Experimental studies of a head/disk interface subjected to impulsive excitation during nonoperation

Experimental studies on a head/disk interface (HDI) subjected to half-sine shock acceleration during nonoperation have been carried out using a dummy drive. Permanent damage to the disk surface due to the collision between head and disk (slap movement), which is an index showing the shock-proof performance, has been investigated by measuring the degradation of recorded signals. Physical quantities of HDI movement under shock acceleration have been measured comprehensively using various sensors housed in the dummy drive. The results are as follows. The sleep movement of the head suspension assembly (HSA) is the dominant phenomenon governing the shock-proof performance of a HDI. This movement does not occur until the inertia force acting on the HSA exceeds the loading force. It is more violent as the magnitude of acceleration increases. Higher- loading force, smaller equivalent mass of HSA, lower rigidity, and higher hardness of the disk contribute to better shock-proof performance. The duration of shock acceleration is not related to resonance frequency of the disk but to that of the HSA. It is possible to estimate the slap movement quantatively from the loading force, the equivalent mass of HSA, and the duration of acceleration.