Aerodynamic characteristics of carriage arm equipped on hard magnetic disks

Kaneko, Shigehiko; Nishihara, Takashi; Watanabe, Tatsuo

doi:10.1007/s00542-006-0354-1

Cited by 7 publications

(3 citation statements)

References 10 publications

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“…Gross et al 2003). Kaneko et al (2005) investigated streamline visualization around HDD arm using a big size model of a carriage arm, which was ten times as big as the actual carriage arm. They observed vortex shedding at the leading edge of the carriage arm and in a wake flow.…”

Section: Introductionmentioning

confidence: 99%

Linear protrusion structure on carriage-arm surface for reduction of flow-induced carriage vibration in hard disk drives

Koganezawa

Ohtsuka

Funabashi³

2011

Microsyst Technol

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One of the major contributors to head positioning errors is carriage vibration in low frequency due to an air flow caused by disk rotation. It is necessary to suppress the disturbance for Hard Disk Drives (HDDs) to have more capacity. We experimentally studied a reduction in the flow-induced carriage vibration using linear protrusion structures by putting wires on carriage arms. This study was carried out using 2.5 inch HDD which has high rotational speed of 10,000 rpm. We measured position error signals (PES) and compared with a conventional carriage. From the experimental results, we found that the linear protrusion structure was effective to reduce the carriage vibration. Leading edge wire configuration and 2 linear protrusion configuration improved average nonrepeatable position errors (NRPE) by 6.9% and 6.4%, respectively.

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Section: Introductionmentioning

confidence: 99%

Linear protrusion structure on carriage-arm surface for reduction of flow-induced carriage vibration in hard disk drives

Koganezawa

Ohtsuka

Funabashi³

2011

Microsyst Technol

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“…These vortices generated a high level of turbulence intensity in the region downstream of the arm and the SSU along the circumferential direction at the inter-disk mid-plane. Kaneko et al (2007) investigated the effect of the installation angle between the actuator arm and the incoming flow upstream of the arm. They submerged a tenfold expanded actuator arm in a water tunnel with various installation angles to create a geometrically-similar model to that in air, but at the slower time scale of the motion than the condition in the air.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of the flow-structure interactions in an air- or helium-filled hard disk drive geometry

2011

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The increased rotating speed of the hard disk drive (HDD) causes an unsteady flow field between each stack of disks and leads to flow induced vibration on the slider suspension unit (SSU). This flow induced vibration can reduce the positioning accuracy of the SSU and lead to failure to read or write data. Therefore, reduction of turbulence kinetic energy around the SSU is an important step to improve the performance of the HDD. Several modifications have been investigated in air to decrease the direct effect of unsteady flows on the SSU (e.g. spoiler, damper, or divider in the region upstream of the arm). However, these methods are not fundamental solutions for reducing the vibrations on the SSU. Since the HDDs currently in use are filled with air, helium was selected to compare the flow pattern due to the differing inertial property. To visualize the flow pattern, particle image velocimetry (PIV) measurements were performed at the inter-disk mid-plane between a pair of disks near the arm and the SSU. The geometry is an expanded 29 model simulating Seagate cheetah 2.5-inch drive. For both the air and the helium filled drives, measurements have been performed for two different locations of the SSU for two different angular velocities of 1,000 and 3,000 rpm, corresponding to 5,000 and 15,000 rpm in the commercial drive. The results reveal that the flow patterns of the air and the helium flow are quite similar. However, with respect to the turbulence intensity around the SSU, the helium flow shows a drastic decrease compared with that of the air flow, resulting in much reduced positioning errors. As such, helium-filled drives have merit and should be looked into.

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“…In addition, vortical structures were generated by the lateral surfaces of the slider. Kaneko et al (2007) tested the aerodynamic character of the actuator arm in the water tunnel with a ten times expanded model for various angles between the incoming flow and the actuator arm. They observed vortex shedding induced by the trailing edge of the arm.…”

Section: Introductionmentioning

confidence: 99%

Numerical study of the flow-structure interactions in an air- or helium-filled simulated hard disk drive

2011

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Since its invention, the Hard Disk Drive (HDD) has been the most widely-used device for data storage. Recently, the volume of data is getting larger and the corresponding rotation speed of the HDD is increasing to allow for better data transfer. The decreasing size of the disk is increasing the density of data on the disk surface. As a result, the positioning accuracy of the Suspension Slider Unit (SSU), where the magnetic head is mounted, is the problem that has to be overcome for better performance of the HDD. Additionally, the increased rotating speed of the disk induces unsteady flow between each pair of disks. This unsteady flow becomes turbulent around the SSU and induces vibrations on the SSU which deteriorate the performance of the HDD. There have been many investigations to understand the fluid mechanics phenomena inside the HDD filled with air. Additionally, many modifications have been tried to minimize the flow-induced vibration on the SSU by placing a blockage upstream of the arm to generate a low velocity region. However, none of these investigations have explored the effect of using gases other than air. In this work, the flow physics in the HDD is investigated numerically with the drive filled with air or helium. Numerical analyses were performed using the commercial code (ANSYS/CFX) with an expanded 2 9 model simulating Seagate cheetah 2.5-inch drive. Despite obvious un-addressed issues in sealing the HDD, the unsteady characteristics of the flow are dissipated sufficiently faster in helium than in air so as to warrant further studies addressing the more practical issues of working with helium. Of particular importance is the unsteady flow around the SSU. This leads to lower levels of flow-induced vibration in the case of helium flow. As such, HDD performance may be improved by using helium to improve the dynamics of the HDD at higher rotation speeds. For both air-and helium-filled drives, calculations have been performed with two different locations of the SSU and two different angular velocities, 1,000 and 3,000 rpm corresponding to 5,000 and 15,000 rpm in 3.5-inch commercial drive. Not only is it shown that the helium-filled drive suffers lower positioning errors, but also the underlying flow physics responsible for such improvement are explained.

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Aerodynamic characteristics of carriage arm equipped on hard magnetic disks

Cited by 7 publications

References 10 publications

Linear protrusion structure on carriage-arm surface for reduction of flow-induced carriage vibration in hard disk drives

Linear protrusion structure on carriage-arm surface for reduction of flow-induced carriage vibration in hard disk drives

Experimental study of the flow-structure interactions in an air- or helium-filled hard disk drive geometry

Numerical study of the flow-structure interactions in an air- or helium-filled simulated hard disk drive

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