**1. Introduction**

14 Tribology in Engineering

**5. References** 

1968.

pp.132-495.

pp. 671-685.

C. Ozel, H. Phtl and M. Gür

*Department of Mecahnaical Engineering Frat University Elaziğ, Turkey* 

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[7] Ovingsbo, Proc. Conf. Wear of Materials, ASME, New York, 1979, p.620.

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Control Handbook, ASME, New York, 1980, pp. 283-312. [10] Y. Wang, T.C. Lei and C.Q. Gao, *Tribol. Int*., 23(1) (1980) 47-53.

[12] T.L. Ho, M.B. Peterson. F.F. Ling, *Wear* 30 (1974) 73-91. [13] T.L. Ho, , M.B. Peterson.. *Wear* 43 (1977) 199-210.

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[19] S.V. Prasad and P.K. Rohatgi, *J. Met*. *Sci*., 39 (11) (1987) 22-26 [20] K.J. Bhansali and R. mehrabian, *J. Met. Sci*., 34 (9) (1982) 30-34

[23] P.R. Gibson, A.J. Cleg and A. A. Das, *Wear,* 95 (1984) 193-198.

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[16] J. Dinwoodie, E. Moore, C.A.J. Langman, W.R. Symes Jr, in: W.C. Harrigan. J. Strife, J. Metallurgical Society of AIME. Metalurgiacal Society of AIME, Warrendale, P.A. 1985,

[21] F.M. Hosking, F. F. Portillo, R. Wunderlin and R. mehrabian, *J. Mater. Sci*., 17 (1982) 477-498.

[17] H.L. Lee, W.H. Lu and S.L.I. Chan, Chin., *J. Mater.Sci*., 24 (1) (1992) 40-52

[22] M.K. Surappa, S. V. Prasad and P.K. Rohatgi, *Wear,* 77 (1982) 295-302.

[25] Y.M. Pan, M.E. Fine and H.S. Cheng, *Scr. Metal*., 24 (1990) 1341-1345. [26] A.K. Jha, S.V.Pprasad and G.S. Upadhyaya, *Wea*r, 133 (1989) 163-172.

[28] A. Wang and H.J. Rack. *Mater. Sci. Eng*., (1991), vol. A147, pp.211-24

[27] E.A Brandes, Metals Reference Book. 6 th edition. Butterworths, London. (1983).

[30] A.T. Alpas and J. Zhang: *Metall. Mater. Trans*. A, (1994), vol. 184, pp. 187-92. [31] W.Ames and A.T. Alpas: *Metall. Mater. Trans*. A, (1995), vol. 26A, pp. 85-98 [32] P.L. Ratnaparkhi and H.J. Rack: *Mater. Sci. Eng*., (1990), vol. A129, pp. 11-19. Aluminum is one of the metals, besides iron and steel, which are widely used in many industrial fields such as aviation, navigation and automotive. The most considerable reasons why aluminum is so widely used are: i) it is light, ii) its alloys have higher strength than the construction steel, iii) it has high heat and electrical conductivity. Because of these excellent characteristics, the usage of aluminum as engineering material has an ever-increasing importance in several technological fields [1,2]. Although aluminum is widely used, there are many problems such as tool abrasion, burr formation and poor hole surface quality in drilling process of aluminum and its alloys [2,3]

The surface quality, which is one of these problems, is quite important for the efficient working of machine parts. The structure of a machined surface is one of the most important criteria in terms of quality, and tribological properties of the machined surface are considerably affected from the surface tissue. Generally the surface quality is characterized with surface roughness. Surface roughness is an important factor which must be considered not only in the conventional subjects of tribology such as abrasion, friction and lubrication but also in different fields such as sealing, hydrodynamics, electrical and heat conductivity. Surface roughness is mainly affected during the machining process by cutting parameters such as cutting speed, feed rate and depth of cut [4,5,6]. If these parameters are not chosen convenient, the surface roughness increases. This situation creates a notch effect and results in crack initiation, decrease in fatigue strength and corrosion resistance. So, the characterization and measurement of surface roughness has a great important in the sense of the optimization of machining process [7,8].

© 2013 Bahçe and Ozel, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 Bahçe and Ozel, licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

In former studies on hole surface quality, Nouari and his colleagues subjected Al 2024-T3 to dry drilling process, and did some optimizations and analysis experimentally for both the dimensional accuracy of the machined surface and longevity of cutting tools [9]. In their study, they used sintered tungsten carbide (STC) cutting tools and high speed stell (HSS) cutting tools, and set the feed rate to 0,04 mm/rev and cutting speed to 25, 65, 165 m/min. They concluded from the experiments that STC cutting tools are more convenient in comparison with HSS cutting tools from the points of tool life, deviation in hole diameter and surface roughness. Lin investigated tool life, surface roughness, tool abrasion and burr formation for the process of the high speed machining of stainless steel material with TiN coated carbide tool [10]. As a result of his researches, he determined that the abrasions in shear edge result from the high feed rate in low cutting speed, and optimum cutting speed for desired burr height and surface roughness was 75 m/min. In addition, he determined that in high speed machining of stainless steels the tool life increased considerably in case of adjusting the feed rate to the values lower than 0,05 mm/rev. Lin and Syhu, studied on the treatment of the tool life and burr formation in the drilling of stainless steel with the drill bits coated by different materials [11]. Kurt et al., investigated the effect of cutting parameters on the drilling temperature, cutting force and surface roughness in the drilling of Al 2024 alloy with DLC coated drill. In their study, they determined that the most effective factors influencing the hole surface quality are feed rate and drill diameter [12]. They observed that the change in feed rate and diameter at high cutting speeds affects the average surface roughness considerably. Dudzinski et al., determined that the tool life was very short in the drilling of Inconel 718; therefore the surface quality gets worse [13]. They determined that the main wear mechanism seen in the cutting tools used was abrasion. In addition, they observed that the chips resulted in the formation of built-up-edge (BUE) by adhering on the cutting tool, and the removal of BUE from the cutting tool repeatedly caused notches. Klçkap investigated the roughness of hole surface and the height of the burrs formed at the hole exit in the drilling of Al 7075 material [14]. Also in another research, Klçkap, experimentally studied on the effects of cutting speed, feed rate and different cooling techniques on the temperature and the roughness of hole surface in the drilling of Al 7075 [15]. In their study, they observed that the most appropriate cooling technique was oil cooling from the point of good surface roughness. Also, they determined that the roughness increased with the increase of the feed rate, while it decreased with the increase of rotation speed. Hanyu et al. investigated the effects of finely crystallized diamond coating method, which was developed by themselves, on the surface roughness in the dry and semi-dry drilling of Al 7075 alloy [16]. They demonstrated experimentally that finely crystallized diamond coating method yields four times better results in comparison with the conventional diamond coating method. Konig and Grass investigated the effects of cutting parameters on the roughness of hole surface and surface tissue in the drilling of fiber reinforced thermosets [17]. They denoted that the surface roughness increases with increase of the feed rate. In his study, Tosun, optimized the drilling parameters affecting the burr height and surface roughness of DIN 42CrMo4 steel material by considering different drill materials, cutting speeds, drill point angles and feed rates with the help of Grey Relational Analysis (GRA) [18]. Sur et al. studied on the effects of Ti alloy on the surface roughness in Experimental Investigation of the Effect of Machining Parameters

on the Surface Roughness and the Formation of Built Up Edge (BUE) in the Drilling of Al 5005 17

the turning of Al 6063 alloy [19]. They observed that the increase of 35 percent in the hardness of the material resulting from the doping of Ti to the material had relatively an inconsiderable effect on the surface roughness of the material in comparison with effects of cutting speed and feed rate. Also, they determined that the increase in the feed rate affected the surface roughness negatively, while the increase in the cutting speed contributed to the treatment of surface roughness positively; however the feed rate had a more dominant effect on the surface roughness in comparison with the cutting speed. Darwish, et al., investigated the effects of cutting speed, feed rate and drill diameter on the hole surface quality, dimensional accuracy and geometric tolerance in soft steel materials [20]. In their study, they observed that cutting speed and feed rate had a great effect on surface quality, and the

In the studies mentioned above, generally the effects of cutting parameters on the roughness of the hole surface were investigated in the machining process of stainless steel and 2000, 6000 and 7000 series aluminum alloys. However, it has drawn attention that the studies on 5000 series aluminum alloys, which are widely used in many industrial fields such as aviation, navigation and automotive, are not sufficient. In this study, Al 5005 material was drilled on CNC milling machine under dry drilling conditions by considering different machining parameters such as various rotation speeds, feed rates, drill diameters and point angles, and the roughness of hole surface and the formation of BUE on cutting edges were

In this study, Al 5005 was drilled by considering various drilling parameters such as diameter, point angle, feed rate and rotation speed. CNC milling machine (Taksan, TMC 700V) with vertical machining centre was used in the experiments. The spindle power of the machine, rotation speed and feed rate values were taken as 5.5 kW, 50-8000 rev/min and maximum 0.6 mm/rev, respectively. Maximum feed rate values of the work table on X, Y and Z axes were 500, 600 and 450 mm, respectively. Factorial design, in which the effects of mostly different and unrelated factors on a definite characteristic are investigated, was taken into consideration in design process of the experiment. In factorial design, the experimental design is established by processing the variable parameters (or their levels) crossingly [21]. In this study, the experiments were conducted in accordance with 72 different combinations (21.32.41) by using 2 levels for the drill diameter, 4 levels for the point angle, 3 levels for the rotation speed and the feed rate. The values of variable parameters in conducted experiment

were selected in compliance with the similar studies as shown in Table 1 [9,10,14,18].

In this study, the cutting fluid was not used in order to observe the effect of drill parameters on the roughness of the hole surface [22]. Al 5005 material used in the experiments was in the dimension of 10mmx70mmx400mm, and its chemical properties were given in Table 2. In the drilling process, the space between the axes of each hole on the sample was adjusted

higher dimensional accuracy was obtained at low cutting speeds and feed rates.

investigated.

**2. Experimental method** 

to be 20 mm (Figure 1).

the turning of Al 6063 alloy [19]. They observed that the increase of 35 percent in the hardness of the material resulting from the doping of Ti to the material had relatively an inconsiderable effect on the surface roughness of the material in comparison with effects of cutting speed and feed rate. Also, they determined that the increase in the feed rate affected the surface roughness negatively, while the increase in the cutting speed contributed to the treatment of surface roughness positively; however the feed rate had a more dominant effect on the surface roughness in comparison with the cutting speed. Darwish, et al., investigated the effects of cutting speed, feed rate and drill diameter on the hole surface quality, dimensional accuracy and geometric tolerance in soft steel materials [20]. In their study, they observed that cutting speed and feed rate had a great effect on surface quality, and the higher dimensional accuracy was obtained at low cutting speeds and feed rates.

In the studies mentioned above, generally the effects of cutting parameters on the roughness of the hole surface were investigated in the machining process of stainless steel and 2000, 6000 and 7000 series aluminum alloys. However, it has drawn attention that the studies on 5000 series aluminum alloys, which are widely used in many industrial fields such as aviation, navigation and automotive, are not sufficient. In this study, Al 5005 material was drilled on CNC milling machine under dry drilling conditions by considering different machining parameters such as various rotation speeds, feed rates, drill diameters and point angles, and the roughness of hole surface and the formation of BUE on cutting edges were investigated.
