Measurement and analysis of bearing and pivot stiffness in hard disk drives

L. M. Xu, N. Guo, R. M. Lin, H. Du, C. D. Deng

Research output: Contribution to journalArticleResearchpeer-review

4 Citations (Scopus)


It is known that the quasi-rigid body mode (QR mode) vibration is one of the main sources for generating the residual vibration in settling operation and limiting the servo bandwidth, and is mainly caused by the stiffness of the pivot, the mass, and structure of the head actuator arm. The ball bearings inside the pivot determine the pivot stiffness, which in turn, determine the effective stiffness of the head actuator assembly. In this paper, the stiffness-related issues among ball bearings, pivot, and head actuator assembly are studied theoretically and experimentally. It shows that the pivot effective radial stiffness depends not only on the stiffness of the ball bearing, but also on the connection method used to attach the pivot to the head actuator arm. It is also shown from the measurement and analysis that the resonance frequency of the QR mode, determined by the pivot effective radial stiffness and inherent properties of the head actuator arm, can be moved to a higher frequency by using a more rigid pivot and a more stiff joint.

Original languageEnglish
Pages (from-to)237-245
Number of pages9
JournalJournal of Information Storage and Processing Systems
Issue number3-4
Publication statusPublished - Jul 2001
Externally publishedYes


  • Ball bearing
  • Head actuator assembly
  • Pivot
  • Quasi-rigid body
  • Stiffness

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