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Air bearing surface designs in consideration of thermomechanical actuation efficiency / Shuyu Zhang in Transactions of the ASME . Journal of tribology, Vol. 130 N° 4 (Octobre 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of tribology > Vol. 130 N° 4 (Octobre 2008) . - 6 p. Titre : Air bearing surface designs in consideration of thermomechanical actuation efficiency Type de document : texte imprimé Auteurs : Shuyu Zhang, Auteur ; Sung-Chang Lee, Auteur ; Dongman Kim, Auteur Année de publication : 2015 Article en page(s) : 6 p. Note générale : Tribology Langues : Anglais (eng) Mots-clés : Pressure  Bearings  Design  Force  Transducers Résumé : Thermomechanical actuation (TMA) at the transducer region of the air bearing surface (ABS) protrudes from the transducer toward the recording media. This actuation induces a change in the air bearing pressure and a concomitant lift of the slider. The actual actuation in flying height divided by the TMA protrusion, defined as the TMA efficiency, is intimately coupled to the ABS design. After introducing an expression describing the changes in the air bearing forces due to the TMA protrusion, three approaches are proposed that facilitate the optimization of the ABS design for improving the TMA efficiency. These approaches include (a) reducing the air bearing pressure, (b) reducing the size of the TMA affected area, and (c) decoupling the peak air bearing pressure area from the TMA affected area. To illustrate these approaches, several ABS designs are evaluated by comparing their TMA efficiencies. En ligne : http://tribology.asmedigitalcollection.asme.org/article.aspx?articleid=1468129 [article] Air bearing surface designs in consideration of thermomechanical actuation efficiency [texte imprimé] / Shuyu Zhang, Auteur ; Sung-Chang Lee, Auteur ; Dongman Kim, Auteur . - 2015 . - 6 p. Tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 130 N° 4 (Octobre 2008) . - 6 p. Mots-clés : Pressure  Bearings  Design  Force  Transducers Résumé : Thermomechanical actuation (TMA) at the transducer region of the air bearing surface (ABS) protrudes from the transducer toward the recording media. This actuation induces a change in the air bearing pressure and a concomitant lift of the slider. The actual actuation in flying height divided by the TMA protrusion, defined as the TMA efficiency, is intimately coupled to the ABS design. After introducing an expression describing the changes in the air bearing forces due to the TMA protrusion, three approaches are proposed that facilitate the optimization of the ABS design for improving the TMA efficiency. These approaches include (a) reducing the air bearing pressure, (b) reducing the size of the TMA affected area, and (c) decoupling the peak air bearing pressure area from the TMA affected area. To illustrate these approaches, several ABS designs are evaluated by comparing their TMA efficiencies. En ligne : http://tribology.asmedigitalcollection.asme.org/article.aspx?articleid=1468129

Characterization of thermally actuated pole tip protrusion for head-media spacing adjustment in hard disk drives / Sung-Chang Lee in Transactions of the ASME . Journal of tribology, Vol. 130 n°2 (Mars/Avril 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of tribology > Vol. 130 n°2 (Mars/Avril 2008) . - 6 p. Titre : Characterization of thermally actuated pole tip protrusion for head-media spacing adjustment in hard disk drives Type de document : texte imprimé Auteurs : Sung-Chang Lee, Auteur ; Brian D. Strom, Auteur Année de publication : 2008 Article en page(s) : 6 p. Note générale : Tribology Langues : Anglais (eng) Mots-clés : Thermomechanically  actuated  pole  tip  Hard  disk  drive Résumé : The effect of thermomechanically actuated pole tip protrusion on adhesive forces is characterized through model and experiment. The roughness of a thermomechanically actuated region is characterized by atomic force microscopy. Using the extracted roughness parameters and estimated apparent area associated with thermal actuation, the intermolecular forces at the head-disk interface (HDI) are calculated using the ISBL (improved sub-boundary lubrication) code. Both roughness and nominal area of contact are found to be significant factors determining adhesive forces. The adhesive forces for various HDI designs—including thermal actuation—are also characterized experimentally in situ using commercial hard disk drive samples. The experimental results are found to be consistent with the model calculations and imply certain advantages for thermally actuated HDI designs. However, the experiments also raise concerns regarding the field application of the technology. En ligne : http://tribology.asmedigitalcollection.asme.org/article.aspx?articleid=1468039 [article] Characterization of thermally actuated pole tip protrusion for head-media spacing adjustment in hard disk drives [texte imprimé] / Sung-Chang Lee, Auteur ; Brian D. Strom, Auteur . - 2008 . - 6 p. Tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 130 n°2 (Mars/Avril 2008) . - 6 p. Mots-clés : Thermomechanically  actuated  pole  tip  Hard  disk  drive Résumé : The effect of thermomechanically actuated pole tip protrusion on adhesive forces is characterized through model and experiment. The roughness of a thermomechanically actuated region is characterized by atomic force microscopy. Using the extracted roughness parameters and estimated apparent area associated with thermal actuation, the intermolecular forces at the head-disk interface (HDI) are calculated using the ISBL (improved sub-boundary lubrication) code. Both roughness and nominal area of contact are found to be significant factors determining adhesive forces. The adhesive forces for various HDI designs—including thermal actuation—are also characterized experimentally in situ using commercial hard disk drive samples. The experimental results are found to be consistent with the model calculations and imply certain advantages for thermally actuated HDI designs. However, the experiments also raise concerns regarding the field application of the technology. En ligne : http://tribology.asmedigitalcollection.asme.org/article.aspx?articleid=1468039

Experimental and FEA scratch of magnetic storage thin-film disks to correlate magnetic signal degradation with permanent deformation / Raja R. Katta in Transactions of the ASME . Journal of tribology, Vol. 132 N° 2 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of tribology > Vol. 132 N° 2 (Avril 2010) . - 11 p. Titre : Experimental and FEA scratch of magnetic storage thin-film disks to correlate magnetic signal degradation with permanent deformation Type de document : texte imprimé Auteurs : Raja R. Katta, Auteur ; Andreas A. Polycarpou, Auteur ; Sung-Chang Lee, Auteur Année de publication : 2011 Article en page(s) : 11 p. Note générale : Tribology Langues : Anglais (eng) Mots-clés : Atomic  force  microscopy  Deformation  Demagnetisation  Finite  element  analysis  Friction  Hard  discs  Magnetic  multilayers  Magnetic  storage  Magnetic  thin  film  devices  Nanoindentation  Perpendicular  magnetic  recording Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Scratch-related magnetic signal degradation can occur during magnetic storage hard disk drive operations when the read-write heads contact the spinning multilayer disks. To investigate this phenomenon, controlled nanoscratch experiments were performed on perpendicular magnetic recording media using various indenters of different radii of curvature. Various loading conditions were used to cause permanent scratches that were measured using atomic force microscopy. The nanoscratch experiments were simulated using finite element analysis (FEA) that included the detailed nanometer scale thin-film multilayer mechanical properties. The permanently deformed field in the subsurface magnetic recording layer was extracted from the FEA results. The residual scratch widths measured on the surface of the magnetic storage disk were directly compared with the residual subsurface widths of the region on the magnetic recording layer, where extensive permanent lateral deformation was present. It was found that the subsurface widths of the deformed regions were significantly larger than the surface scratch widths. Thus, subsurface thin-film layers, such as the magnetic recording layer, could be damaged without observable damage to the protective top surface carbon overcoat. The exact location and extent of damage to the magnetic recording layer depends on the scratch load, size of scratch tip, and the friction at the interface. Such permanent deformation in magnetic recording layer could lead to demagnetization, which has been reported in the literature. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...] [article] Experimental and FEA scratch of magnetic storage thin-film disks to correlate magnetic signal degradation with permanent deformation [texte imprimé] / Raja R. Katta, Auteur ; Andreas A. Polycarpou, Auteur ; Sung-Chang Lee, Auteur . - 2011 . - 11 p. Tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 132 N° 2 (Avril 2010) . - 11 p. Mots-clés : Atomic  force  microscopy  Deformation  Demagnetisation  Finite  element  analysis  Friction  Hard  discs  Magnetic  multilayers  Magnetic  storage  Magnetic  thin  film  devices  Nanoindentation  Perpendicular  magnetic  recording Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Scratch-related magnetic signal degradation can occur during magnetic storage hard disk drive operations when the read-write heads contact the spinning multilayer disks. To investigate this phenomenon, controlled nanoscratch experiments were performed on perpendicular magnetic recording media using various indenters of different radii of curvature. Various loading conditions were used to cause permanent scratches that were measured using atomic force microscopy. The nanoscratch experiments were simulated using finite element analysis (FEA) that included the detailed nanometer scale thin-film multilayer mechanical properties. The permanently deformed field in the subsurface magnetic recording layer was extracted from the FEA results. The residual scratch widths measured on the surface of the magnetic storage disk were directly compared with the residual subsurface widths of the region on the magnetic recording layer, where extensive permanent lateral deformation was present. It was found that the subsurface widths of the deformed regions were significantly larger than the surface scratch widths. Thus, subsurface thin-film layers, such as the magnetic recording layer, could be damaged without observable damage to the protective top surface carbon overcoat. The exact location and extent of damage to the magnetic recording layer depends on the scratch load, size of scratch tip, and the friction at the interface. Such permanent deformation in magnetic recording layer could lead to demagnetization, which has been reported in the literature. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...]

Flying clearance distribution with thermal flying height control in hard disk drives / Sung-Chang Lee in Transactions of the ASME . Journal of tribology, Vol. 132 N° 2 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of tribology > Vol. 132 N° 2 (Avril 2010) . - 04 p. Titre : Flying clearance distribution with thermal flying height control in hard disk drives Type de document : texte imprimé Auteurs : Sung-Chang Lee, Auteur ; George W. Tyndall, Auteur ; Mike Suk, Auteur Année de publication : 2011 Article en page(s) : 04 p. Note générale : Tribology Langues : Anglais (eng) Mots-clés : compensation  disc  drives  hard  discs Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Flying clearance distribution with thermal flying height control (or thermomechanical actuation) is characterized. Especially, factors contributing to variation in the flying clearance are identified based on the flying height change profiles taken from the burn-in process of hard disk drives and Gage R&R (repeatability and reproducibility) test of touch down repeatability. In addition, the effect of static temperature compensation scheme on the flying clearance distribution is investigated, and the disadvantage of static adaptation to temperature change is identified. In order to avoid early catastrophic head-disk interface failures due to poor static temperature compensation, dynamic clearance adjustment is necessary whenever environmental condition changes. Otherwise, static temperature compensation using the individual temperature sensitivity values of each head needs to be applied. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...] [article] Flying clearance distribution with thermal flying height control in hard disk drives [texte imprimé] / Sung-Chang Lee, Auteur ; George W. Tyndall, Auteur ; Mike Suk, Auteur . - 2011 . - 04 p. Tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 132 N° 2 (Avril 2010) . - 04 p. Mots-clés : compensation  disc  drives  hard  discs Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Flying clearance distribution with thermal flying height control (or thermomechanical actuation) is characterized. Especially, factors contributing to variation in the flying clearance are identified based on the flying height change profiles taken from the burn-in process of hard disk drives and Gage R&R (repeatability and reproducibility) test of touch down repeatability. In addition, the effect of static temperature compensation scheme on the flying clearance distribution is investigated, and the disadvantage of static adaptation to temperature change is identified. In order to avoid early catastrophic head-disk interface failures due to poor static temperature compensation, dynamic clearance adjustment is necessary whenever environmental condition changes. Otherwise, static temperature compensation using the individual temperature sensitivity values of each head needs to be applied. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...]

Simulating the air bearing pressure and flying height in a humid environment / Shuyu Zhang in Transactions of the ASME . Journal of tribology, Vol. 130 N°1 (Janvier 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of tribology > Vol. 130 N°1 (Janvier 2008) . - 4 p. Titre : Simulating the air bearing pressure and flying height in a humid environment Type de document : texte imprimé Auteurs : Shuyu Zhang, Auteur ; Brian Strom, Auteur ; Sung-Chang Lee, Auteur Année de publication : 2008 Article en page(s) : 4 p. Note générale : Tribology Langues : Anglais (eng) Mots-clés : Pressure  Temperature  Water  vapor  Bearings  Vapor  pressure  Force Résumé : 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 two air bearing designs, 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. En ligne : http://tribology.asmedigitalcollection.asme.org/article.aspx?articleid=1467969 [article] Simulating the air bearing pressure and flying height in a humid environment [texte imprimé] / Shuyu Zhang, Auteur ; Brian Strom, Auteur ; Sung-Chang Lee, Auteur . - 2008 . - 4 p. Tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 130 N°1 (Janvier 2008) . - 4 p. Mots-clés : Pressure  Temperature  Water  vapor  Bearings  Vapor  pressure  Force Résumé : 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 two air bearing designs, 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. En ligne : http://tribology.asmedigitalcollection.asme.org/article.aspx?articleid=1467969