近年來加工技術提昇的方向主要有兩大趨勢，一為使用高速切削以改善材料移除率，另一為直接使用硬化模具素材進行成型加工，有鑑於此本文針對常用的模具鋼材料SKD11、SKD61以及一般中碳鋼S45C來探討硬度、切速及每刃進給對切削機制、切屑型態及工件表面粗糙度等銑削加工現象的影響，並依據銑削力模式為基礎探討各銑削條件與切削常數及各加工現象的關聯性。實驗結果發現移除材料所需力量，在低切速時高硬度的材料所需切削力較低硬度值小，但隨切速增加低硬度材料所需切削力則會與高硬度材料相當或更低。而在高硬度時，能夠得到較佳的工件表面粗糙度品質，且切削速度對表面粗糙度影響不大，但對低硬度工件，切削速度的提昇則能有效地降低表面粗糙度。實驗結果也發現鋸齒狀切屑形成隨硬度、每刃進給、切削速度增加有明顯關係，根據銑削作頻譜分析且量測並計算工件表面凹痕及鋸齒狀切屑發生頻率，顯示三者頻率相同，因此可證實，當鋸齒狀切屑形成時會造成力量抖動及工件表面產生凹痕。

In the pursuit of improved production efficiency, two major trends emerge in the state-of-the-art industrial machining technology. The first trend is applying high-speed machining, and the other is the direct machining of hardened tool steel. In an attempt to better understand the underlying process mechanics in the application of these two machining technologies, this paper investigates how material hardness, cutting speed, feed per tooth and other cutting parameters affect the cutting mechanisms, the chip formation, the surface texture and roughness in the machining of two common tool materials: SKD11, SKD61 and the medium carbon steel, S45C. The specific shearing energy and ploughing force are shown to decrease for materials of increasing hardness. Although these forces vary among different group of materials, forces for the same material with various hardness levels converge to the same values at higher cutting speed. The surface roughness is found to be generally smaller for harder material, and is improved at higher cutting speed, especially for the softer material. Experiments show that the saw tooth chip has a greater tendency to form for a harder material at a higher cutting speed with higher feed size. The formation of saw tooth chip is found to induce force fluctuation and structure vibration, leading to undesired wavy marks on the work surface.

1.Martellotti, M. E., “An Analysis of the Milling Process,“ Transaction of ASME, Vol.63, pp.677-700, 1941.
2.Martellotti, M. E., “An Analysis of the Milling Process, Part 2: Down Milling,“ Transaction of ASME, Vol.67, pp.233-251, 1945.
3.Koenigsberger, F. and Sabberwal, A. J. P., “An Investigation into the Cutting Force Pulsations During Milling Operations,“ International Journal of Machine Tool Design and Research, Vol.1, pp.15-33,1961.
4.Sabberwal, A. J. P., “Chip Section and Cuting Force During the Milling Operation,“ Annals of the CIRP, Vol.10, pp.197-203 , 1961.
5.Melkote, S. N. and Endres, W. J., “The Importance of Including Size Effect When Modeling Slot Milling,“ ASME Journal of Manufacturing Science and Engineering, Vol.120, pp.69-75, 1998.
6.Tlusty, J. and MacNeil, P., “Dynamics of Cutting Forces in End Milling,” CIRP annals, Vol.24, pp.21-25, 1975.
7.Kline, W. A., DeVor, R.E. and Snareef, I. A., “The Prediction of Cutting Forces in End Milling with Application to Cornering Cuts,“ International Journal of Machine Tool Design and Research, Vol.22, No.1, pp.7-22, 1982.
8.Boothroyd, G., Fundamentals of Metal Machining and Machine Tools, Scripta Book Co, Washington D.C., 1975.
9.Yellowley, I., “Observations on the Mean Values of Forces, Torque and Specific Power in the Peripheral Milling Process,” International Journal of Machine Tool Design and Research, Vol.25, No.4, pp.337-346, 1985.
10.Budak, E., Altintas, Y. and Armarego, E. J. A., “Prediction of Milling Force Coefficients From Orthogonal cutting Data,“ ASME Journal of Manufacturing Science and Engineering, Vol.118, pp.216-224, 1998.
11.Wang, J. J., Liang, S. Y. and Book, W. J., “Convolution Analysis of Milling Force Pulsation,“ ASME Journal of Engineering for Industry, Vol.116, pp.17-25, 1994.
12.Wang, J. J., Zheng, C. M., “An analytical force model with shearing and ploughing mechanisms for end milling,” International Journal of Machine Tools & Manufacture, Vol.42, pp.761-771, 2002.
13.張煌權，包含側邊及底面犁切力之端銑及面銑力模式，國立成功大學機械研究所，九十年碩士論文.
14.Oishi, K., “Built-up Edge Elimination in Mirror Citting of Hardemed Steel,” J. of Engineering for Industry, Vol.117, pp.62-66, February, 1995.
15.Elbestawi, M. A., Srivastava, A. K. and El-Wardany, T. I., “A Model for Chip Formation During Machining of Hardened Steel ,” Annals CIRP, Vol.45, pp.71-76, 1996.
16.Vyas, A. and Shaw, M. C., “Mechanics of Saw-Tooth Chip Formation in Metal Cutting, ” ASME Journal of Manufacturing Science and Engineering, Vol.121, pp.163-172, 1999.
17.Gerard, P. and Alphonse, L., “Hard Turning :Chip Formation Mechanisms and Metallurgical Aspects,” ASME Journal of Manufacturing Science and Engineering, Vol.122, pp.406-412, 2000.
18.El-Wardany, T. I., Kishawy, H. A. and Elbestawi, M. A., “Surface Integrity of Die Material in High Speed Hard Machining, Part 1: Microhardness Variations and Residual Stress,” ASME Journal of Manufacturing Science and Engineering, Vol.122, pp.620-631, 2000.
19.El-Wardany, T. I., Kishawy, H. A. and Elbestawi, M. A., “Surface Integrity of Die Material in High Speed Hard Machining, Part 2: Microhardness Variations and Residual Stress,” ASME Journal of Manufacturing Science and Engineering, Vol.122, pp.632-641, 2000.
20.Ning, Yuan, Rahman, M. and wong, Y.S., “Investigation of chip formation in high speed end milling,” Jounary of Material Processing Technology ,Vol.113, pp.360-367, 2001.
21.Elbestawi, M. A., Chen, L., Becze, C. E. and El-Wardany, T. I., “High-Speed Milling of Die and Molds in Their Hardened State,” Annals of the CIRP, Vol.46, pp.57-62, 1997.
22.Ng, E-G. and Aspinwall, D. K., “The Effect of Workpiece Hardness and Cutting Speed on the Machinability of AISI H13 Hot Work Die Steel When Using PCBN Tooling,” ASME Journal of Manufacturing Science and Engineering, Vol.124, pp.588-594, 2002.
23.Shaw, M. C., “A Quantitized Theory of Strain Hardening as Applied to the Cutting of Metal,” Jounary of Applied Physics, Vol.21, pp.599, 1950.
24.Venkatesh, “A study of chip surface characteristics during the machining of steel”, Annals of the CIRP, Vol.42, 1993.
25.鄭茗元，SKD61硬化模具鋼銑削特性之探討，國立成功大學機械工程研究所碩士論文，九十一年。
26.許鴻利，包含尺寸效應之端銑力模式與刀尖幾何對銑削力影響之探討，國立成功大學機械工程研究所碩士論文，九十一年。
27.王俊志、張煌權，”不同切速及工件硬度對SKD11模具鋼切削現象之探討”，機械月刊第336期，2003。