Why should recurring ultrasonic measurements on machines be performed under conditions that are as consistent as possible?

In condition monitoring, it is often not a single measurement value that is decisive, but rather its change over time.

For measurements to be comparable, the measurement conditions should therefore be as reproducible as possible. Otherwise, changes caused by the measurement method itself could incorrectly be interpreted as changes in machine condition.

Which factors should remain consistent?

For recurring structure-borne sound measurements, the following conditions should remain the same wherever possible:

• the same measurement point,
• the same sensor,
• the same accessories,
• the same coupling method,
• the same sensor orientation and position,
• comparable machine operating conditions.

Speed, load, and process condition can also influence the measured structure-borne sound signal and should therefore be considered during evaluation.

Why is coupling so important?

Structure-borne sound is transferred from the machine surface to the sensor. The coupling method therefore influences the measured signal.

Different accessories or coupling methods can alter the frequency response and therefore the measurement result.

For recurring comparative measurements, the same accessories and coupling method should therefore always be used.

How can a measurement point be prepared?

Particularly when using the BS40, a defined measurement point can be prepared and permanently marked.

For example, a mounting pad can be attached to the machine. This helps provide comparable coupling conditions for recurring measurements.

For semi-stationary measurements, the BS40 can also be attached to a prepared measurement point using a screw connection.

How are changes over time evaluated?

Measurements can be assigned to a defined measurement point and compared over time.

AssetExpert and the SONAPHONE DataSuite can be used to:

• structure measurement points and assets,
• organize inspection routes,
• display historical measurement data,
• use thresholds and alarm levels,
• display condition changes as trends.

This makes it possible to identify gradual changes at an early stage and plan maintenance activities based on actual equipment condition.