2020 yayın kitapçığı

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Avcı et al. / Eskişehir Technical Univ. J. of Sci. and Tech. A – Appl. Sci. and Eng. 21 (1) – 2020 (a) (b) (c) (d) Figure 8. SEM images of (a,b) CTT1, (c,d) CTT2 The analysis zones and EDS spots in SEM-CTT1 are shown in Figure 9 and Tables 3 and 4. For the CTT1 sample, the 1st region (matrix) is rich in terms of iron element and has no oxidized structure. The main region of the 1st microstructure is acceptable for a HSS steel. The 2nd region was enriched tungsten (W) element and increased to 3% to 13% and molybdenum %2 to %7.72 that is because these type carbides would form [17,22] after the cryogenic treatment of HSS steels. Iron (Fe) and manganese (Mn) elements were observed to be decreased compared to the 1st zone. Vanadium (V) and molybdenum (Mn) amounts were also increased. It was observed that there is an increase in the amount of iron (Fe) element in the 3rd region compared to the 1st region. This zone is taken from the interface area where the main phase and the carbide phase formed by the additive material are close. It was observed that the 4th region is almost the same as the 1st region. Figure 9. Analysis zones in SEM-CTT1 229 50

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Avcı et al. / Eskişehir Technical Univ. J. of Sci. and Tech. A – Appl. Sci. and Eng. 21 (1) – 2020 Table 3. a) CTT1-SEM EDS Spot 1., b) CTT1-SEM EDS Spot 2. Element Weight, % W 3.04 Mo 2.00 V 1.47 Cr 4.53 Mn 0.71 Fe 88.25 (a) Element Weight, % W 13.54 Mo 7.72 V 2.51 Cr 5.00 Mn 0.48 Fe 70.75 (b) Table 4. a) CTT1-SEM EDS Spot 3., b) CTT1-SEM EDS Spot 4. Element Weight, % W 3.52 Mo 2.35 V 1.54 Cr 4.52 Mn 0.67 Fe 87.40 (a) Element Weight, % W 2.87 Mo 1.87 V 1.38 Cr 4.48 Fe 89.39 (b) The analysis zones and eds spots for CTT2 sample are shown in Figure 10 and Table 5. The matrix contains the common elements of HSS steels including smaller C content (0.25%) which means that some amount of C is spent for carbide formation. This analysis is parallel with many studies issued cryogenic treatment of HSS steels [3, 6, 17]. The decrease in the amount of iron element in the 2nd region and an increase in the amount of formed secondary phases were observed. The reason for the decrease in the amount of carbon in the 1st region may be due to the tendency of carbide forming with the carbon element of the alloying elements as parallely found in other studies [3, 17, 18]. It is known that the cutting tool performance depends on the carbide properties in the microstructure of HSS steels. With cryogenic treatment and tempering, the carbide particles would be decreased in size and would exhibit much better distribution. It is possible to see a decrease in the size of the particles and a more uniform distribution of these particles due to the dissolution of the precipitates and the fracture of large particles. With the decrease in the size of the carbide particles and their uniform distribution, the interior stresses in the martensite structure are relieved and the micro-cracking sensitivity is minimized, thus providing a significant improvement in the hardness and wear resistance. The precipitation of fine carbides as a result of cryogenic treatment is responsible for the improvement in the wear resistance [3, 17, 22]. 230 51

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Avcı et al. / Eskişehir Technical Univ. J. of Sci. and Tech. A – Appl. Sci. and Eng. 21 (1) – 2020 Figure 10. Analysis zones in SEM-CTT2. Table 5. a) CTT2-SEM Selected Area 1., b) CTT2-SEM Selected Area 2. Element Weight, % C 0.25 W 2.36 Mo 1.85 V 1.45 Cr 4.18 Mn 0.67 Fe 89.24 (a) Element Weight, % C 0.99 W 18.58 Mo 10.81 V 2.84 Cr 4.73 Mn 0.59 Fe 61.66 (b) 3.2 Drilling Test Results 3.2.1. Tool wear test results In this study, the CTT drills showed better performance than the UT drill. The performance mostly depends on the formation and homogeneous distribution of carbides after cryogenic processing and also on their hardness. As a result of 30 drilling experiments, the UT drill bit has the highest wear rate on all three workpieces. The minimum wear rate for 3 drill groups was seen in the sphero workpiece, which is considered to be softer than the other two workpieces. The reduction in the diameter of drills is shown in Figure 11. 231 52

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Avcı et al. / Eskişehir Technical Univ. J. of Sci. and Tech. A – Appl. Sci. and Eng. 21 (1) – 2020 Figure 11. Reduction in the diameter of drills. In Figures 12-14, it is clear that the untreated drill bit has a more abrasive surface than the cryogenic treated drill bits. The cryogenically treated drill bits with different tempering temperatures were found to have improved wear resistance at 250°C. The cryogenic process affected positively the wear of M2 tool steel. The most effective wear on the tool life of M2 material in drilling operations is the flank and crater wear. When the types of wear seen in the cutting tools are examined, it is observed that even though the same amount of hole drilling is performed in the conventional heat treatment team, there is much more wear on the outer corner. Because of the wear resistance, toughness and hardness of the cryogenic treated tools, they can perform the drilling process with longer and less wear amount. (a) (b) (c) Figure 12. a) UT-Lamellar after 30 holes, b) UT-Sphero after 30 holes, c) UT-Steel after 30 holes. (a) (b) (c) Figure 13. a) CTT1-Lamellar after 30 holes, b) CTT1-Sphero after 30 holes, c) CTT1-Steel after 30 holes. 232 53

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Avcı et al. / Eskişehir Technical Univ. J. of Sci. and Tech. A – Appl. Sci. and Eng. 21 (1) – 2020 (a) (b) (c) Figure 14. a) CTT2-Lamellar after 30 holes, b) CTT2-Sphero after 30 holes, c) CTT2-Steel after 30 holes. 3.2.2. Hardness test results The microhardness measurements for both the untreated and the treated specimens are shown in Figure 15. Figure 15: Average hardness values of the samples with standart deviations. The hardness values of all treated specimens were advanced than that of the untreated specimen. This status was because cryogenic treatment formed new eta carbide particles in the microstructure of the turning adds and monotonous and homogeneously distribution of small-sized carbide particles [23]. The fine η carbides present in the inserts obtained using cryogenic treatment develops the hardness and wear resistance without significantly influencing the toughness. Another consequence of this study is that the cryogenic process transformed more residual austenite martensite to a higher volume and hence increased hardness paralel to the previous studies [22, 24]. This improved hardness would also improve the wear resistance and the tool life as also Kıvak et al. [22] showed that there was a strong relationship between the microstructure hardness and the wear properties of steel. 3.2.3. Tool Life (Fracture Test) Results The compare the drill life of three drill groups is shown in Figure 16. The UT drill has completed the tool life after 3 holes, the CTT1 19 holes and the CTT2 23 holes. CTT drills have a longer tool life compared to UT because the austenite martensite conversion in the tool steel after cryogenic processing increases the hardness of the tool steels due to the second carbide precipitation and the homogeneous carbide distribution in the microstructure. It is noteworthy that the drill life is approximately around 600% increase in the CTT1 drill and approximately around %800 increase in the CTT2 drills. A maximum increase in tool life can be 233 54

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Avcı et al. / Eskişehir Technical Univ. J. of Sci. and Tech. A – Appl. Sci. and Eng. 21 (1) – 2020 seen by achieving a maximum hardness value and a minimum wear rate at a temperature of 250 °C. It is well-known that cryogenic treatment (including tempering) of HSS steels not only improves mechanical properties such as hardness (by the formation of fine carbide precipitates) [14, 21] and toughness (by reducing the alloy content of the Fe based matrix) [17] but also remove thermal stresses [20] of the material. In our case, the precipitates of CTT2 sample contain more W and Mo elements which means that there is more W and Mo depletion from the matrix. Therefore, we suggest that the higher tool life of CTT2 material could be not only due to its higher hardness but also its higher toughness since the matrix of CTT2 has less W and Mo content (2.3 and 1.8%) compared to CTT1 (3 and 2%) as seen from Tables 3 and 5. Another reason of better tool life might be because the higher tempering temperature could result in better stress-relief as parallel with other studies [20, 21]. Maximum number of punched holes(for steel workpiece) 25 23 20 19 15 10 5 CTT1 CTT2 3 0 UT Figure 16. Maximum number of holes for drills during fracture testing. Images of the chips formed after tests are shown in Figures 17-19. In the three material groups, it was observed that the drill bit, which had been tempered at 250 °C when compared in three workpieces which had been punched, had a discontinuous chip form due to the harder structure. This situation is supported by hardness test values. Continuous chip formation was observed in the drilling operations on the steel workpiece, which is the most ductile material among the workpieces. (a) (b) (c) Figure 17. Chips of a) UT, b) CTT1, c) CTT2 samples drilled lamellar cast iron. 234 55

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Avcı et al. / Eskişehir Technical Univ. J. of Sci. and Tech. A – Appl. Sci. and Eng. 21 (1) – 2020 (a) (b) (c) Figure 18. Chips of a) UT, b) CTT1, c) CTT2 samples drilled on spheroidical cast iron. (a) (b) (c) Figure 19. Chips of a) UT, b) CTT1, c) CTT2 samples drilled on steel. 4. CONCLUSION Unlike traditional heat treatment, cryogenic process is not a superficial method; affects all material. By homogenizing the carbide distribution with them, it increases the toughness and hardness values of the cutting tools. The cryogenic process applied to the cutting tools increases tool wear resistance and tool life-time because of enhancements in mechanical properties. The ideal tempering temperature maintaining optimal of the cryogenic process is 250 °C. The cryogenic process drill bit at this temperature has the best performance in mechanical tests. It has been observed that the tempered drill bit at 250 °C with cryogenic treatment has the most ideal form in terms of hole surface quality and drill wear together with the chip form it creates during drilling operations. The development of abrasion resistance is mainly due to the conversion of the residual austenite to martensite and the formation of fine, homogeneous carbide particles during cryogenic treatment. This is supported with images taken from the optical microscope and according to SEM images, there are iron elements in the matrix region. The additive elements formed the carbides by interacting with the carbon and these carbide regions were seen as light gray areas in the images taken. In addition, it was observed that the carbides formed had similar dimensions with more uniform distribution and particle size by cryogenic process and after tempering process. It can be said that it additional cryogenic treatment contributes to diffusion wear resistance, hardness and tool life by decreasing carbon ratio due to homogeneous distribution of carbides. In addition, the conversion of retained austenite to martensite plays an effective role in improving hardness values. In fracture tests, up to 800% of tool life observed in cryogenic process drills compared to conventional drill bits supports the cryogenic process to improve the mechanical properties of the material. 235 56

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Avcı et al. / Eskişehir Technical Univ. J. of Sci. and Tech. A – Appl. Sci. and Eng. 21 (1) – 2020 ACKNOWLEDGEMENT The authors would like to acknowledge Oğuzcan Güzelipek and Anil Kaplan for their assistance to organize the drilling tests. REFERENCES [1] Chattopadhyay AB. Machining and Machine Tools. 1st ed. Delhi, INDIA: Wiley, 2011. [2] Bayer AM, Becherer BA, Vasco T. High Speed Tool Steels. ASM Handbook, Volume 16: Machining ASM Handbook Committee, p 51-59. [3] Akincioglu S, Gokkaya H, Uygur I. A review of cryogenic treatment on cutting tools. Int J Adv Man Tech 2015; 78: 1609-1627. [4] Nasir I, The effect of heat treatment on the mechanical properties of stainless steel type 304. Int J Sci Eng and Res (IJSER) 2014; 3: 87-93. [5] Singh R, Heat Treatment of Steels. Applied Welding Engineering 2016: Elsevier Science. [6] Shaojun S, Xianping Z, Chengtong S. Heat-treatment and properties of high-speed steel cutting tools. IOP Conference Series Materials Science and Engineering 2018; 423: 1-6. [7] Bepari MMA, Surface and Heat Treatment Processes, in Comprehensive Materials Finishing, 2017. [8] Geller YA, Artyukhov VF. Effect of annealing on the properties of high-speed steels. Metal Sci Heat Treatment 1976; 18: 940-963. [9] Stoicanescu M, Ene E, Zara A, Giacomelli I, Crisan A. The heat treatment influence of 1.3343 high speed steel on content of residual austenite. Proc Tech 2016; 22: 161-166. [10] Kadirgama K, Noor MM, Sharma KV. Tool life and wear mechanism when machining hastelloy C-22HS. Wear 2011; 270: 258-268. [11] Grzesik W. Advanced Machining Processes of Metallic Materials. 2nd Edition; Elsevier, 2008. [12] Özbek NA, Çiçek A, Gülesin M, Özbek O. Effect of cutting conditions on wear performance of cryogenically treated tungsten carbide inserts in dry turning of stainless steel. Trib Int 2016; 94: 223-233. [13] Deshpande RG, Venugopal KA. Machining With Cryogenically Treated Carbide Cutting Tool Inserts. Mater Today: Proc 2018; 5: 1872–1878. [14] Dhande ST, Kane VA, Dhobe MM, Gogte CL, Influence of soaking periods in cryogenic treatment of tungsten carbide. Proc Manuf 2018; 20: 318-328. [15] Giusti F, Santochi M, TANTUSSI, G. On-line sensing of flank and crater wear of cutting tools, CIRP, 1987; 1: 41-44. [16] Narasimha M, Sridhar K, Kumar RR, Kassie AA. Improving Cutting Tool Life a Review, Int J Eng Res Dev 2013; 7: 67-75. 236 57

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Avcı et al. / Eskişehir Technical Univ. J. of Sci. and Tech. A – Appl. Sci. and Eng. 21 (1) – 2020 [17] Firouzdor V, Nejati E, Khomamizadeh F. Effect of deep cryogenic treatment on wear resistance and tool life of M2 HSS drill. J Mat Proc Tech 2008; 206: 467-472. [18] Cicek A, Kivak T, Uygur I, Ekici E, Turgut Y. Performance of cryogenically treated M35 HSS drills in drilling of austenitic stainless steel. Int J Adv Manuf Tech 2012; 60: 65-73. [19] Krauss G, Tempering of martensite in carbon steels. In: Phase Transformations in Steels: Diffusionless Transformations High Strength Steels Modelling and Advanced Analytical Techniques, 2012. [20] Kumar S, Khedkar NK, Jagtap B, Singh TP. The Effects of Cryogenic Treatment on Cutting Tools. IOP Conf Ser Mater Sci Eng 2017; 225: 012104. [21] Cicek A, Kara F, Kıvak T, Ekici E, Uygur I. Effects of deep cryogenic treatment on the wear resistance and mechanical properties of AISI H13 hot-work tool steel. J Mater Eng Perfor 2015; 24:4431-4439. [22] Kıvak T, Şeker U. Effect of cryogenıc treatment applied to M42 HSS drills on the machinability of Ti-6Al-4V alloy. Mater Tech 2015; 49(6): 949-956. [23] Padmakumar M, Dinakaran D, Guruprashat J. Characterization of cryogenically treated cemented carbide. Integrated Ferroelectrics 2017; 185: 65-72. [24] Priyadarshini A. A Study Of The Effect Of Cryogenic Treatment On The Performance Of High Speed Steel Tools And Carbide Inserts. MSc, National Institute of Technology Mechanical Engineering, Rourkela, Indie, 2007. 58

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 ADAPTATION OF CRYOGENIC SYSTEMS FOR INTERNAL COOLING DRILL COMPERATIVE BY COOLANTS T. Kavas (1), A.Kayaaltı(2), T. Soyusinmez (3), O. Güzelipek (4) email: [email protected] (1) Prof. Dr. University of Afyon Kocatepe, Turkey (2) Totomak - General Manager , Turkey (3) Totomak - R&D Manager, Turkey (4) Totomak - R&D Engineer, Turkey Abstract Coolants are well-known as for being expensive, non-stable on machining process and contaminated waste for the environment. On the other hand, studies are mainly based on some casting types and most used standard steel parts because of research on cryogenic machining has been turning about operation of hard steel alloys commonly. In this study, application of cryogenic systems on machining surface had been experimentally compared with conventional cutting fluids effects on surface quality, tool life, dimensional changes based on capability calculation based. In addition to, during internal cooling drills contact phase with cutting fluids and cryogenic system and with effect area on the parts had checked for internal microstructural changes during, before and after machining process. Keywords: Coolants, cryogenic machining, hard steel alloys, internal microstructure 1. Introduction Cryogenic methods, which deliver liquid nitrogen to cool the cutting edge, enable more parts to be cut in same amount of time with the same machine. Nearly any machine, regardless of brand or type, can be retrofitted with cryogenic systems. Cryogenic machining used to be difficult and costly to implement, as methods focused on spraying the liquid nitrogen at the tool. Spraying the tool required a high flow rate that caused nitrogen to mostly evaporate before reaching the cutting surface and ultimately reduced cooling capacity. Trough-tool cooling provides the most efficient heat transfer and consumes the least amount of liquid nitrogen. As such, new machining techniques such as dry machining and cryogenic machining were proposed to replace conventional machining. They are liquid carbon dioxide and liquid nitrogen. The boiling points for both gases are -78,5 C and -196 C. Both gases are abundant and can be recycled the can be compressed to liquid form, cool the cutting tools and evaporate become gas again. In this study, the cutting forces, friction coefficients tool life and internal microstructure during with two methods have been examined for comparing the cryogenic systems and conventional cooling liquids. 2. State of The Art Magnesium, Steel, Titanium and Nickel alloys had studied for working parts as controlling the improvement machinability of various work checking the tooling wear and cutting forces [1–5]. 59

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Jawahir et al [6] had focused on LN2 and CO2 for cryogenic coolants and controlled effect on machining application like milling, drilling, turning. Ti-6Al-4V material machining had compared with cryogenic coolants against for dry machining and conventional coolants. In term of Jerold and Kumar [7] experimental trails they achieved cryogenic coolants are reduced temperatures almost %50. Yuan et al [8] had focused of Ti-6Al-4V with dry and wet conditions including MQL with different relatively temperatures to get best tool life. In this study he gets the bet tool life at 22 minutes and mentioned for benefits of the cryogenic machining setup. PVD coated face milling tools used application on the Ti-6Al-4V material with in CO2 in different speeds and flood emulsions and getting the best tool life. In that experimental they used different cooling types with different nozzle diameters to apply coolant on the surface. It was indicated best tool life is offered by CO2 in trails Sadik et al [9]. Su et al [10] controlled different time of machining cutting speeds with cryogenic cooling systems with controlling surface heat changes by thermocouples and controlling the heat removal from surface by coolant applications. Stainless steel trains with carbon dioxide and dry cutting had compared in Cordes et al [11] studies. In different machining speeds effecting on the flank wear had investigated and material removal rate had determined. The aim of this paper is the investigation of the effect of cryogenic CO2 cooling in the development of wear with drilling internal cooling systems and compared with liquid cooling systems on the drilling of grey cast iron, ductile iron and SAE 1117 steel materials. 3. Experimental Setup and Trails Machining trails are focused on grey cast iron, ductile cast iron and SAE 1117 steel bars. The chemical composition and properties of materials on mentioned are shown in Table 1, Table 2 and Table 3. Carbon C 3.1-3.4 Silicon Si 2.5-2.8 Manganese Mn 0.5-0.7 Phosphorus P 0-0.9 Sulfur S 0-0.15 Iron Fe Balance Table 1. ASTM Grade 25 or 175 (F11701) Grey Cast Iron Alloy Composition Carbon C 3.25 – 3.70 Silicon Si 2.40 – 3.00 Manganese Mn 0.10 - 0.30 Phosphorus P 0.015 – 0.08 Sulfur S 0.005 – 0.020 60

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Magnesium Mg 0-0.15 Iron Fe Balance Table 2. EN(-1563-GJS)-600-3) Ductile Cast Iron Alloy Composition Carbon C 0.14-0.20 Silicon Si 1-1.3 Manganese Mn 0.10 - 0.30 Phosphorus P 0-0.04 Sulfur S 0.08-0.13 Iron Fe Balance Table 3. SAE-AISI 1117 (G11170) Carbon Steel Alloy Composition Figure 3. View of The Drilling Tool With Coolant Holes Parameter Value 61

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Diameter of Drill d (mm) 6.80 Feed per Drill fz (mm) 0.18 Surface Speed Vc (mm) 75 Coolant Flood Emulsion Through tool CO2, conventional liquids Table 4. Machining parameters used for the machining trials. During machining trails Ø6.80 internal cooling drill tool had used on 3 different material with machining parameters in Table 4. Cutting tool had presented in Fig.1. to indicate entrance point of cryogenic and conventional coolants. Drilling tool parameters had applied for the same to different materials and controlled changes of the wearing on the tool in different time periods. During this trail tool wears changes with cutting time are presented in Fig. 2. That changes are indicates tool life of the drill had increased all different materials during to using cryogenic cooling and all materials had behaved in same characteristic. Figure 2. Machining parameters used for the machining trials. During the experimental study different types of materials diameters changes after the tooling wear had examined in Fig.3. That test results had shown that cryogenic machining with that drills also improved stability of the diameter changes. Measurement differences also observed in the same variation with the tool wear. 62

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Figure 2. Machining parameters used for the machining trials. 4.Conclusions We have focused and presented of the investigation of wear progression during cryogenic drilling of grey, ductile iron and steel bars with compared conventional cooling systems. A literature review of material from academic and industrial sources has established that while significant variation in results exist, cryogenic machining has the potential to improve tool life, surface finish, productivity and surface integrity when compared with conventional coolant methods. Tool life trails used the cooling options CO2 and conventional coolant methods. The best performance achieved in Cryogenic method was CO2 and in grey cast iron with following steel bars and ductile iron. On the other hand, Cryogenic method always gives a better tool life results and higher capability instead of conventional coolant methods. During performing tests to compare drilling of cast iron, ductile iron and steel with cryogenic and conventional method results indicate that no significant changes on the lower cutting speed and feed but when the test are performed on the actual machining parameters cryogenic cooling systems better than conventional cooling methods. The proposed internal cooling drilling tools with cryogenic systems results are indicated to use that system very effective for cooling tools and machining part, more efficient for tool life and does not harm environment. References [1] K. Busch, C. Hochmuth, B. Pause, A. Stoll, R. Wertheim, Investigation of Cooling and Lubrication Strategies for Machining High-temperature Alloys, Procedia CIRP. 41 (2016) 835–840. [2] Y. Kaynak, T. Lu, I.S. Jawahir, Cryogenic Machining-Induced Surface Integrity: A Review and Comparison with Dry, MQL, and Flood-Cooled Machining, Mach. Sci. Technol. 18 (2014) 149–198. [3] D. Umbrello, F. Micari, I.S. Jawahir, The effects of cryogenic cooling on surface integrity in hard machining: A comparison with dry machining, CIRP Ann. - Manuf. Technol. 61 (2012) 103–106. [4] Y. Yildiz, M. Nalbant, A review of cryogenic cooling in machining processes, Int. J. Mach. Tools Manuf. 48 (2008) 947–964. 63

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 [5] Z. Pu, J.C. Outeiro, A.C. Batista, O.W. Dillon, D.A. Puleo, I.S. Jawahir, Enhanced surface integrity of AZ31B Mg alloy by cryogenic machining towards improved functional performance of machined components, Int. J. Mach. Tools Manuf. 56 (2012) 17–27. [6] I.S. Jawahir, H. Attia, D. Biermann, J. Duflou, F. Klocke, D. Meyer, S.T. Newman, F. Pusavec, M. Putz, J. Rech, V. Schulze, D. Umbrello, (2016), Cryogenic manufacturing processes, CIRP Annals – Manufacturing Technology, 65(2), pp. 713–736. [7] B.D. Jerold, M.P. Kumar, The Influence of Cryogenic Coolants in Machining of Ti–6Al–4V, J. Manuf. Sci. Eng. 135 (2013) 31005. [8] S. M. Yuan, L. T. Tan, W. D. Liu and Q. Liu, “Effect of cooling air temperature on cryogenic machining of Ti-6Al-4V alloy,” Journal of Materials Processing Technology, vol. 211, no. 3, pp. 356-362, 2011. [9] I. B. Sadik, S. Isakson, A. Malakizadi and L. Nyborg, “Influence of coolant flow rate on tool life and wear development in cryogen ic and wet milling of Ti-6Al-4V,” Procedia CIRP, vol. 46, pp. 91-94, 2016. [10] Y. Su, N. He and L. Li, “Effect of cryogenic minimum quantity lubrication (CMQL) on cutting temperature and tool wear in high-speed end milling of titanium alloys,” Applied Mechanics and Materials, Vols. 34-35, pp. 1816-1821, 2010. [11] S. Cordes, F. Hubner and T. Scaarschmidt, “Next generation high performance cutting by use of carbon dioxide as cryogenics,” Procedia CIRP, vol. 14, pp. 401-405, 2014. 64

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 HIGH VIBRATION ABSORPTIVE BODY PRODUCTION FOR TURNING CUTTING TOOLS WITH ADDITIVE MANUFACTURING TECHNOLOGY U.Malayoglu (1), T. Soyusinmez (2), O. Güzelipek (3), G.Akkus (3) email: [email protected] (1) Prof. Dr. University of Dokuz Eylül, Turkey (2) Totomak - R&D Manager, Turkey (3) Totomak - R&D Engineer, Turkey (4) Totomak - R&D Engineer, Turkey Abstract The dynamic behaviour of a machine tools body directly influences key metal cutting performance like cutting speed, cutting depth or minimize movements on the high-speed movements. That will affect directly results of the parts surface quality, cutting time and also tool life. In this study, usage of the alternative material with complex geometry for tool body with additive manufacturing methods had been experimentally checked for effects on the surface quality, machining parameters, dimensional changes and tool life. Alternative body material usage effect which can absorb high vibration on the system and experimentally test results had compared on different materials like grey and ductile iron casting and SAE 1117 steel. Keywords: Vibration, Cutting tools, Additive manufacturing 1. Introduction Different kinds of sensors and signal processing techniques have been developed for the direct or indirect detection of tool wear, breakage and vibration analysis in machining process. Vibration measurement is one of the indirect methods of tool condition monitoring [1]. Metal cutting processes can entail three different types of mechanical vibrations that arise due to the lack of dynamic stiffness of one or several elements of the system composed by the machine tool, the tool holder, the cutting tool and the workpiece. These three types of vibrations are known as free vibrations, forced vibrations and self-excited vibrations [1, 4]. Several machining variables, such as cutting speed, depth of cut, feed rate, workpiece material, and cutting tool geometry have significant effects on the machining process and vibrations. In a machining process, three different types of mechanical vibrations are present due to a lack of dynamic stiffness and rigidity of the machine tool system comprising tool, tool holder, work piece and machine tool itself. These are the free, forced and self-excited vibrations. Free or transient vibrations, are induced by shock, such as impulses transferred to the structure of machine tool or from the initial engagement of cutting tools. Forced vibrations, resulting from periodic forces within the system such as unbalance defects in machine tool components (like gears, spindles and bearings), and vibration transmitted through the foundations from other machinery in the shop. 2. Material Information’s and Design of Experiment In this trail the work-piece is a round bar (50mm diameter and 200mm long) of SAE 117 steel. The chemical composition of the steel had present on Table 1. The cutting tool and tool holder figures are presented on Figure 1 and Figure 2. On the other hand, during the machining trails have been conducted in under cutting fluid which density %6. Tool work-piece combination have significant role on cutting forces and vibration signals. The cutting conditions are presented in Table 2. 8 65

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 SAE No. C Mn P S 1117 0.14 to 0.20 1.00 to 1.30 0.040 max 0.08 to 0.13 Table 1. Chemical Composition of SAE 1117 Figure 1. Actual Photograph of Tool Holder Figure 2. Actual Photograph of Cutting Tool Insert The experimental machining process parameters had used as Table 2. Trail Cutting Speed (m/min) Feed (mm/rev) Depth of Cut (mm) 1 150 0,3 1 2 175 0,5 1,5 3 200 0,7 2 Table 2. Machining Process Parameters 3. Experimental Details Experimental test had completed within CNC machine, FFT analyser, digital tool dynamometer, and accelerometer and tool dynamometer sensor. Digital tool dynamometer sensor and accelerometer is mounted on tool holder as close to cutting tool insert. Figure 3 shows the design of the experimental set-up test machine and Table 3 indicates CNC machine details. Specification Bed Length -500U in 610 mm / 24.02 in Capacity Maximum Swing 350 mm /13.780 in 77 mm / 3.0 in Maximum Machining Diameter 483 mm / 19.020 in Maximum Bar Work Capacity 10 in Maximum Machining Length 4000 rpm 26 kw / 35.0 hp Main Chuck Size 12 Spindle Maximum Speed 190 mm / 7.48 in Motor Output (30 minute rating) 515 mm / 20.28 in 525 mm / 20.67 in Turret Number of Tools (Upper) Feed Axes Travel (X Axis) Travel (Z Axis) Travel (W Axis) Table 3. CNC Machine Specifications 9 66

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Figure 3. Experimental set up During the machining phase 3 different cutting force effect on the tool and the body. With additive manufacturing we had designed the damping capacity of a material is an evaluation of the energy dissipated in the material during mechanical vibration. High damping materials, which possess the ability to dissipate mechanical vibration energy, are valuable in the application fields of noise control and for stabilizing structures to suppress mechanical vibrations and attenuate wave propagation. Practical applications need low density materials that simultaneously exhibit a high damping capacity and good mechanical properties. However, in metals these properties are often incompatible, due to the dependence of the microscopic mechanisms involved in strengthening and damping [5,8]. Therefore, it would be of interest to develop new materials that simultaneously exhibit good mechanical properties and high damping. This is possible only when the microscopic mechanisms responsible for dissipation of the vibration energy are independent of that of the hardening and strengthening. Such a compromise can be achieved by the development of two- phase composites, in which each phase plays a specific role: damping or providing mechanical strength. Metal matrix composites (MMCs) are good candidates because firstly, MMC processing allows the possibility of tailoring the resultant damping properties by selecting high damping reinforcements, secondly, MMC processing modifies the microstructure of metals and alloys, thus introducing energy dissipation sources and thirdly, typically hard and high strength reinforcements will improve the mechanical properties of the composites [9,12]. Figure 4. Tool and Tool Holder Force Diagram 10 67

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 4. Result and Discussion During the machining trails 3 different test had applied with current and MMC tool holder for each combination of cutting speed, feed rate and depth of cut the output results of cutting forces and Vibration signals in tangential (Va), Feed (Vr) and Radial (Vt) direction are presented in Table 4 and Table 5. Speed (m/rev) Feed (mm/rev) DOC (mm) Fa Force (kg) Va Vibration (Hz) 595 150 0,3 1 Fr Ft 52 Vr Vt 651 175 0,5 1,5 104 45 49 685 200 0,7 2 101 41 47 458 888 98 39 533 955 632 985 Table 4. Test Results Observation Table for Current Tool Holder Speed (m/rev) Feed (mm/rev) DOC (mm) Fa Force (kg) Va Vibration (Hz) 553 150 0,3 1 Fr Ft 48 Vr Vt 584 175 0,5 1,5 93 42 47 614 200 0,7 2 91 39 43 383 823 85 36 461 870 567 907 Table 5. Test Results Observation Table for Additive MMC Tool Holder On the other hand, frequency during the cutting trails with MMC Tool Holder had present on Figure 5 during rough cutting time and Figure 6 during with finish cutting time. Figure 5. Rough Cutting Tool Vibration Analysis 11 68

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 5. Conclusions This study is carried out to investigate the cutting forces and vibration signal at different cutting tool holder condition using the standard and MMC material. The results shows that the tangential force is largest followed by the feed force and radial force. The vibration signal and the cutting forces well to investigate the tool state as well as the different occurrences during turning. The following are the main points out during this investigation. • The vibration signal measured along the three directions tangential, feed, and radial direction respectively shows the same chronological order as like the cutting forces. • During this investigation it is observed that MMC tool holder absorb vibration and force better than current material tool holders. • MMC tool holder is present better results and absorption for all different cutting conditions. References [1] Teti R., Jemielniak K., Donnell G. O, Dornfeld D. Advanced monitoring of machining operations. CIRP Annals – Manufacturing Technology, Vol. 59, 2010, p. 717-739. [2] S. A. Tobias Machine Tools Vibrations (Vibraciones en Ma ´quinas-Herra- mientas). URMO,Spain, 1961. [3] Dimla E. Dimla Snr. Sensor signals for tool-wear monitoring in metal cutting operations – a review of methods. International Journal of Machine Tools & Manufacture, Vol. 40, 2006, p. 1073-1098. [4] G. Litak, R. Rusinek Vibrations in stainless steel turning: multifractal and wavelet approaches. Journal of Vibroengineering, Vol. 13, Issue 1, 2011, p. 102-108 [5] Choi, G. H., Wang, Z. X., Dornfeld, D. A., Tsujino, K., 1990, Development of an intelligent on-line tool wear monitoring system for turning operation, Proc. USA-Japan Symposium on Flexible Automation, A pacific Rim Conference ISCIE, Kyoto, Japan, 683-690. [6] Byrne, G., Dornfeld, D., Inasaaki, I., Koning, W., Teti, R., 1995, Tool condition monitoring system (TCMS)- the state of research and industrial application, annals of CIRP, (49), 541-567. 12 69

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 [7] Oraby, S. E., Hayhurst, D. E., 1991, Development of models for tool wear force relationship in metal cutting, International Journal of Mechanical Tool Manufacturing, (33), 125-138. [8] Jemieelniak, K., Bombin’ski, S., Arissimuno, P.X., 2008, Tool condition monitoring in micromilling based on hierarchical integration of signal measure, Manufacturing Technology, (57), 21- 124. [9] Burke, L. I., 1989, Automated identification of tool wear states in machining processes: an application of self of self- orgnising neural networks, Ph.D. thesis, Department of Industrial Engineering and Operation Research, UC at Berkeley. [10] Bhuiyan, M. S. H., Choudhary, I.A., Yuoff, N., 2012, A new approach to investigate tool condition using dummy tool holder and sensor set-up, International Journal of Advanced Manufacturing & Technology, (61), 465-479. [11] Li, X., 2002, A brief Review: Acoustic emission method for tool wear monitoring during turning, Interanational Journal of Machine Tool & Manufacturer, (42), 157-165. [12] Abouelatta, O., Madi, J., 2001, Surface roughness prediction based on cutting parameter and tool vibrations in turning operation, Journal of Material Process & Technology, (118), 269-277 13 70

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 EUROPEAN Research Paper MECHANICAL SCIENCE e-ISSN: 2587-1110 Crack Analysis in the Sae 1117 Steel Shafts for Inclusion and Heat Treatment Combination Effect Tuğrul Soyusinmez1*, Murat Ardan Kayaaltı2, Oğuzcan Güzelipek3, Gökçe Akkuş4, Taner Kavas5 1,2,3,4Totomak Machinery and Spare Parts Co., Turkey 5Afyon Kocatepe University; [email protected] ORCID: T.Soyusinmez (0000-0001-8333-1961) Abstract Surface hardening in steels is a process in which a chemical composition is changed by thermo-chemical processes in a determined region and, accordingly, some micro-structure is changed. In order to obtain a harder layer than the inner region starting from the surface to a certain depth, it is mostly provided by diffusion of elements such as nitrogen and carbon. The process is particularly important in low and medium carbon steels in terms of increasing wear resistance, tensile strength and fatigue strength. The amount of elements used in cementation together with the duration of cementation is extremely important in terms of the harmonious change of structural differentiation. The effect of size and position of inclusions on the cracked structures which is affected from heat treatment is presented in the paper. Keywords: Inclusion, Cracks, SAE 1117, Heat Treatment 1. INTRODUCTION vides inclusions into two classes, which are endogenous and exogenous inclusions, respectively. The inclusion type as a The surface hardening processes in the steels are the pro- result of the reactions in the molten metal is endogenous and cesses in which the chemical composition and thus some its shapes, sizes and contents vary according to the pro-cess microstructure are changed by thermochemical processes in a applied to the molten metal. Another type of inclusion, determined region. In order to obtain a harder layer from the exogenous inclusions, is formed by the effect of slag formed interior to a certain depth starting from the sur-face, it is during the production of steel. This inclusion was found to be mostly provided by the diffusion of elements such as nitrogen larger, more irregular and complex in shape than endog-enous and carbon. The process is particularly import-ant for low and inclusion [1,2]. In general, the size of the inclusions is greater medium carbon steels to improve wear re-sistance, tensile than ~ 0.5 µm and is found as a chemical compound in the strength and fatigue strength. In addition, the amount of the structure of metals and alloys. For example, the oxide (Al2O3) element used in cementation and the time of cementation are or sulphide (MnS) inclusions we see in the steel are the best extremely important for the change of structural examples. Many factors are caused by inclusion and we can differentiation. list these factors as casting sand, pollution from the refractories or slag mixing. In addition to these main causes, On the other hand, it is also a fact that inclusions are formed elemental impurities also show differences in some regions. due to different reasons during production / casting. The The inclusions are beneficial to the material rather than the reasons for the inclusion are cast sand, pollution or slag harmful aspects. For example, oxide inclusions in the steel mixing from the refractories are shown as the main reasons, interact with dislocations to increase the hardness of the but elemental (especially silica, alumina, manganese or iron material and significantly change the yield strength of the oxide) impurities have been shown to cause differentiation in material. One of the other positive factors provided by the the melt. inclusions is that they can be encountered in the automaton steels with resulfillations. Thanks to the resulphurisation, MnS We can define inclusions as foreign substances found in steels inclusions in the steel are formed and the workability of the in general. These substances are generally particulate material is increased. In addition to this, increasing structures that are insoluble from the material matrix such as sulfur, oxide, silicate. One of the researchers, Sims, di- *Corresponding authour European Mechanical Science, December 2018; 2(4): 119-127 Email: [email protected] doi: https://doi.org/10.26701/ems.477224 Received: November 6, 2018 Accepted: November 20, 2018 71

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Crack Analysis in the Sae 1117 Steel Shafts for Inclusion and Heat Treatment Combination Effect MnS sizes and decreasing MnS amount increase the work- mm2. In addition, the section taken from the sample should be ability [3]. As it is understood from the examples given, in- parallel to the longitudinal plane and perpendicular to the clusions can be harmful or useful, and the general factors that rolling plane of the section. determine this are the types, sizes, shapes, distributions and quantities. The inclusions are usually multi- phase and the composition of inclusions in the steel varies according to the elemental content of the steel. Polarized light and electron- probe micro analyzer are used to determine inclu-sions. In this article, inclusions occurring in steel shafts were examined with microscopic camera systems and the cracks produced by inclusions were analyzed. 2. METHODOLOGY Figure 2. a) Representative samples obtained after first cutting with water jet b) Second cutting lines of samples In this study, microstructure and inclusion studies were planned on the samples (Figure 1. a) and the samples were first cut by water jet so that the microstructure was not af- fected from the external conditions as shown in Figure 1. b. Then, the samples were re-cut with the help of water jet and the surface was polished for microstructure studies. Repre- sentative samples obtained after first cutting with water jet has been shown in Figure 2. Parts are polished after being cut with water jet. Figure 3 shows the dimensioning of the samples after the second cut (a), unpolished parts (b), and photos after polishing (c). The images of this experiment, which are examined by camera system. As experimental method, two types of methods can be used for inclusions. The first of these is microscopic test methods and the polis-hed surface is examined by a light microscope and several representative photographs are made by reporting the inc-lusion types encountered in the sample. Surface polishing is carried out for a satisfactory and more consistent result. The experiment is carried out with samples from three different positions of the part. In order to determine the microscopic image, the polished surface area should be minimum 160 Figure 1. a) Representative examples provided by the Totomak Figure 3. a) Dimensioning of the samples after the second cut. b) A.Ş. b) First Water jet cutting of samples Unpolis-hed parts, c) Polished parts 120 European Mechanical Science, December 2018; 2(4): 119-127 Each sample was first examined by polarizing microscope doi: https://doi.org/10.26701/ems.477224 and the images of each group are given below. For the group A; Figure 4 shows the image taken at 20 magnifications from sample A1. Figure 5 shows the image taken at 20 magnifica- tions from sample A2. Figure 6 shows the image taken at 20 magnifications from sample A3. For the group B; Figure 7 shows the image taken at 20 magnifications from sample B1. Figure 8 shows the image taken at 20 magnifica- tions from sample B2. Figure 9 shows the image taken at 20 magnifications from sample B3. For the group C; Figure 10 shows the image taken at 20 magnifications from sample C1. Figure 11 shows the image taken at 20 magnifi- cations from sample C2. Figure 12 shows the image taken at 20 magnifications from sample C3. 72

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Tuğrul Soyusinmez, Murat Ardan Kayaaltı, Oğuzcan Güzelipek, Gökçe Akkuş, Taner Kavas Figure 4. Sample A1 (20X) Figure 8. Sample B2 (20X) Figure 9. Sample B3 (20X) Figure 5. Sample A2 (20X) Figure 6. Sample A3 (20X) Figure 10. Sample C1 (20X) Figure 7. Sample B1 (20X) Figure 11. Sample C2 (20X) European Mechanical Science, December 2018; 2(4): 119-127 1121 doi: https://doi.org/10.26701/ems.477224 73

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Crack Analysis in the Sae 1117 Steel Shafts for Inclusion and Heat Treatment Combination Effect Figure 12. Sample C3 (20X) Figure 14. Chemical analysis of group A along the axis On the other hand, the samples with the most intense inc- For the group B; lusion and superficial cavities under polarizing microscope were firstly taken before the polishing and then after the po- Figure 15 shows the elemental mapping of B group sample. lishing (SEM) images and the figures obtained are given be- As shown in figure 15, the red colors show the iron element, low. In addition, chemical analysis and elemental mapping the green colors are carbon and blue colors are aluminum. The analysis were performed for each group. microstructure area of the elemental mapping analysis is shown in Figure 16. In addition, chemical analysis was For the group A; performed on the green line area in Figure 16. The results of the chemical analysis are shows in Figure 16. Figure 13 shows the elemental mapping of A group sample. As shown in figure 13, the red colors show the iron element, the green colors are carbon and blue colors are aluminum. The microstructure area of the elemental mapping analysis is shown in Figure 14. In addition, chemical analysis was performed on the yellow line determined in Figure 14. The results of the chemical analysis are shows in Figure 14. Figure 15. Elemental mapping of B coded sample Figure 13. Elemental mapping of A coded sample Figure 16. Chemical analysis of group B along the axis 122 European Mechanical Science, December 2018; 2(4): 119-127 doi: https://doi.org/10.26701/ems.477224 74

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Tuğrul Soyusinmez, Murat Ardan Kayaaltı, Oğuzcan Güzelipek, Gökçe Akkuş, Taner Kavas For the group C; Figure 17 shows the elemental mapping of C group sample. As shown in figure 17, the red colors show the iron element, the green colors are carbon and blue colors are aluminum. The microstructure area of the elemental mapping analysis is shown in Figure 18. In addition, chemical analysis was performed on the green line area in Figure 18. The results of the chemical analysis are shows in Figure 18. Figure 17. Elemental mapping and chemical analysis of C coded sample Figure 19. Vertical section microstructure image and chemical analysis of sample A Figure 18. Chemical analysis of group C along the axis Following the microstructure analysis above, section analy- zes of each sample were carried out and the data obtained are given below. Figure 19 show the vertical section microstructure image and chemical analysis of sample A. Figure 20 show the ver-tical section microstructure image and chemical analysis of sample B. Figure 21 show the vertical section microstructu-re image and chemical analysis of sample C. Figure 20. Vertical section microstructure image and chemical analysis of sample B European Mechanical Science, December 2018; 2(4): 119-127 1123 doi: https://doi.org/10.26701/ems.477224 75

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Crack Analysis in the Sae 1117 Steel Shafts for Inclusion and Heat Treatment Combination Effect Figure 22. Polished surface microstructure analysis of sample A Figure 21. Vertical section microstructure image and chemical analysis of sample C Finally, the surface of each sample was polished and then the electron microscope image was taken. Their microstructure images are given below. Figure 22. show the polished surface microstructure analysis of sample A. Figure 23. show the polished surface micro- structure analysis of sample B. Figure 24. show the polished surface microstructure analysis of sample C. Figure 23. Polished surface microstructure analysis of sample B 124 European Mechanical Science, December 2018; 2(4): 119-127 doi: https://doi.org/10.26701/ems.477224 76

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Tuğrul Soyusinmez, Murat Ardan Kayaaltı, Oğuzcan Güzelipek, Gökçe Akkuş, Taner Kavas Figure 24. Polished surface microstructure analysis of sample C 3. RESULTS As a result of the analyzes, all inclusions seen in the parts are solved as a result of optimization of heat treatment parame- ters as they are in ASTM E45 standards [4]. Trial parameters and results are shown on Table 1. Table 1. Trial parameters and results TRAIL 1 Figure 25. Results of Trial 1 Purpose: Decreasing the stress of heat treatment step to ma- TRAIL 2 terial. It’s thought that if an amount of stress, which steel with high Purpose: Decreasing the volume change difference between inclusions can stand, is loaded, there will be no cracks. case and core. Action: Decreasing diffusion Cp to have low amount of mar- It’s thought that if the amount of martensite in the core is tensite, decreasing quenching temperature to have less ther- increased, there will be less stress gradians between case and mal shock, decreasing oil agitation to have slower cooling core. rate. Action: Increasing quenching temperature. Conclusion: Good hardness values, there are still radial cracks. It is approved that crack is not related with stress Conclusion: Good hardness values, there is no radial cracks, which comes from heat treatment step. The cracks after the but there are cracks which reach to surface (cylindrical area trail 1 is shown in the Figure 25. of pin). The volume change difference idea works. It is evalu- ated carbides which cause cracks at surface area. The cracks after the trail 2 is shown in the Figure 26. European Mechanical Science, December 2018; 2(4): 119-127 1125 doi: https://doi.org/10.26701/ems.477224 77

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Crack Analysis in the Sae 1117 Steel Shafts for Inclusion and Heat Treatment Combination Effect Action: Increasing diffusion Cp and time, increasing preheat temperature, decreasing furnace temperature at idle condi- tion, increasing soak time at quenching temperature. Conclusion: Good hardness values, we don’t have any cracks. Retained austenite increased to 8%. The microstruc-ture images observed after the trail 4 are shown in Figure 28. Figure 26. Results of Trial 2 TRAIL 3 Purpose: Getting rid of carbides which cause cracks on grain boundaries. Action: Decreasing boost Cp, decreasing diffusion Cp, in- creasing diffusion time. Conclusion: Good hardness values, there is no radial cracks, but there are still cracks which reach to surface (cylindrical area of pin). Retained austenite decreased below 3%, espe- cially at crack area. It is observed less carbides. The cracks after the trail 3 is shown in the Figure 27. Figure 28. Results of Trial 4 Figure 27. Results of Trial 3 4. CONCLUSION TRAIL 4 The micro-structure and chemical analysis of the samples A, B and C and the water-jet specimens are given below. Purpose: Increasing retained austinite to have more elastic case structure, decreasing thermal shocks between pre- - All 3 groups (A, B and C) were found to contain heating and carburizing process, to be sure all parts are at quenching temperature just before quenching step. variable and similar proportions of superficial voids and inclusion in the sample. - It is determined that the source of the cavities and inclusions formed in each of the 3 groups are most- ly Al, Mn and Si-sourced. - It is seen that B group samples contain more super- ficial space (spherical) than other samples. - In each of the 3 groups, the gap and the inclusion were determined to be at the level of all the other steels and sometimes slightly more (especially at A and C). - The inclusions and gaps determined in all three samples are thought to originate from the sec-ondary elements entering the structure externally during the shaping of the metal. 126 European Mechanical Science, December 2018; 2(4): 119-127 78

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Tuğrul Soyusinmez, Murat Ardan Kayaaltı, Oğuzcan Güzelipek, Gökçe Akkuş, Taner Kavas - All samples had inclusions and gaps in a non-ho- mogeneous structure. In addition, all 3 samples show a change in shape. - Polarized microscopy studies in the samples showed fewer coarse grains. In the electron mi-croscope examination, there was more space and inclusion (about 5-10 microns in size), which was small but did not affect the properties. Further-more, it was observed that linear errors increased in A and C sample as the magnification increased. This is interpreted as the formation of linear grain boundaries during formation of nucleation due to conditions during cooling. Moreover, these linear structures are thought to occur due to different surface energies (properties or contact angles) of the secondary elements in the system. - Both micro and macro segregation were observed in all samples. - It is thought that the larger dimensional defects determined in the samples may be caused by the difference in dissolution during casting. As a result; It is thought that the cavities and inclusions de- termined in all samples are at a level that will not signifi- cantly affect the mechanical or chemical wear, hardness, mechanical friction resistance, elastic modulus, ductility, fracture behaviour and load during operation. In addition, the non-cracking heat treatment parameter was determined from the result of 4 different heat treatment parameters. As a result, the heat treatment parameters have been optimized and the crack problem has been solved. REFERENCES [1] “Metallography and Microstructure”, Metals Handbook, American Society for Metals, Vol. 9, p. 9, 1985. [2] C. E. Sims, “Transactions of the Metallurgical Society of AIME”, p. 367-393, 1959. [3] R. Kiessling and N. Lange, “Non-Metallic Inclusions in Steel”, Second Edition, Book No. 194, 1978. [4] ASTM E45-18a, Standard Test Methods for Determining the Inc-lusion Content of Steel, ASTM International, West Conshohocken, PA, 2018, www.astm.org European Mechanical Science, December 2018; 2(4): 119-127 1127 doi: https://doi.org/10.26701/ems.477224 79

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Investigation of Fatigue Behavior of Collets With Material Standard SAE 4140 and 50CrMo4 by Ansys Finite Element Method and Fatigue Test Device Oğuzcan GÜZELİPEK , Tuğrul SOYUSİNMEZ , Furkan ÇETİN Abstract In this study, the previously designed SAE 4140 and 50CrMo4 material standard lathe collets was found to be inadequate in terms of service life and the new 50CrMo4 material standard collet was designed. Fatigue tester was designed and manufactured for fatigue analysis to determine the life of the collet. When designing fatigue tester, 2.2kw Volt motor and Siemens control are used for field usage conditions. Analyzes were made with Ansys software then the collets were tested under 25 bar hydraulic pressure and the results were compared. As a result of analysis and fatigue tests, fatigue behaviors of collets were compared Key words: Collet, Hydraulic Pressure, Fatigue, SAE 4140, 50CrMo4, Finite Element Method SAE 4140 ve 50CrMo4 Malzeme Standardına Sahip Penslerin Yorulma Davranışlarının Ansys Sonlu Elemanlar Yöntemi ve Yorulma Test Cihazı İle İncelenmesi Özet Bu çalışmada, önceden tasarlanmış olan SAE 4140 malzeme standardına sahip torna pensinin kullanım ömrü açısından yetersiz bulunup geliştirmesi amaçlanmış ve yeni 50CrMo4 malzeme standardına sahip pens tasarlanmıştır. Bu penslerin ömrünü belirlemek için test cihazı tasarlanmış ve imalatı gerçekleştirilmiştir. Yorulma test cihazı tasarlarken 2.2kw Volt motor ve Siemens kumanda ile saha kullanım şartları sağlanmıştır. Ansys yazılımı ile analizleri yapılmış ardından pensler, 25 Bar hidrolik basınç altında teste tabi tutulmuş ve sonuçlar karşılaştırılmıştır. Yapılan analizler ve yorulma testleri sonucunda SAE 4140 ve 50CrMo4 malzeme standartlarında üretilen torna penslerinin yorulma davranışları karşılaştırılmıştır. Anahtar Kelimeler: Pens, Hidrolik Basınç, Yorulma, SAE 4140, 50CrMo4, Sonlu Elemanlar Yöntemi 80

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 1.Introduction With the rapid development of power machinery equipment, while meeting the requirements of high efficiency, lightweight, and high reliability of equipment, the overall design requirements are put forward for the long life of its key components. In view of the fact that many components suffer from fatigue failure under cyclic loading below the traditional fatigue limit, it is necessary to study the fatigue characteristics of high strength steels alloy in long‐life regime [1] The well-known effects from crack geometry and residual stresses from press fit and heat treatment are short crack behaviour [2] and load sequence effects under variable amplitude loadings. [3-8]. Steel structures can normally be subject to various damages during service. Some of these damages corrosion and fatigue cracking, which are generally age-related. Predicting fatigue in mechanical components is extremely important to avoid dangerous situations. Fatigue begins with the onset of the crack, then the small crack becomes a complete fracture. [9] In this study, it was aimed to observe the increase in cycle life with material standards and design change by learning the fracture formation in sample by Ansys finite element method. Machine parts and components used in industry work under repeated stresses and vibrations that are smaller than static strength during use. Because of this, after a certain repetition, cracking and subsequent rupture occurs. This is called fatigue. Fatigue stress is a brittle fracture, it is very difficult to predict where and when. Under repeated stresses, significant plastic cracks without deformation and this crack spreads over time, ending with sudden breakage.[10,11,12]. Fatigue was first observed in the early 1800s by cracks in components in bridges and railways subjected to repetitive loads by researchers in Europe. İ As the use of metals became widespread with the increasing use of machinery in the later times, fatigue became a more important issue. Today, the desire to use high strength materials has increased the importance given to fatigue. Approximately 80% of the damages in the machines are thought to be caused by fatigue. [13,14]. The first fatigue test was carried out by Wöhler on the railway axes in the 1850s. As shown in Figure 1, there is a lower fatigue limit for steel, while others do not. This is because steel is a material that can undergo working hardening or otherwise hardening. However, in non-steel materials, the strength of the fatigue curve decreases as the number of repetitive stresses increases due to the absence of hardening. At the end of this decreases, the material goes breaking.[15,16] Figure 1. Wöhler Fatigue Diagram There are many reasons that affect the fatigue performance of machining parts. Factors affecting fatigue strength should be well known. These factors are related to stress, geometry of the part, properties and external environment. [10]. The tools that enable the cutting tools to be connected to the spindle easily and securely are called tool holders. Collet holders are one of the most widely used types of holders on the market. The reason for this is that it is easily available, cheap compared to other holders, easy to use, many tools such as guide, drill, end mill and reamer can be connected to this holder. Each time the tools are inserted into and removed from 81

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 the collet and each part of the tool is operated, the collet is affected by this situation and remains under repetitive stresses. This causes the fatigue, which causes a sudden break after a certain time. 2. Experimental tests In this study, collets having the same geometry in SAE 4140 and 50CrMo4 material standards and collets having different geometry in 50CrMo4 material standards were examined by Ansys finite element method and subjected to fatigue test under 25 bar hydraulic pressure with 2.2 kW motor with Volt brand. Results received by Siemens brand remote control and finally the comparison has been made. As a tool holder, it was aimed to design a collet with a higher fatigue strength and a new collet collar with a new 50CrMo4 material standard with new chemical and physical properties was produced. In this experiment, the fatigue strength of the collets was tested and the analysis was made considering the differences between them. As shown in Figure 2 and Figure 3, the only difference between them is not only their chemical properties but also the physical design of the new collets. In order to ease the loads on the ends, 4 side channels were opened next to the main channels. When we look at Table 1 and Table 3, the chemical properties of the previous collet and the newly manufactured collet are shown in Table 2 and Table 4. The mechanical properties are shown. Figure 2. SAE 4140 Pens Figure 3. 50CrMo4 Pens Element Ratio (%) Cr 0.80 - 1.10 Mn 0.75 - 1.0 C 0.380 - 0.430 Si 0.15 - 0.30 Mo 0.15 - 0.25 S P 0.040 0.035 Tensile strength Yield Strength Table 1. SAE 4140 Chemical properties. 655 MPa 415 MPa 82

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Shear Modulus 80 GPa Elasticity Modulus Poisson's Ratio 190-210 GPa 0.27-0.30 Table 2. SAE 4140 Mechanical properties The test consists of 3 main parts. These; The electric motor specified in Table 5, which produces a hydraulic pressure of 25 bar acting on the collets, is the control that allows us to observe the number of times the lathe collets tested and the lathe collets tested in Table 1, 2, 3 and 4 are subjected to mechanical and chemical properties. 2.1 Materials The materials of the collets used in the experiment are SAE 4140 and 50CrMo4. Mo Other C% Sİ Mn Cr 0.50 0.25 0.62 1.04 0.18 Pb Table 3. 50CrMo4 Chemical Properties >100 – 160 >160 – 250 60<t<100 100<t<160 Radius r(mm) < 16 >16 – 40 >40 – 100 min. 650 min. 600 Thickness t(mm) < 8 8<t<20 20<t<60 850 - 1000 800 - 950 min. 13 min. 13 0,2%Yield min. 900 min. 800 min. 700 Strength Rp0,2 [N/mm² 1100 – 1300 1000 - 1200 900 - 1100 Tensile Strength min. 9 min. 10 min. 12 Rm [N/mm²] Elangation A5 [%] Table 4. 50CrMo4 Mechanical properties 2.2 Motor used in the test As can be seen in Figure 4, the engine that applies hydraulic pressure to the collets in the experiment and the properties of this engine are given in Table 4. Figure 4. Motor used in the test 2.2kw Three Phase Electric Motor Insulation Class: F Housing material: Aluminum Body Type: 100-4 Type Protection Class: IP55 83

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Power V Hz A KW Factor 1/min Efficiency Power 230 50 8,1 2,2 0,79 1430 400 50 4,7 2,2 0,79 1430 %75 82.6 480 60 4,7 2,64 0,78 1716 %50 80.5 Table 5. Properties of the Motor. 2.3 Control unit used in test In this experiment, the Siemens SIMATIC S7-1200 controller given in Figures 5 and 6 was used to see how many times the collets was tested. Figure 5. ve 6. Siemens SIMATIC S7-1200 which used in the test The test pieces were tested by applying 25 Bar hydraulic pressure of 2.2kw Volt engine. Collet’s life is calculated by breaking the test pieces as a result of repeated stresses. As a result of this experiment, the fatigue strength of the parts was revealed. On the Siemens control, the number of times the test is repeated until it is broken, waiting in forward time (300ms), waiting in behind time (500ms). 3. Experimental and Structural analysis Firstly, the old collet was analyzed with SAE 4140 material in Ansys software. Then, 50CrMo4 material was used as material in the same collet. Finally, The newly designed collet with 50CrMo4 material was analyzed. In the test setup, old collet with SAE 4140 material standard and new collet with 50CrMo4 material standard were tested. 3.1 Ansys finite element method analysis In this experiment, collets were designed with Solidworks software and then fatigue and static structral analysis was performed in Ansys Workbench program. The finite element model with the SAE 4140 material standard collet’s mesh consists of 1579795 nodes and 1125047 elements. And the average element quality is 0.896980. The finite element model of the former collet with 50CrMo4 standards consists of 1147139 nodes and 811281 elements. And the average element quality is 0,89462. The finite element model with a 50CrMo4 standard collet’s mesh consists of 1497266 nodes and 1063726 elements. The average element quality is 0.89758. The highest tensile strength of SAE 4140 old collet is 132,12 MPa, The highest stress in the old 50CrMo4 standard was 112.13 MPa while the new stress in the new 50CrMo4 standard was 171.62 MPa. The main reason for this difference is the design difference between the collets. 84

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Figures 7, 8 and 9 show the static structral analysis results of 2.5 MPa pressure applied to the collets. Figure 7. SAE 4140 standard old collet static structral analysis Figure 8. 50CrMo4 standard old collet static structral analysis 85

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Figure 9. 50CrMo4 standard new collet static structral analysis Figures 10, 11 and 12 show the life of the collets as a result of the life analysis. Figure 10. SAE 4140 standard old collet life analysis 86

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Figure 11. 50CrMo4 standard old collet life analysis Figure 12. 50CrMo4 standard new designed collet life analysis 3.2 Experimental analysis in test setup In this experiment, the arrangement of the test device manufactured to test the old design SAE 4140 and the new design 50CrMo4 collets is as shown in Figure 13. 87

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Figure 13. Fatigue testing device In the experiment, fatigue test was performed by applying the 25 bar hydraulic pressure to the collets, which are given in Table 5. With the operation of the motor, 25 Bar hydraulic pressure is transmitted to the collets mounted on the hydraulic system. The collet is activated by this pressure.The collet starts to expand by increasing the volume from bottom to top with the help of pressure. With this process, the collet is provided to hold the spindle, so collet act as a holding tool. In this experiment, the collets were subjected to repeated pressure several times to test how many cycles they would break. Thus, the fatigue strength of the collet is taken into consideration.The test cycle is shown on the Siemens controler. A comparison was made between the collets and the data obtained from controler. The collet is likely to break suddenly as a result of increased stresses and cracking from a point. Because 50CrMo4 material has a hard structure and is a brittle material. The collet can be broken from the bottom or from the top. This depends on where the collet forms the first crack. Mechanical parts are subjected to repeated loads, the resulting cyclic stresses can lead to fatigue crack initiation. The crack initiation period usually starts with nucleation of micro-cracks whose lengths are comparable with the microstructural features of treated material, that is the size of crystal grains. From the standpoint of the microstructure of the material, micro-cracks may be initiated along slip bands by dislocation motion, along grain boundaries or along inclusion interfaces[17]. The further propagation of such micro-cracks is usually termed as ‘short crack growth’ and is governed by interactions between local microstructural features and by the resolved stress state acting as a crack driving force at the crack tip.The significance of these interactions usually extends only for a few crystal grains, when the crack reaches a typical length valid for long cracks. The micro-crack nucleation and its growth until formation of engineering initial crack is in engineering applications usually termed as ‘crack initiation period’. In particular, for high-cycle fatigue and high-strength materials, up to 90% of component’s fatigue life can be determined by the phase of micro-crack nucleation and the propagation of short cracks on microstructural level. Therefore, the appropriate number of stress cycles required for formation of initial ‘long crack’ can be treated as an appropriate fatigue life in such cases. [18] This cracks usually starts on the surface and is transmitted to the middle parts with slip errors. In addition, if the material has micro-cracks and the stress build-up in the cracks is enough to advance the crack, the crack advances. Thus the wear is gradually spread over the entire cross-section. After decomposition progresses sufficiently with wear, the rest of the section becomes unable to withstand the stress and the material breaks. It is not desirable that the collet break from the tip during operation. Because it is possible to damage the part it holds when it breaks from the tip. Fatigue can be overlooked as it does not make a significant plastic deformation on the material, which is dangerous because it does not give warning. 88

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 The most prominent feature of fatigue is the formation of cracks. If the material is sufficiently ductile, excessive energy storage is required for fatigue behavior. These cracks can be tested by periodic maintenance. However, since the 50CrMo4 material is hard and brittle, a crack is expected to occur suddenly and a rupture like knife cutting may occur in the material. Such brittle fracture phenomena can be found in aircraft wings, steel bridges. Fatigue is one of the most important material factors that must be taken into consideration as the fractures in the structures including this type of society will not only damage the material. In order to prevent fatigue or delay a material, either very high surface quality should be produced and crack formation should be prevented, or a ductile material should be produced and the energy required for crack formation should be kept high. The collets exposed to fatigue were examined by scanning electron microscopy. Scanning electron microscopy images of the collets examined are shown in Figures 15 and 17. In Figures 14 and 15, we can observe the fracture formation and sudden fracture of the collet with the material standard of SAE 4140, which visualized by electron microscope. In Figures 16 and 17, we can observe the fracture formation and sudden fracture of the collet with the material standard 50CrMo4, which visualized by electron microscope. Figure 14 and 15. Electron microscope image of SAE 4140 old design collet Figure 16 and 17. Electron microscope image of 50CrMo4 new design collet 89

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 4.Results According to the Ansys finite element method, life time 117120 cycles for SAE 4140 standard collet and 219960 cycles for old collet with 50CrMo4 standards were obtained. However, since the tool holder collets are used in mass production, the desired life value is at least 300000 cycles. As we could not capture this value, we wanted to increase the life value with a new design. 50CrMo4 steel was used in this new design and 305590 cycles were obtained in the analysis results. However, since we never fully know the fatigue strength of a material, it was found that the collets were experimentally tested and different results were obtained. According to the experiment, when we look at Table 6, 50CrMo4 collet under 25 Bar pressure, 338 thousand 502 repeated test results measured in Siemens control, as shown in Figure 18 collet was broken from the tip. The collet with SAE 4140 material standard was broken in 96 thousand 148th cycle. As shown in figure 19 collet was broken from the tip. Material Standard Applied Pressure Waiting in Waiting in Behind Forward Time Time of Collet (bar) Cycle (300ms) (300ms) SAE 4140 25 300 500 96.148 50CrMo4 25 300 500 338.502 Table 6. Clamp Test. Figure 18. Broken 50CrMo4 Collet Figure 19. Broken Collet 4140 Collet diameter, hydraulic pressure acting on collet , hardness of material, brittleness of material and fatigue strength played an active role in this experiment. The main reason of the fracture of the collet is washer which is placed top of the collet. The collet which is under pressure, expands after that collet pressurize to washer and washer forces back to the collet. Because of that cracks occurs. The collet was broken as the crack advances where the maximum load is acting and the crack length reaches the maximum value. As a result, in this experiment, the new collet with 50CrMo4 standard under 25 bar hydraulic pressure was broken under repeated stresses in 338502. Cycle. SAE 4140 material standard old design collet broken under repeated stresses in 96148. cycle. 90

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Thus, the fatigue strength of the redesigned collet with 50CrMo4 material standard given in Figures 2 is higher than that of SAE 4140 material standard collet given in Figure 3. 5.Special Thanks This study was carried out as an R&D project together with Totomak Makine ve Yedek Parça Sanayi ve Ticaret A.Ş. References [1] Deng, H. ‐L., Liu, H., Liu, Q. ‐C., Guo, Y. ‐P., & Yu, H. (2019). Fatigue strength prediction of carburized 12Cr steel alloy: Effects of evaluation of maximum crack sizes and residual stress distribution. Fatigue & Fracture of Engineering Materials & Structures. ISSN 1460-2695 [2] J. Maierhofer, R. Pippan, H.-P. Gänser: Modified NASGRO equation for physically short cracks. International Journal of Fatigue 59 (2014) 200–207 [3] M. Luke, I. Varfolomeev, K. Lütkepohl, A. Esderts: Fracture mechanics assessment of railway axles: Experimental characterization and computation. Engineering Failure Analysis 17 (2010) 617– 623 [4] M. Luke, I. Varfolomeev, K. Lütkepohl, A. Esderts: Fatigue crack growth in railway axles: Assessment concept and validation tests. Engineering Fracture Mechanics 78 (2011) 714–730 [5] M. Sander, H. Richard: Investigations on fatigue crack growth under variable amplitude loading in wheelset axles. Engineering Fracture Mechanics 78 (2011) 754-763 [6] U. Zerbst, M. Schödel, H.Th. Beier: Parameters affecting the damage tolerance behaviour of railway axles. Engineering Fracture Mechanics 78 (2011) 793–809 [7] U. Zerbst, S. Beretta, G. Köhler, A. Lawton, M. Vormwald, H.Th. Beier, C. Klinger, I. Cerny, J. Rudlin, T. Heckel, D. Klingbeil: Safe life and damage tolerance aspects of railway axles – A review. Engineering Fracture Mechanics 98 (2013) 214– 271 [8] U. Zerbst, C. Klinger, D. Klingbeil: Structural assessment of railway axles – A critical review. Engineering Failure Analysis 35 (2013) 54–65 [9] Şık,A., Önder, M., Korkmaz, S., ’’Taşıt Jantlarının Yapısal Analiz İle Yorulma Dayanımının Belirlenmesi’’ Gazi Üniversitesi Fen Bilimleri Dergisi Part: C, Tasarım Ve Teknoloji GU J ISSN 1304-4915 [10] Karamangil, İ., ’’Bir Otomobil Arka Dingilinin Sonlu Elemanlar Metodu ile Yorulma Analizi’’ Pamukkale Üniversitesi Mühendislik Bilimleri Dergisi, 2007 ISSN/eISSN 1300-7009 / 2147-5881 [11] Şık, A., “MIG/MAG Kaynak Yöntemi İle Birleştirilen Çelik Malzemelerde İlave Tel Türleri ve Koruyucu Gaz Karışımlarının Eğmeli Yorulma Ömürlerine Etkilerinin Araştırılması”. Gazi Üniversitesi Mühendislik. Mimarlık. Fakültesi Dergisi,ISSN 1304-4915 [12] Babuška, I., Sawlan, Z., Scavino, M., Szabó, B., & Tempone, R. (2018). Spatial Poisson processes for fatigue crack initiation. Computer Methods in Applied Mechanics and Engineering. ISSN 0045-7825 [13] Elements of Metallurgy and Engineering Alloys, 2008 ASM International. [14] Tosun K.’’ Yapı Malzemesi-I’’ Dokuz Eylül Üniversitesi İnşaat Müh. Bölümü [15] Gençoğlu, O.’’Malzemelerde Yorulma Davranışı’’ On Dokuz Mayıs Üniversitesi Malzeme Bilimi ve Mühendisliği.2013 [16] Stephens, I., Fatemi, A., Stephens, R., Fuchs, H., ‘’Metal Fatigue in Engineering’’ [17] Krupp, U. (2007) Fatigue Crack Propagation in Metals and Alloys, Weinheim, Wiley-VCH, Weinheim.] [18] Glodež, S., Šori, M., & Kramberger, J. (2013). A statistical evaluation of micro-crack initiation in thermally cut structural elements. Fatigue & Fracture of Engineering Materials & Structures, 36(12), 1298–1305.doi:10.1111/ffe.12068 91

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Mühendis ve Makina TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 cilt 58, sayı 684, s. 1-12, 2017 Engineer and Machinery vol 58, no 684, p. 1-12, 2017 Soğutma Sıvısı Bulutunun Vakumlu Santrifüj Yöntemi İle Geri Kazanımı ve Temiz Hava Elde Edilmesi Hakan Çabuk *1 Gökçe Akkuş 2 Tuğrul Soyusinmez 3 Ahmet Keskin 4 Anıl Kaplan 5 ÖZ CNC tezgâhlarda kesici takım ve iş parçası arasında oluşan sürtünmenin ve ortaya çıkan sı- caklığın olumsuz etkilerini ortadan kaldırmak için kullanılan soğutma sıvısı sıcaklık etkisiyle soğutma sıvısı bulutu haline dönüşmektedir. Soğutma sıvısı bulutu çalışma ortamına yayıldık- tan sonra çeşitli iş kazalarına sebep olabilmekte ve çalışma ortamının havasını kirleterek çe- şitli sağlık sorunlarına neden olmaktadır. Bu sorunun çözümü için çeşitli filtreleme makineleri kullanılmasına rağmen, sorunun tamamen ortadan kaldırılması için yeterli olmamaktadır. Bu çalışmada, bu filtreleme sistemlerinin eksik yönleri anlatılarak çözüm olabilecek vakumlu sant- rifüj tipi bir filtre sisteminden bahsedilecektir. Aynı zamanda bu sistemin çeşitli hesaplamaları ve analiz çalışmaları da sunulacaktır. Anahtar Kelimeler: Santrifüj, filtre, CNC, soğutma sıvısı Vacuumed Centrifugal Method Which is Using for Recycling and Get Clean Air from Cooling Fluid Mist ABSTRACT Cooling fluid which is used to abolish negative effects of heat and friction that occurs between cutting tool and workpiece at CNC machine and because of heating, fluid converts into mist. After cooling fluid mist spreads out to environment, it occasions different kind of job accidents, heath problems and dirt in working area. Although varieties of filtration machines have been used to overcome this problem, they aren’t enough for solution. This study will mention about not only these missing sides, but also vacuumed centrifugal filtration to solve these missing sides. Also, this article will present variety of calculation and analysis. Keywords: Centrifugal, filtration, CNC, cooling fluid * İletişim Yazarı : 18.07.2016 Geliş/Received : 24.01.2017 Kabul/Accepted 1 TOTOMAK AŞ. - [email protected] 2 TOTOMAK AŞ. - [email protected] 3 TOTOMAK AŞ. - [email protected] 4 TOTOMAK AŞ. - [email protected] 5 TOTOMAK AŞ. - [email protected] 93

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 1. GİRİŞ CNC tezgâhların çalışması sırasında kullanılan soğutma sıvısının sıcaklık etkisiyle buharlaşması ve buharlaşan bu sıvının çalışma ortamına yayılması, üretim sektörün- deki birçok firmanın ortak sorunlarından biridir. Bu sorunun çözümü için birçok firma filtreleme makineleri kullanmaktadır. Bu makineler belli bir süre zarfında istenilen işlevi yerine getirebilmekte ve ilerleyen aşamalarda bu makinelerin ihtiyaç duyduğu bakımların yapılamaması sonucunda işlevlerini kaybetmektedir. Bunun sonucunda, soğutma sıvısı bulutu tekrardan çalışma ortamına yayılmakta ve aynı sorunlara neden olmaktadır. Soğutma sıvısı ve dolayısıyla soğutma sıvısı bulutu insanlara deri, ağız, burun ve göz yoluyla temas ederek çeşitli sağlık sorunlarına neden olmaktadır. Bu sorunlar; cilt problemleri (Dermatit), solunum rahatsızlıkları ve kanser olarak sınıflandırılabilir [1]. Şekil 1’de, bir filtreleme makinesinin çalışma prensibi gösterilmiştir. Bu ve benzeri Şekil 1. Bir Filtreleme Makinesinin Çalışma Prensibi [2] makinelerin kendi içerisinde birbirinden farklı özellikleri olmasına rağmen, birço- ğunun çalışma prensibi Şekil 1’de gösterildiği gibidir. Şekil 1’de görüldüğü gibi, 1 numaralı bölümden giren soğutma sıvısı bulutu, 5 numaralı fan yardımıyla yukarı çekilirken öncelikle 2 numaralı yıkanabilir bir filtreleme ünitesinden geçmektedir. 94

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Buradan çıktıktan sonrada 3 numaralı filtreleme ünitesine girmektedir. Bu ünitenin daha hassas bir filtreleme içermesinden dolayı son filtreleme görevi görmektedir. 4 numaralı bölüm ise geri dönüşüm drenaj borusu olarak görev almaktadır. Filtreleme ünitelerin belli aralıklarda ihtiyaç duyduğu bakım ve temizlik işlerinden dolayı CNC tezgâhların durması birçok firma sahibi tarafından istenilmeyen bir du- rumdur. Bunun sonucunda, filtreleme üniteleri yeterince temizlenememekte ve işle- vini kaybetmektedir. 2. VAKUMLU SANTRİFÜJ TİPİ FİLTRE SİSTEMİ Santrifüj yöntemi, iki farklı yoğunluktaki akışkanın birbirinden ayrılmasını sağlamak için kullanılan bir yöntemdir. Bu yöntemde, birbiri içerisine karışmış, yoğunlukları farklı iki akışkanın yüksek bir hızda dönerken, yüksek yoğunlukta olan akışkanın dış yüzeye doğru, daha düşük yoğunluktaki akışkanın ise merkezde toplanması sağlan- maktadır [3]. Mevcut filtre sistemlerindeki sorunlara çözüm olabilecek ve tamamen otomatik bir şekilde çalışabilecek bir filtreleme makinesi Şekil 2’de detaylı bir şekilde gösteril- mektedir. Bu makine, içerisinde sahip olduğu santrifüj tipi fanı ile soğutma sıvısı bu- lutunu yoğuşturarak hem bu bulutun çalışma ortamına çıkmasını engellemekte hem de yoğuşturma sonucu elde edilen soğutma sıvısını tekrar kullanılmak üzere CNC tezgaha aktarabilmektedir. Aynı zamanda filtreleme sisteminin çıkış kısmına konu- lan filtre aracılığıyla santrifüj sisteminin yoğuşturamadığı partiküllerin tutulması ve gövde üzerine açılan deliklere bağlanan hortumlar yardımıyla bu bölgede toplanan soğutma sıvısının dışarıda biriktirilmesi hedeflenmektedir. Bu sistem içerisinde kul- lanılan santrifüj fan ve filtre sisteminin sağlıklı çalışması için belirli aralıklarda te- Filtre Santrifüj Temiz Hava Fan Çıkışı Soğutma Sıvısı Bulutu Girişi Şekil 2. Vakumlu Santrifüj Filtre Sisteminin İç Yapısı 95

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 mizlenmesi gerekmektedir. Bu temizlik işlemi için filtre sisteminin içerisine soğutma sıvısı tankından soğutma sıvısı alınarak nozzle yardımıyla hem santrifüj fan hem de filtre temizlenmektedir. Bu işlem, Şekil 3’te gösterilmektedir. Bu işlemlerin otomatik gerçekleşiyor olması herhangi bir zaman kaybına neden olmamaktadır. Bununla birlikte, vakumlu santrifüj tipi filtre sisteminin montaj edildiği bir taşlama tezgahında 144 saat sonunda toplam 850 ml. soğutma sıvısı-kızak yağı karışımı sıvı elde edilmiştir. Toplanan bu yağın 400 mililitresi soğutma sıvısının vakumlu santrifüj Şekil 3. Filtre Sisteminin Soğutma Sıvısı Tankı ile Bağlantısı sistemine girdiği ilk bölümde santrifüj yöntemiyle elde edildiği, kalan kısmının ise filtre bölümünden elde edildiği görülmüştür. 3. VAKUMLU SANTRİFÜJ TİPİ FİLTRE SİSTEMİNİN TEST VE ANALİZ ÇALIŞMALARI 3.1 Sabit Değerler 96 • Partikül Çapı = 186  • Soğutma Sıvısı Yoğunluğu = 1070 kg/m3 [4] • Hava Yoğunluğu = 1,225 kg3/ [5] • ∆t = 1,00E-04 sn. • Fan Debisi = 0,2514 m3/s • Fan Çapı = 0,1725 m • Aparat ile Filtre Makinesi Arasındaki Mesafe = 0,8 m

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 • Kinematik Viskozite = 35,4 cSt [6] • Partikül X Yönünde İlk Hızı = -1 m/sn. (kabul edilmiştir.) • Partikül YYönünde İlk Hızı = +3 m/sn. (kabul edilmiştir.) • Havanın X Yönünde İlk Hızı = 0 m/sn. (kabul edilmiştir.) • Havanın YYönünde İlk Hızı = 0 m/sn. (Kabul Edilmiştir.) 3.1 Hesaplamalar • Fan Alanı A = * D2 0*,17252 0,02 m2 (1) fan (2) (3) fan 4 4 • Fan Hızı = v =  0,2514 = = 10,75667 m/s Afan 0,02 22 Partikül Alanı = * Dpartikül 186 27171,63486 2  =* • 4 4 • Partikül Kütlesi = 4* * D3 * *10-18 (4) 3 partikül 3.1.1.1 Partikülün Başlangıç (x=0) Noktasındaki Değerleri • X Yönündeki Bağıl Hız; (5) V =V -Vx,bağıl x,hava x,partikül (6) = 0-(-1) = 1 m/sn. • Y Yönündeki Bağıl Hız; V =V -Vy,bağıl y,hava y,partikül = 0-3 = -3 m/sn. • V Vx2, bağıl y2, bağıl 12 -32 3,16 m / sn. (7) • Reynold Sayısı; (8) V * Dbağıl,bileşke partikül 3,16 *186 *10-6 16,62 97 v 35,4 *10-6

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Soğutma Sıvısı Bulutunun Vakumlu Santrifüj Yöntemi ile Geri Kazanımı ve Temiz Hava Elde Edilmesi 24 + 6 + 0,4 = 24 + 6 + 0,4 = 3,03 1+ Re 1+ 16,62 Re 16,62 (9) • X Yönünde Sürüklenme Kuvveti; 2 Vx, V partikül 1 * D2 -12 * bağıl (10) 2 * C *V * * 4 *10d bağıl ,bileşke bağıl , bileşke 1 * * 3,03* 3,162 * 1,225* 1862 * 10-12 * -3 = -4,77831* 10-7 N 2 4 3,16 • Y Yönünde Sürüklenme Kuvveti; 1 * * Cd *V *bağıl , bileşke 2 * D2 *10-12 * Vy,bağıl (11) 2 partikül V 4 (12) (13) bağıl ,bileşke 1 1862 -3 -4,77831* 10(-7 ) N * * 3,03* 3,162*1,225* * 10-12* 2 4 3,16 • X Yönündeki Partikül İvmesi; Fd = 1,59277* 10-7 = 5,52 m / sn.2 x m 2,88411*10-8 • Y Yönündeki Partikül İvmesi; Fdy = -4,77831*10-7 = -16,57m / sn.2 m 2,88411* 10-8 • X Yönündeki Partikül Konumu; x +V * t + 1 * a * t2 i x ,partikül 2x (14) 0 + -1* 10-4 +1 * 5,52* 10-42= - 0,00010 m 98 ( )2 ( )

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 0 + 3* 10-4 + 1 * -16,42* 10-4 2 = 0,00030 m ( )2 () • Akış Denklemi (Ψ) = -a*y (16) • Akış Denklemi Sabiti (a) = v = 10,75667 = 13,4458 s-1 (17) (18) L 0,8 (19) • X Yönündeki Hava Hızı; (20) (21)  = u = -a* x = -13,4458* -0,00010 = 0,00134 m / sn. (22) y (23) • Y Yönündeki Hava Hızı; (24) -  = v = a* y = 13,4458* 0,00030 = 0,00403 m / sn. 99 x • X Yönündeki Partikül Hızı; ( )Vx,partikül + ax* t = -1+ 5,52* 10 -4 =1 m / sn. • Y Yönündeki Partikül Hızı; ( )( )Vy,partikül + ay * t = 3 + -16,57 * 10 -4 = 3 m / sn. 3.1.1.1 Partikülün x = -0,08583 m Noktasındaki Değerleri • X Yönündeki Bağıl Hız; V V -Vx ,bağıl 1,1540 - 0,00115 1,15285 m / sn. x,hava x,partikül • Y Yönündeki Bağıl Hız; V V -Vy ,bağıl 6,0671- 3,22 2,84220 m / sn. y,hava y,partikül • Vbağıl, bileşke; V Vx2, bağıl y2, bağıl 1,152852 (2,84220)2 3, 07 m / sn.