Maintenance Terms

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Maintenance Dictionary

Maintenance: the act of maintaining, the state of being maintained, care or upkeep of machinery, the process of maintaining or preserving someone or something, the process of keeping something in good condition, the work of keeping something in proper condition.

Browse our Maintenance Dictionary for other maintenance terms used within the maintenance field.

Actuarial analysis Statistical calculation, especially of life expectancy
Add-on work Work added to a maintenance schedule after the agreed upon cut-off time for the schedule.
Action results Indicator Key Performance Indicators used for measuring results of actions that indirectly or directly impacts the financial performance of the company. Examples
Apprentice An employee in a certified training program to become a craftsperson.
Asset An accounting term for any physical thing owned by a plant, such as buildings, equipment, desks, software, computers etc.
Asset number A number that follows a particular asset in a plant, should be used for accounting purposes. Note an asset number is different from an equipment location number. An equipment location number stays in the same location, where an asset number may move location.
Asset Replacement Value The current accounting value of all combined physical assets in a plant.
Assessment – reliability A study comparing the Current best Practices (CBP) with actual performance. The study assesses the effectiveness of processes in place.
Autonomous Maintenance Maintenance processes driven by hourly workforce without management support or intervention.
Autonomous Training Training that is incorporated into the day-to-day work processes. The training is based on experiences and findings from the daily work and is then communicated on a regular basis.
Availability Percentage of total hours (8760/year) or scheduled operating time a system is available for production.
Backlog Volume of all requested maintenance work, yet not completed
Backlog – approved The approved backlog is all maintenance work that is not completed, but approved for execution.
Benchmarking The continuous, systematic search for, and implementation of, better practices that lead to improved performance
Bill of Materials (BOM) A document of all parts for an asset.
Break down When a piece of equipment ceases to function (according to predetermined parameters)
Break-In job Work that changes a set schedule after an agreed upon cut-off time. Break in job are either:

  1. break-downs
  2. emotional add-on work
Capital work Work done for improvements or betterments which will increase the value of assets.
Capital Spares Spare parts that are depreciated (not expensed) in accounting books.
Charge rate The amount per hour a resource cost for the company. Wages plus benefits. Benefits are usually around 35% of the salary in The USA, 50-60% in Europe. Benefits include insurances, vacations, and other time off.
Component A generic technical part. Many components make up equipment. Hierarchy is that parts make components, makes equipment, makes systems. illustration (30 KB)
Computerized Maintenance Management System (CMMS) A computer program or interfacing programs used to manage the maintenance function in a plant.
Condition Based Maintenance (CBM) Maintenance actions taken as a result of investigated condition of parts or components. The condition is measured or evaluated during programmed inspections of parts and components.
Condition Monitoring All work performed in order to find failures early.
Consequence Of Break-Down (COB) The “cost”, not always measured in money, of a break down of equipment. COB is prioritized as follows:

  1. Environmental damage or safety hazard
  2. Production loss
  3. High Cost (equipment life)
Continuous Improvement Continuous improvement of existing practices resulting in improved performance.
Corrective Maintenance All maintenance performed to correct a break down or failure.
Cost Effective When the monetary benefit exceeds the cost of implementing an improvement.
Crafts people People with professional skills in mechanical, electrical or instrumentation maintenance. Many plants require skills in several of the skills mentioned.
Criticality The criticality of a component, equipment, or system based on the consequence of Break-Down.
Current Best Practice (CBP) The best way known to do something in IDCON’s Results Oriented Maintenance (ROM) philosophy. The future might reveal a better way of doing something and thus change the CBP. A CBP is equal to an element, which is the lowest level of detail in a Key Process.
Cut-off time Time when a schedule closes.
Defect 1 Damage on final product which forces the plant to scrap product, or sell product for lower price.
Defect 2 Can also mean a failure in a part or component.
Downtime Time when a system is not producing product. Downtime includes scheduled and unscheduled downtime.
Downtime scheduled When a system is down, and the downtime was documented as scheduled before cut-off time.
Downtime unscheduled When a system is down, and the downtime was NOT documented as scheduled before cut-off time.
Element In the IDCON assessment. A CBP is equal to an element, which is the lowest level of detail in a Key Process. The best way known to do something. The future might reveal a better way of doing something and thus change the CBP. illustration
Emergency Work Emergency work is a synonym to break-in work.
Equipment An asset that performs a function e.g. a motor coupling pump, pumps water from pint A to point B.
Equipment History Documentation for all events such as repairs, modification, and preventive maintenance performed for a specific equipment.
Equipment location A physical location in the plant for a piece of equipment.
Equipment Location number A unique number assigned to an equipment location.
Equipment reliability Time, speed, and quality performance as it relates to equipment. In IDCON’s ROM philosophy, equipment reliability is the result of maintenance work.
Essential Care A compilation of processes that will prevent failures from occurring. For example lubrication, alignment, balancing, cleaning, and operating procedures, adjustments and installation procedures. Essential Care prevents failures (prolong life of equipment).
Estimated Replacement Value Estimated present value of assets.
Failure When equipment condition reaches an unacceptable level. Example: A motor may run, but the temperature is 250 °F (unacceptable)
Failure Code A classification of a failure.
Failure Developing Period The time lapsed between a failure and the break down. illustration
Failure Mode Any event that may cause a failure.
Failure Mode and Effects Analysis (FMEA) Analysis tool to Identify Failure modes, assign priorities to each failure mode based on cost and occurrences.
Failure Rate An average of how often a component, equipment or system fails in a given time period.
Feedback In maintenance. Most commonly used when referring to written description of the work completed on a work order.
Fixed Time Maintenance (FTM) This tactic provides for scheduled overhauls or replacements of components often based on recommendation from the equipment vendor, general plant experience with similar components or analysis of the maintenance history of an individual piece of equipment and its components. Note: Only 10-15% of all component types have a predictable failure rate. Cost effective use of FTM is therefore limited.
Frequency of Inspection The time period between a repetitive inspection. The inspection frequency should be based on the failure developing period. Note: A rule of thumb is that the inspection frequency should be: Failure Developing Period/ 2.
Gantt Chart A bar chart (histogram) of scheduled tasks. Microsoft Project, and timeline are examples of software using Gantt charts.
Gap Analysis A rated comparison of Current Best Practices and actual performance.
Goal Measurable results you wish to accomplish at a projected point in time.
Iatrogenic In maintenance. Failures induced by own employees. Note: Iatros means physician in Greek, and -genic, meaning induced by, is derived from the International Scientific Vocabulary. Combined, of course, they become iatrogenic, meaning physician-induced. Iatrogenic disease is obviously, then, disease which is caused by a physician.
Infant mortality Component failures occurring during early life of component (1-12 months).
Inspection Any activity performed to find a failure or break-down.
Inspection List The printed list of an inspection route.
Inspection Route Documented instructions for condition monitoring tasks, sorted in an effective walking path through an area. example paper, example handheld
Inspector The person doing the inspection routes. Note: This could be an operator, crafts person, supervisor, engineer or a manager.
Key performance Indicator (KPI) A measurement of process performance.
Key Process The key processes for IDCON’s Current Best Practice (CBP) assessment format are:
1.Leadership and organization
2.Preventive Maintenance
3.Planning and Scheduling
4.Root Cause Problem Elimination
5.Technical Database 6.Materials Management
7.Skills Development maintenance
8.Safety – Maintenance
Life Cycle Cost (LCC) Total cost for acquiring, owning and disposing physical assets. Includes direct operational and maintenance costs and indirect costs for lost production when system fails.
Life Cycle Profit (LCP) The present value of all revenue the equipment has generated less the LCC.
Log Book Usually refers to operations log for problems found during shift.
Logic Tree A charting method for why-why analysis.
Management of Change (MOC) A process used to track and manage any physical or specification changes made to process related equipment in a plant.
Maintainability The ease to maintain equipment.
Maintenance Maintenance consists of corrective maintenance, preventive maintenance, and continuous improvement. illustration
Maintenance Engineering Maintenance Engineers work on design specifications of minor modifications, preventive maintenance documentation, problem identification and elimination, maintenance training, and maintenance technical database.
Maintenance Management Maintenance management is the collective term for describing the management process of leadership and organization, planning and scheduling, preventive maintenance, condition monitoring, execution of maintenance repairs, recording, root cause failure analysis, spare parts management, and management of technical data supporting the processes above.
Maintenance Opportunity See maintenance window
Maintenance Planning See definition for “Planning”
Maintenance prevention All actions performed to prevent failures. Lubrication, alignment, balancing, installation and equipment design, operating procedures, detailed cleaning, adjustments, fixed time replacements, and filtration. Note: Maintenance prevention and condition monitoring are the two components of preventive maintenance
Maintenance Window Defined time slots when maintenance can be performed on equipment without disturbing production.
Mean Down Time (MDT) Average time equipment is down (for any reason).
Mean Time Between Failures (MTBF) Total calendar operating time divided by number of failures.
Mean Time To Repair (MTTR) Average Repair time for component.
Mean Wait Time (MWT) All time during downtime that isn’t repair time. MDT=MWT + MTTR
Mission Statement Summarizes how to achieve a vision.
Model Work Order See Standard Job Plan
Non Destructive testing (NDT) Any material testing that doesn’t destroy material. During the testing process. Note: Usually we think of Ultrasonic Thickness Testing. Also included in NDT is usually dye-penetrant testing, x-ray testing, and electrical resistance testing. Vibration, thermography, look, listen, feel, smell, winding test etc are not included since they are testing components, and equipment, not material.
Non-Scheduled work See unscheduled work
Objective Condition Monitoring Preferred over subjective condition. Objective methods are for example vibration analysis, ultrasonics, and temperature-, pressure-, voltage- and ampere readings. Subjectiveinspections are look, listen, feel and smell
Off-line Downtime for a component or system without affecting production. Note: If production is down it’s considered an outage, or shutdown/ Turnaround.
Oil Analysis Testing of oil in order to find failures early
Operate To Break-Down (OTB) A maintenance strategy which operates equipment until break-down. A maintenance strategy which sometimes can be the most cost effective. Note: OTB is used when the consequence of failure is small enough that the benefit of preventing or finding failure early is more costly. OTB will be the fact for failures that occurs randomly and have no failure developing period.
Outage A shutdown/ turnaround that affects the whole plant for more than 16 hours.
Overall Production Efficiency (OPE) The product of Quality [%] * Speed [%] * Uptime [%] for a production line.
Overall Reliability See Production Reliability
Parts See spare parts
Planned Job A planned job includes:

  • The person planning the job verifies the scope of the job.
  • Lifting Equipment, tools, parts, material and personal. Equipment needed to do the jobs are identified and allocated.
  • Skills needed are identified?
  • A description of job steps is documented.
  • Lock out tag out and other safety requirements are identified.
  • Necessary technical documentation is available.
  • Crafts people are part of the planning process.
  • Estimated job duration by skills and the number of people needed for the job.
  • Required permits available.
  • The cost of each job is estimated.
  • Define physical and environmental constraints.
Planning The process of determining the resources, methods, and processes needed to perform maintenance work efficiently and effectively. Note: Planning is different from scheduling. Planning short definition is to decide what, how and time duration.
Predictive Maintenance A synonym to condition monitoring. Note: IDCON don’t use this term because it is often referred to as ONLY vibration analysis. There are many other condition monitoring tools besides vibration analysis.
Preventive Maintenance Essential care and fixed time maintenance together. Both essential care and fixed time maintenance PREVENTS (both prevent) FAILURES, while Conditions Monitoring only DETECTS FAILURES EARLY.
Priority The assigned importance of a maintenance job.
Priority Code The importance of a maintenance job is defined by a priority code. A priority code represents a deadline for when the maintenance job has to be completed.
Priority Guideline Agreed upon guidelines for assigning a priority to maintenance work.
Proactive Actions that are planned, scheduled and executed before a break-down occurs. Includes maintenance prevention activities.
Problem Any issue that can be improved cost effectively.
Process A work system that is documented, executed, and measured.
Process reliability Time, speed, and quality performance as it relates to manufacturing process.
Production reliability The product of process and equipment reliability.
Purchase Order (PO) The document sent to a supplier to order parts, services, material, or machines.
Reliability Centered Maintenance (RCM) A maintenance philosophy which is heavily designed by engineers supported by sound theoretical practices. Note: No known plant have been able to implement a full RCM strategy. It is often a very complicated theory for simple common sense actions. RCM has a given place in the specification phase when designing new equipment. (IDCON’s opinion).
Reliability – Equipment The product of Quality [%] * Speed [%] * Uptime [%] as it relates to equipment.
Reliability – Process The product of Quality [%] * Speed [%] * Uptime [%] as it relates to the process (operation of equipment).
Reliability – production The product of process reliability and equipment reliability. Measured by Quality [%] * Speed [%] * Uptime [%]
Repair Any activity intended to bring a component, equipment, or system back to a specific condition.
Repetitive work Type of work that are done often in the plant. Repetitive work should have standard job plans.
Results Financial outcome of an action, or several actions.
Results Indicators Global Key Performance Indicators measuring results directly impacting the financial performance of a plant.
Rework All repairs that have to be done again due to a poor repair the first time. Note: A combination of poor planning and scheduling. Usually due to lack of skills, material problem, missing spare parts, or not enough time assigned to do a precision job before starting equipment again.
Results Oriented Maintenance (ROM) Maintenance Philosophy developed by IDCON, INC.
Root Cause Failure Analysis (RCFA) A systematic way to collect select, analyze, and solve failures
Root Cause Problem Elimination (RCPE) A systematic way to collect select, analyze, solve and eliminate a problem. (An IDCON CBP Key Process)
Safety The result of all actions executed to prevent personal injuries.
Service Factor A key performance indicator for the storeroom measuring the % of times the correct quantity of the correct part is received when requested. Note: If the service factor falls below 95% maintenance people begin to lose confidence in the store room’s ability to supply the correct material & parts when needed. Usually result in growth of “unofficial personal stores” at frontline level.
Scheduled job A job put on the schedule before the cut-off time. Specific people, start time and end time is documented.
Scheduling The process of determining what jobs gets worked on, when, and by whom based on the priority and resource/equipment availability. Note: that this process should take place before the job is executed. See definition for ”break-in job”. Scheduling short definition is when and who.
Scheduling compliance A KPI measuring: The sum of Add-on jobs and jobs, on the schedule, not completed OVER the jobs on the schedule before cut-off time.
Shock Pulse measurement (SPM) A condition Monitoring Tool measuring the shock pulse in rotating equipment. Note: Shock pulse is the pressure wave generated through materials when two materials hit each other. A vibration will wave will be generated by the Shock pulse
Shutdown Scheduled or unscheduled downtime for a system or plant area.
Source An event that triggers a failure. illustration
Spare Parts All machine parts, materials and supplies that may be required to repair an asset
Standard Job Plans A documented plan for a type of job that can be used repetitively. See planning for definition of “plan”
Sub process A process with lower hierarchy than a key process in IDCON’s CBP material. illustration
Subjective maintenance Look, listen, feel and smell
System (1) A combination of equipment that are dependent of each other to complete a production task.
System (2) Can refer to a computer software, a work system or production system.
Terotechnology Maintenance management and technology. A term often used by universities in the UK.
Total Productive Maintenance (TPM) A maintenance philosophy. TPM is usually profiled for the strong operator involvement in equipment care.
Trades person See craftsperson
Tribology The science and technology of interacting surfaces in relative motion, including the study of lubrication, friction and wear.
Tribological wear Wear that occurs as a result of relative motion at the surface.
Turnaround See shutdown. Term usually used in steel, alumina, and mining industry.
Unplanned Maintenance work A maintenance job where necessary planned activities are incomplete before job is scheduled. Planning should always be done before scheduling.
Unscheduled Maintenance Work Work added to the schedule after the cut-off time.
Uptime Opposite to Downtime. Time when a component, equipment or system is producing product. Note: The component, equipment or system may produce defect product or at a slower speed than usual.
Vibration Analysis A condition Monitoring tool measuring the vibration in equipment.
Vision Statement Summarizes what an organization (or individual) want to achieve in the future. A vision must be supported by a mission statement and a goal.
Why-why analysis A problem solving method which forces the problem solver to break down and analyze different possible causes as to why a problem occurred.
Work Load All work in the approved backlog. Can be measured as follows: The sum of estimated hours in the approved backlog divided by the craftspeople available for a particular area, or supervisor. Best is to trend this number over time. A well managed maintenance area has about 2-4 weeks of workload.
Work Order An approved work request.
Work Request A request to do maintenance work.

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Torbjörn Idhammar

Torbjörn Idhammar

President & CEO, IDCON Inc. Reliability and Maintenance Consultant

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