In brief
Condition-based maintenance is a strategy that monitors equipment using measured condition parameters and only intervenes when limit values are exceeded.
Contents
What is Condition-based maintenance?
Instead of replacing parts at fixed intervals, condition-based maintenance records the actual condition of a component. EN 13306 classifies it as preventive maintenance because it also intervenes before a failure. It is often abbreviated to CBM. The aim is to make the fullest possible use of the service life of components without risking a failure.
Common methods are vibration measurement on rotating machines, which can detect bearing damage, imbalance or misalignment, for example; thermography to detect overheating at electrical connections or bearings; and oil analysis, which reveals wear particles, water or ageing in lubricating and hydraulic oil. Pressure, current and ultrasound measurements are also used. Measurements are taken on regular rounds or continuously via permanently installed sensors. Warning and alarm limits are set for each parameter.
It must be distinguished from predictive maintenance, which analyses trends and forecasts the time of failure, whereas condition-based maintenance responds to limit values being exceeded. The boundaries are fluid.
In practice: maintenance and procurement
There is often only limited time between a warning and a failure. For monitored units, the lead times of the typically damaged parts, such as rolling bearings or seals, should therefore be known, and critical parts held in stock where appropriate.
Synonyms and abbreviations: CBM · condition monitoring · condition-dependent maintenance · on-condition maintenance
Frequently asked questions
What is the difference between condition-based maintenance and predictive maintenance?
Condition-based maintenance triggers an action as soon as a measured value exceeds a defined limit. Predictive maintenance goes one step further: it analyses the trend of the measurement data and estimates when a failure is likely to occur. This allows interventions to be planned earlier. In practice, the two approaches often build on each other.
Which measuring methods does condition-based maintenance use?
The most common are vibration measurement on motors, pumps, fans and gearboxes, thermography on switchgear and bearings, and the analysis of lubricating and hydraulic oils. In addition, ultrasound, current draw, pressure and flow are measured. Which methods make sense depends on the typical failure patterns of the equipment concerned.
For which equipment is condition-based maintenance worthwhile?
It is worthwhile above all for equipment whose failure causes high consequential costs, and for components whose damage announces itself through measurable changes, such as rolling bearings in rotating machines. For inexpensive, easily replaceable parts with minor failure consequences, the effort of measurement and analysis is often greater than the benefit.