Abstract
Mechanical properties of rotors supported by fluid dynamic bearings (FDBs) cannot be directly measured because most of the mechanical properties of FDBs become active only when the rotors are in revolutionary motion. A typical example is the measurement of mechanical stiffness of the rotors that are used for hard disk drives. A popular measurement method so-called pitch modes requires the rotor to be loaded with disks and rotated at a particular revolutionary speed to maintain a certain mechanical stiffness for the pitch mode measurement. Although the measured pitch modes could represent the mechanical stiffness of the rotors, this approach is rather ad hoc. In this article an attempt is made for eliminating the dummy loads and the mechanical contacts by using hydrodynamic force induced excitations. Applying a compressed airstream to a rotating FDB that generates radial shift of the rotor, the proposed method determines mechanical stiffness of the rotor by relating the air pressure and the radial displacement. A whole design process including numerical validation and component calibration is explained and a series of hardware verification testing is also performed.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Hasegawa T, Du H, Osawa H, Nishimura H, Oe T (2003) Dynamic analysis of a disk-spindle system in a hard disk drive. IEEE Trans Magn 39(2):783–788
Jang G, Lee S (2006) Determination of the dynamic coefficients of the coupled journal and thrust bearings by the perturbation method. Tribol Lett 22(3):239–246
Jintanawan T, Shen IY, Tanaka K (2001) Vibration analysis of fluid dynamic bearing spindles with rotating-shaft design. IEEE Trans Magn 37(2):799–804
Ku C-PR, Shumway M (1998) Experimental investigation of shock responses of Cantilever-shaft design hydrodynamic bearing spindle motors. IEEE Trans Magn 34(4):1913–1915
Lee N-h, Kwon J-m, Koo JC (2005) Automation of feature modeling for HDD fluid dynamic bearing design. Trans Korean Soc Noise Vib Eng 15(2):148–155
Matsuoka K, Obata S, Kita H, Toujou F (2001) Development of FDB spindle motors for HDD use. IEEE Trans Magn 37(2):783–788
Miwa M, Haritaa H, Nishigamia T, Kaneko R, Unozawa H (2003) Frequency characteristics of stiffness and damping effect of a ferrofluid bearing. Tribol Lett 15(2):97–105
Miwa M, Miyazaki H, Kaneko R, Unozawa H (2005) Evaluation of fluid dynamic bearing spindle by vibration base. IEEE Trans Magn 41(2):763–768
Shen IY (1997) Closed-form forced response of a damped, rotating, multiple disk/spindle system. ASME J Appl Mech 64:343–352
Shen IY, Ku C-PR (1997) A nonclassical vibration analysis of a multiple rotating disk and spindle assembly. ASME J Appl Mech 64:165–174
White FM (1999) Fluid mechanics. McGraw-Hill, Prentice Hall
Acknowledgments
This research was partially sponsored by the Ministry of Knowledge Economy and Korea Industrial Technology Foundation through the Human Resource Training Project for Strategic Technology and some equipment were provided by GRRC program of Gyeonggi Province Korea.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Ihn, Y.S., Kim, S.K., Oh, D. et al. Non-contact measurement method of mechanical stiffness for high revolutionary speed precision fluid dynamic bearing rotors. Microsyst Technol 16, 233–240 (2010). https://doi.org/10.1007/s00542-009-0849-7
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00542-009-0849-7