Browse Prior Art Database

Low-Mass, High-Stiffness Disk Substrate

IP.com Disclosure Number: IPCOM000115973D
Original Publication Date: 1995-Jul-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Reidenbach, JR: AUTHOR

Abstract

Described is a solution to the problems caused by the use of aluminum as a magnetic disk substrate.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 77% of the total text.

Low-Mass, High-Stiffness Disk Substrate

      Described is a solution to the problems caused by the use of
aluminum as a magnetic disk substrate.

      Aluminum, which is commonly used for magnetic disk substrates,
has a fairly low modulus of elasticity and is therefore relatively
flexible.  Consequently, disks with aluminum substrates tend to warp
or cone when clamped, flutter due to windage effects, and deflect
when subjected to vibrations and shock.  Also, aluminum when polished
contains small pits or voids which result in magnetic defects after
the substrates are coated.  The coefficient of thermal expansion of
aluminum is considerably higher than steels and consequently an
aluminum hub and clamp ring are needed for disk stacking and
clamping.  The hub and ring function some what like a buffer between
the aluminum disks and the steel spindle elements (bearings, shaft,
motor magnet ring, etc.), and thereby takes up space that could
otherwise be used by the inhub spindle motor and larger diameter
bearings.  The disclosed invention reduces these problems that are
associated with aluminum disk substrates and provides additional
advantages for performance improvements.

      A solution to the problems caused by the use of aluminum as a
magnetic disk substrate is to use an aluminum-beryllium alloy fairly
rich in beryllium.  Electrofusion Corporation, for example, produces
aluminum-beryllium alloys under the tradename of ALBEMET that have
very suitable prop...