Friction Effect on Loading Process and Multiple Stable Flying States of Air Bearing Sliders

[+] Author and Article Information
Qinghua Zeng, Fu-Ying Huang

San Jose Research Center,  Hitachi Global Storage Technologies, 650 Harry Road, San Jose, CA 95120

J. Tribol 128(4), 811-816 (Apr 24, 2006) (6 pages) doi:10.1115/1.2345397 History: Received May 11, 2005; Revised April 24, 2006

Load∕unload (L∕UL) technology has been widely applied in hard disk drives for a long period of time. One main promise of this technology compared with the contact start-stop (CSS) technology was no damage from the friction and stiction between sliders and disks during power on and off that exists in CSS. However, the friction between sliders and disks can still occur and has a strong effect on the L∕UL process because sliders may contact disks during loading. When friction is large and the pitch static attitude (PSA) is not in the preferred range, the loading process might fail. In this paper, a new simplified friction model was proposed based on experimental observations. The model was implemented into a L∕UL simulation code. Two cases were studied: a 10,000rpm84mm server drive and a 3600rpm25.4mm microdrive. The PSA and friction force effects on the loading process were simulated. A large PSA results in slider loaded onto a second stable state with a very large flying pitch angle. In this paper, a third stable state, which results from a small or negative PSA and a sufficiently large friction force, was discovered and investigated. It was found that the friction effect was smaller in the server drive case, while it was dramatic in the microdrive case. In the third stable state, the slider had a negative pitch angle, and its leading edge continuously dragged on the disk. In this state, reading∕writing operation was not possible, and disks and sliders could be damaged.

Copyright © 2006 by American Society of Mechanical Engineers
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Figure 2

Measured friction force versus “contact area” (calculated from Fig. 3 and Fig. 4 of Ref (12))

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Figure 3

Two conceptual sliders used in the case studies (a) server slider; (b) microdrive slider

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Figure 4

Loading process of the server drive (PSA=1.5deg, un=0.3, ua=0)

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Figure 6

Loading process of the server drive (PSA=−0.2deg, un=0.3, ua=0)

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Figure 7

Loading process of the server drive (un=0.1, PSA=−0.2deg); (a) ua=0.5; (b) ua=1.0; (c) ua=1.5; (d) ua=1.7

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Figure 8

Loading process of the server drive (PSA=−0.2deg, un=0.1, ua=1.8)

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Figure 9

Loading process of the microdrive (PSA=1.7deg, un=0.3, ua=0)

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Figure 10

Loading process of the microdrive (PSA=−0.2deg, un=0.3, ua=0)

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Figure 11

Loading process of the microdrive (PSA=−0.2deg, un=0.1, ua=1.0)

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Figure 1

Schematic of slider dynamics

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Figure 5

Loading process of the server drive (PSA=3.0deg, un=0.3, ua=0)




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