Design and Analysis of Slider’s Landing Pads for Fast Take-Off Performance in Magnetic Hard Disk Drives

1999 ◽  
Vol 121 (4) ◽  
pp. 955-960 ◽  
Author(s):  
Yong Hu
Keyword(s):  
Contact Force ◽  
New Technology ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Air Bearing ◽  
Trailing Edge ◽  
And Performance ◽  
Magnetic Hard Disk ◽  
Pad Wear

Exponential growth in both capacity and performance has been exhausting a lot of existing technologies in magnetic hard disk drive industry, one of them being laser zone texturing. Maintaining such a rapid growth requires innovative technologies. Adding landing pads to a slider’s air hearing surface (ABS) appears to be able to further stretch the glide/stiction envelope into the ultra-low glide and stiction regime. To materialize this new technology, the pad wear needs to be minimized, underlining the importance of the fast take-off air bearing characteristics. This paper analyzes the slider’s landing pad designs for fast take-off performance through the partial contact air bearing simulation of a take-off process. Two landing pad designs (3-pad and full texture) are created on a suhambient pressure ABS. The contact force and its center profiles as well as the evolution of the contact pressure contour are used to characterize the movement of the contact location during the take-off process. The effects of the absolute and relative pad heights as well as the rear pad location on both the transition of the contact location and the rate of contact force decrease are calculated. While raising leading pads delays the transition of the contact location from the leading pads to rear pad, distancing the rear pad from the trailing edge greatly facilitates the movement of the contact location from the rear pad to the trailing edge. A fully textured ABS with a reasonably low and uniform pad height as well as rear pads being well distanced from the trailing edge offers a fast take-off performance.

Optimization of Air Bearing Contours for Shock Performance of a Hard Disk Drive

2003 ◽  
Author(s):  
Eric M. Jayson ◽  
Frank E. Talke
Keyword(s):  
Hard Disk Drive ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Element Model ◽  
Time Dependent ◽  
Air Bearing ◽  
Disk Interface ◽  
Shock Response ◽  
Shock Event

Hard disk drives must be designed to withstand shock during operation. Large movements of the slider during shock impulse can cause reading and writing errors, track misregistration, or in extreme cases, damage to the magnetic material and loss of data. The design of the air bearing contour determines the steady state flying conditions of the slider as well as dynamic flying conditions, including shock response. In this paper a finite element model of the hard disk drive mechanical components was developed to determine the time dependent forces and moments applied to the slider during a shock event. The time dependent forces and moments are applied as external loads in a solution of the dynamic Reynolds equation to determine the slider response to a shock event. The genetic algorithm was then used to optimize the air bearing contour for optimum shock response while keeping the steady flying conditions constant. The results show substantial differences in the spacing modulation of the head/disk interface after a shock as a function of the design of the air bearing contour.

Air Bearing Pushback in Heat Assisted Magnetic Recording

2019 ◽  
Author(s):  
Shaomin Xiong ◽  
Robert Smith ◽  
Chanh Nguyen ◽  
Youfeng Zhang ◽  
Yeoungchin Yoon
Keyword(s):  
Magnetic Recording ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Flying Height ◽  
Air Bearing ◽  
Magnetic Media ◽  
Heat Assisted Magnetic Recording ◽  
Height Control ◽  
Different Dimensions

Abstract The air bearing surface is critical to the spacing control in current hard disk drives (HDDs). Thermal protrusions, including thermal flying height control (TFC) and writer coil protrusion, drive the reader/writer elements closer to the magnetic media. The spacing control actuation efficiency depends on the air bearing push back response after the TFC or writer protrudes. In the next generation hard disk drive technology, heat assisted magnetic recording (HAMR), laser induced protrusions further complicate the spacing control. The laser induced protrusions, such as the localized NFT protrusion and a wider change of the crown and camber, have very different dimensions and transient characteristics than the traditional TFC and writer protrusion. The dimension of the NFT protrusion is relatively smaller, and the transient is much faster than the TFC protrusion. However, it is found that the NFT protrusion is large enough to generate an air bearing push back effect, which changes the read and write spacing when the laser is powered on. To accurately control spacing in HAMR, this push back effect has to be taken into account.

Nonlinear Thermal Protrusion and Slider Disk Contact Forces

2007 ◽  
Author(s):  
Bernhard Knigge ◽  
Andreas Moser ◽  
Jia-Yang Juang ◽  
Peter Baumgart
Keyword(s):  
Contact Force ◽  
New Technology ◽  
Hard Disk Drives ◽  
Contact Forces ◽  
Flying Height ◽  
Air Bearing ◽  
Thermal Protrusion ◽  
Trade Offs ◽  
Bearing Design ◽  
Heater Coil

Some of the recently shipped hard disk drives have a new technology to actively control the flying height between slider and disk. The slider to disk spacing is controlled by thermal protrusion actuation using a small heater coil which is located close to the read write element at the trailing end of the slider. By applying an electric current to the heater coil, the slider’s trailing end protrudes towards the disk and can be driven into contact with sufficiently high heating power. The contact force and the thermal protrusion efficiency is mainly controlled by air bearing design. In this paper we want to discuss the trade offs in air bearing design to achieve low contact force and high thermal actuation efficiency. We have done both numerical simulation and experimental measurements to investigate contact force and air bearing stiffness. Typically a softer air bearings will produce less contact force but usually exhibit worse flying height tolerances. We have found a nonlinear clearance change with applied heater power. At closer spacings, the pressure peak increases dramatically leading to reduced actuation efficiency. The actuation efficiency may also vary at different skew angles. For calibration purpose slider to disk touchdown requires contact. Due to different actuation efficiencies at different radii different contact forces are estimated.

Optimization of Air Bearing Contours for Shock Performance of a Hard Disk Drive

2005 ◽  
Vol 127 (4) ◽  
pp. 878-883 ◽  
Author(s):  
Eric M. Jayson ◽  
Frank E. Talke
Keyword(s):  
Hard Disk Drive ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Element Model ◽  
Time Dependent ◽  
Air Bearing ◽  
Disk Interface ◽  
Shock Response ◽  
Shock Event

Hard disk drives must be designed to withstand shock during operation. Large movements of the slider during a shock impulse can cause reading and writing errors, track misregistration, or in extreme cases, damage to the magnetic material and loss of data. The design of the air bearing contour determines the steady-state flying conditions of the slider as well as dynamic flying conditions, including shock response. In this paper a finite element model of the hard disk drive mechanical components was developed to determine the time dependent forces and moments applied to the slider during a shock event. The time-dependent forces and moments are applied as external loads in a solution of the dynamic Reynolds equation to determine the slider response to a shock event. The genetic algorithm was then used to optimize the air bearing contour for optimum shock response while keeping the steady flying conditions constant. The results show substantial differences in the spacing modulation of the head-disk interface after a shock as a function of the design of the air bearing contour.

A Numerical Simulation of the Head-Disk Assembly in Magnetic Hard Disk Files: Part I—Component Models

1990 ◽  
Vol 112 (4) ◽  
pp. 593-602 ◽  
Author(s):  
O. J. Ruiz ◽  
D. B. Bogy
Keyword(s):  
Numerical Simulation ◽  
Natural Frequencies ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Coupled System ◽  
Air Bearing ◽  
Disk Drives ◽  
Air Bearings ◽  
Magnetic Hard Disk ◽  
Component Models

In previous papers the dynamics of air bearing sliders used to carry the read/write transducers in magnetic hard disk files has been studied. These studies are useful in evaluating the steady flying and stability of sliders subjected to various disturbances. They are particularly useful in finding the natural frequencies of the air bearings. However, in hard disk drives the sliders are attached to suspensions, which are highly specialized structures that connect the sliders to the positioning actuators. These suspensions have to be relatively stiff in lateral translation, but very flexible in pitch and roll. This latter feature is accomplished by the gimbal or flexure that connects the slider to the end of the suspension. The suspension-gimbal structure has its own natural frequencies, which can be excited by disturbances such as track seeking and impacting the actuator against the crash stop. In order to study the effect of these structures on the head-disk spacing it is necessary to include them in the numerical simulator. In this two part study such a simulator is developed. In Part I the component parts and their interfaces are modeled. In Part II the numerical simulation of the coupled system is accomplished and the numerical results of several sample simulations are presented and discussed.

Simulating the Air Bearing Flying Height in a Humid Environment

2007 ◽  
Author(s):  
Shuyu Zhang ◽  
Brian Strom ◽  
Sungchang Lee ◽  
George Tyndall
Keyword(s):  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Flying Height ◽  
Test Cases ◽  
Air Bearing ◽  
Humid Environment ◽  
Bearing Design ◽  
Flying Attitude ◽  
Saturation Vapor

For a hard disk drive operating in a humid environment, the water vapor in the slider’s air bearing is typically compressed beyond its saturation vapor pressure, causing the vapor to condense. Consequently, the air bearing pressure decreases and the slider’s flying attitude adjusts to balance the forces from the suspension. A method for calculating this air bearing response to humid air is presented. Using one particular air bearing design as an example, several test cases are analyzed to illustrate the air bearing response for various temperatures and humidity levels. The calculated flying heights agree with those measured in commercial hard disk drives.

Effects of Laser Textured Disk Surfaces on a Slider’s Flying Characteristics

1998 ◽  
Vol 120 (2) ◽  
pp. 266-271 ◽  
Author(s):  
Yong Hu ◽  
David B. Bogy
Keyword(s):  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Dynamic Responses ◽  
Disk Drives ◽  
Landing Zone ◽  
Pressure Profiles ◽  
Texture Parameters ◽  
Magnetic Hard Disk ◽  
Fly Height

Recently, laser texturing has captured the attention of head/media interface engineers in the hard disk drive industry because it provides precision in the landing zone placement while eliminating the transition zone of a mechanically textured landing zone. It also offers excellent tribological performance in terms of low CSS stiction and good durability. These advantages make it the solution of choice for high-end magnetic hard disk drives. This paper models the effects of laser bumps and laser textured disk surfaces on the Headway AAB slider’s flying characteristics. Two commonly used laser bump profiles (“Sombrero” and “Volcano” types) and various texture patterns are numerically generated in the simulator. The slider’s dynamic responses to these moving laser bumps and textures under two outer rail flying conditions are simulated, and the effects of various bump/texture parameters on the slider’s fly height, pitch, roll and their modulations are discussed. The laser texture mechanism is explained by examining the air bearing pressure profiles induced by the moving laser textures.

Operational Shock Failure Mechanisms in Hard Disk Drives

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Liping Li ◽  
David B. Bogy
Keyword(s):  
Work Performance ◽  
Structural Model ◽  
Failure Mechanisms ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Air Bearing ◽  
Disk Interface ◽  
Bearing Force ◽  
Positive Shock

The work performance of a hard disk drive (HDD) in mobile devices depends very much on its ability to withstand external disturbances. In this study, a detailed multibody structural model integrated with a complete air bearing model is developed to investigate the disk drive's response during external shocks. The head disk interface (HDI) failure mechanisms when the HDD is subjected to different shock cases are discussed. For a negative shock case in which the disk initially moves towards the head, with long pulse width, the air bearing becomes very stiff before the slider crashes on the disk, and the HDI fails only when the external load overcomes the air bearing force. For other shock cases, the slider contacts the disk due to a negative net bearing force caused by the slider-disk separation. Finally, a stiffer suspension design is proposed to improve the drive shock performance, especially during a positive shock, as under these conditions, the slider contacts the disk primarily due to the stiffness difference of the different drive components.

Simulating the Air Bearing Pressure and Flying Height in a Humid Environment

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Shuyu Zhang ◽  
Brian Strom ◽  
Sung-Chang Lee ◽  
George Tyndall
Keyword(s):  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Flying Height ◽  
Test Cases ◽  
Air Bearing ◽  
Disk Drives ◽  
Humid Environment ◽  
Flying Attitude ◽  
Saturation Vapor

For a hard disk drive operating in a humid environment, the water vapor in the slider’s air bearing is typically compressed beyond its saturation vapor pressure, causing the vapor to condense. Consequently, the air bearing pressure decreases and the slider’s flying attitude adjusts to balance the forces from the suspension. A method for calculating this air bearing response to humid air is presented. Using two air bearing designs, several test cases are analyzed to illustrate the air bearing response for various temperatures and humidity levels. The calculated flying heights agree with those measured in commercial hard disk drives.

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