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.

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.

Stability and Dynamics of Non-Linear Slider Behaviour Due to Disk Waviness in the Presence of Intermolecular and Electrostatic Forces

2005 ◽  
Author(s):  
Vineet Gupta ◽  
David B. Bogy
Keyword(s):  
Resonance Frequency ◽  
Equations Of Motion ◽  
Disk Surface ◽  
Air Bearing ◽  
Electrostatic Forces ◽  
Disk Interface ◽  
Non Linear ◽  
Bearing Stiffness ◽  
Stiffness And Damping ◽  
Nonlinear Nature

In this paper we present a theoretical investigation of the stability and the dynamics of the non-linear behavior of a slider at very low head media spacing. A single DOF head disk interface (HDI) model, with constant air bearing stiffness and damping has been used to study the effect of disk waviness on the nonlinear slider dynamics in the presence of intermolecular and electrostatic forces. A variational approach based on the principle of least action was used to derive the equations of motion of the slider. Further, a stability criteria was derived that helped to better understand the instabilities that appear in slider when the slider is flying in close proximity to the disk surface. Due to extremely nonlinear nature of the interaction between the slider and the disk, we observed some strange features of the motion of the slider. In particular the effects of the nonlinear interaction force, air bearing stiffness and damping on the instabilities of the periodic motions of the slider are discussed in detail. We found that the branch associated to the disk waviness frequencies larger than the resonance frequency is always stable and the branch associated to the disk waviness frequencies smaller than the resonance frequency exhibits two stable domains and one unstable domain. This analysis was further extended to include the nonlinear nature of air bearing stiffness and damping as well as contact at the HDI.

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.

Air-Bearing Design Towards Super Stable Head-Disk Interface

2006 ◽  
Author(s):  
Bo Liu ◽  
MingSheng Zhang ◽  
Yijun Man ◽  
Shengkai Yu ◽  
Gonzaga Leonard ◽  
...  
Keyword(s):  
Air Bearing ◽  
Head Disk Interface ◽  
Disk Interface ◽  
Bearing Design

Efficient Air Bearing Modeling for Operational Shock Analysis in 2.5-Inch HDD

2014 ◽  
Author(s):  
Kyoung-Su Park ◽  
Geonyup Lim ◽  
No-Cheol Park ◽  
Young-Pil Park
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Air Bearing ◽  
Contact Modeling ◽  
Advanced Method ◽  
Disk Contact ◽  
Approach Method ◽  
Bearing Stiffness ◽  
Operational Shock ◽  
Decoupled Method

As use of mobile computing devices has spread rapidly, it is very important to accurately analyze and predict anti-shock performance of the HDD system. In this paper, we proposed an efficient air bearing modeling method to analyze op-shock performance for the in 2.5-inch HDD system with ramp-disk contact behavior. We first constructed the decoupled approach method using linear air bearing springs in finite element method and used the Lagrange multiplier method for contact modeling between disk and ramp. With the constructed finite element model, the effect of linear air bearing stiffness was investigated in the decoupled method. We found that air bearing stiffness affects the behavior of the slider dominantly in the HDDs system with ramp-disk contact. Based on the numerical results, the advanced method able to efficiently reflect air bearing characteristics was proposed and evaluated.

Improved Analysis of Unstable Bouncing Vibration and Stabilizing Design of Flying Slider in Near-Contact Regime

2005 ◽  
Author(s):  
Kyosuke Ono ◽  
Masami Yamane
Keyword(s):  
Parametric Study ◽  
Adhesion Force ◽  
Design Method ◽  
Contact Stiffness ◽  
Frictional Coefficient ◽  
Disk Surface ◽  
The Self ◽  
Air Bearing ◽  
Excited Vibration ◽  
Bearing Stiffness

We proposed a design method of a flying head slider that can suppress the bouncing vibration in a near-contact regime, based on parametric study using an improved slider and contact models. At first, we numerically calculated the characteristics of contact force and adhesive force between air bearing pad and disk surface under the current small roughness conditions and found that the contact characteristics can be modeled by constant contact stiffness, a constant adhesion force and the separations of beginning and end of contact. Next we numerically computed the slider dynamics of a 2-DOF slider model by using these contact characteristics and nonlinear air-bearing stiffness. As a result, we could get the self-excited bouncing vibration whose general characteristics are more similar to the experimented results compared to our previous study. Parametric study shows that the frictional coefficient, attractive force and contact stiffness should be decreased and front and rear air-bearing stiffness and ratio of rear to front air-bearing stiffness should be increased in order to realize a stable flying slider in a smallest possible spacing. Moreover, we elucidated the effect of micro-waviness on the self-excited vibration of the slider.

High air-bearing stiffness slider design

2006 ◽  
Vol 303 (2) ◽  
pp. e76-e80 ◽  
Author(s):  
Y.F. Han ◽  
B. Liu ◽  
X.Y. Huang
Keyword(s):  
Air Bearing ◽  
Slider Design ◽  
Bearing Stiffness

Wear Characteristics of Padded Air Bearing Sliders During a Contact Take-Off Process

1999 ◽  
Vol 122 (3) ◽  
pp. 628-632 ◽  
Author(s):  
Yong Hu
Keyword(s):  
New Technologies ◽  
Interface Roughness ◽  
Wear Volume ◽  
Air Bearing ◽  
Wear Factor ◽  
Wear Characteristics ◽  
Disk Interface ◽  
Force Profile ◽  
Bearing Design ◽  
Wear Law

The pressing and challenging demand for resolving the stiction/glide-height conflict, driven by today’s ever decreasing head/disk spacing, forces us to constantly search for new technologies. One of them is padding the slider’s air bearing surface. Although the padded air bearing sliders can significantly reduce the stiction, the wear of these landing pads becomes a central issue. This paper attempts to analytically predict the wear characteristics of the landing pads during a contact take-off process. A wear factor derived from the adhesive wear law is employed to measure the wear extent of the landing pads. The contact force profile and wear factor of each pad are calculated through the partial contact air bearing simulation of a slider’s take-off process. It is found that the rear pad wears an order magnitude more than the leading pads. The wear volume of the rear pad increases exponentially with pad height, interface roughness and altitude. Raising the leading pads alone slightly reduces the wear of the rear pad. Placing the rear pad away from the slider’s trailing edge, however, substantially alleviates the wear of the rear pad. Finally, a lightly textured pad/disk interface decreases the pads’ wear to a minimum value for a given padded air bearing design. [S0742-4787(00)01903-2]

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