Browse Prior Art Database

Transit Locking Technique for HDA Actuators

IP.com Disclosure Number: IPCOM000121770D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Fowler, RV: AUTHOR

Abstract

A manufacturing accessory is described for use with magnetic disk file head-disk-actuator (HDA) assemblies to reduce damage to disks by accidental mechanical movement of actuators suffered in transit by mechanical shock. Inexpensive protection extends from in-plant HDA handling to field spares exposed to the hazards of travel and storage outside control of the plant. The principle employed is that unintended motion of the actuator motor coil produces a back EMF and an opposing coil current which greatly damps down the primary motion.

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Transit Locking Technique for HDA Actuators

      A manufacturing accessory is described for use with
magnetic disk file head-disk-actuator (HDA) assemblies to reduce
damage to disks by accidental mechanical movement of actuators
suffered in transit by mechanical shock. Inexpensive protection
extends from in-plant HDA handling to field spares exposed to the
hazards of travel and storage outside control of the plant.  The
principle employed is that unintended motion of the actuator motor
coil produces a back EMF and an opposing coil current which greatly
damps down the primary motion.

      Media damage caused by head to disk interactions during
shipping has a severe effect on the data integrity due to the nature
and size of the defects.  These defects are radial covering a few
tracks but very thin, sufficient to affect only a byte or so.
Defects of this size are highly pattern-sensitive and may range from
zero (i.e., good) through ECC correctable to hard error.

      Normally the heads are held in the landing zone outer diameter
(OD) for shipping by a weak retract spring on the actuator.  If the
retract spring is overcome during shipping, the only other holding
force is head-to-disk stiction and friction.  On files with no
stiction the head-to- disk friction is low and the actuator could
move away from the landing zone.  Generally, the actuator could
rebound with a net force of 13 Nmm unless the outward force was
sufficient to hit the inner diameter (ID) end stop when the rebound
off the rubber would add to the...