Condition monitoring, which involves regularly checking a machine’s status by measuring key parameters, is undertaken to improve safety and efficiency.
An extremely reliable rapid-response safety system (emergency shut-off) can be created based on sensor data analysed in real time. Most of the current systems, including vibration sensors, are much less precise and do not contribute to explaining why and how damage occurs. Online condition monitoring makes it possible to shut off the machine based on the data that has been recorded, therefore also making it possible to analyse the factor that caused the disturbance.
Monitoring the machine’s condition is the essential prerequisite for "condition-oriented maintenance", a new strategy that replaces the previously widely used “preventive” maintenance. Preventive maintenance involved shutting down a machine at regular intervals to check components and replace them if necessary and often resulted in intact components being exchanged, wasting their remaining useful life.
Condition monitoring places extreme demands on the sensors and measurement processing and requires in-depth knowledge of the equipment being monitored. However, it also offers the greatest potential cost savings, because critical machine elements are used virtually until the end of their service life and any maintenance can be scheduled to fit in with the production plan.
Condition-oriented monitoring is an interdisciplinary field drawing from mechanics, acoustics, system theory, electronics and informatics and has not yet been fully researched, though it is developing very rapidly. While it has already proved to be unerringly accurate in the monitoring of individual components, condition-oriented monitoring of complex machinery grows less precise as the number of signals originating from different places within a system rises. There has also been a lack of suitable sensors capable of picking up signals directly in the zones where the wear and tear and damage occur. Microsystems technology may provide the answer here in the future, for example by applying sensors in thin-film technology that can be applied directly to the structure to be monitored.
Putting it simply: what needs to be monitored, when, how and what with?
What condition monitoring can not do is to recognise and prevent spontaneous failures such as fatigue fractures in shafts.