The purpose of this study is to propose a practlcal technique for damping and stlffness characteristics iniprovement on the drilling of a smal [ and deep. In this paper , the damping and stiffhess characteristics of a composite structure drill model are experimentally investigated . The composite structure dri } 1 models weremade by inserting column in aluminum pipe . The effects of composite column size and material on damping and stiffhess ' characteristics are examined in the case of

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... e lnserting of different column size and composite inserting of different column material . The experiments show that the damping and stiffhess characteristics are affec ピ 6d by the composite column size and material , and it is confirmed that the damping capacity and stiffness are effectively improved .