Superlubricity Relevant in Hard Disk Drive Applications

2016 ◽  
Author(s):  
Shou-Mo Zhang ◽  
Cuong-C. Vu ◽  
Qun-Yang Li ◽  
Norio Tagawa ◽  
Quan-Shui Zheng
Keyword(s):  
Temperature Dependence ◽  
Hard Disk Drive ◽  
Large Scale ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Force Sensor ◽  
Lubricant Layer ◽  
Single Crystalline ◽  
Crystalline Graphite

Reduction of head-media spacing (HMS) keeps crucial during the increase of areal density of hard disk drives (HDD). The design of hard disk drive with a superlubric interface is reported with two schemes for HDI design to realize superlubricity. For the first scheme, the DLC layer is kept on the disk while removing the lubricant layer. The DLC layer on the transducer is replaced by graphene-like layer. The direct contact between head and disk could reduce the HMS to about 2.3 nm. For the second scheme, the DLC layer on disk is further replaced by graphene and the HMS could be reduced to below 1 nm. For the first scheme, the basic proof of concept experiments are conducted using micro-scale graphite island samples. Ultralow COF, with the average of 0.0344 on the interface of single crystalline graphite surface and DLC substrate is demonstrated by AFM. What’s more, the temperature dependence of friction between single crystalline graphite and DLC is measured by micro-force sensor mounted on micro-manipulator. The results show that heating helps to significantly decrease the friction. Desorption of contaminants along the interface is speculated to be the key mechanism for temperature dependence of friction. This work provides the concept of large-scale superlubricity relevant in HDD applications, which could be a promising technology to ultimately reduce HMS for future HDI development.

Optimization of Air Bearing Contours for Shock Performance of a Hard Disk Drive

2003 ◽  
Author(s):  
Eric M. Jayson ◽  
Frank E. Talke
Keyword(s):  
Hard Disk Drive ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Element Model ◽  
Time Dependent ◽  
Air Bearing ◽  
Disk Interface ◽  
Shock Response ◽  
Shock Event

Hard disk drives must be designed to withstand shock during operation. Large movements of the slider during shock impulse can cause reading and writing errors, track misregistration, or in extreme cases, damage to the magnetic material and loss of data. The design of the air bearing contour determines the steady state flying conditions of the slider as well as dynamic flying conditions, including shock response. In this paper a finite element model of the hard disk drive mechanical components was developed to determine the time dependent forces and moments applied to the slider during a shock event. The time dependent forces and moments are applied as external loads in a solution of the dynamic Reynolds equation to determine the slider response to a shock event. The genetic algorithm was then used to optimize the air bearing contour for optimum shock response while keeping the steady flying conditions constant. The results show substantial differences in the spacing modulation of the head/disk interface after a shock as a function of the design of the air bearing contour.

SHOCK RESPONSE OF THE CLAMPED DISK IN SMALL FORM FACTOR HARD DISK DRIVE

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1592-1597 ◽  
Author(s):  
BIN GU ◽  
DONGWEI SHU ◽  
BAOJUN SHI ◽  
GUOXING LU
Keyword(s):  
Finite Element ◽  
Form Factor ◽  
Hard Disk Drive ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Element Model ◽  
Small Form ◽  
Shock Response ◽  
Small Form Factor

As small form factor (one-inch and smaller) hard disk drives are widely used in portable consumer appliances and gadgets, their mechanical robustness is of greater concern. In the previous work, it is found that when the disk is more tightly clamped, it helps to decrease the shock response of the disk and then avoid the head slap. In this paper, the real boundary condition of the disk for a small form factor hard disk drive from Seagate is investigated numerically. The disk is clamped between the clamp and the hub. The shock response of the disk under a half-sine acceleration pulse is simulated by using the finite element method. In the finite element model, both contact between disk and clamp and contact between disk and hub are considered. According to the simulation results, how to decrease the shock response of the disk is suggested.

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.

Optimization of Air Bearing Contours for Shock Performance of a Hard Disk Drive

2005 ◽  
Vol 127 (4) ◽  
pp. 878-883 ◽  
Author(s):  
Eric M. Jayson ◽  
Frank E. Talke
Keyword(s):  
Hard Disk Drive ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Element Model ◽  
Time Dependent ◽  
Air Bearing ◽  
Disk Interface ◽  
Shock Response ◽  
Shock Event

Hard disk drives must be designed to withstand shock during operation. Large movements of the slider during a shock impulse can cause reading and writing errors, track misregistration, or in extreme cases, damage to the magnetic material and loss of data. The design of the air bearing contour determines the steady-state flying conditions of the slider as well as dynamic flying conditions, including shock response. In this paper a finite element model of the hard disk drive mechanical components was developed to determine the time dependent forces and moments applied to the slider during a shock event. The time-dependent forces and moments are applied as external loads in a solution of the dynamic Reynolds equation to determine the slider response to a shock event. The genetic algorithm was then used to optimize the air bearing contour for optimum shock response while keeping the steady flying conditions constant. The results show substantial differences in the spacing modulation of the head-disk interface after a shock as a function of the design of the air bearing contour.

Spindle Motor Simulator for Hard Disk Drive: A Design Tool for Predicting Spinup Time and Headroom Safety for High Volume Manufacturing

2016 ◽  
Author(s):  
Sandip D. Kulkarni ◽  
Nasim Mirnateghi ◽  
JiangHong Ding ◽  
Ashok Desai
Keyword(s):  
Hard Disk Drive ◽  
Large Scale ◽  
Failure Modes ◽  
Hard Disk ◽  
High Volume ◽  
Disk Drive ◽  
Spindle Motor ◽  
Design Tool ◽  
Model Parameters ◽  
Large Sample Size

This paper presents a novel simulator for hard disk drive (HDD) spindle motor, developed to accelerate motor design verification for large volume product by predicting spin-up time (a performance metric) and voltage headroom (an important reliability metric). The simulator comprises of a BLDC (brushless DC) spindle motor model, firmware block, and power device block. The simulator integrates physics-based model structures with more complex measurement-based behavioral aspects at various temperatures and speeds. All model parameters incorporate realistic environmental factors and part variations; simulation of large sample size of in silico drive design based on Monte Carlo (MC) selection of parameters yields theoretical results capable of predicting defective parts per million in field. The simulator uses a modular approach allowing changing of firmware settings, details of Power Large Scale Integration (PLSI), and motor mechanics, which are product specific. This simulator model can be used for feasibility assessment of new electromechanical designs, available design margins for motor selection and it is also a reliable tool to provide boundaries for firmware (FW) settings to avoid reaching failure modes.

Modeling and Simulation for Head/Disk Electromechanical Systems Interface During Load/Unload Process of a Hard Disk Drive

2016 ◽  
Author(s):  
Nasim Mirnateghi ◽  
Sandip D. Kulkarni ◽  
JiangHong Ding ◽  
Ashok Desai
Keyword(s):  
Hard Disk Drive ◽  
Large Scale ◽  
Voice Coil Motor ◽  
Hard Disk ◽  
Operating Mode ◽  
Disk Drive ◽  
Spindle Motor ◽  
Detailed Model ◽  
Feasibility Assessment ◽  
And Performance

This paper presents a novel design and reliability assessment simulator focusing on HDD (Hard Disk Drive)’s L/UL (Load and Unload) operations. The model is structured to incorporate theoretical effects of environmental factors, component variations, and temperature effects in addition to empirical dependencies on product operating mode. The simulator includes detailed model of VCM (Voice Coil Motor), spindle motor, PLSI (Power Large Scale Integration), and all other related components and their effects on the load and unload operations. The tool can be used for feasibility assessment of new electromechanical designs and available design margins, and it is also a reliable tool to provide accurate tunings for FW (firmware) Load, Unload, Emergency Unload and EPOR (Emergency Power Off Retract). The simulator is also capable of accurately estimating the potential DPPM (Defective Part Per Million) related to the various potential failures using latest statistical analysis. The predictions and performance reliability of the model have been verified experimentally through comparison with HDD product reliability test data.

scholarly journals Flying Instability due to Organic Compounds in Hard Disk Drive

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Koji Sonoda
Keyword(s):  
High Temperature ◽  
Hard Disk Drive ◽  
Organic Compounds ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Disk Interface

The influence of organic compounds (OCs) on the head-disk interface (HDI) was investigated in hard disk drives. The drives were tested at high temperature to investigate the influence of gaseous OC and to confirm if the gaseous OC forms droplets on head or disk. In the experiment, errors occurred by readback signal jump and we observed the droplets on the disk after full stroke seek operation of the drive. Our results indicate that the gaseous OC condensed on the slider and caused flying instability resulting in drive failure due to slider contact with a droplet of liquid OC. Furthermore, this study shows that kinetic viscosity of OC is an important factor to cause drive failure using alkane reagents.

Scratch Detection on Hard Disk Drive Media to Reduce Head Disk Interaction and Prevent Data Loss

2021 ◽  
Author(s):  
Karthik Venkatesh ◽  
Abhishek Srivastava ◽  
Rahul Rai ◽  
Bernhard Knigge
Keyword(s):  
Hard Disk Drive ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Growth Direction ◽  
Disk Drives ◽  
Data Loss ◽  
Defect Growth ◽  
Efficient Alternative ◽  
The Media

Abstract Accurately detecting irregularities in the media — thermal asperities and delamination — and mapping them out from further usage is critical to prevent data loss and minimize head disk interaction (HDI). Defect growth is a common concern in hard disk drives (HDD) and the immediate vicinity of media defects are also mapped out to provide sufficient protection against defect growth. A class of media defects that prove more complex to protect against defect growth is scratches on the media. Margining a media scratch involves filling in the gaps between the components of a scratch and margining the vicinity of the scratch in the defect growth direction. While Hough transform based techniques and deeplearning models have been developed to identify media patterns, they cannot be implemented in the hard disk drive firmware due to memory and computational limitations. Here, we present a computationally simple and efficient alternative to identify scratches on the media by combining clustering and an iterative parameter estimation to fit a line to the scratch in noisy conditions. The result is a method that is capable of modeling linear, spiral and parabolic scratches on a media and fill gaps in the scratch and extend the margining at either end of the scratch.

Online Identification of System Uncertainties Using Coprime Factorizations With Application to Hard Disk Drives

2015 ◽  
Author(s):  
Omid Bagherieh ◽  
Behrooz Shahsavari ◽  
Roberto Horowitz
Keyword(s):  
Hard Disk Drive ◽  
Closed Loop ◽  
Transfer Functions ◽  
Feedforward Control ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Estimation Algorithm ◽  
Disk Drive ◽  
Dual Stage ◽  
Coprime Factorizations

In hard disk drive (HDD) magnetic recording bit patterned media (BPM), data are written in predetermined paths. The deviation of these paths from the perfect circle is categorized as repeatable run-out (RRO) which needs to be tracked. An adaptive RRO following algorithm was developed in [1,2] in order to track the RRO. This algorithm uses models of the closed-loop sensitivity transfer functions, from the feedforward injection points to position error signal (PES), to estimate the feedforward control actions that are needed to track the RRO. The phase difference between these models and the actual transfer functions must be less than 90 degrees, in order to guarantee the convergence of the adaptive RRO following algorithm. The dual-stage actuators’ gains and resonance modes are affected by temperature variations, which in turn affect all closed loop sensitivity transfer functions. As a consequence, the 90-degree criteria may be violated unless these transfer functions are periodically updated. In this paper, the coprime factorizations method has been used to factorize and identify the uncertain part of the model instead of identifying the entire transfer function of the model. Experimental results conducted on a hard disk drive equipped with dual-stage actuation, confirm the effectiveness of the proposed estimation algorithm.

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