Search

With the increased use of hard disk drives (HDDs) in mobile and consumer applications combined with the requirement of higher areal density, there is enhanced focus on reducing head disk spacing, and consequently there is higher susceptibility of slider/disk impact damage during HDD operation. To investigate this impact process, a dynamic elastic-plastic finite element model of a sphere (representing a slider corner) obliquely impacting a thin-film disk was created to study the effect of the slider comer radius and the impact velocity on critical contact parameters. To characterize the energy losses due to the operational shock impact damage, the coefficient of restitution for oblique elastic-plastic impact was studied using the finite element model. A modification to an existing physics-based elastic-plastic oblique impact coefficient of restitution model was proposed to accurately predict the energy losses for a rigid sphere impacting a half-space. The analytical model results compared favorably to the finite element results for the range from low impact angles (primarily normal impacts) to high impact angles (primarily tangential impacts). [DOI: 10.1115/1.3078770] Keywords: magnetic storage tribology, oblique impact, shock, elastic-plastic impact, coefficient of restitution

As the use of hard disk drives in mobile applications increases, the susceptibility of disk damage due to high velocity slider-disk impact presents a serious challenge. The impact could result in extremely high contact stresses, leading to the failure of the head-disk interface. An elastic-plastic contact-mechanics-based impact model was developed and implemented to study the impact between a slider corner and a disk. The impact model is based on the contact of a rigid sphere on a deformable half-space. The effect of slider corner radii and impact velocities on the contact parameters was initially investigated for a homogeneous disk substrate. To examine the effects of thin-film layers on the disk, the model was extended to a realistic layered disk, where the actual layered mechanical properties were directly measured. At high impact velocities and/or small slider corner radii, the impact was found to be dominated by the substrate and the effect of layers was negligible. At low impact velocities and/or large slider corner radii, the effect of nanometer thick layers could be clearly seen, as these layers are stiffer than the substrate protecting the disk from potential damage at lighter loads. Realistic dynamic impact experiments involving a slider and a spinning thin-film disk were performed using an operational shock tester. The impact damage was characterized in terms of residual penetration depth caused by the impact force of the shock and the impact velocity of the slider However, the results were inconclusive in correlating with the impact model. To better control the experimental parameters, quasistatic nanoindentation experiments were performed on actual thin-film media and were successfully compared with the model predictions. Keywords: magnetic storage tribology, impact, elastic-plastic contact, shock, thin-film media

The continuous reduction of head-disk spacing has made the use of supersmooth media a necessity in gaining ultrahigh magnetic recording areal density. It is shown that the padded slider technology offers a viable alternative to the ramp load technology as a head-disk interface solution for the ultrahigh areal density.

The continuous reduction of head–disk spacing has made the use of supersmooth media a necessity in gaining ultrahigh magnetic recording areal density. To overcome the stiction barrier associated with supersmooth disks without compromising the head flyability requirement, texture features can be transferred from the disk surface to the slider surface, creating a new type of head–disk interface, the padded slider interface. The tribology of a padded slider interface is in many ways different from that of the traditional head–disk interface with texture on the disk only. In this article, various unique tribological aspects of the padded slider interface are discussed in detail. Both theoretical modeling results and experimental data are presented to elucidate the stiction, friction, and wear behaviors of this novel head–disk interface. It is shown that the padded slider technology offers a viable alternative to the ramp load technology as a head–disk interface solution for the ultrahigh areal density. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

It is anticipated that a radical shift in design paradigm will be required in order to enable perpendicular magnetic recording (PMR) areal densities beyond 1 \Tb/in^2. The shift in question will involve the use of advanced magnetic recording assist technologies such as patterned media, heat-assisted magnetic recording (HAMR), or microwave-assisted magnetic recording (MAMR). This paper is concerned with one of the challenges associated with the practical implementation of patterned media technology, namely, the impact of non-planarity, and shifts in pattern orientation (at data-servo transitions, in particular) on the dynamic fly performance of air bearing sliders. The nature of the latter challenge becomes apparent when considering that key to realizing recording areal densities exceeding 1 \Tb/in^2 will be air bearing sliders with superior dynamic fly stability at sub-2 nm clearances. Of the two types of patterned media technologies in development in the disk drive industry, namely, discrete track media (DTM) and bit patterned media (BPM), the former was chosen as a case study in this work. [ABSTRACT FROM AUTHOR]