Experimental Study of High-Speed Contact at Head-Disk Interface in a Magnetic Hard Disk

2005 ◽  
Author(s):  
Mingwu Bai ◽  
Stephen M. Hsu
Keyword(s):  
Acoustic Emission ◽  
High Speed ◽  
Hard Disk ◽  
Disk Drive ◽  
Test Method ◽  
Head Disk Interface ◽  
Emission Analysis ◽  
Disk Interface ◽  
Emission Signal ◽  
Carbon Overcoats

Tribological performance of the head-disk interface will have significant impact on the performance and durability of the hard disk drive. A high-speed contact test method has been developed for the purpose of evaluating nanometer-thick lubricant film/carbon overcoats materials on hard-disk surfaces. Four different thickness overcoats were used in high speed contact experiments. High speed contact force was calculated based on the calibration of acoustic emission signal by proposed ball dropping tests. Acoustic emission analysis, frequency spectrum analysis, and surface morphology imaging were used to analyze the deformation and fracture at high speed contacted area. The availability of an experimental technique enables effective screening of different material chemistries and lubricant combinations to improve the level of protection for hard disk technology.

The Gas Bearing Interface of Opposed Recording Heads in a Disk Drive Utilizing Helium and Thin Titanium Foil Disks

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
James White
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Hard Disk ◽  
Disk Drive ◽  
Titanium Foil ◽  
Metal Foil ◽  
Mechanical Shock ◽  
Disk Interface ◽  
Recording Heads ◽  
Gas Bearing

Increased storage capacity and decreased power consumption are two key motivations in the development of hard disk drive (HDD) storage products. Two ideas that address these areas have recently received attention in the literature. These are (1) the use of helium instead of air as the working gas in the drive and (2) the incorporation of a thin metal foil as the disk substrate, replacing the much thicker aluminum or glass substrate of the hard disk (HD). The work that has been previously reported considered either the use of helium or thin foil substrates, but not both. This paper does consider both. It reports dynamic gas bearing simulation results for the helium filled interface between opposed recording heads and a disk whose substrate is a thin titanium foil. Motivation for the selection of titanium as the foil material is described in the paper. The thickness of the foil is chosen so as to achieve an optimal combination of centrifugal force and bending force that will provide required disk flatness and stability during high-speed rotation. Large-scale dynamic simulation is used to track the response of the recording head slider-foil disk interface due to mechanical shock in the vertical, pitch, and roll directions. Results are described and compared with those of the configuration that includes helium and a HD. Attention is focused on response to off-design conditions that can create head crash with the HD.

Thermal Asperities Sensitivity to Particles: Methodology and Test Results

2000 ◽  
Vol 123 (2) ◽  
pp. 376-379
Author(s):  
Larry Y. Wang ◽  
Mike Sullivan ◽  
Jim Chao
Keyword(s):  
Giant Magnetoresistance ◽  
Disk Drive ◽  
Test System ◽  
Test Method ◽  
Aluminum Silicate ◽  
Disk Interface ◽  
Carbon Overcoats ◽  
Sensor Temperature ◽  
Sensitivity Data ◽  
Read Signal

Thermal asperities (TA’s) are tribological events that cause repercussions for giant magnetoresistance (GMR) and MR heads in the hard disk drive industry. A TA is a read signal spike caused by sensor temperature rise due to contact with disk asperities or contaminant particles. TA events may cause GMR and MR heads to temporarily lose their reading capability, and may potentially damage the transducer. It is difficult to completely avoid particle contamination in hard drive applications. Hence it is necessary to design heads/media with a minimum TA sensitivity to particles. A test method for TA sensitivity to particles is needed. This work developed a test method for TA sensitivities to particles. The test system includes a CSS tester with TA detection capability, a chamber to contain the head/disk interface, a particle atomizer, and a particle counter. Aluminum silicate particles used in the test have sizes ranging from 0.2 to 1.0 μm. Particles are injected into the chamber during head scan for TA’s from ID to OD with adjustable air-borne concentrations in the chamber from 10×106 to 30×106particles/m3. TA counts of 30 scans are averaged to obtain reliable TA sensitivity data. Media with different lubricant thickness, different carbon overcoats, and different lubricant types are tested with this method. The results indicated that this methodology can effectively differentiate TA sensitivity to particles for the media studied.

Dynamic Analysis of Sliding Contacts at Head-Disk Interface

2002 ◽  
Author(s):  
T.-J. Chuang ◽  
S. M. Hsu
Keyword(s):  
Data Storage ◽  
High Speed ◽  
Time History ◽  
Disk Drive ◽  
Element Model ◽  
Disk Surface ◽  
Magnetic Data ◽  
Head Disk Interface ◽  
Sliding Contacts ◽  
Disk Interface

As magnetic data storage technology moves towards higher areal data density with higher rotational speeds and lower flying heights, the propensity of severe sliding contacts at the head-disk interface is bound to increase. The tribological performance of the head-disk interface will have significant impact on the durability and service life of the hard disk drive (HDD). A 3D finite element model is constructed to simulate the high speed impact event of a slider on the disk surface. For a given design of the disk with known layer thicknesses and properties, as well as that of the slider with its surface texture, the model predicts contact zone, depth force and duration as well as time-history of energy transfer and its partition, substrate stress and plastic zone for a given impact velocity. The effects of the material properties and layer thicknesses on the performance of the HDD are investigated.

Wear Analysis of Head-Disk Interface During Contact

2005 ◽  
Vol 127 (1) ◽  
pp. 171-179 ◽  
Author(s):  
Wei Peng ◽  
James Kiely ◽  
Yiao-Tee Hsia
Keyword(s):  
Hard Disk Drive ◽  
Wear Mechanism ◽  
Adhesive Wear ◽  
Contact Stiffness ◽  
Hard Disk ◽  
Disk Drive ◽  
Head Disk Interface ◽  
Wear Coefficient ◽  
Disk Interface ◽  
Fly Height

To achieve a higher storage density in a hard disk drive, the fly height of the air bearing slider, as part of the magnetic spacing, has to be minimized. At an ultralow fly height, the intermittent–continuous contact at the head–disk interface (HDI) is unavoidable and directly affects the mechanical and magnetic performance of the hard disk drive, and is of great interest. The HDI wear has a nonlinear and time-varying nature due to the change of contact force and roughness. To predict the HDI wear evolution, an iterative model of Coupled Head And Disk (CHAD) wear, is developed based on the contact mechanics. In this model, a composite transient wear coefficient is adopted and multiple phases of the wear evolution are established. A comprehensive contact stiffness is derived to characterize the contact at the HDI. The abrasive and adhesive wear is calculated based on the extended Archard’s wear law. The plastic and elastic contact areas are calculated with a three-dimensional (3D) sliding contact model. Based on the CHAD wear model, for the first time, the coupling between head and disk wear evolutions is thoroughly investigated. Accelerated wear tests have also been performed to verify the disk wear effect on the slider wear. A wear coefficient drop with time is observed during the tests and it is attributed to a wear mechanism shift from abrasive to adhesive wear. A shift in the type of contact from plastic to elastic accounts for the wear mechanism change.

Effect of Non-Operational Shock on Interaction Between Suspension Lift-Tab and Load/Unload Ramp

2005 ◽  
Author(s):  
Aravind N. Murthy ◽  
Eric M. Jayson ◽  
Frank E. Talke
Keyword(s):  
Hard Disk Drive ◽  
Failure Modes ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Areal Density ◽  
Disk Drive ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Disk Interface ◽  
Operational Shock

Most hard disk drives manufactured in the last few years have Load/Unload (L/UL) technology. As opposed to the Contact Start/Stop (CSS) technology, L/UL technology has the advantage of improved areal density because of more disk space availability and better shock performance. The latter characteristic has significant benefits during the non-operational state of the hard disk drive since head/disk interactions are eliminated and the head is parked on a ramp adjacent to the disk. However, even if head/disk interactions are absent, other failure modes may occur such as lift-tab damage and dimple separation leading to flexure damage. A number of investigations have been made to study the response of the head disk interface with respect to shock when the head is parked on the disk ([1], [2]). In this paper, we address the effect of non-operational shock for L/UL disk drives.

Humidity effects on lubricant transfer in the head-disk interface of a hard disk drive

2009 ◽  
Vol 105 (7) ◽  
pp. 07B704 ◽  
Author(s):  
Sang Hoon Kim ◽  
Qing Dai ◽  
Bruno Marchon ◽  
Karl Flechsig
Keyword(s):  
Hard Disk Drive ◽  
Hard Disk ◽  
Disk Drive ◽  
Head Disk Interface ◽  
Lubricant Transfer ◽  
Disk Interface ◽  
Humidity Effects
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