No excuses for High Vibrations: proof by the numbers

In this article, we will be borrowing a slogan from our partner LUDECA, and put it in numbers.

It’s admitted that vibrations affect the useful life of mechanical components, roller bearings being among the most important ones due to their impact on assets uptime in case of failure.

The following process defines the parameters involved from Excitation to life expectancy:

Force => Vibration => Load => Strain => Fatigue => Reduced Life

Fortunately, for roller bearings, we have all the theoretical tools to predict the expected life under known operating conditions. Using the same theory, we will study the effect of a decrease in vibration on the roller bearings.

The following figure represent the life increase vs total load reduction.

We can easily read that a 30% decrease in total load reduction we result in 200 % increase in the expected life of the bearing.

Static load and dynamic load :

The previous graph assumes that 100% of the load is provided by the dynamic excitation. To study a more realistic case, we will focus the analysis on the dynamic part of the load, considering that total load applied on a bearing consist on 2 components:

  • Dynamic load: Vibration, harmonic forces (unbalance/misalignment), impacts…
  • Static load: rotor weight, belt tension …

In the following section, we will study the behavior of the increase of bearing life as function of the dynamic load vs Static load ratio

If the total load applied on a bearing is coming from 50% static load, and 50% dynamic load (Vibration), a decrease in vibration of 50% will produce a 137% increase of the bearing Life.

This means that under reasonable assumption (load ratio), if we decide for example to tighten our balancing procedures and implement better practices allowing to go from an ISO balancing grade of 6.3 to 2.5, we will see an increase of the bearing life of 192%.

This also imply that the overall vibration level calculated over time can be an excellent KPI the directly reflects the expected life of mechanical components, and more globally the uptime of your assets.

These KPI are embedded in VibWorks Supervisor and VibWorks Mobile, allowing reliability engineers to track with high accuracy the efficiency of their CM program, to quantify the impact of their decisions on assets uptime.

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