Nonlinearity of Thermal Spacing Control in Hard Disk Drives

ASME/STLE 2009 International Joint Tribology Conference

2009

Particle contamination on a slider in a hard disk drive (HDD) affects the HDD's reliability. With the introduction of the thermal flying-height control (TFC) slider, the temperature in the head-disk interface (HDI) becomes non-uniform, which induces a temperature-gradient dependent force on particles moving in the HDI. The present article investigates the effect of this force, the so called thermophoretic force, on a particle's motion in the HDI as well as its effect on particle contamination on the TFC slider. By numerical simulation of the particle's trajectory together with an analytical analysis, we show that the thermophoretic force is always negligible compared to the Saffman lift force, which points to a direction parallel to the thermophoretic force. We conclude that the current particle contamination simulator without any thermophoretic forces included would not be significantly altered by the inclusion of these forces.

Section: Resultsmentioning

confidence: 99%

Particle Contamination on a Thermal Flying-Height Control Slider

Liu

ASME/STLE 2009 International Joint Tribology Conference

2009

“…They found that reducing the insulator's thermal conductivity and increasing its thickness are helpful. Aoki and Watanabe [9] numerically and experimentally studied how the power applied to the heater element affects the distance between the transducer and the disk. They found that the relationship is non-linear and the distance is mainly affected by the slider's thermal protrusion.…”

Section: Introductionmentioning

confidence: 99%

Thermo-mechanical aspects of thermal flying-height control sliders for hard disk drives

Liu¹,

Zheng

Mathematics and Mechanics of Solids

2011

Thermal flying-height control sliders are currently used in most hard disk drives as an approach to increase the capacity and reliability. This paper discusses our recent numerical studies of the sliders’ flying performances, namely, the heat transfer between the slider and the disk, the flyability of the sliders at different altitudes, and the effect of the disk’s lubricant and roughness on the slider’s flying stability. We validate previous investigations based on a heat transfer model derived from the first-order slip theory and identify the instability regimes for a slider flying over a lubricated rough disk.

“…Thermal flying-height control (TFC) technology can be applied to produce a protruded part on the air bearing surface [1][2][3]. When actuated, this protruded part can penetrate into the lubricant layer during reading or writing.…”

Section: Introductionmentioning

confidence: 99%

“…By adopting a sub-boundary lubrication model [11] based on the classical DeryaginMuller-Toporov model (the DMT model), we include the effects of lubricant-and solid-contacting adhesion where the deformed contact profile is taken into account. The real TFC protrusion profile is applied for an industry-produced femto-sized slider (0.85 9 0.70 9 0.23 mm 3 ). The equilibrium solution is examined as a function of the thermal protrusion height.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Flying-Height Stability of Thermal Fly-Height Control Sliders in Lubricant or Solid Contact with Roughness

Zheng

2010

Tribol Lett

When the magnetic spacing in hard disk drives is reduced to sub-3 nm, contact between the slider and disk becomes inevitable. Stability analysis is used in this study to investigate the head-disk interface (HDI) stability of thermal fly-height control (TFC) sliders in light contact with the disk lubricant or solid roughness. We implement an improved DMT model with sub-boundary lubrication into the CML air bearing program and analyze the stability of equilibrium states of a TFC slider under different thermal actuations. It is found that stability is lost when the slider penetrates deeper into the lubricant layer, due to a fast growth in the adhesion force, and it is restored when the solid roughness contact develops. In addition, the critical point for the onset of this instability and the range of this instability region is found to vary with lubricant thickness and protrusion surface steepness, while keeping the air bearing design the same.