Terminology in Maintenance (Industry 4.0)

In this post, we will define several words and acronyms used in the world of maintenance, some of them unknown to most of the public, with the aim of clarifying the concepts associated with maintenance.

What is Industrial Maintenance?

Industrial maintenance is usually defined as the set of techniques aimed at keeping equipment and industrial facilities in service for as long as possible (seeking the highest availability) and with maximum performance.

The application of new technologies, maintenance strategies, indicators and control system, etc. incorporate more and more a set of terminology in the jargon of industrial maintenance. For this reason, we will try to explain in the following article some terms that we will find in the world of advanced maintenance:

APM – Asset Performance Management

Strategy that encompasses the tools and methodologies that allow the systematic planning and control of physical assets throughout their life through the implementation of new technologies (IoT, AI, Machine Learning, Virtual Reality…). With the clear objective of improving the reliability, safety and performance of the equipment.

Utilization Time

Percentage of time in which a piece of equipment is available and used for its intended purpose.

Life Cycle

Period of time during which an asset retains its capacity for use. The period goes from its purchase until it is replaced or is subject to restoration.

Shutdown/Stoppage

Event that determines a machine out of service. The Shutdown can be scheduled or unscheduled and includes all types of maintenance and repair activities except: lubrication stops, fuel and execution inspections during lubrication and fuel filling. Operational shutdowns, for example; shift change, collation, etc., are not included as a shutdown event. Grouped repairs count as a single shutdown. Accounting for a shutdown is independent of the duration of the event or complexity.

Reliability

It is the probability that a piece of equipment will fulfill a specific mission under determined conditions of use in a determined period. Relationship between producer and machine. Reliability is a measure that quantitatively summarizes the functionality profile of an element and helps when selecting a piece of equipment among several options. The study of reliability is the study of failures of a piece of equipment or component. If you have a piece of equipment without failure, it is said that the equipment is one hundred percent reliable or that it has a probability of survival equal to one. When performing a reliability analysis on a piece of equipment or system, we obtain information about its condition: probability of failure, average time to failure, stage of life in which the equipment is located.

• Bathtub curve: The failure rate function due to its characteristic shape is known as a bathtub curve and expresses the three typical periods of a piece of equipment: Infant mortality, useful life and wear, as shown in the following figure:

• Infant mortality: The period at the beginning of the operation, where premature failures frequently occur due to undetected defects, uncorrected design defects, errors in manufacturing and assembly. In this period the failure rate is decreasing with time. It is also known as the “running-in period” or “infant period”.
• Useful life: is the second interval of the graph where the failure rate is constant, which indicates that the failures are totally random and do not depend on the time elapsed since the last failure.
• Wear: is the last interval of the curve, where the failure rate increases steadily because the elements of the equipment suffer a process of physical deterioration due to mechanical friction or other considerations. At a certain moment, the maintenance and unavailability costs will be so high that the equipment must be replaced.

CBM – Condition Based Maintenance:

They are known as such, a type of tasks that measure the condition of the equipment, through variables that indicate the condition of an element or component, and thus take the appropriate action to manage the consequences of these failures. It is used interchangeably with the term Predictive Maintenance.

CMMS – Computerized Maintenance Management System (Sistema Computarizado De Administración De Mantenimiento):

Acronym in English. Maintenance management system assisted by computer GMAO (in Spanish), whose main objective is to assist with the efficient and effective administration of maintenance activities through technology.

Cause-Effect Diagram:

It is also known as Fish Diagram. Tool to analyze the fluctuation of a process, developed by Kaoru Ishikawa. The diagram illustrates the causes and subcauses that affect a certain process and that produce an effect (Symptom). It is one of the Seven Quality Tools.

EAM (Enterprise Asset Management)

It means Enterprise Asset Management, and they emerged as a natural evolution of the CMMS/GMAO towards a global management model, not limited to a single department. EAM systems traditionally include everything that CMMS/GMAO include, but add additional functionalities such as root cause analysis systems, predictive maintenance, analysis of the asset life cycle or financial costs.

RCA or Root Cause Analysis

It is one of the most important elements in any process of continuous improvement in maintenance. In reality, it is a problem-solving method aimed at identifying its causes or failure modes; it is based on the assumption that problems are not addressed by repairing but by resolving the root cause that caused them.

Availability

Availability is a function that allows estimating globally the percentage of total time that a piece of equipment can be expected to be available to fulfill the function for which it was intended. In other words, it is the probability that the equipment is operating satisfactorily at the time it is required after the start of its operation, when used under stable conditions, where the total time considered includes the time of operation, active repair time, inactive time, time in preventive maintenance (and in some cases) administrative time and logistical time.

Reliability

Reliability is defined as the probability that an asset will function properly during a certain period under specific operating conditions (for example, conditions of pressure, temperature, speed, voltage or shape of an electrical wave, level of vibrations, etc.)

Reliability Centered Maintenance (RCM)

RCM argues that we apply the most appropriate strategy in each case after performing an analysis of failure modes and their consequences, in order to guarantee the availability of productive assets within the desired ranges.

Total Productive Maintenance (TPM)

This system is based on the Japanese conception of “Maintenance at the first level”, in which the user himself performs small maintenance tasks such as: adjustment, inspection, replacement of small things, etc., providing the maintenance manager with the necessary information so that then the other tasks can be done better and with greater knowledge of the cause.

Maintainability

Maintainability is a characteristic inherent to an element, associated with its capacity to be recovered for service when the necessary maintenance task is performed as specified. Maintainability could be expressed quantitatively, by the time T used to perform the maintenance task specified in the element under consideration, with the specified support resources. Three factors are involved in the execution of these tasks:

• Personal factors: Skill, motivation, experience, physical capacity, etc.
• Conditional factors: Represent the influence of the operating environment and the consequences that the failure has produced on the physical condition, geometry and shape of the element in recovery.
• The environment: Temperature, humidity, noise, lighting, vibration, time of day, wind, etc.

MTBF Mean Time between Failures

In practice, reliability is measured as the average time between maintenance cycles or the average time between two consecutive failures (Mean Time Between Failures; MTBF).

MTTF Mean Time to Failure

The average time to failure (Mean Time To Failure; MTTF), is another of the parameters used, together with the failure rate to specify the quality of a component or a system.

Y(T) Failure Rate Function

Or risk function or instantaneous failure rate, and it is a reliability characteristic. The failure rate function has no direct physical interpretation, however, for sufficiently small values of t it can be defined as the probability of failure of the component in an infinitely small time dt when at time t it was operational.

MTTR Mean of Technical Repair Times

In practice, the repair rate can be measured through the Mean Time To Repair MTTR.

OEE. (Overall Equipment Effectiveness) )

It is an indicator that serves to measure the productive efficiency of industrial machinery. This indicator adds or collects information from other ratios such as equipment availability, product quality and performance or efficiency of the facilities. Its formula is obtained by multiplying three factors: availability x performance x quality.

% Availability.

Quotient of Productive Time, between Available Time, for a determined production period. It is affected by the stops that occur in the manufacturing process such as, for example: machine start-ups, changes, breakdowns and waits.

% Performance

Quotient of Real Production, between Productive Capacity, for a determined production period. Performance is affected by micro-stops and reduced speed.

% Quality

Quotient of Good Production, between Real Production. The percentage of quality is weighed down by re-work or defective parts.

We have already entered the terminology of industrial maintenance, in any case, do not hesitate to consult us any questions you may have:

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