Partial Contact Head-Disk Interface With Thermal Protrusion

2009 ◽  
Author(s):  
Du Chen ◽  
David B. Bogy
Keyword(s):  
Vibration Amplitude ◽  
Dynamic Performance ◽  
Flying Height ◽  
Air Bearing ◽  
Head Disk Interface ◽  
Dynamic Simulations ◽  
Disk Interface ◽  
Partial Contact ◽  
Thermal Protrusion ◽  
Bearing Design

A new partial contact head disk interface (HDI) with thermal protrusion is proposed for magnetic recording with densities of 1 Tbit/in2 and above. This HDI has the advantage of maintaining light contact between the slider and the disk, so that both the bouncing vibration amplitude and the contact force are small compared with a traditional partial contact HDI. The slider’s dynamic simulations are carried out to analyze the effect of various factors within the HDI on the slider’s dynamic performance, including the friction and adhesion between the slider and the disk, the track profile morphology of the disk and the air bearing design. It is found that the bouncing vibration amplitude can be reduced to the level of the flying height modulation (FHM) of a non-contact air bearing slider without thermal protrusion.

Air-Bearing Design Towards Highly Stable Head–Disk Interface at Ultralow Flying Height

2007 ◽  
Vol 43 (2) ◽  
pp. 715-720 ◽  
Author(s):  
Bo Liu ◽  
Shengkai Yu ◽  
Mingsheng Zhang ◽  
Leonard Gonzaga ◽  
Hui Li ◽  
...  
Keyword(s):  
Flying Height ◽  
Air Bearing ◽  
Head Disk Interface ◽  
Disk Interface ◽  
Bearing Design

Air-Bearing Design Towards Super Stable Head-Disk Interface

2006 ◽  
Author(s):  
Bo Liu ◽  
MingSheng Zhang ◽  
Yijun Man ◽  
Shengkai Yu ◽  
Gonzaga Leonard ◽  
...  
Keyword(s):  
Air Bearing ◽  
Head Disk Interface ◽  
Disk Interface ◽  
Bearing Design

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.

Nonlinear Thermal Protrusion and Slider Disk Contact Forces

2007 ◽  
Author(s):  
Bernhard Knigge ◽  
Andreas Moser ◽  
Jia-Yang Juang ◽  
Peter Baumgart
Keyword(s):  
Contact Force ◽  
New Technology ◽  
Hard Disk Drives ◽  
Contact Forces ◽  
Flying Height ◽  
Air Bearing ◽  
Thermal Protrusion ◽  
Trade Offs ◽  
Bearing Design ◽  
Heater Coil

Some of the recently shipped hard disk drives have a new technology to actively control the flying height between slider and disk. The slider to disk spacing is controlled by thermal protrusion actuation using a small heater coil which is located close to the read write element at the trailing end of the slider. By applying an electric current to the heater coil, the slider’s trailing end protrudes towards the disk and can be driven into contact with sufficiently high heating power. The contact force and the thermal protrusion efficiency is mainly controlled by air bearing design. In this paper we want to discuss the trade offs in air bearing design to achieve low contact force and high thermal actuation efficiency. We have done both numerical simulation and experimental measurements to investigate contact force and air bearing stiffness. Typically a softer air bearings will produce less contact force but usually exhibit worse flying height tolerances. We have found a nonlinear clearance change with applied heater power. At closer spacings, the pressure peak increases dramatically leading to reduced actuation efficiency. The actuation efficiency may also vary at different skew angles. For calibration purpose slider to disk touchdown requires contact. Due to different actuation efficiencies at different radii different contact forces are estimated.

Contact ABS Design Concepts

2002 ◽  
Author(s):  
Junguo Xu ◽  
Hidekazu Kohira ◽  
Shozo Saegusa
Keyword(s):  
Frequency Shift ◽  
Friction Force ◽  
Flying Height ◽  
Air Bearing ◽  
Head Disk Interface ◽  
Bearing Surface ◽  
Disk Interface ◽  
Design Concepts ◽  
Smooth Disk

The design of a head-disk interface for an ultra-low flying height was studied from the viewpoint of contact vibration. It is known that a super-smooth disk is necessary for a slider to fly at an ultra-low flying height; however, such a disk increases the friction force, which potentially increases the vibration of the slider. To solve this problem, the head-disk interface must be optimized to reduce this increased vibration. We found that the use of micro-texture on the air bearing surface can prevent contact vibration. Combining trimming with the use of a micro-texture was most effective in reducing contact vibration. A frequency-shift-damping slider was also found to damp vibration effectively.

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.

Effect of Intermolecular Forces on the Static and Dynamic Performance of Air Bearing Sliders: Part II—Dependence of the Stability on Hamaker Constant, Suspension Preload and Pitch Angle

2005 ◽  
Vol 128 (1) ◽  
pp. 203-208 ◽  
Author(s):  
Vineet Gupta ◽  
David B. Bogy
Keyword(s):  
Pitch Angle ◽  
Dynamic Performance ◽  
Hard Disk Drives ◽  
Intermolecular Forces ◽  
Flying Height ◽  
Total Force ◽  
Air Bearing ◽  
Force Increase ◽  
The Stability ◽  
Fly Height

Intermolecular and surface forces contribute significantly to the total forces acting on air bearing sliders for flying heights below 5 nm. Their contributions to the total force increase sharply with the reduction in flying height, and hence their existence can no longer be ignored in air bearing simulation for hard disk drives. Various experimentally observed dynamic instabilities can be explained by the inclusion of these forces in the model for low flying sliders. In this paper parametric studies are presented using a 3-DOF model to better understand the effect of the Hamaker constants, suspension pre load and pitch angle on the dynamic stability/instability of the sliders. A stiffness matrix is used to characterize the stability in the vertical, pitch, and roll directions. The fly height diagrams are used to examine the multiple equilibriums that exist for low flying heights. It has been found that the system instability increases as the magnitude of the van der Waals force increases. It has also been found that higher suspension pre load and higher pitch angles tend to stabilize the system.

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