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Machined Rail Slider Design for Improved Fly Height Profile for Rotary Actuator

IP.com Disclosure Number: IPCOM000115981D
Original Publication Date: 1995-Jul-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 4 page(s) / 121K

Publishing Venue

IBM

Related People

Chhabra, DS: AUTHOR

Abstract

As a magnetic head slider attached to a rotary actuator moves from the Inner Diameter (ID) position to the Outer Diameter (OD) position on a disk surface, the angle between the air flow direction and the slider, known as skew angle, changes continuously. Using the generally accepted sign convention, the skew angle in most file designs becomes more positive as the slider moves toward the OD. For most conventional air bearing designs, and particularly for two-rail machined slider designs, the effect of the increasing skew angle is to reduce the fly height. There is a compensating effect from the increasing air velocity as the slider moves toward the OD which causes the fly height to increase.

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Machined Rail Slider Design for Improved Fly Height Profile for Rotary
Actuator

      As a magnetic head slider attached to a rotary actuator moves
from the Inner Diameter (ID) position to the Outer Diameter (OD)
position on a disk surface, the angle between the air flow direction
and the slider, known as skew angle, changes continuously.  Using the
generally accepted sign convention, the skew angle in most file
designs becomes more positive as the slider moves toward the OD.  For
most conventional air bearing designs, and particularly for two-rail
machined slider designs, the effect of the increasing skew angle is
to reduce the fly height.  There is a compensating effect from the
increasing air velocity as the slider moves toward the OD which
causes the fly height to increase.  Depending on the disk speed
(determined by the disk radius and rpm), the skew angles at ID and
OD, and the ID fly height, the fly height profile over the disk can
vary significantly from one file design to another, and from one rpm
to another even for the same file.  Only fortuitously will a file
design  result in a desirable fly height profile.  The disk size,
rpm, and ID fly height are determined from performance
considerations.  Therefore, skew angle is the only file parameter
that may be selected for optimum fly height  profile.  However, even
the skew angles can probably be changed only slightly and that too
only in the first design iteration of the file.  As the fly height
and rpm are changed in the subsequent design enhancements, the fly
height profile may change significantly and it will not be practical
to readjust the skew angles.  Therefore, one can expect little help
from the file parameters in modifying the flying height profile.

      The fly height profile can be changed by changing the load on
the slider applied by the suspension.  However, the load is usually
determined by the ID fly height requirement, and by the head/disk
interface considerations such as stiction force and disk wear due to
start/stop of the slider on the disk, etc.  Other Head Suspension
Assembly (HSA) parameters that effect the fly height profile are
slider-to-suspension skew angle, load point offset in the slider
width direction, and roll static attitude of the suspension.
However, changing any of these parameters is not desirable since it
complicates the HSA assembly process and it also degrades the dynamic
performance of the HSA.

      There are several slider parameters that also have effect on
the fly height profile.  Two methods related to the slider design and
process that can be used to improve the f...