Performance of Sliders Flying Over Discrete-Track Media

2007 ◽  
Vol 129 (4) ◽  
pp. 712-719 ◽  
Author(s):  
Jianhua Li ◽  
Junguo Xu ◽  
Yuki Shimizu
Keyword(s):  
Estimation Method ◽  
Simulation Method ◽  
Measured Data ◽  
Flying Height ◽  
Height Loss ◽  
Air Bearing ◽  
Slider Air Bearing ◽  
Discrete Track ◽  
Flying Attitude ◽  
Manufacturing Variation

A simulation method in which grooves are virtually distributed on the slider air bearing instead of on the grooved medium surface has been developed and used to investigate the performance of sliders flying over the surface of a discrete-track medium. The simulated flying height loss due to a discrete-track medium coincides well with the measured data, whereas the average-estimation method overestimates flying height loss. Among the characteristics of a slider flying over the surface of a discrete-track medium that were studied are the flying attitude, the effect of groove parameters on flying profile, and the flying height losses due to manufacturing variation and altitude. The results indicate that when a slider is flying over the surface of a discrete-track medium, it will have a higher 3σ of flying height, be more sensitive to altitude, and will have a greater flying height loss.

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.

Optimal Design of Slider Air-Bearing for Discrete Track Recording Technology

2009 ◽  
Vol 45 (5) ◽  
pp. 2296-2299
Author(s):  
Sang-Joon Yoon ◽  
Seok-Ho Son ◽  
Jihoon Kang ◽  
Hyunki Kim ◽  
Jingyoo Yoo ◽  
...  
Keyword(s):  
Optimal Design ◽  
Air Bearing ◽  
Recording Technology ◽  
Slider Air Bearing ◽  
Discrete Track

Slider Air Bearing Design Enhancements for High Speed Flexible Disk Recording

2005 ◽  
Vol 127 (3) ◽  
pp. 522-529 ◽  
Author(s):  
James White
Keyword(s):  
High Speed ◽  
Numerical Solutions ◽  
Hydrodynamic Pressure ◽  
Flying Height ◽  
Air Bearing ◽  
Mechanical Shock ◽  
Current Effort ◽  
Slider Air Bearing ◽  
Flexible Disk ◽  
Air Film

The current effort was motivated largely by the fact that computing and communication platforms are becoming more portable and mobile with increased demands for both speed and disk storage. This work makes use of an asymmetric opposed slider arrangement to provide both static and dynamic improvements to the recording head air bearing interface for high speed flexible disk applications. The combination of a longitudinally slotted rail opposed by an uninterrupted rail that functions as a noncontact hydrodynamic pressure pad causes the disk to deflect at the submicron level over critical areas of the slider interface. This allows the required static minimum flying height to be focused over the recording transducer while higher clearances are positioned elsewhere, resulting in minimized exposure to contact between slider and disk. The high stiffness and low flying height of the air film at the recording element together with the low stiffness and high flying height of the opposing air film provides a noncontact air bearing interface that is especially immune to mechanical shock. A computer code called FLEXTRAN was developed that provides both static and dynamic numerical solutions of the air bearing interface composed of two opposed gimbal mounted sliders loaded against a high speed flexible disk. Simulations of the asymmetric opposed slider configuration are presented and compared with those of other slider air bearing designs.

Simulating the Air Bearing Flying Height in a Humid Environment

2007 ◽  
Author(s):  
Shuyu Zhang ◽  
Brian Strom ◽  
Sungchang Lee ◽  
George Tyndall
Keyword(s):  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Flying Height ◽  
Test Cases ◽  
Air Bearing ◽  
Humid Environment ◽  
Bearing Design ◽  
Flying Attitude ◽  
Saturation Vapor

For a hard disk drive operating in a humid environment, the water vapor in the slider’s air bearing is typically compressed beyond its saturation vapor pressure, causing the vapor to condense. Consequently, the air bearing pressure decreases and the slider’s flying attitude adjusts to balance the forces from the suspension. A method for calculating this air bearing response to humid air is presented. Using one particular air bearing design as an example, several test cases are analyzed to illustrate the air bearing response for various temperatures and humidity levels. The calculated flying heights agree with those measured in commercial hard disk drives.

Identification of the Multiple Flying Heights in a Loading Process

2008 ◽  
Author(s):  
Shuyu Zhang ◽  
Mike Suk ◽  
George Tyndall
Keyword(s):  
Stable State ◽  
Disk Surface ◽  
Flying Height ◽  
Air Bearing ◽  
Loading Process ◽  
Flying Attitude

The slider of a Load/unload (LUL) drive can be loaded to a high flying stable state under certain conditions, which positions the read/write transducers much higher from the disk surface than the normal flying height (FH) and resulting in the issues in read or write. To avoid the issues caused by the high flying loading, it is necessary to find ways to recognize the existence of the high FH and eliminate it in the design stages. In this paper, we introduce a method that can identify the existences of the multiple FHs in loading process conveniently. The basic idea is to plot surfaces of air bearing forces in a domain of flying attitude, and then check if multiple FHs exist to generate the same air bearing forces that match the suspension forces. The analysis results indicate that the method is easy and efficient in identifying multiple FHs in loading process.

The Effect of the Accommodation Coefficient on Slider Air Bearing Simulation

1999 ◽  
Vol 122 (2) ◽  
pp. 427-435 ◽  
Author(s):  
Weidong Huang ◽  
David B. Bogy
Keyword(s):  
Flow Rate ◽  
Hard Disk Drives ◽  
Direct Simulation Monte Carlo ◽  
Accommodation Coefficient ◽  
Flying Height ◽  
Positive Pressure ◽  
Air Bearing ◽  
Unit Value ◽  
Slider Air Bearing ◽  
Molecular Gas Film Lubrication

In solving the slider air bearing problem, both the Molecular Gas-film Lubrication (MGL) model and the Direct Simulation Monte Carlo (DSMC) model require the accommodation coefficient as input. The accommodation coefficient represents the fraction of the air molecules that interact with solid boundaries in a diffusive manner. In general, the value 1 is used for the accommodation coefficient, which represents a fully diffusive reflection. However, in magnetic hard disk drives, the disk and slider surfaces are becoming ever smoother with different kinds of lubrication on the disk, while the temperature is becoming higher due to the faster spindle speed. Under these conditions the unit value of the accommodation coefficient may no longer be suitable. In order to understand the effect of the accommodation coefficient on the slider’s flying parameters, we used Kang’s new database for the Poiseuille flow rate Qp and Couette flow rate Qc to solve the modified Reynolds equation for two groups of sliders, e.g., negative and positive pressure sliders (“negative” refers to sliders with subambient pressure zones). The results show that, in general, the smaller the accommodation coefficient, the lower the flying height and pitch angle. Positive pressure sliders are more sensitive to the accommodation coefficient than are negative pressure sliders. The typical discrepancy in flying height is around 10%. Also, it is shown that for positive pressure sliders the lower the flying height, the larger the discrepancy percentage. [S0742-4787(00)00402-1]

Effects of Pitch Static Attitude and Roll Static Attitude on the Steady Performance of Air Bearing Sliders

2007 ◽  
Vol 129 (3) ◽  
pp. 689-694 ◽  
Author(s):  
Hong Zhu ◽  
David B. Bogy
Keyword(s):  
Flying Height ◽  
Air Bearing ◽  
Suspension Stiffness ◽  
Air Bearing Slider ◽  
Flying Attitude ◽  
Steady Performance

This paper addresses the effects of pitch static attitude (PSA) and roll static attitude (RSA) on air bearing slider steady performance, especially for ultralow flying height sliders. We performed simulations for three different low flying sliders with flying heights (FHs) of 7nm, 5nm, and 3.5nm using the static simulator code of the Computer Mechanics Laboratory. We found that PSA and RSA have quite significant effects on the steady performance of these air bearing slider designs, and the effect is more important the smaller the size and the lower the FH of the slider. We also investigated the effects of suspension stiffness on the air bearing sliders’ flying attitude (pitch and roll) and found that these effects are similar to those of PSA and RSA.

Flying Characteristics of the Transverse and Negative Pressure Contour (“TNP”) Slider Air Bearing

1997 ◽  
Vol 119 (2) ◽  
pp. 241-248 ◽  
Author(s):  
J. W. White
Keyword(s):  
Negative Pressure ◽  
Ambient Pressure ◽  
Flying Height ◽  
Air Bearing ◽  
Skew Angle ◽  
Disk Radius ◽  
Pressure Contour ◽  
Side Rail ◽  
Slider Air Bearing ◽  
Bearing Stiffness

The TNP contour air bearing slider is composed of oversized transverse pressure contour (TPC) outer rails and a central negative pressure (NP) cavity. The NP cavity is separated from the TPC rails by an ambient pressure reservoir which serves two functions. First, it prevents direct hydrodynamic interaction between the various component air bearing surfaces and thus, eliminates pressure distortion and dilution, common causes of problems related to flying height and roll angle control. Second, the ambient reservoir allows the TPC rails and NP cavity to be configured and dimensioned independently so that they will track each other with a nearly constant force difference, resulting in a flying height that has significantly reduced sensitivity to altitude change. The multi-function TPC sections of the outside rails are able to overcome the effects of a changing radius and wide skew angle variation over the disk radius as well as a changing vacuum load and asymmetry of the NP cavity pressure, in order to provide a truly constant low flying height over the entire data surface. The combination of a high air bearing stiffness and a gradually developing cavity vacuum as disk velocity increases produces a rapid slider take-off from the disk surface. Dynamic stability of the TNP slider air bearing is enhanced by the unusual combination of a high air bearing stiffness and high air film damping in each of the three slider excursion modes. Finally, the TNP slider experiences a reduced sensitivity of flying height to manufacturing and operational tolerances as compared to non-NP type sliders. The entire TNP slider air bearing is created by a two-etch process. A shallow etch creates the TPC sections and leading edge step. A deeper etch forms the NP cavity, ambient pressure reservoir, and outermost edge of each side rail.

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