Browse Prior Art Database

Head-Slap Restraint for Direct-Access Storage Devices

IP.com Disclosure Number: IPCOM000112679D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 4 page(s) / 105K

Publishing Venue

IBM

Related People

Boutaghou, ZE: AUTHOR [+5]

Abstract

Disclosed is a method to minimize the slider return velocity, thereby extending the range of allowable file acceleration before the onset of disk or head damage.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 50% of the total text.

Head-Slap Restraint for Direct-Access Storage Devices

      Disclosed is a method to minimize the slider return velocity,
thereby extending the range of allowable file acceleration before the
onset of disk or head damage.

      Head/disk impact (slap) occurs after the head is subject to a
disk-normal acceleration (a) yielding a force acting on the
head/suspension assembly (HSA) large enough to overcome the preload
force (Fp) and the stiction force (Fs).

A first-order analysis shows that if the acceleration (a) is larger
than

      <F sub p + F sub s> over <m sub s + <m sub lb> times <a over
L>>
slider separation will occur.  Disk damage occurs when the stored
energy in the suspension due to shock loading is transformed into
kinetic energy, giving high slider/disk separation and return
velocities.  The impulsive loading of the slider onto the disk on the
return flight causes damage to the disk surface, and sometimes also
to the head Air Bearing Surface (ABS).

      The following drop tests were performed with 1.8 Al disks and
IBM 0661 suspension and sliders.  No damping/polymer layer was added
to the restraint.  The restraint is made out of Al.  Drop tests were
performed at the highest achievable g levels that the present
equipment permitted.  The duration of the shocks was less than 0.2
ms.  The results are summarized in Table 1.

  Test Matrix for Drop Test of 1.8 Al Disk
 +----------------------------------------------------------+
 | Acceleration |   Surface    | No Restraint |   Restraint |
 | Level (3K    |              |              | at 0.125 mm |
 | filter)      |              |              |             |
 +----------------------------------------------------------+
 |              |              |              |             |
 |   440 g's    |   Top        |   Little     |   No damage |
 |              | Surface      | Damage       |             |
 +----------------------------------------------------------+
 |              |              |              |             |
 |   440 g's    |   Bottom     |   Severe     |   No damage |
 |              | Surface      | Disk Damage  |             |
 +----------------------------------------------------------+
 |              |              |              |             |
 |   950 g's    |   Top        |   Little     |   No damage |
 |              | Surface      | Damage       |             |
 +----------------------------------------------------------+
 |              |              |              |         ...