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.

Analysis of Bouncing Vibrations of a 2-DOF Tripad Contact Slider Model With Air Bearing Pads Over a Harmonic Wavy Disk Surface

1999 ◽  
Vol 121 (4) ◽  
pp. 939-947 ◽  
Author(s):  
Kyosuke Ono ◽  
Kan Takahashi
Keyword(s):  
Contact Stiffness ◽  
Disk Surface ◽  
Design Parameters ◽  
Air Bearing ◽  
Static Contact ◽  
Tracking Ability ◽  
The Coefficient Of Friction ◽  
Bearing Stiffness ◽  
Perfect Contact ◽  
Contact Slider

In this study, the authors numerically analyzed the bouncing vibrations of a two-degree-of-freedom (2-DOF) model of a tripad contact slider with air bearing pads over a harmonic wavy disk surface. The general features of bouncing vibrations were elucidated in regard to the modal characteristics of a 2-DOF vibration system and design parameters such as contact stiffness, contact damping, air hearing stiffness, the rear to front air bearing stiffness ratio, static contact force and the coefficient of friction. The design of a contact slider was discussed in terms of tracking ability and wear durability. In addition, two sample designs of a perfect contact slider with sufficient wear durability were also presented.

An Optimization Method for Design of Subambient Pressure Shaped Rail Sliders

1999 ◽  
Vol 121 (3) ◽  
pp. 575-580 ◽  
Author(s):  
Dong-Hoon Choi ◽  
Tae-Sik Kang
Keyword(s):  
Design Methodology ◽  
Optimization Method ◽  
Flying Height ◽  
Air Bearing ◽  
Bearing Surface ◽  
Programming Technique ◽  
Design Synthesis ◽  
Method Of Feasible Directions ◽  
Design Variables ◽  
Simulation Results

This study proposes a design methodology for determining configurations of subamient pressure shaped rail sliders by using a nonlinear programming technique in order to meet the desired flying characteristics over the entire recording band. The desired flying characteristics considered in this study are to minimize the variation in flying height from a target value, to keep the pitch angle within a suitable range, and to ensure that the outside rail flies lower than the inside rail even with the roll distribution due to manufacturing process. The design variables selected are recess depth, geometry of the air bearing surface, and pivot location in the transverse direction of the slider. The method of feasible directions in Automated Design Synthesis (ADS) is utilized to automatically find the optimum design variables which simultaneously meet all the desired flying characteristics. To validate the suggested design methodology, a computer program is developed and applied to a 30 percent/15 nm twin rail slider and a 30 percent/15 nm tri-rail slider. Simulation results for both sliders demonstrated the effectiveness of the proposed design methodology by showing that the flying characteristics of the optimally designed sliders are enhanced in comparison with those of the initial ones.

Analysis of Tracking Characteristics and Optimum Design of Tri-Pad Slider to Micro-Waviness

2002 ◽  
Vol 125 (1) ◽  
pp. 152-161 ◽  
Author(s):  
Masami Yamane ◽  
Kyosuke Ono ◽  
Kohei Iida
Keyword(s):  
Resonance Frequency ◽  
Air Bearing ◽  
Resonance Amplitude ◽  
Lower Mode ◽  
Stiffness Model ◽  
Tracking Ability ◽  
Spacing Variation ◽  
Bearing Stiffness ◽  
Bearing Design ◽  
Two Degree Of Freedom

This paper describes optimum air-bearing design of a tri-pad slider in terms of tracking ability to micro-waviness based on theoretical analysis of the two-degree-of-freedom slider model and the distributed and concentrated air-bearing stiffness model. Although a short tri-pad type slider was introduced through the load/unload technique, we point out that this type of slider is superior to the traditional rail type slider in terms of tracking ability to micro-waviness. More importantly, the distance between head-gap position and the rear air-bearing center should be made as small as possible. The spacing variation due to lower mode resonance can be eliminated if the positions of front and rear air-bearing centers are located at the center of percussion. The resonance amplitude of the higher order mode in spacing variation can be reduced if the length of the rear air-bearing pad is designed to be 1.2∼1.3 times the wavelength of the higher mode resonance frequency. Since the momental stiffness of the front air-bearing prevents the head-gap from tracking micro-waviness, the front air-bearing length should be made short or the ratio of rear to front air-bearing stiffness should be made large. If the resonance amplitude of the lower mode must be decreased, the front air-bearing length should be designed to be 1.2∼1.3 times the wavelength of the lower mode resonance frequency.

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.

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

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.

Numerical Investigation of Bouncing Vibrations of a Partial Contact Slider

2007 ◽  
Author(s):  
Du Chen ◽  
David D. Bogy
Keyword(s):  
Hard Disk Drives ◽  
Disk Surface ◽  
Air Bearing ◽  
Nonlinear Dynamic Model ◽  
Frequency Spectra ◽  
Disk Interface ◽  
Partial Contact ◽  
Adhesion Contact ◽  
Contact Situation ◽  
Contact Slider

A nonlinear dynamic model is developed to analyze the bouncing vibration of a partial contact air bearing slider, which is designed for the areal recording density in hard disk drives of 1 Tbit/in2 or even higher. In this model the air bearing with contact is modeled using the generalized Reynolds equation modified with the Fukui-Kaneko slip correction and a new second order slip correction for the contact situation [1]. The adhesion, contact and friction between the slider and the disk are also considered in the model. It is found that the disk surface roughness, which moves into the head disk interface (HDI) as the disk rotates, excites the bouncing vibrations of the partial contact slider. The frequency spectra of the slider’s bouncing vibration have high frequency components that correspond to the slider-disk contact.

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