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    Effects of slider geometry change on helium filled HDD
    (2014-01-01)
    Mongkolwongrojn, Mongkol
    ;
    Kuanoon, Kunchit
    This paper describes the static characteristics of helium filled hard disk drive for a s two rails flat slider gas bearing. Numerical scheme based on the finite difference with multigrid 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. © (2014) Trans Tech Publications, Switzerland.
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    Theoretical analysis of flying characteristics for air-helium filled HDD
    (2014-01-01)
    Mongkolwongrojn, Mongkol
    ;
    Kuanoon, Kunchit
    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 multigrid 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. © (2014) Trans Tech Publications, Switzerland.
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    Effect of Al2O3 nanoparticles additives on thermo-elastohydrodynamic with Newtonian lubricant
    (2013-10-04)
    Rattapasakorn, Sountaree
    ;
    Mongkolwongrojn, Mongkol
    This paper presents the effect of Al<inf>2</inf>O<inf>3</inf> nanoparticles additives on thermo-elastohydrodynamic with Newtonian lubricant. The modified Reynolds equation and energy equation have been formulated and solved numerically with initial conditions using multi-grid multi-level method. Simulation results show the operating with Al<inf>2</inf>O<inf>3</inf> nanoparticles blended particularly with SAE-90 lubricant. The maximum pressure and temperature decreases, as compared to SAE-90 oil without nanoparticles additives. © (2013) Trans Tech Publications, Switzerland.
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    Transient EHL of two surfaces under elliptical contact with non-Newtonian lubricant
    (2012-02-23)
    Mongkolwongrojn, Mongkol
    ;
    Panichakorn, Jesda
    This paper presents the effects of a sudden load change and sudden speed change on the performance characteristics of two surfaces under elliptical contact with elastohydrodynamic lubrication. The non-Newtonian lubricant for the research work are modeled based on Carreau viscosity model. The time dependent modified Reynolds equation and elastic equation were formulated for compressible fluid. Perturbation method, Newton Raphson method and full adaptive multigrid method were implemented and solved to obtain the film pressure, film thickness profiles and friction coefficient in the contact regime at various applied loads and speeds. Simulation results show the friction coefficient increase significantly under sudden loads. The minimum film thickness and friction coefficient both decrease significantly as speed is decreased. © (2012) Trans Tech Publications.