The Double Dimple Magnetic Recording Head Suspension and Its Effect on Fly Height Variability

1995 ◽  
Vol 117 (2) ◽  
pp. 267-271
Author(s):  
J. C. Harrison ◽  
K. P. Hanrahan
Keyword(s):  
Degrees Of Freedom ◽  
Initial Conditions ◽  
Flying Height ◽  
Air Bearing ◽  
Bearing Surface ◽  
Percent Reduction ◽  
Recording Head ◽  
Head Gimbal Assembly ◽  
Magnetic Recording Head ◽  
Fly Height

A gimbal forming modificaton is presented which, when implemented, leads to significant reduction in air bearing surface (ABS) static attitude and flying height variability within head-gimbal assembly (HGA) populations. The modification requires no additional parts or steps in the manufacture of the suspension assembly. An experimental test of the concept is described, along with the procedure on which it is based. The resulting reduction in product variability is obtained without measurement of (or tailoring to) the initial conditions of the constitutive parts of each HGA. A ≈ 50 percent reduction in static attitude variability, and a ≈ 33 percent reduction in flying variability, was experimentally shown to result from the adoption of the Double Dimple design concept, in all flying degrees of freedom.

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.

An Optimization Method for Design of Subambient Pressure Shaped Rail Sliders

1999 ◽  
Vol 121 (3) ◽  
pp. 575-580 ◽  
Author(s):  
Dong-Hoon Choi ◽  
Tae-Sik Kang
Keyword(s):  
Design Methodology ◽  
Optimization Method ◽  
Flying Height ◽  
Air Bearing ◽  
Bearing Surface ◽  
Programming Technique ◽  
Design Synthesis ◽  
Method Of Feasible Directions ◽  
Design Variables ◽  
Simulation Results

This study proposes a design methodology for determining configurations of subamient pressure shaped rail sliders by using a nonlinear programming technique in order to meet the desired flying characteristics over the entire recording band. The desired flying characteristics considered in this study are to minimize the variation in flying height from a target value, to keep the pitch angle within a suitable range, and to ensure that the outside rail flies lower than the inside rail even with the roll distribution due to manufacturing process. The design variables selected are recess depth, geometry of the air bearing surface, and pivot location in the transverse direction of the slider. The method of feasible directions in Automated Design Synthesis (ADS) is utilized to automatically find the optimum design variables which simultaneously meet all the desired flying characteristics. To validate the suggested design methodology, a computer program is developed and applied to a 30 percent/15 nm twin rail slider and a 30 percent/15 nm tri-rail slider. Simulation results for both sliders demonstrated the effectiveness of the proposed design methodology by showing that the flying characteristics of the optimally designed sliders are enhanced in comparison with those of the initial ones.

scholarly journals Parametric Investigations at the Head-Disk Interface of Thermal Fly-Height Control Sliders in Contact

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Sripathi V. Canchi ◽  
David B. Bogy ◽  
Run-Han Wang ◽  
Aravind N. Murthy
Keyword(s):  
Hard Disk Drives ◽  
Air Bearing ◽  
Head Disk Interface ◽  
Bearing Surface ◽  
Surface Design ◽  
Disk Interface ◽  
Height Control ◽  
Experimental Findings ◽  
And Control ◽  
Fly Height

Accurate touchdown power detection is a prerequisite for read-write head-to-disk spacing calibration and control in current hard disk drives, which use the thermal fly-height control slider technology. The slider air bearing surface and head gimbal assembly design have a significant influence on the touchdown behavior, and this paper reports experimental findings to help understand the touchdown process. The dominant modes/frequencies of excitation at touchdown can be significantly different leading to very different touchdown signatures. The pressure under the slider at touchdown and hence the thermal fly-height control efficiency as well as the propensity for lubricant pickup show correlation with touchdown behavior which may be used as metrics for designing sliders with good touchdown behavior. Experiments are devised to measure friction at the head-disk interface of a thermal fly-height control slider actuated into contact. Parametric investigations on the effect of disk roughness, disk lubricant parameters, and air bearing surface design on the friction at the head-disk interface and slider burnishing/wear are conducted and reported.

Flying Height Deviation Measurements at Ultra Low Fly Heights

2003 ◽  
Author(s):  
Dongman Kim
Keyword(s):  
Attitude Change ◽  
Flying Height ◽  
Air Bearing ◽  
Size Measurement ◽  
Feature Size ◽  
Head Gimbal Assembly ◽  
Air Bearing Slider ◽  
Calibration Techniques ◽  
Flying Attitude

The flying height tester contribution to flying height tolerance is investigated with different calibration techniques in this study. The flying attitude change in head gimbal assembly (HGA) by supplying writing current is discussed along with newly proposed methodology for feature size measurement on the air bearing slider (ABS) using a flying height tester.

Slider Curvature Control through Dicing Process

2011 ◽  
Vol 103 ◽  
pp. 92-96
Author(s):  
Chirawat Srisang ◽  
Krisda Siangchaew ◽  
Jakrapong Kaewkhao ◽  
Artorn Pokaipisit ◽  
Pichet Limsuwan
Keyword(s):  
Feed Rate ◽  
Cutting Speed ◽  
Air Bearing ◽  
Bearing Surface ◽  
Separation Processes ◽  
Slider Air Bearing ◽  
Fly Height ◽  
Curvature Control

In the manufacturing of slider, the final step is a dicing process of the rowbars into individual slider. However, in all slider separation processes seem to affect the curvature of the slider air bearing surface (ABS). As a result, the change in ABS crown and camber which can significantly affect the fly height of the slider. This paper investigates the influence of three types of dicing process, with the same feed rate and cutting speed, on the ABS curvature.

Multi-Resolution HDD Contact Detection Technique for Low SNR Applications

2013 ◽  
Author(s):  
Antanas Daugela ◽  
Jon D. Trantham ◽  
Srinivas Tadepalli
Keyword(s):  
High Volume ◽  
Flying Height ◽  
Air Bearing ◽  
Recording Head ◽  
Low Snr ◽  
Enhanced Sensitivity ◽  
High Volume Production ◽  
Embedded Particles ◽  
Short Product ◽  
Passive Acoustic

A quick and reliable active flying height calibration is critical in today’s hard disc drive short product development and high volume production cycles. In addition to the servo signals, passive HDI acoustic and proximity monitoring techniques are tracking equilibrium of the head gimble assembly and air bearing modes. Passive acoustic HDI monitoring had been proven to be capable in active head protrusion detection applications [1] where derived passive and active Air Bearing flying profiles help to set active flying clearance. With enhanced sensitivity, passive acoustic techniques such as AE can detect embedded particles [2]. The drawback of this technique is that noisy HDD environment causes loss of detectability of the useful AE signal [3]. Special attention has to be paid for extracting desirable HDI information. On the other hand, recording head based proximity probes are immune to torsional HDI modes and operate on pitch mode induced modulation. Advanced HDD today uses a combination of recording head based proximity sensors that are designed to sense HDI modulation at close proximity to the disc. It has to be pointed out that interpretation of proximity probe contact signatures always has been challenging.

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

2004 ◽  
Author(s):  
Vineet Gupta ◽  
David B. Bogy
Keyword(s):  
Pitch Angle ◽  
Dynamic Performance ◽  
Hard Disk Drives ◽  
Intermolecular Forces ◽  
Flying Height ◽  
Air Bearing ◽  
Parametric Studies ◽  
The Stability ◽  
Hamaker Constants ◽  
Fly Height

Intermolecular and surface forces contribute significantly to the total forces acting on air bearing sliders for flying heights below 5nm. Their contributions to the total forces 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.

Flying Height Modulation Due to Disk Waviness of Sub-5 nm Flying Height Air Bearing Sliders

2002 ◽  
Vol 124 (4) ◽  
pp. 762-770 ◽  
Author(s):  
Brian H. Thornton ◽  
A. Nayak ◽  
D. B. Bogy
Keyword(s):  
Disk Drive ◽  
Flying Height ◽  
Mode Shapes ◽  
Air Bearing ◽  
Bearing Surface ◽  
Dynamic Effects ◽  
Complex Phase ◽  
Edge Response ◽  
Percent Decrease ◽  
Geometric Effects

Two new air bearing slider designs are presented for storage densities greater than 100 Gb/in2 in hard disk drive (HDD) applications. Their dynamic frequencies and mode shapes are characterized, and they are used to study the flying height modulation (FHM) over wavy disks due to geometric effects as opposed to dynamic effects. It is found that low pitch designs experience large FHM at wavelengths on the order of the length of the sliders to one-eighth the length of the sliders due to a complex phase shift in the sliders trailing edge response as compared to the disk waviness. FHM due to disk waviness wavelengths from 2 mm to 0.16 mm was found to be a function of the sliders’ attitude (pitch angle) and the air bearing surface (ABS) geometry (pressure distribution over the ABS). The results presented suggest that the pitch should be greater than 100 μrad for the ABS designs presented and attention needs to be focused on the ABS design and disk morphology to avoid unacceptable FHM. An ABS design was introduced to reiterate the findings on geometric FHM showing an 83 percent decrease in geometric FHM. The FHM due to geometric effects of the slider designs studied in this paper could possibly be predicted by the disk morphology alone.

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