Journal articles: 'Hard disk drive (HDD)'

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SUGAWARA, Nobuhiro, Katsuya HIRATA, and Jiro FUNAKI. "FLOW VISUALIZATION OF HARD DISK DRIVE." Journal of the Visualization Society of Japan 24, Supplement2 (2004): 51–54. http://dx.doi.org/10.3154/jvs.24.supplement2_51.

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Lin, Chen-Chi. "Finite Element Analysis of a Computer Hard Disk Drive Under Shock." Journal of Mechanical Design 124, no. 1 (October 1, 2000): 121–25. http://dx.doi.org/10.1115/1.1424299.

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Shock of computer hard disk drives (HDD) in both portable and desktop computers is a common problem. Shock of an HDD can occur during installing the HDD into the computer, HDD testing, HDD handling, and so forth. It is important to identify key design parameters to improve HDD shock performance. This paper presents the finite element studies of a HDD under a non-operational linear drop shock. A complete HDD model is built in ANSYS finite element package. GP commands are used to apply the preload and define the interface between the head and the disk. Shock pulses with different amplitudes and pulse widths are applied to the HDD. The minimum shock amplitude required to lift off the head from the disk is determined for different shock pulse width. Discrete Fourier Transform studies are used to identify critical frequency ranges for different shock pulse widths. The design guideline for the minimum space required between the swage plates and the disk is provided. The effects of drive base stiffness, disk thickness, actuator arm stiffness, and bearing stiffness on HDD shock performance are investigated.

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Mongkolwongrojn, Mongkol, and Kunchit Kuanoon. "Effects of Slider Geometry Change on Helium Filled HDD." Advanced Materials Research 971-973 (June 2014): 1210–13. http://dx.doi.org/10.4028/www.scientific.net/amr.971-973.1210.

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This paper describes the static characteristics of helium filled hard disk drive for a self-acting two rails flat slider gas bearing. Numerical scheme based on the finite difference with multi-grid multi-level technique were implemented for the ultra-low flying height sliders. The effect of slider geometry change in both crown and camber on flying height have been examined in this research work. The results show that the flying height change is significantly with a few nanometers change in crown and camber. The flying height of helium filled magnetic flat slider head equal to 3.5 nm at trailing edge. The spacing for helium filled hard disk drive is lower than 4 nm when compared with conventional air filled hard disk drive. The increase of slider crown, the flying height increases rapidly but the increase of slider camber, the flying height decreases continuously.

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Nebenzahl, L., R. Nagarajan, J. Wong, L. Volpe, and G. Whitney. "Chemical Integration and Contamination Control In Hard Disk Drive Manufacturing." Journal of the IEST 41, no. 5 (September 14, 1998): 31–35. http://dx.doi.org/10.17764/jiet.41.5.b3m3376867pj0232.

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As we approach the turn of the century, the demand for storage is rapidly increasing, fueled by multimedia and its associated applications. Hard disk drive (HDD) manufacturers continue to respond by chasing the areal density curve to provide higher capacity and higher performance disk drives. The required technology changes are expected to aggravate performance and reliability problems, such as stiction, associated with organic contamination; thermal asperities, associated with particulate contamination; and corrosion, associated with ionic contamination. Anticipation and proactive resolution of chemical integration and contamination control problems are key to the successful development and manufacturing of advanced HDDs. In this paper, types and sources of contamination that can impact HDD performance are described; various contamination-related problems are reviewed; and a methodology by which successful chemical integration in the hard disk drive business can be accomplished is outlined.

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Mongkolwongrojn, Mongkol, and Kunchit Kuanoon. "Theoretical Analysis of Flying Characteristics for Air-Helium Filled HDD." Advanced Materials Research 971-973 (June 2014): 844–47. http://dx.doi.org/10.4028/www.scientific.net/amr.971-973.844.

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This paper presents the flying characteristics of air-helium filled hard disk drive for a self-acting two rails flat slider bearing. Numerical scheme based on the finite difference with multi-grid multi-level technique were implemented for the ultra-low flying height sliders. The characteristics of air-helium filled HDD have been examined in this research work. The results shown that the change of flying height is significantly for various fraction of air-helium filled, at various operating conditions such as temperature velocity and mass of slider. Increase of velocity, flying height increase. Increase both the temperature and the mass load, flying height decrease. Increasing of fraction in helium gas, the flying height decreases rapidly for 40% to 60 % of fraction in helium filled. The flying height for air-helium filled magnetic flat slider head equal to 1.3 nm at trailing edge with mass load 12 mN and velocity 20 m/s. The spacing for helium filled hard disk drive is lower than 3 nm when compared with conventional air filled hard disk drive.

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Koo, Ja Choon, Sean W. Kang, Y. S. Han, and Yeon Sun Choi. "Numerical Modeling for the Characterization of Flow Excitation for the HDD Disk Vibration Control." Solid State Phenomena 110 (March 2006): 143–50. http://dx.doi.org/10.4028/www.scientific.net/ssp.110.143.

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This article presents a modeling method for air flow analysis of a hard disk drive. Air flow excitation causes disk vibration that aggravates TMR budget of the design of modern high performance hard drives. And it is the most expensive budget consumer so that controlling of the flutter becomes the primary design issue of the data storage industry. In the presented work, air flow excitation forces are characterized by LES modeling and the results are verified with experiments. A squeeze-film-type disk damper is employed in the experiments and it is applied for a hardware design improvement for disk flutter reduction. LES and RANS are compared and alternately used in a calculation in order to minimize computational efforts.

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Barbier, Charlotte, Joseph A. C. Humphrey, and Eric Maslen. "Experimental Study of the Flow in a Simulated Hard Disk Drive." Journal of Fluids Engineering 128, no. 5 (March 13, 2006): 1090–100. http://dx.doi.org/10.1115/1.2236135.

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Instantaneous circumferential and radial velocity components of the air flowing past a symmetrical pair of suspension/slider-units (SSUs) attached to an E-Block/arm were measured in a specially designed corotating disk apparatus simulating a hard disk drive (HDD) using the particle image velocimetry technique. The geometrical dimensions of the components in the apparatus test section were scaled up by a factor of two, approximately, relative to those of a nominal 312 inch HDD. Most of the measurements were obtained on the interdisk midplane for two angular orientations of the arm/SSUs: (a) One with the tip of the SSUs near the hub supporting the disks; (b) another with the tip of the SSUs near the rims of the disks. Data obtained for disk rotational speeds ranging from 250 to 3000rpm (corresponding to 1250 to 15,000rpm, approximately, in a 312 inch HDD) were post-processed to yield mean and rms values of the two velocity components and of the associated shear stress, the mean axial vorticity, and the turbulence intensity (based on the two velocity components). At the locations investigated near the arm/SSUs, and for disk rotational speeds larger than 1500rpm, the mean velocity components are found to be asymptotically independent of disk speed of rotation but their rms values appear to still be changing. At two locations 90 and 29deg, respectively, upstream of the arm/SSUs, the flow approaching this obstruction displays features that can be attributed to the three-dimensional wake generated by the obstruction. Also, between these two locations and depending on the angular orientation of the arm/SSUs, the effect of the obstruction is to induce a three-dimensional region of flow reversal adjacent to the hub. Notwithstanding, the characteristics of the flow immediately upstream and downstream of the arm/SSUs appear to be determined by local flow-structure interactions. Aside from their intrinsic fundamental value, the data serve to guide and test the development of turbulence models and numerical calculation procedures for predicting this complex class of confined rotating flows, and to inform the improved design of HDDs.

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Nasyrov, Iskandar Nailovich, Ildar Iskandarovich Nasyrov, Rustam Iskandarovich Nasyrov, and Bulat Askarovich Khairullin. "Spin Retry Count Relation with Other hdd Parameters." Journal of Computational and Theoretical Nanoscience 16, no. 12 (December 1, 2019): 5303–6. http://dx.doi.org/10.1166/jctn.2019.8603.

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The change of the SMART parameter 10 Spin retry count values depending on the operating time is considered; this parameter characterizes the number of repeated attempts to spin the disks up to operating speed if the first attempt was unsuccessful. This parameter is critical in the sense that if the value of the attribute increases, then the likelihood of malfunctions in the mechanical part of the hard disk drives is high. The scientific task of the study is to establish the relationship between this parameter in failed hard drives and the values of other reliability parameters for information stores from various manufacturers. In the course of the study, the drives of the HGST, Hitachi, Samsung, ST, Toshiba, WDC trademarks operated in the Backblaze largest commercial data centre were analysed. As a result of the analysis, the relationship between the specified parameter and such parameters as 3 Spin-up time (time of spinning the disk package from standstill to operating speed), 4 Start/stop count (counting the spindle start/stop cycles), 12 Power cycle count (number of full drive switching on/off cycles), 192 Power-off retract count (the number of shutdown cycles, including emergency), 193 Load cycle count (the number of magnetic head block moves in the parking zone/in working position cycles). It is shown that the nature of the change in the values of the considered parameters depends on the manufacturer of the hard drives. It is proposed to carry out an individual assessment of the information storage device rotation mechanism reliability using the parameters identified as a result of the study.

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Garner, Harry D., Kok-Meng Lee, and Lin Guo. "Development of a Grating Interferometer with Application to HDD Servo-Track Writing." Journal of Manufacturing Science and Engineering 123, no. 3 (April 1, 2000): 445–52. http://dx.doi.org/10.1115/1.1360694.

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The development of a grating interferometer with application to the angular measurement of a hard disk drive actuator arm for application to the servo-track writing process is presented. First, the theoretical background related to the linear type grating interferometer is presented, and this theory is extended to the measurement of the angular displacement of a hard disk drive actuator arm using a linear grating. A vector based diffraction technique has also been developed as a tool for visualization and analysis of the grating interferometer design. Finally, experimental setups and results from a prototype grating interferometer design are presented and discussed to demonstrate the feasibility of the grating interferometer measurement system.

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Thongsri, Jatuporn, and Wutthinan Suksawaeng. "Numerical Investigation of Airflow Pattern inside Environmental Chamber." Advanced Materials Research 931-932 (May 2014): 1048–52. http://dx.doi.org/10.4028/www.scientific.net/amr.931-932.1048.

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In industrial hard disk drive research and development laboratories, an environmental chamber is normally used to perform a mechanical verification test of Head Gimbal Assembly (HGA). It is very important to verify that the airflow pattern in the chamber is comparable to that in a real hard disk drive. Hence, we applied a transition shear stress transportation turbulence model (transition SST), one of the robust mathematical models in computer fluid dynamics, to simulate the airflow behavior inside both an environmental chamber and a hard disk drive (HDD). We found that, overall, the two patterns of airflow were not comparable at all. The air velocity vectors around the HGA in VENA were smaller than that in HDD. The reason for this is likely to be that there was more space between the top cover of the chamber and the platter than the space between the top cover of the hard disk drive and its platter.

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Jayson, Eric M., J. Murphy, P. W. Smith, and Frank E. Talke. "Effects of Air Bearing Stiffness on a Hard Disk Drive Subject to Shock and Vibration." Journal of Tribology 125, no. 2 (March 19, 2003): 343–49. http://dx.doi.org/10.1115/1.1509770.

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A finite element model of a hard disk drive (HDD) is developed to investigate the transient response of an operational HDD subject to shock and vibration. The air bearing stiffness of the head disk interface is determined from a finite element solution of the Reynolds equation and approximated with linear springs. The structural response is analyzed for several types of sliders with a wide range of air bearing stiffness. Results show the response of the head-disk interface subject to shock and the modes excited by vertical and lateral vibrations of the HDD.

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Mokal, Vaibhav Umesh. "Hard Disk Drive Failure Detection Using Hybrid Algorithm." International Journal for Research in Applied Science and Engineering Technology 9, no. 9 (September 30, 2021): 1233–44. http://dx.doi.org/10.22214/ijraset.2021.37976.

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Abstract: The data is the most valuable thing in this modern world of Information Technology. As we can see the day to day the data is increasing as each and every people using the World Wide Web. This all system generated data or may be the personal or informative data will get generated in a huge amount of size. That data will get stored at the data centers or on cloud. But those will get stored on the Hard Disk Drives in data centers. So in some situation if the HDD got crashed then we will have lost our data. This work proposes to develop the failure prediction of Hard disk drive. We have chosen the accuracy and review measurements, generally important to the issue, and tried a few learning strategies, Adaboost, Naive Bayes, Logistic Regression and Voting. Our investigation shows that while we can't accomplish close to 100% forecast precision utilizing ML with the present information we have accessible for HDDs, we can improve our expectation exactness over the standard methodology Keywords: Machine learning, Adaboost, Naive Bayes, Voting, Logistic Regression

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Thongsri, Jatuporn, and Vana Pongkom. "Simulated Trajectories of Particles and the Number of Particles Trapped by the Circulating Filter in a Hard Disk Drive." Advanced Materials Research 931-932 (May 2014): 1058–62. http://dx.doi.org/10.4028/www.scientific.net/amr.931-932.1058.

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The particle trajectories and the number of them trapped by circulating filter of a 2.5 inch dual platter hard disk drive (HDD) were numerically investigated using a transition shear stress transport turbulence model (transition SST). Four head gimbal assemblies (HGAs) were placed at the outer diameter positions where tiny particles of alumina were released. The simulation revealed the results of airflow, particle trajectories and efficiency of a circulating filter. This result can be applied as fundamental information to design HDD layout in order to reduce its contamination. Keywords: Airflow, Circulating Filter, Hard Disk Drive, Particle Trajectory, Computational Fluid Dynamics

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Rahman, Md Arifur, Abdullah Al-Mamun, and Zhang Lei. "Hysteresis Analysis of High Precision PZT Actuator in Dual-Stage Hard Disk Drive." Advanced Materials Research 875-877 (February 2014): 708–14. http://dx.doi.org/10.4028/www.scientific.net/amr.875-877.708.

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In Hard disk drive (HDD) industry, the demand for faster HDD with higher storage capacities had led to the use of a dual-stage servo system with a high precision PZT actuator. However, the PZT actuator is made of piezoelectric material which exhibits hysteresis. Hysteresis causes inaccuracies and oscillations in the system responses. In this paper, the hysteresis behavior is examined for a new high resolution (a few nanometers) PZT actuator fabricated for dual stage actuator. The new PZT actuator has the first resonance at a frequency twenty times higher than the first resonant mode of PZT actuator used at present in HDD. A generalized Prandtl-Ishlinskii (GPI) model is obtained by using curve-fitting with the examined hysteresis behavior. Then the inverse of the GPI model is extracted which can be used as the hysteresis compensator. Finally a model-free hysteresis compensator using adaptive Neural Network algorithm is being proposed for future research.

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Pongtrairat, Aunticha, and Angsumalin Senjuntichai. "Spiral Defect Reduction of Hard Disk Drive Media." Applied Mechanics and Materials 421 (September 2013): 93–98. http://dx.doi.org/10.4028/www.scientific.net/amm.421.93.

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The objective of this study is to reduce a number of defects in Hard Disk Drive (HDD) manufacturing due to spiral scratch on media by applying DMAIC steps of Six Sigma approach. The spiral scratch is firstly identified as the significant loss with 6.03% defective rate. Secondly, the paddle to disk space, top cover edge sharpness, pitch static attribute and number of load/unload cycle are found to be the key process input variables (KPIV). The experiment based on four KPIVs is then designed following Box Behnken design. With the results from the experiment, the response surface method is applied to determine the optimal setting for these four KPIVs with respect to the minimum percentage of the spiral scratch. Finally, the process with the optimal settings of the paddle to disk space at 3 mm, top cover edge sharpness at 0.002 inch, pitch static attitude at 0.01 inch and number of load/unload cycle at 10,000 times is implemented and monitored by the p control chart. After the improvement, the defective rate of the spiral scratch is decreased by 48.8% from 6.03% to 3.09%.

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Tzeng, H. "Characteristics of Particle Deposition on Disks in Disk Drives." Journal of the IEST 37, no. 2 (March 1, 1994): 34–39. http://dx.doi.org/10.17764/jiet.2.37.2.e80828272442j127.

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The characteristics of particle deposition on disk surfaces in hard disk drives (HDDs) was studied. The density of tracer particles deposited on the disks was measured to determine the deposition profile. The circumferentially averaged deposition density increases monotonically with radius. The number of deposited particles on the two outermost disk surfaces is more than twice that on other disk surfaces in the HDD. An obstruction to the flow unequally enhances the particle deposition on the disk: 15 percent to the two outermost surfaces, and 55 percent to the other surfaces. These features can be explained satisfactorily by the airflow characteristics in the HDD.

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Wasala, Sahan, Yutong Xue, Lon Stevens, Ted Wiegandt, and Tim Persoons. "Numerical simulations of flow induced noise from a dual rotor cooling fan used in electronic cooling systems." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 5 (August 1, 2021): 1308–19. http://dx.doi.org/10.3397/in-2021-1809.

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Hard Disk Drive (HDD) system enclosures in a data center require effective cooling systems to avoid HDD overheating. These systems often rely on air cooling because of their cost effciency and maintainability. Air cooling systems typically consist of an array of axial fans which push or pull the air through the system. These fans emit high level tonal noise particularly at high tip speed ratios. High-capacity HDDs, on the other hand, are sensitive to high acoustic noise, which consequently increases the risk of read/write error and deteriorates drive performance. Therefore, cooling fan noise adversely affects the function of the HDD enclosure systems which emphasizes the need to understand the noise sources and develop methods to mitigate HDD noise exposure.

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ZHANG, SHAOANG, FENG-BIN SUN, and ROSS GOUGH. "APPLICATION OF AN EMPIRICAL GROWTH MODEL AND MULTIPLE IMPUTATION IN HARD DISK DRIVE FIELD RETURN PREDICTION." International Journal of Reliability, Quality and Safety Engineering 17, no. 06 (December 2010): 565–77. http://dx.doi.org/10.1142/s0218539310003950.

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Appropriate model assumption and robust model estimation are critical for accurate hard disk drive (HDD) field return prediction. Parametric distribution models that are conventionally used in HDD reliability analyses do not describe well HDD field survival. A biological growth model, Bertalanfy-Richards growth model, is introduced in this paper to model HDD field survival within warranty period. A nonparametric multiple missing value imputation approach is used to improve model estimation when not enough observations of field returns are available at early stage of product life. Tests of the model and the missing value imputation approach using actual HDD field survival data suggest they perform well in describing and predicting HDD warranty field returns.

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Ibaraki, Soichi, and Masayoshi Tomizuka. "Tuning of a Hard Disk Drive Servo Controller Using Fixed-Structure H∞ Controller Optimization." Journal of Dynamic Systems, Measurement, and Control 123, no. 3 (June 9, 2000): 544–49. http://dx.doi.org/10.1115/1.1386391.

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As the storage capacity of hard disk drives (HDDs) increases dramatically, the demand for positioning control accuracy of a read/write head of HDD is becoming more stringent. This paper presents a tuning methodology for fixed-structure controllers using the H∞ optimization. The tuning of a PID (Proportional plus Integral plus Derivative) controller for head positioning of an HDD is presented as an application example. The H∞ optimization problem of fixed-structure controllers can be locally solved by using the transformation into an H∞ synthesis problem of static output feedback control. Simulation and experimental results show the effectiveness of the proposed approach as a fine tuning method to improve controller performance without requiring profound knowledge and experiences in manual loop-shaping.

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Shen, Jing, Yongjian Ren, Jian Wan, and Yunlong Lan. "Hard Disk Drive Failure Prediction for Mobile Edge Computing Based on an LSTM Recurrent Neural Network." Mobile Information Systems 2021 (February 11, 2021): 1–12. http://dx.doi.org/10.1155/2021/8878364.

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With the increase in intelligence applications and services, like real-time video surveillance systems, mobile edge computing, and Internet of things (IoT), technology is greatly involved in our daily life. However, the reliability of these systems cannot be always guaranteed due to the hard disk drive (HDD) failures of edge nodes. Specifically, a lot of read/write operations and hazard edge environments make the maintenance work even harder. HDD failure prediction is one of the scalable and low-overhead proactive fault tolerant approaches to improve device reliability. In this paper, we propose an LSTM recurrent neural network-based HDD failure prediction model, which leverages the long temporal dependence feature of the drive health data to improve prediction efficiency. In addition, we design a new health degree evaluation method, which stores current health details and deterioration. The comprehensive experiments on two real-world hard drive datasets demonstrate that the proposed approach achieves a good prediction accuracy with low overhead.

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Zhao, Da Peng, Xiong Fei Wei, Bin Liu, Yu Wang, Sheng Xiang Chen, and Lin Hua Lan. "In Situ Spacing Fluctuation Monitoring of Hard Disk Drive with Thermal Asperity Sensors." Applied Mechanics and Materials 284-287 (January 2013): 790–94. http://dx.doi.org/10.4028/www.scientific.net/amm.284-287.790.

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This paper presents an investigation of spacing fluctuation characterization (SFC) of Hard Disk Drive (HDD) using thermal asperity (TA) sensor. Firstly, the spacing fluctuation monitored by TA sensor is correlated with that monitored by a Laser Doppler Vibrometer (LDV). Secondly, a series of experiments are conducted to study the factors affecting the spacing fluctuation, including disk distortion, head crown sensitivity, ZH sensitivity. Good disk assembly and small crown sensitivity and ZH sensitivity will be helpful to reduce spacing fluctuation.

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TAKAHASHI, Masafumi, Itsuro KAJIWARA, and Toshihiro ARISAKA. "218 Optimization of Smart Structure for Improving Servo Performance of Hard Disk Drive." Proceedings of OPTIS 2008.8 (2008): 241–46. http://dx.doi.org/10.1299/jsmeoptis.2008.8.241.

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Ishiguro, S., R. Ogatsu, T. Inami, T. Nakano, Dong Ying Ju, N. Abe, and K. Ishigawa. "Effect of Sputtering Process Conditions on Microstructure and Mechanical Properties of Pt-Fe Nano Film." Materials Science Forum 675-677 (February 2011): 655–58. http://dx.doi.org/10.4028/www.scientific.net/msf.675-677.655.

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One of the vertical magnetic recordings medium materials of the hard disk drive (HDD) is a Pt-Fe thin film. The development of ultra-high density magnetic recording medium in next generation is expected the magnetic disks such as HDD with capacity enlargement of the data. In order to study effectiveness of the proposed sputtering method, we evaluated micro structure, magnetic and the mechanical properties of a Pt-Fe thin film by some sputtering process conditions. From research results, effect sputtering conditions on micro-structure and mechanical properties of Pt-Fe nano film are verified.

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SUN, FENG-BIN, and DONALD GILLIS. "SYSTEM RELIABILITY WITH COMPETING COMPONENTS AND LOAD SHARING — A HDD HEAD-DISK INTERFACE PERSPECTIVE." International Journal of Reliability, Quality and Safety Engineering 18, no. 04 (August 2011): 377–90. http://dx.doi.org/10.1142/s0218539311004305.

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The authors of this paper present a quantitative insight of a long argued question in hard disk drive (HDD) industry about the reliability effects of the number of head-disk interfaces (HDI). The competition between complexity and data transfer load is modeled from system reliability perspective: competing components with load sharing. Product failure probability ratio and steady-state MTTF ratio between different data storage capacities are derived in terms of their head-disk interface number ratio and data transfer ratio. It is found that the reliability dominance of these two factors is conditional to the mathematical characteristics of their governing failure physics. The detailed discussion is conducted on the system reliability with head-disk interface failures governed by Weibull life distribution and Inverse Power Law stress-life relationship.

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Min, He Qun, Xiao Yang Huang, and Qi De Zhang. "Pressure Fluctuations and Flow-Induced Vibration Measurements in a Hard Disk Drive under Different Rotation Speeds." Applied Mechanics and Materials 197 (September 2012): 292–96. http://dx.doi.org/10.4028/www.scientific.net/amm.197.292.

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Flow-induced vibration (FIV) of a head gimbals assembly (HGA) in hard disk drives (HDDs) limits the positioning accuracy of magnetic head in the HGA for higher HDD magnetic recording density. The pressure fluctuations characterize turbulent fluctuations exciting the HGA off-track vibration (HGA-OTV). In this paper, experimental studies have been carried out to investigate the spectrum characteristics correspondence between pressure fluctuations around an HGA and the simultaneous HGA-OTV under different HDD rotation speeds. A practical and effective experimental setup has been implemented to enable the simultaneous measurements on both the pressure fluctuation and HGA-OTV signals, where pressure fluctuations are measured with a pressure transducer through a small hole on the HDD top cover and the direct HGA-OTV signals are detected through a laser Doppler vibrometer. Results under conditions of three different HDD rotation speeds of 7200, 9000, 10800 rpm have been investigated and compared. It is shown that the HGA off-track vibration spectra are highly associated with those of the pressure fluctuations in terms of principal peaks in four frequency bands around 1.8 kHz, 2.5-3.5 kHz, 7-7.5 kHz and 11.5-12.5 kHz. With increasing HDD rotation speed, it is shown that the spectrum magnitudes of both the pressure fluctuation and the HGA off-track vibration increase correspondingly, while the principal peak positions in spectra of either pressure fluctuation or the HGA off-track vibration always hold the line. This study demonstrates a causal nexus from the pressure fluctuation to the HGA off-track vibration and suggests the feasibility of controlling the HGA-OTV through suppression of pressure fluctuations around the HGA.

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Harmoko, Hendri, Fook Fah Yap, Nader Vahdati, and Chuan Li. "Design and Analysis of Shock and Random Vibration Isolation of Operating Hard Disk Drive in Harsh Environment." Shock and Vibration 16, no. 2 (2009): 143–54. http://dx.doi.org/10.1155/2009/959714.

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An effective vibration isolation system is important for hard disk drives (HDD) used in a harsh mechanical environment. This paper describes how to design, simulate, test and evaluate vibration isolation systems for operating HDD subjected to severe shock and random vibrations based on military specifications MIL-STD-810E. The well-defined evaluation criteria proposed in this paper can be used to effectively assess the performance of HDD vibration isolation system. Design concepts on how to achieve satisfactory shock and vibration isolation for HDD are described. The concepts are tested and further enhanced by the two design case studies presented here. It is shown that an effective vibration isolation system, that will allow a HDD to operate well when subjected to severe shock and random vibration, is feasible.

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Shi, B. J., Dong Wei Shu, J. Luo, Q. Y. Ng, and J. H. T. Lau. "Experimental and Numerical Analyses of a Head Arm Assembly of a Micro-Drive." Key Engineering Materials 326-328 (December 2006): 1585–88. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.1585.

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Hard disk drives (HDD) are now the most important means of information storage, and they continue to be made smaller in size, higher in capacity, and lower in cost. The dynamic performance of an HDD has been an increasingly important consideration for its design, as we move forward toward its consumer applications. The dynamic properties of the head arm assembly (HAA) of a micro-drive were investigated using both experimental and numerical techniques. A finite element model for studying the dynamic property of the HAA was created and modified according to the experimental results. Good correlation between the experimental results and those by finite element simulation was achieved.

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Atsumi, Takenori. "Head-Positioning Control of Hard Disk Drives Through the Integrated Design of Mechanical and Control Systems." International Journal of Automation Technology 3, no. 3 (May 5, 2009): 277–85. http://dx.doi.org/10.20965/ijat.2009.p0277.

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A Hard Disk Drive (HDD) is an inexpensive mass-production product, but the head-positioning control systems of HDDs require nanometer-scale positioning performance. Therefore, we have studied head-positioning control systems of HDD using designs which integrate mechanical and control systems to improve their control performance while curbing cost increases. In this paper, we introduce “disturbance suppression in high-frequency ranges through phase stable design for high-order mechanical resonances” and “high servo-bandwidth design through mode shape design of mechanical resonance” as examples of techniques that have been developed and are easily applied to products.

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TAKAHASHI, Masafumi, Toshio UCHIYAMA, Itsuro KAJIWARA, and Toshihiro ARISAKA. "219 Optimization of Smart Structure for Improving Servo Performance of Hard Disk Drive." Proceedings of the Dynamics & Design Conference 2008 (2008): _219–1_—_219–6_. http://dx.doi.org/10.1299/jsmedmc.2008._219-1_.

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Polsawat, Achinee, Warunee Tipcharoen, and Apirat Siritaratiwat. "Utilization of CD and DVD Pick-Up Heads for Scratch Inspection of Magnetic Disk in Dynamic State Using Microcontroller." Applied Sciences 10, no. 19 (October 1, 2020): 6897. http://dx.doi.org/10.3390/app10196897.

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A non-destructive technique to inspect a scratch on all magnetic disks in the beginning process of hard disk drive (HDD) manufacturing by using CD and DVD pick-up heads as the detector is proposed. It requires a 100% disk inspection of micrometer-sized scratches in a quick measurement with low cost inventing. Most of the previous studies were in static state but this is the first time to be done in dynamic study using the microcontroller in order to promptly serve for industrial utilization. The size, position, and shape characteristic of scratches are examined using light reflection technique. The results show that, when the laser beam is targeted on a magnetic disk in a position, either scratch or non-scratch, the reflected light intensity differs. The DVD pick-up head can detect the width and the surface characteristic of the scratches, which is similar to the results from scanning electron microscope (SEM) for all scratches sizes less than 100 µm. It is also found that using a DVD pick-up head provides a better resolution of shape characteristic and roughness of scratches surface than a CD pick-up head. Hence, the scratch size of 10s µm scale on the magnetic disk can be accurately characterized by this proposed technique, which can be further utilized for magnetic disk inspection in the hard disk drive manufacturing process.

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Hredzak, B., and G. Guo. "New passive balancing algorithm for high-density hard disk drives." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 218, no. 4 (April 1, 2004): 401–10. http://dx.doi.org/10.1177/095440620421800405.

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One of the major sources of vibrations in hard disk drives (HDDs) is unbalance caused by an uneven distribution of the mass on the rotational part of the HDD. Vibrations are limiting the increase in the storage density of the HDDs; therefore it is of paramount importance to identify major sources of vibrations and to reduce them to the minimum level. This paper proposes a new passive balancing algorithm which can achieve significant reduction in the HDD unbalance at low cost and with a high yield rate. The unbalance reduction is achieved using a balancing ring with a large number of holes which are used for the placement of balancing masses of a given weight. The optimum number and position of the balancing masses is then found in order to reduce the residual unbalance to minimum level. Guidelines on optimum selection of the correction mass are also proposed.

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Namiki, Norikazu, Akihiro Komtasu, Keiji Watanabe, and Naoki Kagi. "Surface Corrosion of HDD Media and Subsidiary Particle Formation Due to SO2 Gas Adsorption." Journal of the IEST 50, no. 2 (October 1, 2007): 38–51. http://dx.doi.org/10.17764/jiet.50.2.wh12q7h78l005042.

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The storage capacity of hard disk drives (HDDs) for personal computers has increased more than 10,000 times in the past decade. Meanwhile, the gap between the disk and the magnetic head (flying height) has decreased from sub-micrometers to a few nanometers. The lower flying height leads to more sensitive disk-to-surface contamination linked to fatal failures. Many studies have reported that disk surface contamination is related to the adsorption of volatile organic compounds (VOCs) and the corrosion of the magnetic layer of the disk. However, surface contamination derived from sulfur dioxide (SO2) gas in the surrounding area has been discussed insufficiently. In this work, to ascertain the mechanism of disk surface contamination and the subsidiary particle generation, HDD disks were intentionally exposed to SO2 gas, followed by an evaluation of disk operation performance during endurance testing. After the series of endurance tests, a large quantity of sulfate and nickel, which is a main component of the disk substrate layer, was detected on the SO2-contaminated disk surface, as well as a small quantity of cobalt, which is a main component of the magnetic layer. From these findings, the mechanism of surface contamination of HDD disks in the coexistence of SO2 and water was inferred. Nickel is supplied from the substrate layer to the top layer through holes and cracks in the films of disks because of the corrosion triggered by adsorbed water. High temperature and humidity causes the desorption of SO2 from SO2-contaminated disk surfaces to react with nickel. Eventually, the products of nickel sulfate are precipitated on the surface to be released in the form of particles by contact with the head.

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KAJIWARA, Itsuro, Toshio UCHIYAMA, and Toshihiro ARISAKA. "218 Vibration Control of Hard Disk Drive with Smart Structure Technology for Improving Servo Performance." Proceedings of the Dynamics & Design Conference 2008 (2008): _218–1_—_218–6_. http://dx.doi.org/10.1299/jsmedmc.2008._218-1_.

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Tada, Hajime, and Masao Hanya. "A-1-4 PZT life prediction for dual stage actuator in a hard disk drive by accelerated test." Proceedings of the Conference on Information, Intelligence and Precision Equipment : IIP 2011 (2011): 107–9. http://dx.doi.org/10.1299/jsmeiip.2011.107.

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MATSUI, Tohru, and Minoru SASAKI. "203 Comparison of Feedback controllers for a Dual-Stage Hard Disk Drive." Proceedings of the Conference on Information, Intelligence and Precision Equipment : IIP 2001 (2001): 147–52. http://dx.doi.org/10.1299/jsmeiip.2001.147.

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XU, DAQING, ERJIA LIU, BO LIU, HOOIIN TAN, WENG-KONG CHAN, and SHIH-FU LING. "CORROSION STUDY OF HARD DISKS BY OSA AND XPS." International Journal of Nanoscience 03, no. 06 (December 2004): 853–57. http://dx.doi.org/10.1142/s0219581x04002759.

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Perfluoropolyethers (PFPE) are most commonly employed as lubricants at head-disk interface in hard disk drives (HDD) to reduce friction and wear. Corrosion behavior is an important issue in high density magnetic recording disk-drives. The magnetic materials used in the magnetic storage layers as well as those used for making read–write transducers are not very corrosion resistant. In the presence of humidity and at elevated temperatures, corrosion occurs and materials from the magnetic layers and the NiP plating layers of the recording rigid media can migrate to the disk surfaces and form protrusions that are easily much larger than the head-disk clearances. As PFPE is sensitive to temperature, especially its mobile fraction, movement of the PFPE molecules will allow the magnetic media to be exposed to the environment through the micro pores existing in DLC overcoat, which will cause occurring of corrosion. In this paper, the corrosion characteristics of the magnetic media of the hard disks were analyzed using optical surface analyzer (OSA). X-ray photoelectron spectroscopy (XPS) was also used to characterize the distribution of the elements on the surfaces of hard disks. A relationship between heating time, lubricant layer thickness, number of corrosion spots and distribution of elements was attempted. It was found that the corrosion spots for the disks are related to the heating time. A small change in the thickness of lubricant layer can cause a drastic change in corrosion rate.

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Sasaki, Minoru, Yoshihiro Inoue, and Hiroyuki Yamada. "Active Vibration Control of a Microactuator for the Hard Disk Drive Using Self-Sensing Actuation." Smart Materials Research 2012 (March 5, 2012): 1–7. http://dx.doi.org/10.1155/2012/920747.

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This paper presents the self-sensing control of a microactuator for hard disk drives. The microactuator uses a PZT actuator pair installed on the suspension assembly. The self-sensing microactuator forms a combined sensing and actuation mechanism. Direct velocity feedback and positive position feedback are used in this paper. Our experimental results show that both strategies are effective in suppressing vibrational modes and successfully demonstrate the feasibility of using a self-sensing actuator on an HDD suspension assembly.

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Jang, G. H., S. H. Lee, and H. W. Kim. "Finite Element Analysis of the Coupled Journal and Thrust Bearing in a Computer Hard Disk Drive." Journal of Tribology 128, no. 2 (October 17, 2005): 335–40. http://dx.doi.org/10.1115/1.2162918.

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This paper proposes a method to calculate the characteristics of a coupled fluid dynamic journal and thrust bearing of a hard disk drive (HDD) spindle motor. The governing equations for the journal and thrust bearings are the two-dimensional Reynolds equations in the θz and rθ planes, respectively. The finite element method is appropriately applied to analyze the coupled bearing under the conditions of the continuity of mass and pressure at the interface between the journal and thrust bearings. The pressure in the coupled bearing was calculated by applying the Reynolds boundary condition. The validity of this application was verified by comparing the analytical results of the flying height at various rotating speeds with experimental results. The characteristics of the coupled journal and thrust bearing were also investigated due to the Reynolds and Half-Sommerfeld boundary conditions and the coupled and separate analysis. This research demonstrates that the proposed method can accurately and realistically describe the coupled fluid dynamic bearing in a HDD system.

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Yuwono, Doddy Teguh, and Yunanri W. "Analisis Perbandingan File Carving Dengan Metode Nist." Jurnal Sains Komputer dan Teknologi Informasi 2, no. 2 (May 6, 2020): 1–6. http://dx.doi.org/10.33084/jsakti.v2i2.1472.

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Pemulihan data adalah bagian terpenting dari Digital Forensic. Bagi penyidik ??negara untuk menghasilkan bukti yang sah di pengadilan sangat penting dan wajib. Memori Flash, Hard Disk Drive (HDD) dan Solid State Drive (SDD) adalah beberapa Media Penyimpanan yang digunakan sebagai tempat untuk meletakkan semua jenis data dan informasi dalam berbagai format file digital. Karena bentuk digitalnya sehingga memungkinkan berbagai format file digital disembunyikan, dihapus, dan bahkan diformat di media penyimpanan, sedangkan semua data dan informasi harus ditemukan oleh penyelidik negara. Prinsip dasar data atau informasi digital jika telah disalin pada Memori Flash, Hard Disk Drive (HDD) dan Solid State Drive (SDD) tidak akan pernah hilang secara permanen dan bahkan data atau informasi digital hilang karena dihapus, diformat dengan cepat atau sistem macet. Jadi, mengembalikan data sangat mungkin. Dalam penelitian ini, tes dilakukan menggunakan Foremost, FTK Imager, dan Scalpel, yang merupakan Alat OpenSource yang dapat digunakan pada sistem operasi Propietary dan OpenSource. Metode yang digunakan adalah Institut Teknologi Standar Nasional (NIST). NIST memiliki panduan kerja yang sangat baik tentang kebijakan dan standar untuk memastikan setiap Penguji mengikuti alur kerja yang sama, sehingga pekerjaan mereka didokumentasikan dan hasilnya dapat ditinjau dan dapat dipertahankan saat pelaporan sebelum dijadikan sebagai bukti yang valid. Hasil penelitian ini membuktikan bahwa Foremost, FTK Imager, dan Scalpel dapat mengembalikan data yang dihapus, disembunyikan, dan diformat.

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Sideq, Salleh, and S. Izman. "Effects of Friction Modifier Additives on HDD Substrate Defects and Surface Topography during CMP." Advanced Materials Research 845 (December 2013): 894–98. http://dx.doi.org/10.4028/www.scientific.net/amr.845.894.

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This study investigates the effects of Friction Modifier Additives (FMA) added into the polishing slurry on Aluminium Nickel Phosphorous plated (Al-NiP) Hard-Disk Drive (HDD) substrates surface topography and surface defects during Chemical Mechanical Polishing (CMP) process. It is confirmed that addition of Friction Modifier Additives into the slurry reduces the overall coefficient of friction (CoF) during CMP process. By increasing the FMA concentration in the polishing slurry, the substrate surface topography such as waviness and surface roughness were improved significantly. It also lowered the defects counts especially scratch and sub-micron damage as revealed under Optical Surface Analyser (OSA) and Atomic Force Microscope (AFM) analysis.

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Sun, Feng-Bin, and Yao Zhang. "Long-Term Life Test Data Modeling and Field Correlation — An HDD Experience." International Journal of Reliability, Quality and Safety Engineering 24, no. 02 (March 30, 2017): 1750008. http://dx.doi.org/10.1142/s0218539317500085.

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Not every company can afford or is willing to invest in long-term life testing due to time and cost constraints. But such a test can provide very valuable insight about product field behavior during its lifetime. Authors of this paper present a case study on hard disk drive long-term life test data analysis. In order to deal with the non-monotonic hazard rate behavior, the bi-modal mixed life distribution and bi-modal competing failure modeling are applied to fit the time to failure data. The model parameters’ estimation, their physical implications, and field long-term reliability predictions using these two approaches are discussed and compared. The recommendations are given regarding the applicability of each model from an engineering application perspective.

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N. Nasyrov, Iskandar, Ildar I. Nasyrov, Rustam I. Nasyrov, and Bulat A. Khairullin. "Dependence of Reallocated Sectors Count on HDD Power-on Time." International Journal of Engineering & Technology 7, no. 4.7 (September 27, 2018): 200. http://dx.doi.org/10.14419/ijet.v7i4.7.20544.

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The problem of SMART-data ambiguity in different models of hard disk drives of the same manufacturers is considered. This circumstance creates obstacles for the use of SMART technology when assessing and predicting the reliability of storage devices. The scientific task of the work is to study the dependence of the hard disk failure probability on the reliability parameters values for each individual storage device of any model of any manufacturer. In the course of the study, two interrelated parameters were analyzed: “5 Reallocated sectors count” and “9 Power-on hours” (the number of hours spent in the on state). As a result of the analysis, two types of dependences were revealed: drooping and dome shaped. The first means the maximum failure frequency of information storage devices immediately after commissioning, the second - after a certain period of time, actually coinciding with the warranty period for the products (two years). With the help of clustering in plane according to the coordinates of the number of reallocated sectors and the time of operation, two different reasons for the failure of the drives were discovered: due to deterioration of the disk surface and due to errors in the positioning of the read / write heads. Based on the variety of types of causes and consequences of equipment failure, the task of individual assessment of an individual data storage device reliability is proposed to be solved using several parameters simultaneously.

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Eguchi, Takehiko, and Teruhiro Nakamiya. "An Improved Component-Mode Synthesis Method to Predict Vibration of Rotating Spindles and Its Application to Position Errors of Hard Disk Drives." Journal of Vibration and Acoustics 128, no. 5 (February 25, 2005): 568–75. http://dx.doi.org/10.1115/1.2349539.

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This paper describes an accurate mathematical model that can predict forced vibration of a rotating spindle system with a flexible stationary part. In particular, we demonstrate this new formulation on a hard disk drive (HDD) spindle to predict its position error signal (PES). This improved method is a nontrivial extension of the mathematical model by Shen and his fellow researchers, as the improved method allows the flexible stationary part to comprise multiple substructures. When applied to HDD vibration, the improved model consists not only a rotating hub, multiple rotating disks, a stationary base, and bearings (as in Shen’s model) but also an independent flexible carriage part. Moreover, the carriage part is connected to the stationary base with pivot bearings and to the disks with air bearings at the head sliders mounted on the far end of the carriage. To build the improved mathematical model, we use finite element analysis (FEA) to model the complicated geometry of the rotating hub, the stationary base and the flexible carriage. With the mode shapes, natural frequencies, and modal damping ratios obtained from FEA, we use the principle of virtual work and component-mode synthesis to derive an equation of motion. Naturally, the stiffness and damping matrices of the equation of motion depend on properties of the pivot and air bearings as well as the natural frequencies and mode shapes of the flexible base, the flexible carriage, the hub, and the disks. Under this formulation, we define PES resulting from spindle vibration as the product of the relative displacement between the head element and the disk surface and the error rejection transfer function. To verify the improved model, we measured the frequency response functions using impact hammer tests for a real HDD that had a fluid-dynamic bearing spindle, two disks, and three heads. The experimental results agreed very well with the simulation results not only in natural frequencies but also in gain and phase.

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Suthaweesub, Somkid, and Arbtip Dheeravongkit. "Tolerance Ring Design in the Actuator Arm of a Hard Disk Drive Using Finite Element Analysis." Applied Mechanics and Materials 275-277 (January 2013): 716–30. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.716.

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This paper presents conceptual designs for the tolerance ring in the Hard Disk Drive (HDD) in order to reduce the total deformation of the tolerance ring and decrease the installation force during the assembly process of the actuator arm, while maintaining the natural frequency within the specification range. In this research, finite element analysis was employed to compare and analyze the installation forces, total deformations of the tolerance ring and the natural frequencies of Actuator Pivot Flex Assembly (APFA). Around its cylindrical body, the tolerance ring consists of several waves which provide rigidity for the APFA assembly to resist the axial rocking motion of the actuator arm. The idea is to decrease the contact surface area between the waves and the e-block by smoothing the contact surface of the waves along the installation direction while maintaining sufficient friction to resist the axial rocking motion. The objective of this research was to minimize the total deformation and installation force. The three input variables, i.e. width, length and height of the alternating flat curve design, were analyzed together by using the engineering optimization. The decreasing of the total deformation of the tolerance ring and installation force during APFA assembly would increase the number of cycles of the reworking process which can help increase the productivity and efficiency of HDD manufacturing.

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Hossain, Alamgir, and Md Arifur Rahman. "Comparative Analysis among Single-Stage, Dual-Stage, and Triple-Stage Actuator Systems Applied to a Hard Disk Drive Servo System." Actuators 8, no. 3 (September 3, 2019): 65. http://dx.doi.org/10.3390/act8030065.

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In modern times, the design and optimization of different actuator systems for controlling a high-precision position control system represent a popular interdisciplinary research area. Initially, only single-stage actuator systems were used to control most of the motion control applications. Currently, dual-stage actuation systems are widely applied to high-precision position control systems such as hard disk drive (HDD) servo systems. In the dual-stage system, a voice coil motor (VCM) actuator is used as the primary stage and a piezoelectric micro-actuator is applied as the secondary stage. However, a dual-stage control architecture does not show significant performance improvements to achieve the next-generation high-capacity HDD servo system. Research continues on how to fabricate a tertiary actuator for a triple-stage HDD servo system. A thermal positioning controller (TPC) actuator is considered promising as the tertiary stage. The triple-stage system aims to achieve greater bandwidth, track density, and disk speed, with minimum sensitivity and greater error minimization. In this work, these three actuation systems with different combinations of proportional plus integral (PI), proportional plus derivative (PD), and proportional plus integral plus derivative (PID) controller, lag-lead controller, lag filter, and inverse lead plus a PI controller were designed and analyzed through simulation to achieve high-precision positioning. The comparative analyses were done on the MATLAB/Simulink simulation platform.

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Sunami, Yuta, Mohd Danial Ibrahim, and Hiromu Hashimoto. "Optimum Design of Oil Lubricated Thrust Bearing for Hard Disk Drive with High Speed Spindle Motor." International Journal of Rotating Machinery 2013 (2013): 1–11. http://dx.doi.org/10.1155/2013/896148.

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This paper presents the application of optimization method developed by Hashimoto to design oil lubricated thrust bearings for 2.5 inch form factor hard disk drives (HDD). The designing involves optimization of groove geometry and dimensions. Calculations are carried out to maximize the dynamic stiffness of the thrust bearing spindle motor. Static and dynamic characteristics of the modeled thrust bearing are calculated using the divergence formulation method. Results show that, by using the proposed optimization method, dynamic stiffness values can be well improved with the bearing geometries not being fixed to conventional grooves.

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Thongsri, Jatuporn, and Vana Pongkom. "A Simulation of the Number of Particles Trapped by the Circulating Filter of a Hard Disk Drive and their Trajectories." Applied Mechanics and Materials 548-549 (April 2014): 953–57. http://dx.doi.org/10.4028/www.scientific.net/amm.548-549.953.

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A transition shear stress transport turbulence model and a discrete phase model of Fluent software were employed to simulate numerically the trajectories of loose particles and the number of them trapped by the circulating filter of a hard disk drive (HDD). The filter was located either at the left or the right of a 2.5 inch dual platter HDD rotating at 7200 rpm. Particles were released from the middle diameter position where four head gimbal assemblies (HGAs) were located. The simulation included airflow and particle trajectories released from any of the four HGAs. The results of this simulation can help determine the efficiency of a circulating filter and its optimal placement.

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48

Rahman, Md Arifur, Poh Wee Han, and Abdullah Al Mamun. "Hysteresis Modeling and Inverse Feedforward Compensation for PZT Actuator in Dual-Stage Hard Disk Drive." Advanced Materials Research 740 (August 2013): 152–58. http://dx.doi.org/10.4028/www.scientific.net/amr.740.152.

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With the growth of hard disk storage, it would be difficult to meet the specification of the high track density with conventional single actuator. Therefore the next generation of high speed hard disk drive uses the concept of dual-stage actuated hard disk drive where a secondary actuator is mounted onto the VCM actuator. This helps to achieve higher servo bandwidth and, therefore, more precise tracking. Improved tracking error allows higher track density and hence higher storage capacity. Piezoelectric actuator has been a popular choice as the secondary stage. However, the piezoelectric actuators exhibit an unavoidablecharacteristic of hysteresis which causes inaccuracies and oscillations in the system responses.In this paper, the hysteresis behaviour is investigated for asuspension based PZT actuator which is used as the secondary actuator of HDD available in the market. The Generalized Prandtl-Ishlinskii (GPI) hysteresis model which is a phenomenological based model is obtained usingnon-linear least square curve-fitting. In the secondexperiment, a second order linear dynamics model of the PZT actuator is obtained using frequency response identificationmethod. High frequency resonance modes of the PZT actuator are eliminated using a notch filter. By integrating the obtained GPI hysteresis model with this second-order lineardynamics, a nonlinear dynamic model and an inverse feedforward controller are developed.Preliminary simulation results demonstrate that inverse feedforward controller can be appliedfor precise tracking of triangular and multiple frequency sinusoidal trajectories.

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Smutkupt, Uttapol, and Supaluk Kamrungsee. "Electropolishing Parameters for Nickel Coating Replacement of Hard Disk Actuator Arm." Applied Mechanics and Materials 799-800 (October 2015): 319–23. http://dx.doi.org/10.4028/www.scientific.net/amm.799-800.319.

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For hard disk drives (HDD), loose particles that are trapped between the head and disk during HDD operations can create damages to HDD. As a result, a nickel coating is used to minimize their loose particles. However, nickel is one of many carcinogenic metals known to be an environmental and occupational pollutant. Therefore, an electropolishing technique is proposed to replace a nickel coating process. To do experiments, a stainless steel actuator arm is set as an anode, a steel plate is set as a cathode, and a sulfuric acid is used as an electrolyte. With a design of experiment (DOE) technique, four parameters of the electropolishing technique which are an electrolyte concentration, an electrolyte temperature, a polishing time, and an electric intensity, are tested. The experiment result shows that the electrolyte concentration and electric intensity are not made any change for loose particles counts with liquid particle counter (LPC) testing whereas only two parameters which are the electrolyte temperature and polishing time play significant roles for LPC values. The lower LPC shows the smaller percentage of HDD failure. From these Box-Behnken DOE experiments, the optimal solution is 90 Celsius of the electrolyte temperature and 40 minutes of the polishing time. Although, the electrolyte concentration and electric intensity are not made any impact for LPC but they are set as a standard to be 0.2 mol/l and 0.25 A/cm2 consequently. With these parameters, the predicted LPC is only 442,106 counts/part. This LPC is still in an accepted level standard that will not cause failure to HDD. This means that the electropolishing technique initially can be used to replace a nickel coating process without loose particles.

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Gu, Bin, Dong Wei Shu, Yusaku Fujii, and Bao Jun Shi. "Dynamic Response Measurement of 1-Inch HDD Head Arm Assembly." Applied Mechanics and Materials 36 (October 2010): 52–56. http://dx.doi.org/10.4028/www.scientific.net/amm.36.52.

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In this paper, dynamic response of 1-inch hard disk drive (HDD) head arm assembly (HAA) against an impact load is obtained by means of a 3D non-linear finite element model in ANSYS/LS-DYNA and experiments using Optical method. A mass is modeled as a rigid body and is made to collide with the arm. The velocity, displacement, acceleration and the inertial force of the mass are obtained from the time- history of finite element analysis (FEA). In the experiment, a mass that is levitated with an aerostatic linear bearing, and hence encounters negligible friction, is made to collide with the HAA and the dynamic bending test for the arm is realized. During the collision the Doppler frequency shift of the laser beam reflecting from the mass is accurately measured using an optical interferometer. The velocity, the position, the acceleration and the inertial force of the mass are calculated from the measured time-varying Doppler frequency shift. A good correlation between the experimental data and FEA results is observed.

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Journal articles on the topic 'Hard disk drive (HDD)'

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