Shock Impulse Evaluation; The Shock Impulse Carpet Value - WAGO 750-645 Manual

14 • Condition Monitoring
Machine Condition Monitoring with VIB-I/O Modules

2.2.3.2 Shock Impulse Evaluation

The following scale for the evaluation of shock impulses has been created.
The measured shock impulses are classified here in the categories of the
bearing state, from 'good, to 'limited' and finally to 'poor'.
dB
60
40
20
0
Fig. 2.2.3-1: Evaluation of shock impulses
The illustration shows the progress of a trend measurement from originally
good values to poor values (bearing damage).
This provides a quick and clear overview of the evaluation of the
measurement results, without complex terminology or calculation.
Note
Because roughness is rolled into the surface during operation, but new damages
also occur, the measured values may strongly rise or decline for short periods
of time. For this reason, the "snapshot" of a measured value is less
representative than a trend measurement and trend monitoring over a longer
period of time.

2.2.3.3 The Shock Impulse Carpet Value

Roughness in the surface can cause a quick sequence of low shock impulses,
together creating the carpet value of a bearing. This is the basic noise which is
audible through a screwdriver pressed to the bearing. The carpet value is
measured in decibel (dBc = decibel carpet value). The carpet value (
provides information to the lubrication of a bearing, the assembly condition
and the different load of a bearing (e.g. due to alignment errors). The carpet
value directly corresponds to the lubricant thickness between roller bearings
and rolling path. If the rolling path and roller bearings are separated by a
complete and sufficient lubrication layer, the carpet value is low. This is
shown in the following diagram.
N
50%
poor
limited
good
100%
WAGO-I/O-SYSTEM 750
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I/O-Modules