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Wang Y.,Xian Jiaotong University | Wang Y.,City University of Hong Kong | Wei X.,SAE Technologies Development Dongguan Co. | Zi Y.,Xian Jiaotong University | Tsui K.-L.,City University of Hong Kong
Shock and Vibration | Year: 2015

This paper investigated the instability of head-disk interface caused by the voice coil motor (VCM) end crashing the crash stop during the seeking of magnetic head. To make the whole process of that clear, an in situ measurement method based on maximum likelihood estimation and extended Kalman filter for seeking speed at component level was developed first and was then calibrated by a high speed camera. Given a crash between VCM end and crash stop that may be a consequence of the continuous increasing seeking speed, the seeking speed was carefully controlled by using our developed method to find a critical value that may induce vigorous head-disk interface instability. Acoustic emission sensor and laser Doppler vibrometer were used to capture the transient dynamic behaviors of magnetic head when the crash is happening. Damage analysis and mode identification were carried out to reveal the relationship between the damage patterns on disk surface and head dynamics. The results of this study are helpful to optimize the track seeking profile during the HDD operation, as well as the design of components such as head and head arm. © 2015 Yu Wang et al.

Wang G.-G.,Harbin Institute of Technology | Zhang H.-Y.,Harbin Institute of Technology | Zhou H.-F.,Harbin Institute of Technology | Kuang X.-P.,Harbin Institute of Technology | And 4 more authors.
Applied Surface Science | Year: 2010

There are higher technical requirements for protecting layer of magnetic heads and disks used in future high-density storage fields. In this paper, ultra-thin (2 nm thickness) tetrahedral amorphous carbon (ta-C) films were firstly prepared by filtered cathodic vacuum arc (FCVA) method, then a series of nitriding treatments were performed with nitrogen plasma generated using electron cyclotron resonance (ECR) microwave source. Here it highlighted the influence of nitrogen flow and applied substrate bias voltage on the structural characteristics of ta-C films during the plasma nitriding process. The chemical compositions, element depth distribution profiles, physical structures and bonding configurations of plasma-nitrided ta-C films were investigated by X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and UV-vis Raman spectroscopy. The experimental results show that the carbon nitride compounds (CNx) are formed in nitrogenated ta-C films in which the N content and its depth distribution depends on bias voltage to large extent rather than N2 flow. The N content of nitrogenated ta-C films can reach 16 at.% for a substrate bias of -300 V and a N2 flow of 90 sccm. With increasing nitrogen content, there is less G peak dispersion and more ordering of structure. Furthermore, appropriate nitriding treatment (substrate bias: -100 V, N2 flow: 150 sccm) can greatly increase the fraction of sp3 and sp3C-N bonds, but the values begin to fall when the N content is above 9.8 at.%. All these indicate that suitable ECR-assisted microwave plasma nitriding is a potential modification method to obtain ultra-thin ta-C films with higher sp3 and sp3C-N fractions for high-density magnetic storage applications. © 2009 Elsevier B.V. All rights reserved.

SAE Technologies Development Dongguan Co. | Date: 2011-06-27

A bonding method of row bars comprises step (1), attaching a flexible member on a flat bottom surface of a pressurized member; step (2), applying a wax layer on a support surface of a support device; step (3), disposing a row bar on the support surface with the wax layer; and step (4), controlling the pressurized member to fall down, so as to press and even out the row bar. The present invention can make the row bar obtain a desired bending degree that is beneficial to the subsequent lapping process, and in turn, improve the quality of the sliders produced from the row bar, and finally improve the read/write performance of the sliders.

SAE Technologies Development Dongguan Co. | Date: 2013-05-06

A flexure for a suspension of a head gimbal assembly includes a substrate layer, a dielectric layer formed thereon, a conducting layer formed on the dielectric layer, and an insulating cover layer covered on the conducting layer, wherein at least one window is configured at a surface of the insulating cover layer thereby a portion of the conducting layer is exposed, and an antistatic adhesive is adhered to at least one side wall of the window and contacted with the conducting layer. The new structure of the flexure can avoid or eliminate electro-static discharges enduringly without dipping water. A head gimbal assembly and a disk drive unit with the same, a manufacturing method for the flexure are also disclosed.

Zhao D.,SAE Technologies Development Dongguan Co. | Wei X.,SAE Technologies Development Dongguan Co. | Liu B.,SAE Technologies Development Dongguan Co. | Wang Y.,City University of Hong Kong | And 2 more authors.
Applied Mechanics and Materials | Year: 2013

This paper presents an investigation of spacing fluctuation characterization (SFC) of Hard Disk Drive (HDD) using thermal asperity (TA) sensor. Firstly, the spacing fluctuation monitored by TA sensor is correlated with that monitored by a Laser Doppler Vibrometer (LDV). Secondly, a series of experiments are conducted to study the factors affecting the spacing fluctuation, including disk distortion, head crown sensitivity, ZH sensitivity. Good disk assembly and small crown sensitivity and ZH sensitivity will be helpful to reduce spacing fluctuation. © (2013) Trans Tech Publications, Switzerland.

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