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This study was aimed to investigate the machining stability of a spindle tool with different preloaded amount. To this end, the vibration tests were conducted on the spindle unit with different preload to assess the dynamic characteristics and machining stability of the milling machine. Current results demonstrate that the tool tip frequency response characteristics and the machining stabilities in X and Y direction are affected to change due to the different preload of spindle bearings. As found from the results, a high preloaded spindle tool shows higher limited cutting depth at mid position, while a spindle with low preload shows a higher limited depth. This indicates that the machining stability of a milling machine is affected to vary by the spindle unit when it was assembled with different bearing preload., {"references":["E. Abele, Y. Altintas, C. Brecher, \"Machine Tool Spindle Units,\" CIRP\nAnnals – Manufacturing Technology, vol. 59, no. 4, pp. 781–802, 2010.","M. Weck, A. Koch, \"Spindle-bearing systems for high-speed applications\nin machine tools,\" CIRP Annals-Manufacturing Technology, vol. 42, no.\n1, pp. 445–448, 1993.","S. P. Harsha, L. Sandeep, R. E. Prakash. \"Effects of Preload and Number\nof Balls on Nonlinear Dynamic Behaviors of Ball Bearing System,\"\nInternational Journal of Nonlinear Science and Numerical Simulation.\nvol. 4, no. 3, pp. 265-278, 2003.","Y. Cao, Y. Altintas, \"Modeling of Spindle-Bearing and Machine Tool\nSystems for Virtual Simulation of Milling Operations,\" International\nJournal of Machine Tools and Manufacturing. vol. 47, no. 9 pp.\n1342-1350, 2007.","M. A. Alfares, A. A. Elsharkawy. \"Effects of Axial Preloading of Angular\nContact Ball Bearings on the Dynamics of a Grinding Machine Spindle\nSystem,\" Journal of Materials Processing Technology. vol. 136, no. 3, pp.\n48-59, 2003.","S. A. Spiewak, T. Nickel. Vibration Based Preload Estimation in Machine\nTool Spindles, International Journal of Machine Tools & Manufacture.\nvol. 41, no. 4, pp. 567-588, 2001.","A. Gunduz, J. T. Dreyer, R. Singh. \"Effect of Bearing Preloads on the\nModal Characteristics of a Shaft-Bearing Assembly: Experiments on\nDouble Row Angular Contact Ball Bearings,\" Mechanical Systems and\nSignal Processing. vol. 31, pp. 176-195, 2012.","J. Tlusty, .M. Polacek. \"The Stability of Machine Tools Against\nSelf-Excited Vibrations in Machining,\" Trans. ASME, International\nresearch in production engineering. Pp. 465-474, 1963.","S. A.Tobias, W. Fishwick. \"The Chatter of Lathe Tools under Orthogonal\nCutting Conditions\", Trans. ASME, Journal of Engineering for Industry,\nvol. 80, pp. 1079-1088, 1958.\n[10] E. Ozturk, U. Kumar, S. Turner, T. Schmitz. \"Investigation of Spindle\nBearing Preload on Dynamics and Stability Limit in Milling,\" CIRP\nAnnals-Manufacturing Technology. vol. 61, no. 1, pp. 343-346, 2012.\n[11] C. W. Lin, J. F. Tu. \"Model-Based Design of Motorized Spindle Systems\nto Improve Dynamic Performance at High Speeds,\" Journal of\nManufacturing Processes. vol. 9, no. 2, pp. 94-108, 2007.\n[12] S. Jiang, H. Mao. \"Investigation of Variable Optimum Preload for a\nMachine Tool Spindle,\" International Journal of Machine Tools and\nManufacture. vol.50, no. 1, pp. 19-28, 2010.\n[13] S. Jiang, H. Mao. \"Investigation of Variable Optimum Preload for a\nMachine Tool Spindle,\" International Journal of Machine Tools and\nManufacture. vol.50, no. 1, pp. 19-28, 2010.\n[14] Y. Altintas, E. Budak. \"Analytical prediction of stability lobes in\nmilling,\" Annals of the CIRP Vol. 44, pp.357–362, 1995.\n[15] J. P. Hung, Y. S. Lai, T. L. Luo, K. D. Wu, Y. Z. Zhan, \" Effect of\nDrawbar Force on the Dynamic Characteristics of a Spindle-Tool Holder\nSystem,\" World Academy of Science, Engineering and Technology,\nInternational Journal of Mechanical, Industrial Science and Engineering\nvol. 8, no.5, pp. 970-975, 2014"]}

This paper presents the variation of the dynamic characteristics of a spindle with the change of bearing preload. The correlations between the variation of bearing preload and fundamental modal parameters were first examined by conducting vibration tests on physical spindle units. Experimental measurements show that the dynamic compliance and damping ratio associated with the dominating modes were affected to vary with variation of the bearing preload. When the bearing preload was slightly deviated from a standard value, the modal frequency and damping ability also vary to different extent, which further enable the spindle to perform with different compliance. For the spindle used in this study, a standard preload value set on bearings would enable the spindle to behave a higher stiffness as compared with others with a preload variation. This characteristic can be served as a reference to examine the variation of bearing preload of spindle in assemblage or operation., {"references":["E. Abele, Y. Altintas, C. Brecher, \"Machine Tool Spindle Units,\" CIRP\nAnnals – Manufacturing Technology, vol. 59, no. 4, pp. 781–802, 2010.","M. Weck, A. Koch, \"Spindle-bearing systems for high-speed applications\nin machine tools,\" CIRP Annals-Manufacturing Technology, vol. 42, no.\n1, pp. 445–448, 1993.","S. P. Harsha, L. Sandeep, R. E. Prakash. \"Effects of Preload and Number\nof Balls on Nonlinear Dynamic Behaviors of Ball Bearing System,\"\nInternational Journal of Nonlinear Science and Numerical Simulation.\nvol. 4, no. 3, pp. 265-278, 2003.","Y. Cao, Y. Altintas, \"Modeling of Spindle-Bearing and Machine Tool\nSystems for Virtual Simulation of Milling Operations,\" International\nJournal of Machine Tools and Manufacturing. vol. 47, no. 9 pp.\n1342-1350, 2007.","M. A. Alfares, A. A. Elsharkawy. \"Effects of Axial Preloading of Angular\nContact Ball Bearings on the Dynamics of a Grinding Machine Spindle\nSystem,\" Journal of Materials Processing Technology. vol. 136, no. 3, pp.\n48-59, 2003.","S. A. Spiewak, T. Nickel. Vibration Based Preload Estimation in Machine\nTool Spindles, International Journal of Machine Tools & Manufacture.\nvol. 41, no. 4, pp. 567-588, 2001.","A. Gunduz, J. T. Dreyer, R. Singh. \"Effect of Bearing Preloads on the\nModal Characteristics of a Shaft-Bearing Assembly: Experiments on\nDouble Row Angular Contact Ball Bearings,\" Mechanical Systems and\nSignal Processing. vol. 31, pp. 176-195, 2012.","J. Tlusty, .M. Polacek. \"The Stability of Machine Tools Against\nSelf-Excited Vibrations in Machining,\" Trans. ASME, International\nresearch in production engineering. Pp. 465-474, 1963.","S. A.Tobias, W. Fishwick. \"The Chatter of Lathe Tools under Orthogonal\nCutting Conditions\", Trans. ASME, Journal of Engineering for Industry,\nvol. 80, pp. 1079-1088, 1958.\n[10] NSK Technologies Company. \"NSK super precision bearings Part 5:\nTechnical guides,\" http://www.nsk.com/products/spb/, 2003.\n[11] E. Ozturk, U. Kumar, S. Turner, T. Schmitz. \"Investigation of Spindle\nBearing Preload on Dynamics and Stability Limit in Milling,\" CIRP\nAnnals-Manufacturing Technology. vol. 61, no. 1, pp. 343-346, 2012.\n[12] C. W. Lin, J. F. Tu. \"Model-Based Design of Motorized Spindle Systems\nto Improve Dynamic Performance at High Speeds,\" Journal of\nManufacturing Processes. vol. 9, no. 2, pp. 94-108, 2007.\n[13] S. Jiang, H. Mao. \"Investigation of Variable Optimum Preload for a\nMachine Tool Spindle,\" International Journal of Machine Tools and\nManufacture. vol.50, no. 1, pp. 19-28, 2010.\n[14] J. P. Hung, Y. S. Lai, T. L. Luo, K. D. Wu, Y. Z. Zhan, \" Effect of\nDrawbar Force on the Dynamic Characteristics of a Spindle-Tool Holder\nSystem,\" World Academy of Science, Engineering and Technology,\nInternational Journal of Mechanical, Industrial Science and Engineering\nvol. 8, no.5, pp. 970-975, 2014."]}

The machining performance is determined by the frequency characteristics of the machine-tool structure and the dynamics of the cutting process. Therefore, the prediction of dynamic vibration behavior of spindle tool system is of great importance for the design of a machine tool capable of high-precision and high-speed machining. The aim of this study is to develop a finite element model to predict the dynamic characteristics of milling machine tool and hence evaluate the influence of the preload of the spindle bearings. To this purpose, a three dimensional spindle bearing model of a high speed engraving spindle tool was created. In this model, the rolling interfaces with contact stiffness defined by Harris model were used to simulate the spindle bearing components. Then a full finite element model of a vertical milling machine was established by coupling the spindle tool unit with the machine frame structure. Using this model, the vibration mode that had a dominant influence on the dynamic stiffness was determined. The results of the finite element simulations reveal that spindle bearing with different preloads greatly affect the dynamic behavior of the spindle tool unit and hence the dynamic responses of the vertical column milling system. These results were validated by performing vibration on the individual spindle tool unit and the milling machine prototype, respectively. We conclude that preload of the spindle bearings is an important component affecting the dynamic characteristics and machining performance of the entire vertical column structure of the milling machine., {"references":["Yoshimi Ito, Modular design for machine tool, McGraw Hill Company,\n2008.","Y. Seo, D. P. Hong, I. Kim, T. Kim, D. Sheen, and G. B. Lee, Structure\nmodeling of machine tools and internet-based implementation,\nProceedings of the 2005 Winter Simulation Conference, December 2005,\nOrlando, Florida, USA.","J. Tlusty, M. Polacek, The stability of machine tools against self-excited\nvibrations in machining, 1963, in: Proceedings of the ASME\nInternational.","J. Tlusty, Dynamics of high-speed milling, Trans. ASME, Journal of\nEngineering for Industry 108 (2) (1986) 59-67.","F. Koenisberger, J. Tlusty, Machine tool structuresÔÇöVol. I: stability\nagainst chatter, Pergamon Press, Englewood Cliffs, NJ, 1967.","S.A. Tobias, W. Fishwick, The chatter of lathe tools under orthogonal\ncutting conditions, Trans. ASME, Journal of Engineering for Industry 80\n(1958) 1079-1088.","N. Akt├╝rk, M. Uneeb, M. R. Gohar, The effects of number of balls and\npreload on vibrations associated with ball bearings, Trans. ASME,\nJournal of Tribology 119 (4) (1997) 747-753.","S. P. Harsha, K. Sandeep, R. E. Prakash, Effects of preload and number of\nballs on nonlinear dynamic behaviors of ball bearing system,\nInternational Journal of Nonlinear Science and Numerical Simulation\n4(3) (2003 ) 265-278.","Y. Cao, Y. Altintas, Modeling of spindle-bearing and machine tool\nsystems for virtual simulation of milling operations, International Journal\nof Machine Tools and Manufacturing 47 (2007) 1342-1350.\n[10] M. A. Alfares, A. A. Elsharkawy, Effects of axial preloading of angular\ncontact ball bearings on the dynamics of a grinding machine spindle\nsystem, Journal of Materials Processing Technology 136(1-3) (2003)\n48-59.\n[11] N. Lynagh, H. Rahnejat, M. Ebrahimi, R. Aini, Bearing induced vibration\nin precision high speed routing spindles, International Journal of Machine\nTools and Manufacture 40(4) (2000) 561-577.\n[12] M.R. Movahhedy, P Mosaddegh, Prediction of chatter in high speed\nmilling including gyroscopic effects. International Journal of Machine\nTools and Manufacture, 46(9) (2006) 996-1001.\n[13] C. W Lin, J. F. Tu, and J. Kamman, An integrated thermo mechanical\ndynamic model to characterize motorized machine tool spindles during\nvery high speed rotation, International Journal of Machine Tools and\nManufacture, 43(2003)1035-1050.\n[14] S. Y. Jiang, S. F. Zheng, A modeling approach for analysis and\nimprovement of spindle-drawbar bearing assembly dynamics.\nInternational Journal of Machine Tools and Manufacture, 50(\n2010)131-142.\n[15] Y. Altintas and S. Park, Dynamic compensation of spindle-integrated\nforce sensors. CIRP Annals - Manufacturing Technology 53(1\n(2004)305-308.\n[16] Y. Altintas and Y. Cao, Virtual design and optimization of machine tool\nspindles. CIRP Annals Manufacturing Technology, 54(1)(2005) 379-382.\n[17] J. P. Hung, Load effect on the vibration characteristics of a stage with\nrolling guides, Journal of Mechanical Science and Technology 23(1)\n(2009) 92-102.\n[18] C. Y. Lin, J. P. Hung, and T. L. Lou, Effect of preload of linear guides on\ndynamic characteristics of a vertical column-spindle system,\nInternational Journal of Machine Tools and Manufacture 5(8) (2010)\n741-746.\n[19] K. J. Johnson, Contact mechanics, Cambridge University Press (1985).\n[20] T.A. Harris, in: Rolling Bearing Analysis, third ed., John Wiley and Sons,\nNew York, 1991.\n[21] D. E. Brewe, B. J. Hamrock, Simplified solution for elliptical-contact\ndeformation between two elastic solid, Trans. ASME, Journal of\nLubrication Technology 99 (1997) 485-487.\n[22] J. A. Greenwood, Analysis of elliptical Herztian contacts, Tribology\nInternational 30 (1997) 235-237.\n[23] J. P. Hung, Y.L. Lai, C. Y. Lin, and T. L. Lou, Modeling the machining\nstability of vertical milling machine under the influence of the preloaded\nlinear guide, International Journal of Machine Tools and Manufacture.\n51(9)(2011)731-739.\n[24] Hiwin Technologies Company. Hiwin linear guideway technical\ninformation. Taiwan: 2000. http://www.hiwin.com/online_cat\n[25] Hiwin Technologies Company. Hiwin ballscrews technical information.\nTaiwan:2000. http://www.hiwin.com/online_cat\n[26] THK Technologies Company. THK Ball screw technical information:\nball screw peripheral. http://www.thk.com/online_cat.\n[27] THK CO., LTD., Features of the LM Guide,\nhttp://www.thk.com/online_cat.\n[28] Y. Altintas, E. Budak, Analytical prediction of stability lobes in milling,\nAnnals of the CIRP 44 (1995) 357-362.\n[29] E. Budak, Y. Altintas, Analytical prediction of chatter stability in\nmillingÔÇöPart I: general formulation; Trans. ASME, Journal of Dynamic\nSystems, Measurement, and Control 120 (1998) 22-30."]}