HDI-09 APPLICATION OF SQP METHOD IN DESIGNING THRUST AIR BEARING FOR HARD DISK DRIVE SPINDLE MOTOR(Head/Disk Interface and Tribology III,Technical Program of Oral Presentations)

A finite element model of a hard disk drive (HDD) is developed to investigate the transient response of an operational HDD subject to shock and vibration. The air bearing stiffness of the head disk interface is determined from a finite element solution of the Reynolds equation and approximated with linear springs. The structural response is analyzed for several types of sliders with a wide range of air bearing stiffness. Results show the response of the head-disk interface subject to shock and the modes excited by vertical and lateral vibrations of the HDD.

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Head–disk interface (HDI) degradation risk reduction in hard disk drive (HDD) during thermal asperity (TA) track follow mapping and seeking

Microsystem Technologies ◽

10.1007/s00542-020-05170-4 ◽

2021 ◽

Author(s):

Abhishek Srivastava ◽

Bernd Lamberts ◽

Karthik Venkatesh ◽

Rahul Rai ◽

Ning Li ◽

...

Keyword(s):

Risk Reduction ◽

Hard Disk Drive ◽

Hard Disk ◽

Disk Drive ◽

Head Disk Interface ◽

Disk Interface

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Optimization of Air Bearing Contours for Shock Performance of a Hard Disk Drive

Magnetic Storage Symposium: Frontiers of Magnetic Hard Disk Drive Tribology and Technology ◽

10.1115/2003-trib-342 ◽

2003 ◽

Cited By ~ 1

Author(s):

Eric M. Jayson ◽

Frank E. Talke

Keyword(s):

Hard Disk Drive ◽

Hard Disk Drives ◽

Hard Disk ◽

Disk Drive ◽

Element Model ◽

Time Dependent ◽

Air Bearing ◽

Disk Interface ◽

Shock Response ◽

Shock Event

Hard disk drives must be designed to withstand shock during operation. Large movements of the slider during shock impulse can cause reading and writing errors, track misregistration, or in extreme cases, damage to the magnetic material and loss of data. The design of the air bearing contour determines the steady state flying conditions of the slider as well as dynamic flying conditions, including shock response. In this paper a finite element model of the hard disk drive mechanical components was developed to determine the time dependent forces and moments applied to the slider during a shock event. The time dependent forces and moments are applied as external loads in a solution of the dynamic Reynolds equation to determine the slider response to a shock event. The genetic algorithm was then used to optimize the air bearing contour for optimum shock response while keeping the steady flying conditions constant. The results show substantial differences in the spacing modulation of the head/disk interface after a shock as a function of the design of the air bearing contour.

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A Method to Reduce Head-Disk Interface (HDI) Degradation Risk During Thermal Asperity (TA) Mapping in a Hard Disk Drive

ASME 2020 29th Conference on Information Storage and Processing Systems ◽

10.1115/isps2020-1960 ◽

2020 ◽

Author(s):

Abhishek Srivastava ◽

Rahul Rai ◽

Karthik Venkatesh ◽

Bernhard Knigge

Keyword(s):

Hard Disk Drive ◽

Bias Voltage ◽

Disk Drive ◽

Test Time ◽

Head Disk Interface ◽

Disk Interface ◽

Height Control ◽

Contact Sensor ◽

Fly Height ◽

Sample Set

Abstract One of the issues in thermal asperity (TA) detection using an embedded contact sensor (ECS) is the degradation caused to the read/write elements of the head while interacting with the TA. We propose a method to reduce such head-disk interaction (HDI) during TA detection and classification by flying higher at low thermal fly-height control (TFC) power, which minimizes the interaction of the TA with the head. The key idea is to scan the head at higher fly height, but with higher ECS bias voltage. Initial experiments have shown that the TA count follows a negative cubic relationship with the backoff at various bias levels, and that it follows a square relationship with bias at various backoff levels. Using a sample set, the calibration curves i.e. the golden relationship between these parameters can be established. Using these, one can start the TA detection at the highest backoff and high ECS bias, and start to estimate the nominal TA count. By mapping out these TAs and ensuring the head does not fly over them again to prevent HDI, the fly height can then be lowered, and the rest of the TA cluster can be scanned. Following this method iteratively, the entire TA cluster can be mapped out with minimal interaction with the head. Although this method entails an increase in the test time to detect and map all TAs, compared to detecting them with TFC being on, this can help improve the reliability of the drive by protecting the sensitive read/write elements especially for energy assisted recording from HDI.

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