Effect of Lubricant on Flyability and Read-Write Performance in the Ultra-Low Flying Regime

2001 ◽  
Vol 124 (2) ◽  
pp. 259-265 ◽  
Author(s):  
Xiaoding Ma ◽  
David Kuo ◽  
Jianping Chen ◽  
Huan Tang ◽  
Jing Gui
Keyword(s):  
Acoustic Emission ◽  
Laser Doppler Vibrometer ◽  
Disk Surface ◽  
Laser Doppler ◽  
The Other ◽  
Flying Height ◽  
Magnetic Spacing ◽  
Instability Characteristic ◽  
Step Thickness

The effect of lubricant on flyability and read-write performance in ultra-low flying regime has been studied over the disks with lubricant on one half of disk surface thicker than the other half. The dynamics of a slider was monitored using Acoustic Emission (AE) and Laser Doppler Vibrometer (LDV). An instability characteristic of a slider flying over the thick lubricant region has been observed and this instability intensifies as flying height decreases and the step thickness increases. After the slider flies over the disks, it has been found that lubricant re-distribution occurs as lubricant is “carried” by the flying slider from the thick lubricant region and deposited onto the thin lubricant region. Possible mechanisms were discussed to explain the observations. Finally, recording tests were performed and the magnetic spacing loss due to the lubricant steps was estimated.

A Scanning Method to Study the Influence of Roughness, Microwaviness, and Lubricant Thickness Variation on Slider Dynamics

2005 ◽  
Author(s):  
Maik Duwensee ◽  
Bernhard E. Knigge ◽  
Peter Baumgart ◽  
Frank E. Talke
Keyword(s):  
Acoustic Emission ◽  
Disk Surface ◽  
Flying Height ◽  
Thickness Variation ◽  
Emission Measurement ◽  
Lubricant Thickness ◽  
Scanning Method ◽  
Displacement Maps ◽  
Acoustic Emission Measurement ◽  
A Current

Flying height modulation maps and microwaviness maps are obtained by using laser Doppler vibrometry (LDV) and acoustic emission (AE) transducers which are moved radially over the complete disk surface. The sensitivity of the acoustic emission measurement is improved by applying a current to the write element, thereby increasing pole tip protrusion. Disk and slider displacement maps are obtained using a radially scratched disk. Acoustic emission maps are presented for a scratched disk and for a non-scratched disk. For the non-scratched disk, AE maps are obtained with an inactive and active write element.

Experimental Study of Suspension and Slider Vibrations Measured by Laser Doppler Vibrometer

2013 ◽  
Author(s):  
Tatsuhiko Nishida ◽  
Masao Hanya
Keyword(s):  
Hard Disk Drives ◽  
Laser Doppler Vibrometer ◽  
Vertical Direction ◽  
Servo System ◽  
Voice Coil Motor ◽  
Laser Doppler ◽  
Track Width ◽  
Recording Density ◽  
Magnetic Spacing ◽  
Dual Stage

The magnetic spacing of Hard Disk Drives (HDD) needs to be reduced for high recording density. On the other hand, it is necessary to prevent contact between the slider and disk for reliability of HDDs. Various research was carried out for the flying stability of the slider [1–3]. Furthermore, the magnetic track width also needs to be narrowed for high recording density. The Dual Stage Actuator (DSA) servo system is used for high positioning accuracy [4]. The DSA servo system uses a piezoelectric actuator on a suspension in addition to Voice Coil Motor (VCM). In this study, we measured vibrations to the slider and suspension caused by the PZT and VCM actuations. Two Laser Doppler Vibrometers (LDV) were used for the measurement. Moreover, we performed a numerical analysis to estimate the roll moment of the Air Bearing Surface (ABS) of the slider caused by PZT actuation. As results, we confirmed that the ABS vibrated in vertical direction due to the suspension’s vibrations caused by PZT and VCM actuations.

An Investigation of Slider Vibrations in Near Contact Recording Using a Digital Laser Doppler Vibrometer

2003 ◽  
Vol 125 (3) ◽  
pp. 571-575 ◽  
Author(s):  
Shinji Yonemura ◽  
Lin Zhou ◽  
Frank E. Talke
Keyword(s):  
Noise Level ◽  
Laser Doppler Vibrometer ◽  
Laser Doppler ◽  
Flying Height ◽  
Design Consideration ◽  
Skew Angle ◽  
Torsion Mode ◽  
And Control ◽  
Contact Recording ◽  
Important Design

At a flying height of 10 nanometers, contacts between slider and disk are likely to occur, and control of contact-induced slider vibrations is an important design consideration. In this study, slider vibrations during contact are investigated using a digital laser Doppler vibrometer (LDV). The noise level of the digital interferometer is compared with that of a conventional analog LDV. In addition, acoustic emission (AE) sensors are used to evaluate the contact behavior of the slider. A comparison of AE and LDV data is performed. The results show that the noise level of the digital LDV is lower than that of the analog LDV, and that suspension sway mode vibrations and torsion mode vibrations are excited during contact as a function of the skew angle.

Temperature coefficient of Young’s modulus of silver microwhiskers determined by a laser Doppler vibration measurement

2021 ◽  
pp. 2150350
Author(s):  
Yijun Jiang ◽  
Mingyuan Lu ◽  
Shiliang Wang ◽  
Han Huang
Keyword(s):  
Temperature Dependence ◽  
Temperature Coefficient ◽  
Single Crystals ◽  
Young’S Modulus ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Young's Modulus ◽  
Laser Doppler Vibrometer ◽  
Laser Doppler ◽  
Vibration Measurement

Temperature dependence of Young’s modulus of Ag microwhiskers was determined by a laser Doppler vibrometer. The Ag whiskers with diameters in sub-microns were synthesized by the use of physical vapor deposition (PVD). They have a five-fold twinned structure grown along the [1 1 0] direction. The temperature coefficient of Young’s modulus was measured to be [Formula: see text] ppm/K in the range of 300 K to 650 K. The measured values are very close to the reported values of [Formula: see text] ppm/K for bulk Ag single crystals. This finding can benefit the design of Ag-based micro/nano-electromechanical systems or micro/nano-interconnectors operated at elevated or lowered temperatures.

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