Contact Take-Off Characteristics of Proximity Recording Air Bearing Sliders in Magnetic Hard Disk Drives

1999 ◽  
Vol 121 (4) ◽  
pp. 948-954 ◽  
Author(s):  
Yong Hu
Keyword(s):  
Hard Disk Drives ◽  
Air Bearing ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Taper Angle ◽  
Wear Factor ◽  
Disk Interface ◽  
Partial Contact ◽  
Magnetic Hard Disk ◽  
Wear Law

A partial contact air bearing model and Archard’s wear law are used to investigate the air bearing and wear characteristics of proximity recording sliders during a take-off process. The air bearing pitch torque, pitch and contact force are used to characterize the contact take-off process. In addition, the wear factor derived from the Archard’s wear law is employed to measure the take-off performance. The results indicate the existence of two distinct take-off stages: a period of rapidly increasing pitch preceding a relatively steady take-off event. The proper range of taper angle and step height, which produce a rapid initial pitch increase and steady subsequent take-off as well as less wear in the head/disk interface, are determined through simulation. While the simulation results demonstrate the negligible effect of crown height on the rate of the initial pitch increase, larger crown values are shown to yield higher pitch and smaller wear in the head/disk interface during the take-off process. In summary, the partial contact air bearing simulation and the wear factor calculation of the take-off process, developed in this study, offers a fast and accurate analytical tool to optimize ABS design for the fast take-off performance.

Boundary Effect on Particle Motion in the Head Disk Interface

2007 ◽  
Author(s):  
Nan Liu ◽  
David B. Bogy
Keyword(s):  
Drag Force ◽  
Particle Motion ◽  
Boundary Effect ◽  
Hard Disk Drives ◽  
Areal Density ◽  
Air Bearing ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Bearing Surface ◽  
Disk Interface

Simulation of particle motion in the Head Disk Interface (HDI) helps to understand the contamination process on a slider, which is critical for achieving higher areal density of hard disk drives. In this study, the boundary effect—the presence of the slider and disk—on particle motion in the HDI is investigated. A correction factor to account for this effect is incorporated into the drag force formula for particles in a flow. A contamination criterion is provided to determine when a particle will contaminate a slider. The contamination profile on a specific Air Bearing Surface is obtained, which compares well with experiments.

Novel Ultra-Sensitive Air Bearing Excitation Based Resonance Contact Detection in Heat Assisted Magnetic Recording (HAMR)

2017 ◽  
Author(s):  
Sukumar Rajauria ◽  
Erhard Schreck ◽  
Robert Smith
Keyword(s):  
Acoustic Signal ◽  
Near Field ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Contact Detection ◽  
Air Bearing ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Disk Interface ◽  
At Resonance

Resonance based enhanced contact detection is investigated at high sliding head-disk interface of hard disk drives. Acoustic signal arising from the contact in between the head and the disk is dominated by the resonance of the head air bearing frequencies. We show that modulation the head at resonance during the contact enhances greatly the acoustic signal generated during the contact between the head and the disk. As an application for HAMR HDDs, we used this scheme to detect the contact in between the near field transducer (NFT) and the disk which so far has been elusive.

The Physical Effects of Intra-Drive Particulate Contamination on the Head-Disk Interface in Magnetic Hard Disk Drives

1999 ◽  
Vol 121 (2) ◽  
pp. 352-358 ◽  
Author(s):  
Kenneth J. Altshuler ◽  
Joshua C. Harrison ◽  
Evelyn Ackerman
Keyword(s):  
Surface Characterization ◽  
Hard Disk Drives ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Contributing Factors ◽  
Physical Damage ◽  
Track Width ◽  
Disk Interface ◽  
Particulate Contamination ◽  
Magnetic Hard Disk

The physical damage at the Head-Disk Interface (HDI), caused by common ceramic particles found in the manufacturing environments of the heads and disks in hard magnetic disk drives, is reported. The need for this study arises from industry wide reliability problems due to particulate induced damage at the HDL The intent of this study is to characterize the head/disk damage caused by 1 μm diamond, 1–2 pm Tie particles, 0.2–1 μm alumina particles, the alumina and TiC grains sintered to make Al-TiC (the slider body), and sputtered alumina. These particles were introduced to the HDI in over thirty disk drives. The drives were then made to perform magnetic recording and retrieval operations for known data sequences, with the resultant reading errors tabulated. After the functional testing, the drives were opened and resulting damage was examined with a number of surface characterization tools. This study confirms that the severity of problems with the read-back signal, caused by particle damage, has an inverse relationship with the magnetic track width. In addition, the harshness of physical damage to the HDI has a positive relationship with particle hardness. Finally, particle shape and size can be contributing factors in damaging the HDL.

Numerical Investigation of Bouncing Vibrations of a Partial Contact Slider

2007 ◽  
Author(s):  
Du Chen ◽  
David D. Bogy
Keyword(s):  
Hard Disk Drives ◽  
Disk Surface ◽  
Air Bearing ◽  
Nonlinear Dynamic Model ◽  
Frequency Spectra ◽  
Disk Interface ◽  
Partial Contact ◽  
Adhesion Contact ◽  
Contact Situation ◽  
Contact Slider

A nonlinear dynamic model is developed to analyze the bouncing vibration of a partial contact air bearing slider, which is designed for the areal recording density in hard disk drives of 1 Tbit/in2 or even higher. In this model the air bearing with contact is modeled using the generalized Reynolds equation modified with the Fukui-Kaneko slip correction and a new second order slip correction for the contact situation [1]. The adhesion, contact and friction between the slider and the disk are also considered in the model. It is found that the disk surface roughness, which moves into the head disk interface (HDI) as the disk rotates, excites the bouncing vibrations of the partial contact slider. The frequency spectra of the slider’s bouncing vibration have high frequency components that correspond to the slider-disk contact.

Wear Characteristics of Padded Air Bearing Sliders During a Contact Take-Off Process

1999 ◽  
Vol 122 (3) ◽  
pp. 628-632 ◽  
Author(s):  
Yong Hu
Keyword(s):  
New Technologies ◽  
Interface Roughness ◽  
Wear Volume ◽  
Air Bearing ◽  
Wear Factor ◽  
Wear Characteristics ◽  
Disk Interface ◽  
Force Profile ◽  
Bearing Design ◽  
Wear Law

The pressing and challenging demand for resolving the stiction/glide-height conflict, driven by today’s ever decreasing head/disk spacing, forces us to constantly search for new technologies. One of them is padding the slider’s air bearing surface. Although the padded air bearing sliders can significantly reduce the stiction, the wear of these landing pads becomes a central issue. This paper attempts to analytically predict the wear characteristics of the landing pads during a contact take-off process. A wear factor derived from the adhesive wear law is employed to measure the wear extent of the landing pads. The contact force profile and wear factor of each pad are calculated through the partial contact air bearing simulation of a slider’s take-off process. It is found that the rear pad wears an order magnitude more than the leading pads. The wear volume of the rear pad increases exponentially with pad height, interface roughness and altitude. Raising the leading pads alone slightly reduces the wear of the rear pad. Placing the rear pad away from the slider’s trailing edge, however, substantially alleviates the wear of the rear pad. Finally, a lightly textured pad/disk interface decreases the pads’ wear to a minimum value for a given padded air bearing design. [S0742-4787(00)01903-2]

On the Touchdown-Takeoff Hysteresis Observed at the Head-Disk Interface in Hard Disk Drives

2005 ◽  
Author(s):  
Rohit P. Ambekar ◽  
David B. Bogy
Keyword(s):  
Experimental Approach ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Intermolecular Forces ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Contributing Factors ◽  
Factors Affecting ◽  
Disk Interface

The touchdown-takeoff velocity hysteresis observed in hard disk drives during CSS or L/UL tests is analyzed using an experimental approach. Tests similar to L/UL were conducted for different slider-disk combinations at different humidities. Factors affecting the touchdown and takeoff velocity were identified on the basis of their domain of operation. It is concluded that the intermolecular forces and meniscus forces are contributing factors to hysteresis, which is also influenced by disk topography and slider dynamics.

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