Glossary category
Reliability & failure analysis
Concepts and methods for understanding failures and preventing recurrence. All 36 terms are available as direct static HTML links.
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Root cause analysis (RCA)
A systematic approach to addressing the underlying causes of a problem rather than only its symptoms.
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FMEA (Failure Mode and Effects Analysis)
A structured method for evaluating potential failures, their effects, and suitable preventive actions early.
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5 Whys
A structured technique that asks "why" repeatedly, each answer building on the last, to trace a problem back to its root cause.
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Availability
The fraction of time an asset is actually able to perform its function, combining both how often it fails and how fast it is restored.
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Bad actor
An asset that generates a disproportionately high share of failures, cost, or downtime compared to similar equipment.
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Bathtub curve
A model describing how failure rate typically changes over an asset's life: high early, low and steady in the middle, high again near end of life.
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Cavitation
The formation and violent collapse of vapor bubbles in a liquid, typically in a pump, causing erosion and characteristic noise.
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Common cause failure
A single underlying cause that triggers multiple, otherwise independent failures at the same time, defeating redundancy.
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Contamination
The presence of foreign material (particles, moisture, or chemicals) in a system where it degrades function or accelerates wear.
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Corrosion
The chemical or electrochemical degradation of a material, typically a metal reacting with its environment, that reduces its structural integrity over time.
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Degradation
A general, progressive decline in an asset's condition or performance over time, without specifying the underlying mechanism.
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Diagnostic reasoning
The cognitive process of connecting observations to a justified diagnosis, weighing competing explanations against the evidence.
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Failure cause
The specific circumstance or defect that initiated a failure: why it happened, as opposed to how it developed or what it affected.
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Failure effect
The consequence a specific failure mode has on the system, process, safety, or output: what happens as a result of the failure.
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Failure mechanism
The physical or chemical process (fatigue, corrosion, wear) by which a cause actually degrades a component over time.
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Failure mode
The specific way a function actually stops meeting its requirement: the observable manner of failure, as used in FMEA.
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Failure Mode, Effects and Criticality Analysis
FMEA extended with a formal criticality ranking that combines severity and probability to prioritize which failure modes need action most urgently.
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Fatigue
Progressive material cracking caused by repeated cyclic loading, even at stress levels well below the material's static breaking strength.
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Fault isolation
Narrowing a detected problem down to the specific system, subsystem, or component actually responsible for it.
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Fault Tree Analysis
A top-down logic diagram that maps every combination of contributing events that could lead to a specific top-level failure.
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Functional failure
The broader state in which an asset no longer meets a specific required function, regardless of the particular manner in which it failed.
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Imbalance
An uneven mass distribution around a rotating component's axis, producing a characteristic vibration at the rotational speed frequency.
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Maintainability
How easily and quickly an asset can be restored to a functioning condition once it fails, under defined repair conditions.
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Mechanical looseness
Excessive, unintended play or clearance between connected mechanical parts, producing a distinctive vibration pattern with multiple harmonics.
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Misalignment
A deviation between the intended centerlines of two connected rotating components, producing a characteristic vibration signature and premature wear.
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Overheating
A general condition in which a component or system runs at a temperature above its safe or rated operating limit.
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P-F interval
The time span between when degradation first becomes detectable and when the asset actually experiences a functional failure.
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Pareto analysis
A ranking technique that orders problems by contribution to identify the small number of causes responsible for most of the impact.
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Potential failure
An identifiable, measurable early condition that indicates a functional failure is developing but has not yet occurred.
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Redundancy
A design approach that adds a backup component or path so a single failure does not bring down the whole system.
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Reliability
The probability that an asset performs its required function, without failure, for a defined period under stated conditions.
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Repeat failure
The same failure mode occurring again on the same asset after a prior repair, indicating the earlier fix did not address the real cause.
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Single point of failure
A single component or path whose failure alone would cause the entire system to fail, with no backup available.
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Vibration
The oscillating mechanical motion of a machine or component, whose pattern and frequency content indicate its mechanical condition.
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Wear
The gradual removal of material from a surface due to mechanical contact, friction, or relative motion between two surfaces.
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Weibull analysis
A statistical method that fits failure data to a Weibull distribution to characterize an asset population's specific failure behavior over time.
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