Parametric Investigations at the Head-Disk Interface of Thermal Fly-Height Control Sliders in Contact

Abstract

Accurate touchdown power detection is a prerequisite for read-write head-to-disk spacing calibration and control in current hard disk drives, which use the thermal fly-height control slider technology. The slider air bearing surface and head gimbal assembly design have a significant influence on the touchdown behavior, and this paper reports experimental findings to help understand the touchdown process. The dominant modes/frequencies of excitation at touchdown can be significantly different leading to very different touchdown signatures. The pressure under the slider at touchdown and hence the thermal fly-height control efficiency as well as the propensity for lubricant pickup show correlation with touchdown behavior which may be used as metrics for designing sliders with good touchdown behavior. Experiments are devised to measure friction at the head-disk interface of a thermal fly-height control slider actuated into contact. Parametric investigations on the effect of disk roughness, disk lubricant parameters, and air bearing surface design on the friction at the head-disk interface and slider burnishing/wear are conducted and reported.

Voltage assisted asymmetric nanoscale wear on ultra-smooth diamond like carbon thin films at high sliding speeds

“…The initial clearance (physical gap) between the head and the disk is typically 10 nm . Clearance is controlled precisely using the embedded micro-heater in the head 31 32 . We estimate the wear depth by continuous monitoring of the micro-heater power and later verified the wear using AFM, scanning electron microscope (SEM) and Auger electron microscopy (Auger) 33 .…”

“…Clearance is controlled precisely using the embedded micro-heater in the head. 31,32 We estimate the wear depth by continuous monitoring of the micro-heater power and later verified the wear using AFM, scanning electron microscope (SEM) and Auger electron microscopy (Auger). 33 Contact between head and disk is detected using an acoustic emission (AE) sensor.…”

Nanoscale wear and kinetic friction between atomically smooth surfaces sliding at high speeds

“…The micro-heater generates a localized protrusion on the head surface, thus bringing it in contact with the disk. Contact between the head and the disk is detected using an acoustic emission (AE) sensor, which detects elastic propagating waves generated during the head-disk contact events [17]. A calibrated strain gauge is instrumented to measure the friction force at the head disk interface along the sliding direction.…”