicians directly observe equipment for signs of degradation—leaks, corrosion, discoloration, loose components, wear patterns. Visual inspection is low-cost, requires minimal training, and provides immediate feedback. Regular visual inspections catch many problems before they escalate.
A formal document or digital record authorizing and tracking maintenance work—including task description, equipment identification, priority level, assigned technicians, estimated duration, required parts, and actual completion details. Work orders are the central record of all maintenance activity and provide essential data for analytics and compliance.
A classification system (emergency, high, medium, low) determining the urgency and scheduling sequence for maintenance work. Priority levels should reflect business impact and safety consequences—emergency orders (safety hazards, critical production equipment) get immediate attention, while low-priority preventive work can be scheduled flexibly.
Related:
The percentage of a technician's shift actually spent performing hands-on maintenance work versus non-productive activities (waiting for parts, searching for documentation, traveling, meetings, administrative work). Healthy operations achieve 50–65% wrench time; increasing wrench time through better planning, parts availability, and processes improves technician productivity and maintenance capacity.
Related:
Understanding maintenance fundamentals is the first step. Dovient's CMMS platform helps you implement the strategies and metrics covered in this glossary.
