Reduction in Adsorption of Bearing Oil From Fluid Dynamic Bearings of Hard Disk Drive Spindle Motor by Diamagnetism

Abstract In this paper we investigate the vibration characteristics of a rotor system with flexible disks. The coupled vibration mode between rotating shaft and the flexible disk are analyzed for lateral and axial vibrations respectively. Gyro and sheer effects are considered for the modeling of lateral vibrations. An assumed mode method was used for the disk modeling considering gyro effects. For a numerical example hard disk drive is considered. The natural frequencies of the motor-spindle system with flexible disk of hard disk drive was calculated and compared to the experimental data.

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Experimental Characterization Techniques for High Performance Hard Disk Drive Ball Bearing Spindle Motors

Volume 7A: 17th Biennial Conference on Mechanical Vibration and Noise ◽

10.1115/detc99/vib-8331 ◽

1999 ◽

Author(s):

Andrew Chong ◽

Lu Yi ◽

S. X. Chen ◽

Q. D. Zhang

Keyword(s):

Hard Disk Drive ◽

High Speed ◽

High Performance ◽

Ball Bearing ◽

Hard Disk ◽

Disk Drive ◽

Spindle Motor ◽

Hard Disks ◽

Steel Balls ◽

Test Requirements

Abstract The key task for the spindle motor in a hard disk drive is to provide stable, reliable and consistent turning power for many years to allow the hard drive to function properly. As hard disks become more advanced, virtually every component in them is required to do more & perform better, and the spindle motor is no exception. Increasing the rotational speed at which the platters spin means that the data can be read off the disk faster, and also reduces rotational latency, the time that the heads must wait for the correct sector number to come under the head. For this reason, there has been a push to increase the speed of the spindle motor. Since the launching of hydro-dynamic bearing spindle technology for high speed application will not be in due course, current ball bearing technology will still be around for a couple of years provided the spindle speed does not exceed around 15 Krpm. Therefore optimizing the steel balls in the spindle system is an alternative to deal with the ever-increasing performance requirements of the hard disk drive. To accomplish this, we have to understand the failure phenomenon in the spindle, thereby set test requirements to overcome the failure mechanism. These test requirements will help us to understand the performance characteristic and robustness of the spindle motor. In this paper, the test requirements is set according to modal, load and vibration methods to quantify the hard disk drive ball bearing spindle motor.

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Deformation of Hard Disk Drive Media Caused by Thermal Stress and Induced Air Flow

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1061-1062.866 ◽

2014 ◽

Vol 1061-1062 ◽

pp. 866-873

Author(s):

Pakornwit Padtha ◽

Kiatfa Tangchaichit

Keyword(s):

Thermal Stress ◽

Hard Disk Drive ◽

High Speed ◽

Air Flow ◽

Voice Coil Motor ◽

Hard Disk ◽

Disk Drive ◽

Spindle Motor ◽

High Rotational Speed ◽

The Media

The spindle motor in a hard disk drive spins at a high rotational speed. These rotations generate air flow and thermal stress. Air flow is induced by the surface roughness of the media that is moving at a high speed through air. This air passes over the surface of many parts in the drive, including the media. Thermal stress is generated by heat in the parts, e.g. voice coil motor, pre-amplifier, slider pole tips, which are heated by electric power and by the spinning of the spindle motor. The air flow and thermal stress cause a change in the media shape called deformation.Simulation results show the trend of deformation has more bending when the slider moves outward from the media axis. The pressure acted more on the underside than on the upper side which caused the media to bend up to the top cover side of hard disk drive. The maximum deformation, 15 μm, occurred at the rim of media while the distance between the media and the slider is 30 μm; thus they did not contact each other.

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Finite Element Analysis of the Coupled Journal and Thrust Bearing in a Computer Hard Disk Drive

Journal of Tribology ◽

10.1115/1.2162918 ◽

2005 ◽

Vol 128 (2) ◽

pp. 335-340 ◽

Cited By ~ 31

Author(s):

G. H. Jang ◽

S. H. Lee ◽

H. W. Kim

Keyword(s):

Finite Element ◽

Hard Disk Drive ◽

Thrust Bearing ◽

Fluid Dynamic ◽

Hard Disk ◽

Disk Drive ◽

Flying Height ◽

Separate Analysis ◽

Element Analysis ◽

Thrust Bearings

This paper proposes a method to calculate the characteristics of a coupled fluid dynamic journal and thrust bearing of a hard disk drive (HDD) spindle motor. The governing equations for the journal and thrust bearings are the two-dimensional Reynolds equations in the θz and rθ planes, respectively. The finite element method is appropriately applied to analyze the coupled bearing under the conditions of the continuity of mass and pressure at the interface between the journal and thrust bearings. The pressure in the coupled bearing was calculated by applying the Reynolds boundary condition. The validity of this application was verified by comparing the analytical results of the flying height at various rotating speeds with experimental results. The characteristics of the coupled journal and thrust bearing were also investigated due to the Reynolds and Half-Sommerfeld boundary conditions and the coupled and separate analysis. This research demonstrates that the proposed method can accurately and realistically describe the coupled fluid dynamic bearing in a HDD system.

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