Paul R. Peck

Scaling Criteria for Slider Miniaturization Using the Generalized Reynolds Equation

The current trend in the magnetic storage industry is the reduction of the slider size and the height at which the sliderflies over a rigid disk. Lower flying heights are achieved by miniaturizing sliders and reducing the normal load. In this paper, force scaling criteria are determined for 3370 and 3370K sliders that are dynamically loaded or operated in contact start/stop mode. Two forms of the generalized Reynolds equation (the first-order and continued fraction formulations) are incorporated into the analysis. The new scaling equation relates the steady-state flying height to design and operating parameters such as the disk velocity, normal load, ambient pressure, and the shape and dimension of the slider rail

Behavior of the head-disk interface in future disk drives

A critical review of existing head-disk interface modeling capabilities is given. Modeling of two important technologies, miniaturization of current air-bearing devices and viscoelastic bearings, e.g., VISqUS technology, is studied in a unified manner. New developments are: (i) the Fokker-Planck equation is adopted for rarefaction effects (instead of Boltzmann equation) in air-bearing technology; and (ii) systematic studies on incompressible liquid bearings are performed. >

Mathematical modeling of lubrication for the head‐disk interface using incompressible fluids

In order to keep pace with the demand for higher storage densities in magnetic recording disk drives, new technology must be developed to reduce the tribological problems associated with ultralow flying. Non‐Newtonian liquid bearings may become a feasible alternative to slider miniaturization due to the decrease in slider‐disk contacts. Issues pertaining to modeling the head‐disk interface are presented, and non‐Newtonian effects are described. Generalized Newtonian fluid models describe the dependence of the apparent viscosity on the shear rate for bulk fluids, but the extremely high shear rate and the confined geometry at ultralow flying heights complicate conventional non‐Newtonian rheological models. Equations are developed for generalized Newtonian fluids which can determine the flying characteristics of recording sliders in viscoelastic drives. Order‐of‐magnitude analyses are performed in order to determine the effect of drive parameters and fluid properties on the load bearing capacity of the slider and power consumption due to frictional forces. The results obtained are new and may become important in providing design criteria for VISqUS drives or to related design engineers.

A novel accelerated wear test for magnetic recording disks

Future disk files will operate at lower flying height, thus increasing the possibility of asperity contacts. Conventional tests include sliding (pin-on-disk or slider-on-disk), flying (flyability tests), or contact start/stop modes of operation. A novel accelerated water test (NAWT) was developed to produce intermittent asperity contacts. The NAWT operates in a mixed sliding and flying region, and is designed to operate in a zone of interaction where a significant number of asperity contacts occur. The NAWT uses an acoustic emission sensor to detect asperity contacts. The signal is processed by fast Fourier transform to detect significant increase in the frequency and severity of the contacts. The new apparatus and procedure are presented along with illustrative results. >

TRANSIENT RESPONSE OF ULTRALOW FLYING SLIDERS OVER CONTAMINATED AND TEXTURED SURFACES

The transient flying dynamics of positive and negative pressure sliders over nonsmooth surfaces were investigated. Surface roughness was modeled by variously oriented sinusoidal waves, and contaminated surfaces were modeled as series of asperities and pits. A finite element algorithm was used which incorporates a generalized form of the Reynolds equation based upon the linearized Boltzmann equation. A new kinetic equation descriptive of ultralow flying was also discussed. Spectral analysis using fast Fourier transformation was adopted to explore the transient behavior of sliders in the frequency domain.