Special-purpose Machinery

Structure-borne Sound Testing / Airborne Sound Testing at Ejector Bearings

Task and Process

The system described below is used to carry out noise tests on finished release bearings. A sensor placed on the bearing casing records the structure-borne noise of the driven bearing. Also, the air-borne noise is measured via an acoustic recording device.

First, the operator inserts the part and then the test process starts automatically: After the sound protection door is closed, the bearing is clamped and the inner ring is rotated by means of the hydrodynamically-supported spindle. An axial load is also applied to the bearing. Then the structure-borne sensor moves on the part surface and records the operating noises of the bearing. At the same time, the air-borne noise is measured. After the end of the test, the sound protection door is opened and the operator can remove the part. In the case of non-conforming parts, the test is repeated. If the parts are still nonconforming after this test, the protective door is only opened after a confirm button has been pressed. The part is then placed manually into the nonconforming container.

The analysis allows damage to balls, and outer and inner rings to be detected. It also allows bearings to be sorted that had faults in previous processing steps and now have surfaces that are too rough after honing or sanding.

20 sec./part

100 – 5000 N settable

100 – 3000 1/min. settable

> 98%

5 min.

Reduction by 30 dB to output level (75 dB)


Bernhard Beck

phone: +49 (0) 9771 68877-610