A very small acoustic vibration during operation can indicate a major defect in a small-sized precision motor. The acoustic vibration is normally detected using a sounding bar applied to the ear of an inspector who judges whether to reject or pass a motor by listening to its sound during operation.
This method produces different judgments according to each individual inspector, and automation is not possible. With this unit, a highly sensitive acceleration-type detector is applied to the bearing area of a motor, to directly defect the acoustic vibration.
The resultant measurement is not influenced by environmental noise, and an absolute and accurate measurement can be made. Automatic judgment of whether to reject or pass a motor is also possible by incorporating an optional comparator.