HDI detection by using an AE technique

Acoustic Emission(AE) sensors are commonly used in non-destructive testing to monitor generation and propagation of contact, bending, torsion and crack in material; including magnetic head-disk interaction (HDI). In Hard Disk Drive (HDD) manufacturing process, HDI is the one of mechanical failure which need to scrap all components due to cleanliness concerns. However, the segregating process between true and false HDI failures are mainly difficult to detect due to inadequate information. differentiate actual from false HDI. This paper presents the detection of the HDI using AE sensor - stress wave technique with Bending and Torsional modes during spin up and loading head state. The AE sensor is placed outside the HDD to measure AE voltage signal since the drive start up. The AE voltage will be converted to be AE rms. The AE rms threshold, which is used the delta of AE rms between spin up and loading head to disk, can be used as a criterion to differentiate actual from false HDI.