Investigation of Slider Dynamics and Tribology of the Head-disk Interface PDF Download

Author: Saurabh K. Deoras
Publisher:
ISBN:
Category :
Languages : en
Pages : 424

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Author: Jianfeng Xu
Publisher:
ISBN:
Category :
Languages : en
Pages : 215

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Book Description
This thesis presents experimental and theoretical studies of the characteristics of the head/disk interface at very low flying height. The study starts with a discussion of the tribological background of the head/disk interface and presents a review of the literature related to studies of the head/disk interface. Then, mechanical scaling laws for hard disk drives are discussed. Numerical results for failure inception of brittle and ductile hard disks due to high shock levels are presented. An experimental setup for measuring slider dynamics in five degrees-of-freedom (DOF) is presented. This is followed by experimental studies of slider vibrations due to slider/disk contacts. Thereafter, a study of slider vibrations due to write-head induced "thermal" pole-tip-protrusion is presented. Numerical simulations of slider vibrations are compared with experimental results. A method for measuring the magnetic spacing based on the read-back signal is presented. Finally, the results of this thesis are summarized and directions for future research are given.

Author: Vijay Prabhakaran
Publisher:
ISBN:
Category : Magnetic recorders and recording
Languages : en
Pages : 436

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Author: YUNG-KAN CHEN
Publisher:
ISBN:
Category :
Languages : en
Pages : 125

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Book Description
The magnetic recording hard disk drive has been one of the most important storage strategies since 1956. Among all storage solutions, hard disk drives possess the unrivaled advantageous combination of storage capacity, speed, reliability and cost over optical strategies and flash memory. Unlike other storage solutions, hard disk drives utilize a mechanical interface to perform the magnetic read/write process, and therefore its success relies heavily on the stability of the head-disk interface (HDI) which is composed of a magnetic transducer carried by an air bearing slider, an air gap of a few nanometers thick, and a disk surface coated with multiple layers of molecularly-thin films. This dissertation addresses the physics of the interface in terms of contact detection, lubricant modulation and wear. Contact detection serves as one of the core requirements in HDI reliability. The writing process demands a strict spacing control, and its accuracy is based on a proper choice of a contact reference from slider dynamics and therefore the heads’ signal. While functioning in a real drive the only feedback signal comes from sensors neighboring the read-write transducer, and a high speed head-disk contact is associated with complex structural responses inherent in an air-bearing/suspension/lubricant system that may not be well explained solely by magnetic signals. Other than studying the slider-disk interaction at a strong interplay stage, this dissertation tackles the contact detection by performing component-level experimental and simulation studies focusing on the dynamics of air-bearing sliders at disk proximity. The slider dynamics detected using laser Doppler vibrometry indicates that a typical head-disk contact can be defined early as in-plane motions of the slider, which is followed by vertical motions at a more engaged contact. This finding confirms and is in parallel with one of the detection schemes used in commercial drives by magnetic signals. Lubricated disk surfaces play an important role in contact characteristics. As the nature of contact involves two mating surfaces, the modulation of disk lubricant films should be investigated to further understand the head-disk contact in addition to the slider dynamics. In this dissertation, the lubricant modulation is studied under various contact conditions with reference to slider dynamics. It is found that lubricant modulation can be directly associated with the slider’s dynamics in a location specific way, and its evolution is likely to affect the slider’s stable back-off fly-height as the contact is retracted. In addition to modulations at contact proximities, the lubricant response to passive flying and continuous contacting conditions are also addressed for different lubricant types and thicknesses. By integrating the observations from slider dynamics and lubricant modulations, we can establish an insightful understanding towards the transition from flying to the onset of contact. Head wear is also a concern when an erroneous contact detection occurs or imperfections from disk surface exists. Typically a protective diamond-like carbon (DLC) layer of thickness 1-2 nm is coated over the area of the reader/writer shields, and this film loss poses a threat to long term reliability. In this dissertation, in-situ methods of monitoring head wear is proposed in two ways. One method is to evaluate the touchdown power variations as a measure of spacing increase by DLC wear, which was verified by using Auger Electron Spectroscopy, and the other method studies the temperature contact sensor response to gauge mechanical wear. The later possesses the advantage of detecting wear without going into actual contact, but it may be affected by the location difference between the touchdown sensor and wear area.

Author: Stefan Weissner
Publisher:
ISBN:
Category : Computer storage devices
Languages : en
Pages : 324

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Author: Mike Suk
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 320

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Author:
Publisher:
ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 400

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Author: Min Yang
Publisher:
ISBN:
Category : Computer interfaces
Languages : en
Pages : 316

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Author: Qing Zhao
Publisher:
ISBN:
Category : Computer storage devices
Languages : en
Pages : 424

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Book Description

Author: Jianbin Luo
Publisher: Springer Science & Business Media
ISBN: 3642036538
Category : Technology & Engineering
Languages : en
Pages : 1040

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Book Description
"Advanced Tribology" is the proceedings of the 5th China International Symposium on Tribology (held every four years) and the 1st International Tribology Symposium of IFToMM, held in Beijing 24th-27th September 2008. It contains seven parts: lubrication; friction and wear; micro/nano-tribology; tribology of coatings, surface and interface; biotribology; tribo-chemistry; industry tribology. The book reflects the recent progress in the fields such as lubrication, friction and wear, coatings, and precision manufacture etc. in the world. The book is intended for researchers, engineers and graduate students in the field of tribology, lubrication, mechanical production and industrial design. The editors Jianbin Luo, Yonggang Meng, Tianmin Shao and Qian Zhao are all the professors at the State Key Lab of Tribology, Tsinghua University, Beijing.