Lubricant Flow and Accumulation on the Air Bearing Surface of a Hard Disk Drive

2013 ◽  
Author(s):  
Alejandro Rodriguez-Mendez ◽  
David B. Bogy
Keyword(s):  
Thin Layer ◽  
Hard Disk Drive ◽  
Driving Forces ◽  
Hard Disk ◽  
Disk Drive ◽  
Flying Height ◽  
Air Bearing ◽  
Bearing Surface ◽  
Lubricant Flow ◽  
Disk Spacing

During normal operations of a hard disk drive (HDD), a slider flies over the surface of a spinning disk lifted by a thin layer of air. The disk surface is coated by a molecularly-thin layer of lubricant to protect it against corrosion and reduce wear on the read/write head. The flying height of the slider should be as small as possible in order to achieve higher recording densities. In current HDDs the head-to-disk spacing is on the order of 1–3 nm [1]. At this ultra-low spacing lubricant from the disk often transfers to the slider’s air bearing surface (ABS) forming a thin film that imposes a significant degradation on its performance. Problems such as head instabilities, flying stiction, disk lubricant depletion and increase in head-disk spacing occur when lubricant is present on the ABS [2]. To avoid this condition, modern sliders should be able to remove the lubricant from the ABS as fast as possible. Hence, it is necessary to have a thorough understanding of the lubricant flow process and its driving forces.

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.

Bifurcation Approach to the Analysis of Multiple Flying Height States in Load/Unload Hard Disk Drive Systems

2005 ◽  
Author(s):  
Pyung Hwang ◽  
Polina V. Khan
Keyword(s):  
Hard Disk Drive ◽  
Hard Disk ◽  
Disk Drive ◽  
Numerical Continuation ◽  
Continuation Methods ◽  
Multiple Equilibrium ◽  
Flying Height ◽  
Drive Systems ◽  
The Relationship ◽  
Force Equilibrium

The application of numerical continuation methods to calculate suspension force-equilibrium position curve for hard disk drive sliders is proposed. The method efficiently detects multiple equilibrium positions. The relationship between suspension force offset and critical preload is found for the femto slider.

Air Entrapment in Nanometer-Thick Lubricant Films and its Effect on Slider Flying Height in a Hard Disk Drive

2012 ◽  
Vol 47 (3) ◽  
pp. 349-355 ◽  
Author(s):  
B. Marchon ◽  
X. C. Guo ◽  
S. Canchi ◽  
R. H. Wang ◽  
N. Supper ◽  
...  
Keyword(s):  
Hard Disk Drive ◽  
Hard Disk ◽  
Disk Drive ◽  
Flying Height ◽  
Air Entrapment ◽  
Lubricant Films

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.

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