Role of disk surface roughness on slider flying height and air-bearing frequency

1990 ◽  
Vol 26 (5) ◽  
pp. 2493-2495 ◽  
Author(s):  
M. Suk ◽  
B. Bhushan ◽  
D.B. Bogy
Keyword(s):  
Surface Roughness ◽  
Disk Surface ◽  
Flying Height ◽  
Air Bearing

Effects of Surface Roughness on the Fly-Ability of a Thermal Protrusion Air Bearing Slider

2009 ◽  
Author(s):  
Wei Hua ◽  
Bo Liu ◽  
Shengkai Yu ◽  
Weidong Zhou ◽  
Leonard Gonzaga
Keyword(s):  
Surface Roughness ◽  
Electrostatic Force ◽  
Flying Height ◽  
Total Force ◽  
Air Bearing ◽  
Intermolecular Force ◽  
Average Roughness ◽  
Thermal Protrusion ◽  
Bearing Force ◽  
Air Bearing Slider

A femto air bearing slider with thermal protrusion is studied based on three groups of surface roughness. It is observed that the air bearing force and the contact force are proportional to the value of average roughness in the minimum flying height region studied, while the intermolecular force or the electrostatic force is the smallest for the smoothest surfaces when the minimum flying height is above a certain value. As a result, the total force on the slider is the largest on the smoothest surfaces in a certain minimum flying height region. When the minimum flying height is designed in that region, the fly-ability of the slider is maximized.

Identification of the Multiple Flying Heights in a Loading Process

2008 ◽  
Author(s):  
Shuyu Zhang ◽  
Mike Suk ◽  
George Tyndall
Keyword(s):  
Stable State ◽  
Disk Surface ◽  
Flying Height ◽  
Air Bearing ◽  
Loading Process ◽  
Flying Attitude

The slider of a Load/unload (LUL) drive can be loaded to a high flying stable state under certain conditions, which positions the read/write transducers much higher from the disk surface than the normal flying height (FH) and resulting in the issues in read or write. To avoid the issues caused by the high flying loading, it is necessary to find ways to recognize the existence of the high FH and eliminate it in the design stages. In this paper, we introduce a method that can identify the existences of the multiple FHs in loading process conveniently. The basic idea is to plot surfaces of air bearing forces in a domain of flying attitude, and then check if multiple FHs exist to generate the same air bearing forces that match the suspension forces. The analysis results indicate that the method is easy and efficient in identifying multiple FHs in loading process.

Modeling the Flying Characteristics of a Rough Magnetic Head Over a Rough Rigid-Disk Surface

1991 ◽  
Vol 113 (4) ◽  
pp. 739-749 ◽  
Author(s):  
R. M. Crone ◽  
M. S. Jhon ◽  
B. Bhushan ◽  
T. E. Karis
Keyword(s):  
Surface Roughness ◽  
Steady State ◽  
Three Dimensional ◽  
Disk Surface ◽  
Information Storage ◽  
Flying Height ◽  
Limiting Factor ◽  
Finite Width ◽  
Rigid Disk ◽  
The Impact

The volumetric information storage density of rigid disk drives continues to increase through decreases in the slider-disk separation (i.e., the flying height). Reductions in slider-disk separations are achieved primarily through smoother surfaces on the magnetic media. The limiting factor in decreasing the slider-disk separation is the interactions that occur between the slider and the diminishing surface roughness and the impact that this roughness has on the transient and steady-state flying characteristics of the recording head. In this paper, we present a new finite element algorithm to solve the modified Reynolds equation that is specifically designed to utilize state of the art vector/parallel hardware. To the authors’ knowledge, this is the first numerical simulation of the flying characteristics of a finite width slider over a rigid disk surface which directly incorporates three-dimensional surface roughness. The effects that the magnitude, orientation, shape, and location (i.e., roughness on the disk or slider) of the surface roughness has on the steady-state slider flying characteristics are presented.

Effect of the Intermolecular Forces on the Flying Attitude of Sub-5 NM Flying Height Air Bearing Sliders in Hard Disk Drives

2002 ◽  
Vol 124 (3) ◽  
pp. 562-567 ◽  
Author(s):  
Lin Wu ◽  
D. B. Bogy
Keyword(s):  
Hard Disk Drives ◽  
Three Dimensional ◽  
Disk Surface ◽  
Intermolecular Forces ◽  
Flying Height ◽  
Positive Pressure ◽  
Vertical Force ◽  
Air Bearing ◽  
Triangular Cell ◽  
Flying Attitude

When the spacing between the slider and the disk is smaller than 10 nm, the effect of the intermolecular forces between the two solid surfaces can no longer be ignored. This effect on the flying attitude of practical slider designs is investigated here numerically. The three-dimensional slider surface is discretized into non-overlapping unstructured triangles. The intermolecular forces between each triangular cell of the slider and the disk surface are formulated, and their contributions to the total vertical force, as well as the pitch and roll moments, are included in a previously developed steady state air bearing design code based on a multi-grid finite volume method with unstructured triangular grids [3–5]. It is found that the van der Waals force has significant influence on the flying height and has non-negligible effect on the pitch angle for both positive pressure sliders and negative pressure sliders, when the flying height is below 5 nm. When the flying height is below 0.5 nm, the repulsive portion of the intermolecular force becomes important and also has to be included.

Analysis of Surface Textured Air Bearing Sliders With Rarefaction Effects

2007 ◽  
Author(s):  
Aravind N. Murthy ◽  
Izhak Etsion ◽  
Frank E. Talke
Keyword(s):  
Dynamic Performance ◽  
Form Factors ◽  
Disk Surface ◽  
Flying Height ◽  
Air Bearing ◽  
Optimum Pressure ◽  
Texture Parameters ◽  
Texture Size ◽  
Comparison Of The Results ◽  
Stiffness And Damping

A numerical model is developed to study the effect of texture on air bearing sliders at large Knudsen numbers. The effect of texture location, texture size, and density on the pressure generation is studied. First, a textured plane slider parallel to the disk surface is investigated and the texture parameters are determined that result in optimum pressure generation. Then, a plane inclined slider is studied using optimum texture parameters found in the parallel slider case. Thereafter, the effect of texture on the steady state flying characteristics of an actual magnetic recording slider is investigated. Finally, the flying height modulation, pitch and roll motion of a textured slider (pico and femto form factors) are determined numerically by exciting the slider using a step on the disk. Comparison of the results for textured and untextured sliders is made. It is found that textured sliders show better dynamic performance compared to the untextured sliders in terms of stiffness and damping.

Dynamic Characteristics and Design Consideration of a Tripad Slider in the Near-Contact Regime

2002 ◽  
Vol 124 (3) ◽  
pp. 600-606 ◽  
Author(s):  
Kohei Iida ◽  
Kyosuke Ono ◽  
Masami Yamane
Keyword(s):  
Friction Coefficient ◽  
Design Methodology ◽  
Dynamic Contact ◽  
Disk Surface ◽  
Flying Height ◽  
Air Bearing ◽  
Surface Waviness ◽  
Friction Forces ◽  
Tracking Ability ◽  
Spacing Variation

We numerically investigated the tracking ability, the dynamic contact and friction forces of a 2-DOF model of a tripad slider over a random wavy disk surface with 1 nm rms value in the near-contact regime. The air bearing was modeled as a lumped spring and dashpot in order to consider a general design methodology of the flying slider in the near-contact regime. The nominal flying height was changed from the contact regime to the near-contact regime. We studied the effects of the front and rear air bearing stiffnesses, the nominal flying height and the friction coefficient on the tracking ability and contact force. As a result, we found that the spacing variation is caused not only by the slider dynamics but also by the micro-waviness of the disk surface and the distance of the contact pad (head-gap) position from the rear air bearing center. We also derived the closed form frequency response functions of the spacing variation to the disk surface waviness. The approximation agreed with the numerical simulation. The effect of the friction coefficient on the tracking ability can be neglected when the flying height is more than 1 nm.

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