Experimental investigation of AE and friction signals related to the durability of head/disk interface

The durability of a hard disk drive is one of the most critical issues that must be optimized for best performance. Especially as the flying height of the head slider of a hard disk drive decreases over the years, the concern for surface damage and head contamination continues to grow. In this paper the characteristics of AE and friction signals for various operating conditions using CSS and drag tests were investigated from the durability point of view. Also, the wear characteristics of the laser bumps on a magnetic disk were compared between the CSS and drag tests. The general shapes of the AE and friction signals during a single CSS test were quite similar even under less than ideal operating conditions. However, it was found that the AE signal was more sensitive than the friction signal in assessing the damage of the slider/disk interface. Finally, a correlation was established between the CSS and drag testing methods with respect to the laser bump wear. This outcome suggests that the drag test may be used to accelerate the surface damage effect of head/disk system.