Maintenance and CMMS glossary
Short definitions of the terms most used in maintenance, with a link to the guide that explains each in detail.
A
- Asset
- Any piece of equipment, machine, installation or component that an organisation maintains and whose condition, cost and history are worth recording: a pump, a compressor, an air handling unit or a conveyor belt.
- Availability
- The proportion of time that equipment is in a condition to operate. It is calculated as MTBF ÷ (MTBF + MTTR). Read the guide →
B
- Backlog (pending work)
- The set of open work orders not yet carried out, measured in number of orders or in estimated hours.
C
- CMMS (GMAO)
- Computerised maintenance management system. It brings assets, work orders, preventive maintenance, spare parts and maintenance costs into a single system. Read the guide →
- Corrective maintenance
- Work carried out after the equipment has failed, to bring it back to a working state. Read the guide →
- Criticality
- The importance of an asset according to the consequences of its failure (safety, production, customer service, cost). It is used to decide which equipment gets more preventive or predictive maintenance. Read the guide →
F
- FMEA (AMFE)
- Failure mode and effects analysis. A technique to identify how equipment can fail, what consequences it has and which preventive actions are worth taking.
G
- GMAO (Gestion de maintenance assistée par ordinateur)
- The Spanish and French acronym equivalent to CMMS: a computerised maintenance management system. Read the guide →
H
- Hysteresis (in alarms)
- A technique that avoids false alarms: the alarm is triggered when a value is exceeded and is only cleared when the reading drops below a lower value, so it does not switch on and off continuously around the threshold. Read the guide →
I
- Improvement maintenance
- Modifying equipment to make it more reliable or easier to maintain, usually after analysing breakdowns that repeat for the same cause. Read the guide →
M
- Meter
- A cumulative measure of an equipment’s usage (operating hours, cycles, kilometres) used to trigger maintenance by usage instead of by calendar.
- Minimum stock (reorder point)
- The quantity of a spare part below which it must be replenished. It is calculated from average consumption, replenishment lead time and a safety margin. Read the guide →
- MTBF (mean time between failures)
- Mean Time Between Failures. Operating time divided by the number of breakdowns. It measures the reliability of repairable equipment: the higher, the more reliable. Read the guide →
- MTTF (mean time to failure)
- Mean Time To Failure. Average life until failure of items that are replaced rather than repaired. Read the guide →
- MTTR (mean time to repair)
- Mean Time To Repair. Total repair time divided by the number of repairs. It measures how quickly equipment is recovered after a failure. Read the guide →
O
- OEE (overall equipment effectiveness)
- Overall Equipment Effectiveness. A production indicator that multiplies the availability, performance and quality of a piece of equipment. It complements, but does not replace, maintenance indicators.
P
- Predictive maintenance (condition-based)
- Maintenance that decides when to intervene based on the real condition of the equipment, measured with sensors or inspections, instead of doing it by calendar. Read the guide →
- Preventive compliance
- The percentage of preventive tasks done on time compared with those scheduled. A low value usually indicates an unrealistic plan or a lack of resources. Read the guide →
- Preventive maintenance
- A set of scheduled checks, adjustments and replacements, by calendar or by equipment usage, carried out to reduce the likelihood of a breakdown. Read the guide →
- Preventive plan
- The definition of a recurring maintenance task on an asset (what is done and how often) that automatically generates work orders when its date or meter reading comes up. Read the guide →
- PWA (progressive web app)
- A web application that is installed on the phone like an app and can work offline. It is what allows a technician to check and close work orders without coverage.
R
- RCM (reliability-centred maintenance)
- Reliability Centered Maintenance. A methodology that analyses the functions of each piece of equipment and its failure modes to decide which maintenance task adds the most value in each case.
S
- SLA (service level agreement)
- Service Level Agreement. A commitment agreed with a client, for example maximum response and resolution times for a breakdown according to its priority. Read the guide →
T
- Timesheet
- The record of the hours worked by a person, usually weekly, which is approved and allocated to work orders to calculate the labour cost of each job.
- TPM (total productive maintenance)
- Total Productive Maintenance. A philosophy that involves operators and maintenance in the daily care of equipment to reduce losses and breakdowns.
W
- Work order (WO)
- The record of a maintenance job on an asset: what has to be done, who does it, when, how much time is spent and what material is consumed. Each machine’s history and costs come from work orders. Read the guide →
From glossary to practice
Put these concepts to work: assets, work orders, preventive maintenance and indicators in a single system.
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