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.

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.

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.

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.

Effect of Non-Operational Shock on Interaction Between Suspension Lift-Tab and Load/Unload Ramp

2005 ◽  
Author(s):  
Aravind N. Murthy ◽  
Eric M. Jayson ◽  
Frank E. Talke
Keyword(s):  
Hard Disk Drive ◽  
Failure Modes ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Areal Density ◽  
Disk Drive ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Disk Interface ◽  
Operational Shock

Most hard disk drives manufactured in the last few years have Load/Unload (L/UL) technology. As opposed to the Contact Start/Stop (CSS) technology, L/UL technology has the advantage of improved areal density because of more disk space availability and better shock performance. The latter characteristic has significant benefits during the non-operational state of the hard disk drive since head/disk interactions are eliminated and the head is parked on a ramp adjacent to the disk. However, even if head/disk interactions are absent, other failure modes may occur such as lift-tab damage and dimple separation leading to flexure damage. A number of investigations have been made to study the response of the head disk interface with respect to shock when the head is parked on the disk ([1], [2]). In this paper, we address the effect of non-operational shock for L/UL disk drives.

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