Experimental Investigation on Touch-Down/Take-Off of Air Bearing Slider in the Head/Disk Interface

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.

Download Full-text

Boundary Effect on Particle Motion in the Head Disk Interface

ASME/STLE 2007 International Joint Tribology Conference, Parts A and B ◽

10.1115/ijtc2007-44492 ◽

2007 ◽

Author(s):

Nan Liu ◽

David B. Bogy

Keyword(s):

Drag Force ◽

Particle Motion ◽

Boundary Effect ◽

Hard Disk Drives ◽

Areal Density ◽

Air Bearing ◽

Disk Drives ◽

Head Disk Interface ◽

Bearing Surface ◽

Disk Interface

Simulation of particle motion in the Head Disk Interface (HDI) helps to understand the contamination process on a slider, which is critical for achieving higher areal density of hard disk drives. In this study, the boundary effect—the presence of the slider and disk—on particle motion in the HDI is investigated. A correction factor to account for this effect is incorporated into the drag force formula for particles in a flow. A contamination criterion is provided to determine when a particle will contaminate a slider. The contamination profile on a specific Air Bearing Surface is obtained, which compares well with experiments.

Download Full-text

Pumping Effect of Slider Air Bearing Surface for Non-Langmuir Adsorption

STLE/ASME 2010 International Joint Tribology Conference ◽

10.1115/ijtc2010-41110 ◽

2010 ◽

Author(s):

Bo Zhang ◽

Akira Nakajima

Keyword(s):

Disk Surface ◽

Air Bearing ◽

Head Disk Interface ◽

Bearing Surface ◽

Adsorption Model ◽

Adsorbed Film ◽

Disk Interface ◽

Langmuir Adsorption ◽

Langmuir Adsorption Model ◽

Slider Air Bearing

Numerical analysis of the adsorbed film thickness at the air bearing surface is conducted using the non-Langmuir adsorption model. It is found that the adsorbed film at the air bearing surface becomes significant when the viscosity of adsorbed film is higher than about 1 Pa s. The adsorbed contaminant will accumulate at the rear end of the slider, and it is possible that the accumulated liquid-like contaminant may form a liquid tail which will directly contact with the disk surface, resulting in a crush of the head/disk interface.

Download Full-text

Contact Take-Off Characteristics of Proximity Recording Air Bearing Sliders in Magnetic Hard Disk Drives

Journal of Tribology ◽

10.1115/1.2834160 ◽

1999 ◽

Vol 121 (4) ◽

pp. 948-954 ◽

Cited By ~ 2

Author(s):

Yong Hu

Keyword(s):

Hard Disk Drives ◽

Air Bearing ◽

Disk Drives ◽

Head Disk Interface ◽

Taper Angle ◽

Wear Factor ◽

Disk Interface ◽

Partial Contact ◽

Magnetic Hard Disk ◽

Wear Law

A partial contact air bearing model and Archard’s wear law are used to investigate the air bearing and wear characteristics of proximity recording sliders during a take-off process. The air bearing pitch torque, pitch and contact force are used to characterize the contact take-off process. In addition, the wear factor derived from the Archard’s wear law is employed to measure the take-off performance. The results indicate the existence of two distinct take-off stages: a period of rapidly increasing pitch preceding a relatively steady take-off event. The proper range of taper angle and step height, which produce a rapid initial pitch increase and steady subsequent take-off as well as less wear in the head/disk interface, are determined through simulation. While the simulation results demonstrate the negligible effect of crown height on the rate of the initial pitch increase, larger crown values are shown to yield higher pitch and smaller wear in the head/disk interface during the take-off process. In summary, the partial contact air bearing simulation and the wear factor calculation of the take-off process, developed in this study, offers a fast and accurate analytical tool to optimize ABS design for the fast take-off performance.

Download Full-text