CBM - Condition Based Maintenance

Condition-Based Maintenance is the way to reduce the risk of unwanted machine stops

Introduction to Condition-Based Maintenance

The condition-based maintenance (CBM)  is a maintenance strategy based on information about machine condition.
The main benefits of implementing CBM are:
  • Availability to ACT ON TIME to mitigate the risk of machine failure and production losses
  • Better planning of maintenance interventions.
  • Avoiding unexpected machine failures.
IMPORTANT: CBM strategy can’t exist without properly implemented Condition monitoring (CM) program.
The CBM and CM are very well described in ISO 13372 and 13373 and in Marine Classification societies rules.
The Marine industry is one of few industries that has officially accepted the CBM and created rules to guide and audit fleet CBM and CM Program.

CBM Cycle

The focus is the machine (functional location).
The first important steps is to collect necessary DATA.
The data as itself do not give us any guidance and therefore must be analyzed. It needs to be done by certified accordion ISO 18436 VA (vibration analyst) that are category II, III or IV.
The machine data analysis process must complete with actionable oriented recommendations based on findings. The recommendations become an input to the CBM strategy and are used in the planning process.
The maintenance team is responsible for the execution and returning the feedback.
The optimum interval for manual data collection is one month and the maximum should be three months.
For the Marine industry two months data collection schedule is sufficient for most of the machines.

CM - Condition Monitoring Data

Most of the people link Condition monitoring to vibrations. The reason is quite simple. The vibration is a movement of a point from a machine. The vibration is a function between force and mobility.
Therefore when the mobility is constant (stiffness of the machine) the increase of vibration will be a result of increased forces. And when the force (load) is constant and there is increase of mobility (loose bolts or cracks) it will cause an increase of vibrations, too.

The vibrations are more dynamic and complex data, compared to other monitoring data sources such as human senses, performance, corrosion, motor current, thermal etc.

We can say that the machine language is called VIBRATIONS.
When we talk about vibrations we consider a wide range of frequencies from 1Hz to 10 000 Hz, where are the running speed and component fault patterns of most of the machines.

Ultrasonic and Acoustic emission are looking in very high frequencies, where we can see very specific fault patterns in the early stage.

This is why Relianeering has decided to focus on vibration data from rotating machines in our ReSES.net cloud based CBM platform.

The vibration monitoring is one of the most sophisticated techniques that require special attention due to:
  • Data collection must provide reliable data (from the right source, from the same location and secured sensor attachment to the CM Point)
  • Data analysis requires certified CM specialists (with valid certification according to ISO 18436-2 and understanding the machines and the maintenance)
  • The vibration data are around 3% of the data sources (CM Points), but they generate 36% of data to be analyzed