Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems, Jan 15, 2011
Transient thermal-mechanical contacts between a slider and a rotating disk in the presence of con... more Transient thermal-mechanical contacts between a slider and a rotating disk in the presence of contamination particles are investigated using finite element analysis. The maximum temperature rise due to frictional heating, the maximum plastically deformed area, and the maximum residual penetration into the disk surface are determined as a function of particle properties for aluminum and glass disk substrate. It is found that contact with soft and deformable particles can cause a large temperature rise, sufficient for thermal erasure, even though physical damage of the media is not observed. Contact with hard and rigid particles can lead to severe plastic deformation as well as high temperature rise of the media, representing the worst case for tribological integrity of the slider-disk interface.
Fretting wear at the dimple/gimbal interface of a hard disk drive suspension was investigated for... more Fretting wear at the dimple/gimbal interface of a hard disk drive suspension was investigated for stainless steel dimples in contact with stainless steel gimbals coated with diamondlike carbon (DLC) of different thicknesses and different elastic moduli. Scanning electron microscopy (SEM) was used to evaluate the size and characteristics of the wear scar of both the dimple and the gimbal. Fretting wear and fatigue-type cracks were found predominantly on the dimple. For different dimple/gimbal combinations tested in this study, the least amount of wear was obtained for the case of a 690 nm thick DLC overcoat. Numerical simulations were performed to calculate the maximum principal stress in the dimple and the gimbal with the goal of correlating wear and the maximum principal stress. The maximum principal stress in both the dimple and the gimbal was found to increase with an increase of the elastic modulus of the DLC overcoat on the gimbal. On comparing the experimental and simulation results, we conclude that wear and fatigue crack formation can be explained by the different level of the maximum principal stress in both the dimple and the gimbal.
Contact between a slider and a magnetic recording disk is modeled as transient contact of a spher... more Contact between a slider and a magnetic recording disk is modeled as transient contact of a sphere on a moving flat. The sphere is assumed to be rigid, and the flat is treated as an elastic-plastic body with isotropic hardening. Heat generation is related to friction at the contact interface. Dimensionless solutions are obtained for maximum temperature rise, maximum contact force, maximum contact area, and maximum penetration as a function of dimensionless vertical initial velocity of the sphere. It is observed that transient thermomechanical contact with elastic-plastic deformation deviates from "classical theories" for dynamic elastic and quasi-static elastic-plastic contacts as the dimensionless vertical initial velocity of the sphere increases. The results are applied to optimize the slider-disk interface in a hard disk drive with respect to slider-disk contacts.
A numerical model for the simulation of fretting wear at the dimple/gimbal interface of a hard di... more A numerical model for the simulation of fretting wear at the dimple/gimbal interface of a hard disk drive suspension has been developed. The friction and wear coefficients used in the model are determined from experimental measurements. Archard’s wear equation is implemented numerically and the contact interface geometry is updated incrementally. The von Mises stress distribution and the worn surface profiles are determined.
ABSTRACT Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Associat... more ABSTRACT Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal
A method was developed to characterize wear between the suspension lift tab and the load/unload r... more A method was developed to characterize wear between the suspension lift tab and the load/unload ramp during load/unload testing in hard disk drives. The change of the friction force between the lift tab and the load/unload ramp was obtained by measuring the change of the voice coil motor (VCM) current. Scanning electron microscopy was used to evaluate the amount of wear debris deposited on the lift tab. The change of the VCM current was correlated with the area of adhering wear debris on the lift tab surface as a function of load/unload cycles and temperature. Energy-dispersive X-ray analysis was performed to identify the chemical composition of the wear debris and determine the wear mechanism.
The mechanical and thermal response of a thermal flying height control slider during contacts wit... more The mechanical and thermal response of a thermal flying height control slider during contacts with a disk asperity is numerically studied. The effect of asperity height and asperity diameter on the scratch dimensions in the read/write shields is investigated, and the maximum temperature at the reader location is determined. The effect of the number of contact cycles is studied.
Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems, Jun 1, 2013
ABSTRACT A time dependent Reynolds equation simulator combined with a finite element-based transi... more ABSTRACT A time dependent Reynolds equation simulator combined with a finite element-based transient contact model between a slider and a disk asperity is used to study slider dynamics induced by contacts with disk asperities. The flying height change at the trailing edge of the slider is investigated as a function of asperity height, asperity diameter, and the spacing between the thermal protrusion of a thermal-flying control slider and a disk asperity. The effect of material properties of the disk asperities is studied. Slider vibrations corresponding to the first and the second pitch modes are excited by disk asperities.
Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems, Jun 6, 2013
Vertical vibrations at the slider leading edge exited by a disk asperity were investigated in a d... more Vertical vibrations at the slider leading edge exited by a disk asperity were investigated in a drive level system, using laser Doppler vibrometry and acoustic emission (AE) sensors. The flying height change at the leading edge of a thermal flying-height control slider was measured for different power inputs to the heater element. The maximum spacing change at the slider leading edge was found to be about 4 nm for an asperity of 26 nm height and 1.1 lm width. A method was investigated to produce ''artificial asperities'' on a disk surface using a nano-indentor. The geometry of the ''artificial asperities'' was characterized using an atomic force microscope. In addition, a spin stand was used to analyze the AE signal of slider vibrations induced by contacts with the ''artificial asperities''. First and second pitch modes of the slider were observed.
Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems, Mar 26, 2015
ABSTRACT The effect of a head void on the heat transfer in the air bearing between two parallel s... more ABSTRACT The effect of a head void on the heat transfer in the air bearing between two parallel surfaces is investigated. The temperature distribution in the air bearing in the presence of the head void is calculated, and the heat flux in the air bearing is determined as a function of boundary pressure, boundary temperature, bottom surface velocity, and void size.
A finite element model is developed to study the transient thermo-mechanical contact between a ri... more A finite element model is developed to study the transient thermo-mechanical contact between a rigid sphere and an elastic-plastic sphere. Interference and tangential displacement are applied to the rigid sphere while the elastic-plastic sphere is stationary. The radius of the rigid sphere is larger than that of the elastic-plastic sphere to model flattening. Universal solutions are obtained for the maximum contact force, the maximum contact area, the maximum residual interference, and the maximum temperature rise independent of sphere radius, material properties and loading parameters. The effects of various parameters (sphere radius, interference, coefficient of friction, sliding velocity and material properties) on the contact characteristics of the deformable sphere are discussed.
Mechanical clearance is a critical parameter of the head/disk interface (HDI) for sliders flying ... more Mechanical clearance is a critical parameter of the head/disk interface (HDI) for sliders flying in close proximity in hard disk drives. It depends on a variety of HDI parameters, such as the air-bearing design, disk roughness, and the disk lubricant. An experimental setup was developed to determine the mechanical clearance locally at any location on the disk. Voltage pulsing is used to add an additional force component to the complex HDI equilibrium. The applied force is attractive in character and therefore reduces the mechanical spacing between the slider and the disk. If the magnitude of the applied voltage is changed, a slight contact between the slider and the disk can be realized. Simultaneous measurement of the induced slider displacement using a laser vibrometer allows the quantification of the mechanical clearance. The effect of disk roughness and microwaviness on the mechanical clearance is investigated.
In current "state of the art" disk drives, the flying height between slider and disk is on the or... more In current "state of the art" disk drives, the flying height between slider and disk is on the order of 10 nm. The flying height will need to be reduced to approximately 3 nm to meet future storage density goals. At a spacing of 3 nm, severe tribological problems will occur with respect to friction, wear and lubrication of the head/disk interface. In this paper, tribology and nano-tribology problems of the head/disk interface are examined as the recording density is increased towards 1Tbit/inch 2 .
Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems, Jun 24, 2012
Contact between a slider and bit patterned media (BPM) is investigated using finite element analy... more Contact between a slider and bit patterned media (BPM) is investigated using finite element analysis. The effect of contact conditions and material properties at the interface between slider and disk on plastic deformation and temperature is studied. In addition, the planarization of bit pattern media on temperature and plastic deformation is investigated for different filler materials. It is found that filler material results in reduction of plastic deformation and temperature.
Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems, Jan 15, 2011
Transient thermal-mechanical contacts between a slider and a rotating disk in the presence of con... more Transient thermal-mechanical contacts between a slider and a rotating disk in the presence of contamination particles are investigated using finite element analysis. The maximum temperature rise due to frictional heating, the maximum plastically deformed area, and the maximum residual penetration into the disk surface are determined as a function of particle properties for aluminum and glass disk substrate. It is found that contact with soft and deformable particles can cause a large temperature rise, sufficient for thermal erasure, even though physical damage of the media is not observed. Contact with hard and rigid particles can lead to severe plastic deformation as well as high temperature rise of the media, representing the worst case for tribological integrity of the slider-disk interface.
Fretting wear at the dimple/gimbal interface of a hard disk drive suspension was investigated for... more Fretting wear at the dimple/gimbal interface of a hard disk drive suspension was investigated for stainless steel dimples in contact with stainless steel gimbals coated with diamondlike carbon (DLC) of different thicknesses and different elastic moduli. Scanning electron microscopy (SEM) was used to evaluate the size and characteristics of the wear scar of both the dimple and the gimbal. Fretting wear and fatigue-type cracks were found predominantly on the dimple. For different dimple/gimbal combinations tested in this study, the least amount of wear was obtained for the case of a 690 nm thick DLC overcoat. Numerical simulations were performed to calculate the maximum principal stress in the dimple and the gimbal with the goal of correlating wear and the maximum principal stress. The maximum principal stress in both the dimple and the gimbal was found to increase with an increase of the elastic modulus of the DLC overcoat on the gimbal. On comparing the experimental and simulation results, we conclude that wear and fatigue crack formation can be explained by the different level of the maximum principal stress in both the dimple and the gimbal.
Contact between a slider and a magnetic recording disk is modeled as transient contact of a spher... more Contact between a slider and a magnetic recording disk is modeled as transient contact of a sphere on a moving flat. The sphere is assumed to be rigid, and the flat is treated as an elastic-plastic body with isotropic hardening. Heat generation is related to friction at the contact interface. Dimensionless solutions are obtained for maximum temperature rise, maximum contact force, maximum contact area, and maximum penetration as a function of dimensionless vertical initial velocity of the sphere. It is observed that transient thermomechanical contact with elastic-plastic deformation deviates from "classical theories" for dynamic elastic and quasi-static elastic-plastic contacts as the dimensionless vertical initial velocity of the sphere increases. The results are applied to optimize the slider-disk interface in a hard disk drive with respect to slider-disk contacts.
A numerical model for the simulation of fretting wear at the dimple/gimbal interface of a hard di... more A numerical model for the simulation of fretting wear at the dimple/gimbal interface of a hard disk drive suspension has been developed. The friction and wear coefficients used in the model are determined from experimental measurements. Archard’s wear equation is implemented numerically and the contact interface geometry is updated incrementally. The von Mises stress distribution and the worn surface profiles are determined.
ABSTRACT Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Associat... more ABSTRACT Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal
A method was developed to characterize wear between the suspension lift tab and the load/unload r... more A method was developed to characterize wear between the suspension lift tab and the load/unload ramp during load/unload testing in hard disk drives. The change of the friction force between the lift tab and the load/unload ramp was obtained by measuring the change of the voice coil motor (VCM) current. Scanning electron microscopy was used to evaluate the amount of wear debris deposited on the lift tab. The change of the VCM current was correlated with the area of adhering wear debris on the lift tab surface as a function of load/unload cycles and temperature. Energy-dispersive X-ray analysis was performed to identify the chemical composition of the wear debris and determine the wear mechanism.
The mechanical and thermal response of a thermal flying height control slider during contacts wit... more The mechanical and thermal response of a thermal flying height control slider during contacts with a disk asperity is numerically studied. The effect of asperity height and asperity diameter on the scratch dimensions in the read/write shields is investigated, and the maximum temperature at the reader location is determined. The effect of the number of contact cycles is studied.
Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems, Jun 1, 2013
ABSTRACT A time dependent Reynolds equation simulator combined with a finite element-based transi... more ABSTRACT A time dependent Reynolds equation simulator combined with a finite element-based transient contact model between a slider and a disk asperity is used to study slider dynamics induced by contacts with disk asperities. The flying height change at the trailing edge of the slider is investigated as a function of asperity height, asperity diameter, and the spacing between the thermal protrusion of a thermal-flying control slider and a disk asperity. The effect of material properties of the disk asperities is studied. Slider vibrations corresponding to the first and the second pitch modes are excited by disk asperities.
Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems, Jun 6, 2013
Vertical vibrations at the slider leading edge exited by a disk asperity were investigated in a d... more Vertical vibrations at the slider leading edge exited by a disk asperity were investigated in a drive level system, using laser Doppler vibrometry and acoustic emission (AE) sensors. The flying height change at the leading edge of a thermal flying-height control slider was measured for different power inputs to the heater element. The maximum spacing change at the slider leading edge was found to be about 4 nm for an asperity of 26 nm height and 1.1 lm width. A method was investigated to produce ''artificial asperities'' on a disk surface using a nano-indentor. The geometry of the ''artificial asperities'' was characterized using an atomic force microscope. In addition, a spin stand was used to analyze the AE signal of slider vibrations induced by contacts with the ''artificial asperities''. First and second pitch modes of the slider were observed.
Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems, Mar 26, 2015
ABSTRACT The effect of a head void on the heat transfer in the air bearing between two parallel s... more ABSTRACT The effect of a head void on the heat transfer in the air bearing between two parallel surfaces is investigated. The temperature distribution in the air bearing in the presence of the head void is calculated, and the heat flux in the air bearing is determined as a function of boundary pressure, boundary temperature, bottom surface velocity, and void size.
A finite element model is developed to study the transient thermo-mechanical contact between a ri... more A finite element model is developed to study the transient thermo-mechanical contact between a rigid sphere and an elastic-plastic sphere. Interference and tangential displacement are applied to the rigid sphere while the elastic-plastic sphere is stationary. The radius of the rigid sphere is larger than that of the elastic-plastic sphere to model flattening. Universal solutions are obtained for the maximum contact force, the maximum contact area, the maximum residual interference, and the maximum temperature rise independent of sphere radius, material properties and loading parameters. The effects of various parameters (sphere radius, interference, coefficient of friction, sliding velocity and material properties) on the contact characteristics of the deformable sphere are discussed.
Mechanical clearance is a critical parameter of the head/disk interface (HDI) for sliders flying ... more Mechanical clearance is a critical parameter of the head/disk interface (HDI) for sliders flying in close proximity in hard disk drives. It depends on a variety of HDI parameters, such as the air-bearing design, disk roughness, and the disk lubricant. An experimental setup was developed to determine the mechanical clearance locally at any location on the disk. Voltage pulsing is used to add an additional force component to the complex HDI equilibrium. The applied force is attractive in character and therefore reduces the mechanical spacing between the slider and the disk. If the magnitude of the applied voltage is changed, a slight contact between the slider and the disk can be realized. Simultaneous measurement of the induced slider displacement using a laser vibrometer allows the quantification of the mechanical clearance. The effect of disk roughness and microwaviness on the mechanical clearance is investigated.
In current "state of the art" disk drives, the flying height between slider and disk is on the or... more In current "state of the art" disk drives, the flying height between slider and disk is on the order of 10 nm. The flying height will need to be reduced to approximately 3 nm to meet future storage density goals. At a spacing of 3 nm, severe tribological problems will occur with respect to friction, wear and lubrication of the head/disk interface. In this paper, tribology and nano-tribology problems of the head/disk interface are examined as the recording density is increased towards 1Tbit/inch 2 .
Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems, Jun 24, 2012
Contact between a slider and bit patterned media (BPM) is investigated using finite element analy... more Contact between a slider and bit patterned media (BPM) is investigated using finite element analysis. The effect of contact conditions and material properties at the interface between slider and disk on plastic deformation and temperature is studied. In addition, the planarization of bit pattern media on temperature and plastic deformation is investigated for different filler materials. It is found that filler material results in reduction of plastic deformation and temperature.
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Papers by Frank Talke