Browse Prior Art Database

Method for Improving Dimensional Stability of Disk Stacks

IP.com Disclosure Number: IPCOM000049954D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Rajac, TJ: AUTHOR

Abstract

A problem which is present in most head disk assembly (HDA) spindle designs in magnetic recording systems is the possibility of disks moving relative to their initial position due to clamp load relaxation with time. This is illustrated in Fig. 1 which shows a plurality of magnetic recording disks 11 clamped by a clamping means including an upper clamp member 12a which is bolted by bolts 12b to a member 12c to pace and hold disks 11 in position for rotation on a spindle 13. It has been shown that the clamping means mechanically relaxes with time and thermal excursions such that, eventually, the position of disks 11 is distorted. This distortion for the different disks in the HDA is shown in Figs. 1a, 1b and 1c.

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Method for Improving Dimensional Stability of Disk Stacks

A problem which is present in most head disk assembly (HDA) spindle designs in magnetic recording systems is the possibility of disks moving relative to their initial position due to clamp load relaxation with time. This is illustrated in Fig. 1 which shows a plurality of magnetic recording disks 11 clamped by a clamping means including an upper clamp member 12a which is bolted by bolts 12b to a member 12c to pace and hold disks 11 in position for rotation on a spindle 13. It has been shown that the clamping means mechanically relaxes with time and thermal excursions such that, eventually, the position of disks 11 is distorted. This distortion for the different disks in the HDA is shown in Figs. 1a, 1b and 1c.

This movement, although in the range of only several hundred microinches, can cause catastrophic performance degradation due to inability of the read/write head to recover the data encoded on disks 11, resulting in hard errors.

Described here is a design which acknowledges this phenomenon and is aimed at preventing it. Fig. 2 shows the current design practice in HDA products. The material mismatch is relieved by the selection of similar materials in the areas which affect the disk load by the use of an aluminum washer ring 14.

Inspection of the structure shown in Fig. 2 will indicate the thermal excursion effects due to material expansivity mismatches. The washer ring 14 has typically been used to ac...