Research Papers: Magnetic Storage

Investigation of Contact Stiffness and Contact Damping for Magnetic Storage Head-Disk Interfaces

[+] Author and Article Information
Xi Shi

School of Mechanical Engineering,  Shanghai Jiao Tong University, P.R.C.

Andreas A. Polycarpou1

Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801polycarp@uiuc.edu


Corresponding author.

J. Tribol 130(2), 021901 (Apr 22, 2008) (9 pages) doi:10.1115/1.2908901 History: Received May 13, 2006; Revised October 26, 2007; Published April 22, 2008

As the areal density of magnetic disk storage continues to increase and head-disk spacing decreases, contact between the recording slider and the rotating media becomes imminent. In order to predict contact forces, fly-height modulations, and off-track motions, dynamic models are typically used. A critical element of these models is the contact stiffness and damping arising from the interfacial interaction between the slider and the disk. In this paper, we review different models for predicting contact stiffness based on roughness and layered media and then we report experimental data of both contact stiffness and contact damping of typical head-disk interfaces. It is found that the contact stiffness models (based on roughness alone) overpredict the contact stiffness of actual head-disk interfaces by as much as an order of magnitude. Also, it is found that the contact damping ratio is typically few percent and its behavior is substrate dependent. In addition, the effects of a molecularly thin lubricant and humidity on contact stiffness and damping were experimentally investigated and no significant effects were found.

Copyright © 2008 by American Society of Mechanical Engineers
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Figure 1

Contact stiffness model predictions for spherical contacts accounting for roughness

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Figure 2

Typical magnetic storage thin film disk showing different layers

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Figure 3

Theoretical total contact stiffness (substrate and asperity contribution) for a typical head-disk interface with glass substrate (σ=1nm)

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Figure 4

Contact stiffness and contact damping microtester: (a) overall view of tester, (b) close-up view of micrometer and impactor, (c) close-up view of tube springs and contact interface, and (d) system dynamic model

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Figure 5

Typical strain gage calibration at low loads

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Figure 6

Typical experimental data: (a) acceleration signal and (b) average spectra (spherical contact)

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Figure 7

Measured results for spherical contact: (a) contact stiffness and (b) contact damping ratio

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Figure 8

Micrograph of actual recording slider used in this study, showing the air-bearing surface (ABS), which is the “tallest” surface

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Figure 9

Measurement results for three actual HDIs: (a) contact stiffness and (b) contact damping ratio

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Figure 10

Molecularly thin lubricant effect on the contact parameters: (a) contact stiffness, (b) contact damping ratio, and glass substrate disk

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Figure 11

Humidity effect on the contact parameters: (a) contact stiffness, (b) contact damping ratio, and glass substrate disk




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