銑削加工過程中刀具產生顫振將嚴重影響工件表面精度，並危及刀具與工 具機的壽命。為了避免顫振的發生，通常會選擇較為保守之加工條件，但卻降 低生產效率。如何在生產效率及減少顫振發生間取得平衡，則需建立一套避免 顫振的加工準則。在加工實務上，刀具切削性能表現，除了受刀具對工件材質 之切削力學行為所影響以外，取決於工具機主軸刀具對切削負荷之動態響應。 因此，欲發揮CNC 機台主軸刀具切削性能，必須充分瞭解主軸刀具之動態特 性以及其切削穩定性範圍，藉此才可以依據最終切削範圍需求，選用適當主軸 刀具系統，以獲得最佳切削加工品質與價值。 本研究旨在探討刀具材質對主軸刀具系統動態特性與切削穩定性之影 響。研究中，分別使用碳化鎢以及高速鋼兩種不同材質刀具，組裝在主軸刀柄 筒夾上進行振動實驗，取得刀具端之頻率響應函數，再導入刀具與工件材質之 切削負荷係數，預測該刀具之全方位切削穩定性範圍，藉以評估該刀具之切削 穩定性。研究結果顯示，碳化鎢銑刀與高速鋼銑刀分別表現出不同切削穩定性 範圍，其軸向臨界切深亦隨進給方向之變化而改變，顯示不同材質刀具確實會 對機台切削穩定性有明顯之影響。另外，主軸在Z 軸向移動時亦會改變機台切 削穩定性範圍，此種改變亦受刀具材質所影響，其變化程度有顯著差異。應用 本研究發展全方位切削穩定性分析法則，將可建立主軸刀具系統在規劃加工行 程內之最佳穩定切削深度，提供選用切削條件之決策依據。

Chatter vibration induced by self-excitation during the chip generation process may produce poor surface quality and cause damage to the cuter and machine tool. To avoid the occurrence of chattering, machining operation was performed under poor conditions with more conservative consideration in tooling selection, but the productivity and efficiency of material removal could be reduced. It is therefore important to establish the machining criteria for achieving optimum material removal rates with the highest machining stability. On the other hand, according to the machining mechanic, chattering is eventually caused by the dynamic interaction between the spindle tool system coupled with machine frame structure and the cutting process. Besides, the machining behavior can be characterized in terms of the stability lobes diagram. Therefore the prediction of machining stability is not only of great importance for the design of a machine tool toward high-precision and high-speed machining, but also can provide information for selecting adequate cutting conditions to achieve stable machining without chattering. This study was aimed to present the criteria for the evaluation of the machining stabilities of a milling machine tool. For this purpose, we first conducted the vibration tests on the spindle tool to assess the tool tip frequency response functions along the principal modal axis. And then, based on the orientation dependent stability analysis model proposed in this study, we evaluated the variation of the dynamic characteristics of the spindle tool and the corresponding machining stabilities at a specific feeding direction. Following the stability analysis model, the limited axial cutting depths for stable machining within the whole interested feeding directions were obtained. Current results demonstrate that the stability boundaries and limited axial cutting depth of a specific cutter were affected to vary with the changing of the feeding direction and the feeding height of spindle head. It was also noticed that the tool material affect the dynamic characteristics and machining stability of the spindle tooling system. It is believed that realizations on the variations of the machining stabilities of a spindle tooling system within the entirety of feeding directions can provide a valuable reference for the selection of machining conditions in tool path planning.