New frequency domain method of nonrepeatable runout measurement in a hard disk drive spindle motor

Author

Jang, Gunhee ; Kim, Dongkyun ; Oh, Jae-Eung

Author_Institution

Sch. of Mech. Eng., Hanyang Univ., Seoul, South Korea

Volume

35

Issue

2

fYear

1999

fDate

3/1/1999 12:00:00 AM

Firstpage

833

Lastpage

838

Abstract

A new frequency domain method was developed and mathematically investigated for measurement and analysis of runout in a computer hard disk drive (HDD) spindle motor. Repeatable runout (RRO) can be represented as the harmonics of the motor rotational frequency in frequency domain. Therefore nonrepeatable runout (NRRO) is the subtraction of the harmonics from total indicated runout (TIR), so that NRRO in time domain can be easily reconstructed by inverse Fourier transform of NRRO in frequency domain. This method is accurate and simple without index signal indispensable to time domain analysis. This research measured runout of a 3.5" HDD spindle motor with both capacitance probe and laser, and also investigated its characteristics statistically and correlated NRRO with defect frequencies of ball bearing, resonance frequency and its mode shape through Campbell diagram

Keywords

AC motors; Fourier transforms; disc drives; frequency-domain analysis; hard discs; small electric machines; 3.5 in; AC motors; capacitance probe; defect frequencies; frequency domain method; hard disk drive; inverse Fourier transform; mode shape; motor rotational frequency; nonrepeatable runout measurement; spindle motor; total indicated runout; Capacitance measurement; Fourier transforms; Frequency domain analysis; Frequency measurement; Hard disks; Laser modes; Probes; Rail to rail outputs; Shape measurement; Time domain analysis;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.753794

Filename

753794