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Investigation of HDD Ramp Unloading Processes with an Efficient Scheme

Published online by Cambridge University Press:  03 June 2015

Yan Liu
School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
Hejun Du*
School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
*Corresponding author. URL:
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Ramp load/unload (L/UL) mechanisms are widely used to rest sliders in hard disk drives (HDDs). Loading/unloading a slider swiftly and smoothly is crucial in a HDD design. A novel, efficient simulation scheme is proposed to investigate the behaviors of a head disk interface (HDI) in ramp unloading processes. A dual scale model is enabled by decoupling the nano-meter scale change of an air bearing and the micro- or milli-meter scale deformation of a suspension. A modified Reynolds equation governing the air bearing was solved numerically. The slider design was characterized with performance functions. Three stages in an unloading process were analyzed with a lumped parameter suspension model. Key parameters for the model were estimated with a comprehensive finite element suspension model. Finally, simulation results are presented for a commercial HDI design.

Research Article
Copyright © Global-Science Press 2011

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[1] Suk, M. and Albrecht, T. R., The evolution of L/UL technology, Microsyst. Technol., 8 (2002), pp. 1016.CrossRefGoogle Scholar
[2] Bogy, D. B., Fong, W. and Thornton, B. H., Some tribology and mechanics issues for 100Gb/in2 hard disk drive, IEEE T. Magn., 38(5) (2002), pp. 18791885.CrossRefGoogle Scholar
[3] Yamada, T. and Bogy, D. B., Load-unload slider dynamics in magnetic disk drives, IEEE T. Magn., 24(6) (1988), pp. 27422744.CrossRefGoogle Scholar
[4] Zeng, Q. H., Chapin, M. and Bogy, D. B., Dynamics of the unload process for negative pressure sliders, IEEE T. Magn., 35(2) (1999), pp. 916920.CrossRefGoogle Scholar
[5] Zeng, Q. H. and Bogy, D. B., A simplified 4-DOF suspension model for dynamic load unload simulation and its application, ASME J. Tribol., 122 (2000), pp. 274279.CrossRefGoogle Scholar
[6] Liu, Y. and Wang, S., A performance surface method for characterizing the nonlinear air bearing forces and moments with application to the unloading process, Proc. STLE/ASME Int. Joint Tribology Conf., (2008), Paper IJTC 2008-71193.CrossRefGoogle Scholar
[7] Liu, Y., Du, H. J. and Wang, S., An efficient simulation scheme for the unloading process with application to parametric studies and trend analyses, Proc. JSME-IIP/ASME-ISPS Joint Conference on Micromechatronics for Information and Precision Equipment 2009, Paper 375027-3.CrossRefGoogle Scholar
[8] Wang, S., Crimi, F. P. and Blanco, R. J., Dynamic behavior of magnetic head sliders and carbon wear in a ramp load process, Microsyst. Technol., 9 (2003), pp. 266270.CrossRefGoogle Scholar
[9] Hua, W., Liu, B., Sheng, G. and Li, J., Further studies of unload process with a 9D model, IEEE T. Magn., 37(4) (2001), pp. 18551858.CrossRefGoogle Scholar
[10] Hu, Y., Jones, P. M. and Li, K., Air bearing dynamics of sub-ambient pressure sliders during dynamic unload, ASME/STLE, International Tribology Conference, 1998.Google Scholar
[11] Wu, L. and Bogy, D. B., A generalized compressible Reynolds lubrication equation with bounded contact pressure, Phys. Fluid, 13(8) (2001), pp. 22372244.CrossRefGoogle Scholar
[12] Tanaka, H., Kohira, H. and Matsumoto, M., Effect of air-bearing design on slider dynamics during unloading process, IEEE T. Magn., 37(4) (2001), pp. 18181820.CrossRefGoogle Scholar
[13] Burgdorfer, A., The influence of the molecular mean free path on the performance of hydrody-namic gas lubricated bearings, J. Basic Eng-T. ASME, 81 (1959), pp. 94100.Google Scholar
[14] Hsia, T. and Domoto, G. A., An experimental investigation of molecular rarefaction effects in gas lubricated bearings at ultra-low clearances, J. Lubric. Tech-T. ASME, 105 (1983), pp. 120130.CrossRefGoogle Scholar
[15] Mitsuya, G., Modified Reynolds equation for ultra-thin film gas lubrication using 1.5-order slip-flow model and considering surface accommodation coefficient, J. Tribol-T. ASME, 115 (1993), pp. 289294.CrossRefGoogle Scholar
[16] Gan, R. F., Lubrication theory at arbitrary Knudsen number, J. Tribol-T. ASME, 107 (1985), pp. 431433.Google Scholar
[17] Wu, L. and Bogy, D. B., Use of an upwind finite volume method to solve the air bearing problem of HDDs, Comput. Mech., 26 (2000), pp. 592600.CrossRefGoogle Scholar
[18] Versteeg, H. K., An Introduction to Computational Fluid Dynamics: The Finite Volume Method, Pearson Education, 2007.Google Scholar