2020 yayın kitapçığı

2020 TOTOMAK ARGE MERKEZİ 2020 Yayın K tapçığı Ataşehir, 10002. Sk. No:4, 35620 Aosb/Çiğli/İzmir

TOTOMAK AR-GE MERKEZİ BİLDİRİ, MAKALE VE ÖZET YAYIN ÇALIŞMALARI

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 İÇİNDEKİLER BÖLÜM- 1 ÖZET YAYINLAR Laser Cladding Applications on Different Materials and Characterization Analysis…………………………………4 Tribological Properties and Machining Performance of Cutting Fluids with Additives Effects…………………5 Crack Analysis on the SAE 1117 Steel Shafts for Inclusion and Heat Treatment Combination Effect…………6 Effect of Cutting Parameters on the Chip Formation for SAE 1117 Steel…………………………………………………7 BÖLÜM -2 İNGİLİZCE YAYINLAR Experimental Trials Fixture Gap on the Reference Diameter Effect for the Dynamic Balance Results………9 Analysis for Lifetime with Alternative Material and Heat Treatment Effect for Utility Car Wheel Hubs…28 Effects of Different Cryogenic Treatments on Drilling Performance of HSS Drills…………………………….……44 Adaptation of Cryogenic Systems for Internal Cooling Drill Comparative by Coolants……………………….…59 High Vibration Absorptive Body Production for Turning Cutting Tools with Additive Manufacturing Technology ............................................................................................................................................. .65 Crack Analysis in the SAE 1117 Steel Shafts for Inclusion and Heat Treatment Combination Effect…………………………………………………………………………………………………………………………………………………..71 Investigation of Fatigue Behavior of Collets With Material Standard SAE 4140 and 50CrMo4 by Ansys Finite Element Method and Fatigue Test Device………………………………………………………………………………… 80 BÖLÜM- 3 TÜRKÇE YAYINLAR Soğutma Sıvısı Bulutunun Vakumlu Santrifüj Yöntemi ile Geri Kazanımı ve Temiz Hava Elde Edilmesi.93 Dökme Demir Malzemelerin Karbür Uçlarla Delme İşleminde Proses Parametrelerinin Optimizasyonu ... ..........................................................................................................................................................106 Elektrik Tahrikli Yük Taşıma Sistemlerinde Malzeme Değişimlerinin Mekanik Dayanımı ve Maliyet Yönünden Karşılaştırılması ...................................................................................................................118 Isıl İşlem Uygulanan Millerde Oluşan Distorsiyon Değişimlerinin Doğrultma Kuvveti ile Olan İlişkisinin İncelenmesi .........................................................................................................………………………………131 Otomatik Kontrollü Briketleme Aracı Tasarımı…………………………………………………………………………………142 Talaş Tiplerinin Takım Hızlarına ve İşleme Derinliklerine Göre İrdelenmesi………………………………………151 2

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 BÖLÜM:1 ÖZET YAYINLAR 3

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 The Internatinonal Conference on Materials Science Mechanical and Automation Engineerings and Technology in ÇEŞME/İZMİR (IMSMATEC’18), April 10-12 2018 Laser Cladding Applications on Different Materials and Characterization Analysis Taner Kavasa and Ardan Kayaaltıb and Tuğrul Soyusinmezc and Oğuzcan Güzelipekd and Gökçe Akkuşe a Afyon Kocatepe Üniversitesi, Afyon,Turkey, E-mail: [email protected] b Totomak AŞ., İzmir, Turkey, E-mail: [email protected] c Totomak AŞ., İzmir, Turkey E-mail: [email protected] dTotomak AŞ., İzmir, Turkey, E-mail: [email protected] e Totomak AŞ., İzmir, Turkey, E-mail: [email protected] Abstract The study investigates the mechanical properties changes of laser cladding application on ductile, gray cast irons and SAE 1117 steel. Laser cladding areas had compared with percentage of martensite, retained austenite, and carbides, and measures an average hardness of surfaces. On the other hand, all samples tensile test results compared with their original material filling on the surfaces. Laser cladding exhibits a significant strengthening mechanism for this ductile, gray cast irons and SAE 1117 steel samples. The test results indicate that the weldability of ductile cast iron can be enhanced by performing laser surface pretreatment to sublimate graphite nodules. Microhardness show some changes due to surface interface with laser cladding heat zone effecting. During the tensile test, failures were limited to the base metal region of the cladded area. When examined the test results show due to heat effected zone determining the results of material characterization and mechanical test results. Keywords: Laser Cladding, Cast Iron, SAE 1117, Characterization Analysis, Mechanical Tests. 4

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Tribological Properties and Machining Performance of Cutting Fluids with Additives Effects Tuğrul Soyusinmez1, Özgür Seydibeyoğlu2, Oğuzcan Güzelipek3 and Gökçe Akkuş4 1 R&D Department, Totomak A.Ş, İzmir, Turkey [email protected] 2 Materials Science and Engineering, İzmir Katip Celebi University, İzmir, Turkey [email protected] 3 R&D Department, Totomak A.Ş, İzmir, Turkey [email protected] 4 R&D Department, Totomak A.Ş, İzmir, Turkey [email protected] The paper presents a review to highlight the tribological aspects of cutting fluids in machining with different chemical additives. The cutting fluids are mainly used as coolants and lubricants in the different machining process like cutting, turning, milling, drilling and grinding. Purpose of the cutting fluids in all machining process is to cool the parts, minimize the friction of the tools and clear away the chips from the surface. In the present work, boric acid and graphene oxide effect on the cutting fluids and different allegation ratio combinations tribology results will be present. The results indicate that there is considerable improvement in the machining performance with boric acid and graphene oxide assisted machining compared without any additive chemical cooling liquid. Keywords: Tribology, Boric Acid, Graphene Oxide, Cutting Fluids, Machining REFERENCES Please use the IEEE style citation and reference format as follows (maximum 5 key references): [1] Bagchi, H.; Mukharjee, N.P.; Basu, S.K., 1972, \"Investigation of metal cutting using molybdenum disulphide as a cutting fluid\", Industrial Lubrication and Tribology, pp: 239-243. [2] Liang, H.; Jahanmir, S., 1995 \"Boric Acid as additive for core-drilling of alumina\", Journal of Tribology, Vol. 117, pp: 65-71. [3] Venkatesh, V.C.; Chandrasekaran, H., 1982, \"Experimental methods in metal cutting\", Prentice Hall of India Pvt Ltd. [4] Benardos, P.G. and Vosniakos, G.C. (2003) Predicting Surface Roughness in Machining: A Review. International Journal of Machine Tools and Manufacture, 43, 833-844 [5] Talib, N. and Rahim, E.A. (2018) Performance of Modified Jatropha Oil in Combination with Hexagonal Boron Nitride Particles as a Bio-Based Lubricant for Green Machining. Tribology International, 118, 89-104. 5

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 3rd International Mediterranean Science and Engineering Congress (IMSEC 2018) October 24-26, 2018, Adana/Turkey Crack Analysis on the SAE 1117 Steel Shafts for Inclusion and Heat Treatment Combination Effect Tuğrul Soyusinmez1, Oğuzcan Güzelipek2 ,Gökçe Akkuş3, Tolga Palanduz4 1 Totomak AŞ,Turkey,[email protected] 2 Totomak AŞ,Turkey,[email protected] 3 Totomak AŞ,Turkey,[email protected] 4 Totomak AŞ,Turkey,[email protected] 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 6

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 3rd International Mediterranean Science and Engineering Congress (IMSEC 2018) October 24-26, 2018, Adana/Turkey Effect of Cutting Parameters on the Chip Formation for SAE 1117 Steel Tuğrul Soyusinmez1, Oğuzcan Güzelipek2 ,Gökçe Akkuş3, Murat Ardan Kayaaltı4 1 Totomak AŞ,Turkey,[email protected] 2 Totomak AŞ,Turkey,[email protected] 3 Totomak AŞ,Turkey,[email protected] 4 Totomak AŞ,Turkey,[email protected] Abstract The paper deals with the experimental, simulation and theoretical study of the chip formation process at SAE 1117 steels. The study of these topic is necessary with respect to the force loading of machining system, tool wear, chip disposal, productivity and machining costs. The effect of the cutting speed on a chip formation process is discussed in the paper. It has been proved that the cutting speed has the dominant effect on the cutting process. There were found out and researched some chips related to a continuous, waved, segmented or saw-tooth chip formation. The research was focused on: theoretical model for chip formation analysis, real cutting and simulation of the cutting process. There were some differences between the areas found. The types of chips that are formed as a results of processing various parts of different tools speed. Keywords: Chip, Tool Speed, CNC Machining, Type of Chips 7

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 BÖLÜM:2 İNGİLİZCE YAYINLAR 8

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 4th International Mediterranean Science and Engineering Congress (IMSEC 2019) April 25-27, 2019 Alanya Lonicera Resort & Spa Hotel Antalya/Turkey Experimental Trials Fixture Gap on the Reference Diameter Effect for the Dynamic Balance Results Tuğrul Soyusinmez1, Oğuzcan Güzelipek2, Tolga Palanduz3, Ardan Kayaaltı4, Gökçe Akkuş5 1 Totomak AŞ., Turkey; [email protected] 2 Totomak AŞ., Turkey; [email protected] 3 Totomak AŞ., Turkey; [email protected] 4 Totomak AŞ., Turkey; [email protected] 5 Totomak AŞ., Turkey; [email protected] Abstract This article will present the effect of the gap on the fixture and different fixture types for the dynamic balancing on the flywheel parts. Dynamic balancing is when the rotation does not produce any resultant centrifugal force or couple. The system will rotate without needing the application of any external force or couple, other than that required to support its weight. When a system or machine is unbalanced, to avoid stress being put upon the bearings, a counterbalancing weight is added. Different type of fixture and torque values are indicating different results and they are compared to each other. Keywords: Dynamic balance, fixture, flywheels, imbalance 1. INTRODUCTION The tolerances used in the rotor production should be adjusted by compensating the production cost with the desired properties from the component. In general, it is more economical to produce parts that do not work and then try to correct them or to compensate them instead of producing perfect parts that do not require correction. Causes of irregularity are processing error, mounting tolerances, distortion due to heat treatment and heterogeneous material. As a result of these irregularities, the actual axis of rotation causes it to coincide with one of the main axes of the inertia. It creates variable annoying forces directly proportional to the rotational speed. In order to eliminate these forces and perform the correct operation, the rotor balancing task must be performed. [1] There are several ways to learn the constant or static balance of a rotating part. Sometimes flywheels, etc. a simple method used for the schema is shown in Figure 1. In Fig. 1, a shaft is placed into the hole of a completed wheel, which is then fixed to the carefully flattened \"parallels\" A. The wheel rotates unevenly until the heavy side is down. It can be said that when 9

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 the heavy parts are in any position after stabilization and reduction, they are in stagnant or static equilibrium. [2] A cylindrical perfectly static may be in equilibrium and is not stable when rotating at high speed. If the track is like a thin disc, static balancing can be accurate at high speeds, if done carefully. However, if an axis is longer in relation to the diameter of the rotating member and in different planes with respect to the unbalanced portion of the part or in different planes with respect to one of them, the balancing must be such that it activates when the centrifugal force of the parts rotates rapidly. This application is called employee balance or dynamic balancing.[2] Flywheel can be balanced by aligning the Flywheel mass with the bearing centre’s.[1] Sketch of unbalance definition as shows on Figure 1. Figure 1: Sketch of unbalance definition ‘’M’’ = Flywheel mass ‘’m’’ = Unbalance mass ‘’C’’ = Center of mass ‘’e’’ = Displacement of mass center ‘’r’’ = Distance from center of flywheel to C.G. of unbalance mass ‘’m’’ ‘’F’’ = Force due to unbalance ‘’U’’ = Flywheel unbalance ‘’N’’ = Flywheel speed (RPM) The Flywheel is symmetrical except for the unbalanced m at radius r: U = m*r = M*e (1) U = M*e so e = U/M = m*r/M (2) The unbalance mass “m” times its radius “r” equals “U” flywheel unbalance. Divide this by flywheel mass and we get “e”, which is a measure of unbalance that is independent of flywheel 10

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 mass. It is called mass eccentricity, or specific unbalance. It is the displacement of the mass center from the bearing center. The mass eccentricity ‘e’ is the measure of the unbalance in terms of the displacement of the mass axis and the bearing axis. Units are linear – inches or mm. The eccentricity multiplied by the rotor mass gives the unbalance. The units are the combination of mass and eccentricity – ounce.inches or gram.millimeter. Guidance for balance quality grades for rotors in a constant (rigid) state as shows on Table 1 and Permissible residual specific unbalance based on balance quality grade G and service speed n shows on Figure 2. Table 1 — Guidance for balance quality grades for rotors in a constant (rigid) state Machinery types: General examples Balance quality Magnitude grade Crankshaft drives for large slow marine diesel engines (piston speed below G eper   9 m/s), inherently unbalanced G 4000 G 1600 mm/s Crankshaft drives for large slow marine diesel engines (piston speed below G 630 4 000 9 m/s), inherently balanced G 250 1 600 G 100 630 Crankshaft drives, inherently unbalanced, elastically mounted G 40 250 G 16 100 Crankshaft drives, inherently unbalanced, rigidly mounted G 6,3 40 Complete reciprocating engines for cars, trucks and locomotives 16 G 2,5 Cars: wheels, wheel rims, wheel sets, drive shafts 6,3 Crankshaft drives, inherently balanced, elastically mounted G1 G 0,4 2,5 Agricultural machinery Crankshaft drives, inherently balanced, rigidly mounted 1 Crushing machines 0,4 Drive shafts (cardan shafts, propeller shafts) Aircraft gas turbines Centrifuges (separators, decanters) Electric motors and generators (of at least 80 mm shaft height), of maximum rated speeds up to 950 r/min Electric motors of shaft heights smaller than 80 mm Fans Gears Machinery, general Machine-tools Paper machines Process plant machines Pumps Turbo-chargers Water turbines Compressors Computer drives Electric motors and generators (of at least 80 mm shaft height), of maximum rated speeds above 950 r/min Gas turbines and steam turbines Machine-tool drives Textile machines Audio and video drives Grinding machine drives Gyroscopes Spindles and drives of high-precision systems 11

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 NOTE 1 Typically completely assembled rotors are classified here. Depending on the particular application, the next higher or lower grade may be used instead. For components, see Clause 9. NOTE 2 All items are rotating if not otherwise mentioned (reciprocating) or self-evident (e.g. crankshaft drives). NOTE 3 For limitations due to set-up conditions (balancing machine, tooling), see Notes 4 and 5 in 5.2. NOTE 4 For some additional information on the chosen balance quality grade, see Figure 2. It contains generally used areas (service speed and balance quality grade G), based on common experience. NOTE 5 Crankshaft drives may include crankshaft, flywheel, clutch, vibration damper, rotating portion of connecting rod. Inherently unbalanced crankshaft drives theoretically cannot be balanced; inherently balanced crankshaft drives theoretically can be balanced. NOTE 6 For some machines, specific International Standards stating balance tolerances may exist (see Bibliography). Figure 2 — Permissible residual specific unbalance based on balance quality grade G and service speed n ISO 1940 is based on the measurement of machinery vibration velocity The ANSI spec is identical but printed by American National Standards Institute. The API specification is written around pump requirements in the Petro-Chemical Industries and classifies unbalance levels as a function of rotor mass and operating speed [1]. ISO 1940 is famous for its classification of vibration in terms of G codes although many people don’t know what they mean it is easy to figure out that G2.5 is a tighter tolerance than G6.3. Notice the choice of words here, tighter not necessarily better. G2.5 means a vibration velocity of 12

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 2.5 mm/s under specified conditions. Unfortunately, it is the theoretical value assuming the rotor was spinning in free space, so it does not relate to actual operating conditions. ISO 1940 uses a set of criteria to classify the acceptable vibration grade – a low speed marine diesel has a coarse grade while a high-speed grinding spindle has a very tight grade. The tightest grades require balancing a rotor in its own bearings and under service conditions. 2. METHODOLOGY In this study, flywheels of the construction equipment engine had balance control with 3 type of fixture and 2 different reference diameters. First type of fixture, Mechanical fixture which is clamping the flywheel from reference diameter and torque wrench use for the clamp part from the top. Reference diameter and the fixture clamping diameter had some gap around 0,02 mm. The mechanical fixture as shows on Figure 3. Flywheel assemble to mechanical fixture as shows on Figure 4. Figure 3 — Mechanical fixture Figure 4 — Flywheel assemble to mechanical fixture Second type of fixture, 2 jaw, 3 jaw and 4 jaw chucks all work on the same principle. The body of the chuck positions and guides the movement of the jaws as they are brought together or separated. In this study, 3 jaw chuck have been used. 3 jaw chucks are the most common type of chuck on hand drills. They are designed to hold round and hexagonal shank drill bits securely in place. 3 jaw chuck as shows on Figure 5. 13

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Figure 5 — 3 jaw chuck Third type of fixture, A clamping system that uses high-pressure liquids to power clamps and hold a work part in place. Hydraulically clamped fixtures have many advantages over manually clamped fixtures. In most cases, these benefits reduce costs for manufacturers allowing them to justify the initial investment for a hydraulic clamping system. Hydraulic clamping enables manufacturers to put more intelligence into the fixture eliminating human error and producing a more stable, predictable processes no matter who the operator is or what production shift your machine runs. Figure 6. as shows hydraulic fixture of used in this study. Figure 6 — Hydraulic fixture Reference diamaters and fixture match up as shows on Table 2. 14

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Table 2 — Reference diameters and fixtures Chuck Reference Diameter Hydraulic Fixture Mechanical Fixture x x Ø72 x x Ø31,75 x 2.1 Balance Machine Technical Details The balancing machine used in the study shows on Figure 7. and technical details of the automatic vertical balancing machine are shown in Table 3. Table 3 — Technical details of the automatic vertical balancing machine AUTOMATIC VERTICAL BALANCING MACHINE CAPACITY MAXIMUM 100 KG ROTOR TYPES CLUTCHES BRAKE DRUMS BRAKE DISCS PULLEYS FLYWHEELS BALANCING PROCESS MANUAL LOADING & UNLOADING AUTOMATIC CLAMPING AUTOMATIC UNBALANCE MEASUREMENT AUTOMATIC UNBALANCE CORRECTION OPTIONS AUTOMATIC LOADING & UNLOADING AUTOMATIC DRILLING / MILLING UNIT AUTOMATIC WELDING UNIT ENTRANCE / EXIT CONVEYOR SYSTEM AUTOMATIC Figure 7 — Automatic vertical balancing machine 15

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 2.2 Setup and Test Parameters 2.2.1 Setup 1. First, carefully mount the navel shafft of the hydraulic fixture into the balancing machine. Figure 8 —First Setup of Mounting of Navel Shaft of Hydraulic Fixture 2. Mount the fixture to the balancing machine by thigtening all screws. Figure 9 — First setup of Mounting of Fixture 3. Reset the secretion of the fixture using the dial gauge. 16

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Figure 10 — First Setup of Resetting the Fixture 4. Mount the hydraulic clamp on the fixture. Figure 11— First Setup of Mount of Hydraulic Clamp to Fixture 5. Select calibration from the balance machine screen and start processing. 17

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Figure 12— First Step of Calibration 6. Use 15 g of witness part for calibration. Figure 13— First Step of Calibration 7. Select the zero compensation option from the balance machine screen and start the process. 18

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Figure 14— First Setup of Calibration 8. Assemble 15 gr of the sample again and start the process. If you find the result of 15 gr you have done the calibration correctly. 19

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Figure 15— First Setup of Calibration 9. After mounting the master sample on the balancing machine, start the measurement and find value close to the result. Figure 16— First Setup of Master Sample Measurement 10. Use the pin to rotate the part 90 degrees and start the compensation process at every 90 degrees. 20

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Figure 17— Compenzation for Each PN 11. After mounting the part on the balancing machine, start the measurement and find the result. 21

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Figure 18— Balance Measurement for Each PN 12. After measurement, rotate the part in the direction of balancing and start drilling. Figure 19— Balancing Operation for Each PN 13. After the balancing operation, measure the part again and find the result. If the result is green part is correct, if result is red turn back the balancing operation again. 22

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Figure 20— After Balancing Operation Measurement for Each PN 2.2.2 Test Parameters 1. 4 different operators were measured the same part 3 times. Measurements were made using 10 Newton / meter, torque meter and reference pin in the chuck. The reference diameter of fixture is 72 mm. The results as shown in Table 4. (Automatic Machine) Table 4 — Chuck Results Chuck Results(10N) Diameter 72 Operator Operator Operator Operator Trial 1 2 3 4 1 8507 8448 8461 8449 2 8470 8454 8515 8444 3 8428 8453 8507 8506 Difference 79 6 54 62 2. 2 different operators were measured the same part 5 times. Measurements were made using 11 Newton/meter, torque meter and reference pin in the chuck. The refence diameter of fixture is 72 mm. The results as shown in table 5. (Automatic Machine) Table 5 — Chuck Results Chuck Results (11N) Diameter 72 Operator Operator Trial 1 2 23

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 1 8526 8484 2 8470 8514 3 8468 8414 4 8484 8404 5 8467 8420 Difference 110 59 3. 2 different operators were measured the same part 5 times. Measurements were made using 11 Newton/meter, torque meter and reference pin in the chuck. The refence diameter of fixture is 31.75 mm. The results as shown in table 6. (Automatic Machine) Table 6 — Chuck Results Chuck Results (11N) Diameter 31,75 Trial Operator 1 Operator 2 1 8480 8465 2 8480 8461 3 8474 8455 4 8464 8419 5 8479 8471 Difference 16 52 4. 2 different operators were measured the same part 5 times. Measurements were made using the reference pin in the mechanical fixture (Ø71.985). The refence diameter of fixture is 72 mm. The results as shown in table 7. (Manual Machine) Table 7 — Mechanical Fixture Results Mechanical Fixture Results Trial Operator 1 Operator 3 1 8808 8838 2 8772 8888 3 8804 8905 4 8767 8989 24

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 5 8754 8853 Difference 54 151 5. The same part was measured 10 times using the reference pin and hydraulic fixture. The reference diameter of fixture is 72 mm. The results as shown in table 8. (Automatic Machine) Table 8 — Hydraulic Fixture Results Hydraulic Fixture Results Trial Operator 1 1 9097 2 9095 3 9087 4 9107 5 9104 6 9100 7 9090 8 9104 9 9106 10 9099 Difference 20 6. The same part was measured 5 times using the reference pin and hydraulic fixture. Before each measurement the part is rotated by 90 ° and bridged. The reference diameter of fixture is 72 mm. The results as shown in table 9. (Automatic Machine) Table 9 — Hydraulic Fixture Results (Compensation part by part) Hydraulic Fixture Results (compensation part by part) Trial Operator 1 1 9097 2 8929 3 8726 4 8820 25

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 5 8810 Difference 371 7. The same part was measured 10 times using the 11 N / m torque wrench and the reference pin in the lathe chuck. Before each measurement the part is rotated by 90 ° and bridged. The reference diameter of fixture is 72 mm. The results as shown in table 10. (Automatic Machine) Table 10— Chuck Results (Compensation part by part) Chuck Results (compansation part by part) Trial Operator 1 1 8613 2 8378 3 8374 4 8403 5 8210 6 8443 7 8058 8 8306 9 8232 10 8253 Difference 555 3. CONCLUSION • The least change was seen in the hydraulic fixture. However, no major balancing changes were found in the same bridging in other fixtures. • Mechanical, hydraulic, mirror-type fixtures, the same machine in the experiment 300-500 gr.mm change was observed inside the same part. • The same type of fixture and two different types of balancing machine between 200-300 gr.mm difference was seen. • On the same machine, even in different setting types made by bridging and compensation method, a difference of 300-400 gr.mm was observed. • MessMatic company's own reference machine, even in the trial of 700 gr.mm difference was seen. 26

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 • Although all external factors were eliminated, different results were observed. (Fixture gap, operator differences, clamping force, adjustment differences, difference of attachment point, machine differences, fixture differences) REFERENCES [1] Derek Norfield, (2006) “Practical Balancing of Rotating Machinery” Elsevier Science; (May 4, 2006) [2] Adegbuyi P. A. O., Lukuman O., (2017) “Design and Construction of an Improved Balancing Machine”, International Journal of Science, Technology and Society, Lagos (Nigeria). 27

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 4th International Mediterranean Science and Engineering Congress (IMSEC 2019) April 25-27, 2019 Alanya Lonicera Resort & Spa Hotel Antalya/Turkey Analysis for Lifetime with Alternative Material and Heat Treatment Effect for Utility Car Wheel Hubs Tuğrul Soyusinmez1, Onurcan Onur2, Oğuzcan Güzelipek3, Yusuf Yıldız4, Gökçe Akkuş5 1 Totomak AŞ., Turkey; [email protected] 2 Totomak AŞ., Turkey; [email protected] 3 Totomak AŞ., Turkey; [email protected] 4 Totomak AŞ., Turkey; [email protected] 5 Totomak AŞ., Turkey; [email protected] Abstract This paper deals with various casting alternatives combination with heat treatment effect on the life time for wheel hubs. Wheel hub and upright assembly is a very critical part of the vehicle suspension system which allows the steering arm to turn the front wheels and support the vertical weight of the vehicle. Tested parts material will be material 100-70-03 ductile iron per ASTM A536 with quench and temper heat treated to 235 – 285 and second will be material 130-90-09 ductile iron per ASTM A897 grade 1 hardness to be 269-341 hbw with austempered heat treatment. That 2 different alternative combination had checked and compare with current type of production systems. Keywords: Wheel hub, Austempered, Heat Treatment, Utility Car 1. INTRODUCTION To improve the transport abilities of utility cars, the speed and the hauling capacity are the quantities that must be increased. Increasing the axle load is an important step in the development of transportation that increases life time and reduces the maintenance costs. As the key components of the utility cars is wheels hub are related to the safety of rail transportation. [1,2,3]. Assembly of the Wheel Hub 28

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 The purpose of the wheel hub is to serve as the glue between the tire and the axle. Tires are attached with studs to the hub assembly. The hub assembly then fits on the axle, which connects the tire component to the rest of the car. Because the wheel hub is the bridge between the tire and the entire vehicle, if one of its parts breaks down, it creates a ripple effect. That could include problems such as impaired steering or a broken axle. The general material in use for the wheel hubs is GGG-45, in that article alternative materials and heat treatment methods effect are investigated. 2. METHODOLOGY In this paper below materials and heat treatments are used for the sample wheel hubs production, First sample is belonging to 100-70-03 ductile iron per ASTM A536 with quench and temper heat treated. Chemical composition and heat treatment graphic are like below. With a minimal tensile strength of 100 psi and a minimal yield strength of 70,000 psi, our V-5 ductile iron stock is well- suited for the production of automotive parts, machinery, pump and compressor components, equipment for steel mills, and other heavy-duty industrial applications. 100-70-03 Ductile Iron Chemical Composition Carbon Silicon Manganese Sulfur Phosphorus 3.5- 2.25- 0.15-0.35% 0.025% 0.05% max 3.9% 3.0% max Material Properties Tensile strength 100,000 psi Yield strength 70,000 psi Elongation, % 3% Brinell hardness average 279 Machinability (1212=100%) 75% Heat treatment response 55-60 (Rc) An austenitizing temperature of 845 to 925°C (1550 to 1700°F) is normally used for austenitizing commercial castings prior to quenching and tempering. Oil is preferred as a quenching medium to minimize stresses and quench cracking, but water or brine may be used for simple shapes. Complicated castings may have to be oil quenched at 80 to 100°C (180 to 210°F) to avoid cracks. The influence of the austenitizing temperature on the hardness of water-quenched cubes of ductile iron shows that the highest range of hardness (55 to 57 HRC) was obtained with austenitizing temperatures between 845 and 870°C (1550 and 1600°F). At temperatures above 870°C, the higher matrix carbon content resulted in a greater percentage of retained austenite and therefore a lower hardness. 29

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Castings should be tempered immediately after quenching to relieve quenching stresses. Tempered hardness depends on as-quenched hardness level, alloy content, and tempering temperature, as well as time. Tempering in the range from 425 to 600°C (800 to 1100°F) results in a decrease in hardness, the magnitude of which depends upon alloy content, initial hardness, and time. Vickers hardness of quenched ductile iron alloys change with tempering temperature and time. Tempering ductile iron is a two-stage process. The first involves the precipitation of carbides similar to the process in steels. The second stage (usually shown by the drop in hardness at longer times) involves nucleation and the growth of small, secondary graphite nodules at the expense of the carbides. The drop in hardness accompanying secondary graphitization produces a corresponding reduction in tensile and fatigue strength as well. Because alloy content affects the rate of secondary graphitization, each alloy will have a unique range of useful tempering temperatures. No tempering after quenching and tempering Other sample is belonging to 130-90-09 ductile iron per ASTM A897 grade with austempered heat treatment. C Mn Si Cr Ni Cu Mo Mg Min% 3.4 2.35 0.025 Max% 3.8 0.3 2.75 0.08 0.055 UTS Physical and Mechanical Properties TS %Elongation 130000 Hardness 90000 9% 269-341 30

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Density lb/in3 (g/cm3) 0.256(7.1) 150 Thermal Conductivity Btu/hr·ft·F (W/m·K) Specific Heat at 70F Btu/lb·F (J/Kg·k) 0.110(461) Coefficient of Thermal Expansion 8.1 Ɛ/F(Ɛ/C)X106 Melting Temperature (F) 2100 F Compressive Strength Ksi (MPa) 200 Austempered Ductile Iron (ADI) offers low cost, design flexibility, good machinability, high strength-to-weight ratio and good toughness, wear resistance and fatigue strength because it can be cast like any other member of the Ductile Iron family, thus offering all the production advantages of a conventional Ductile Iron casting. Subsequently it is subjected to the austempering process to produce mechanical properties that are superior to conventional ductile iron, cast and forged aluminum and many cast and forged steels. Austempered ductile iron (ADI) is finding an ever-increasing worldwide market in the automotive and other sectors. It offers a range of mechanical properties superior to those of other cast irons and shows excellent economic competitiveness with steels and aluminum alloys. ADI is a heat treated form of as-cast ductile iron. The heat treat process, austempering, was developed with the intent of improving on the strength and toughness of ferrous alloys. Ductile iron, with its relative low cost and ease to manufacture, has been one of the largest beneficiaries of the austempering process. As a result, ADI has burst onto the scene in recent years with a host of creative and innovative casting solutions. The term \"cast iron\" designates an entire family of metals with a wide variety of properties. Cast iron contains more than 2% carbon, present as a distinct graphite phase. In ductile cast iron the graphite occurs as spheroids or spherulites rather than as individual flakes as in gray iron. Ductile iron exhibits a linear stress-strain relation, a considerable range of yield strengths, and, as its name implies, ductility. \"Austempering\" is a high-performance heat treatment for ferrous alloys which produces an engineered, tailorable matrix structure. This austempered matrix structure gives tensile strength, toughness, impact strength and fatigue properties that are comparable to heat-treated steels. 2.1 Test Device and Methods Due to control of the hubs below test device had created for the control of the hubs, 31

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Right side of the device utility car wheel hubs can be assembled, and device have modifiable rpm, force values to control parts in different conditions. The samples had been painted, finish machined and came with pressed in serrated studs. After the studs were removed, the pieces were inspected. Machined outer and inner surfaces were free from surface porosity. Cast surfaces were also free from porosity, inclusions, burned in sand and other casting defects. Cast identification markings on these pieces included: Sample 1 \"6L8 1039793 BDS 9\" Sample 2 \"6L8 1039793 BDS 19\" Sample 3 \"6L8 1039793 BDS 15\" 2.2 Examination of the Parts for Microstructure and Surface Hardness 32

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Figure 1. Surface appearance of the samples after the studs had been removed Just sample 1 which is indicate to 100-70-03 ductile iron per ASTM A536 with quench and temper heat treated and sample 3 is indicate to 130-90-09 ductile iron per ASTM A897 grade with austempered heat treatment are examined. Figure 2. Sample 1 – showing the four section planes used for determination of internal soundness 33

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Figure 3. Sample 3 – showing the four section planes used for determination of internal soundness Figure 4. Sample 1, Plane A – the saw cut surface exhibited no internal porosity or other casting defects 34

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Figure 5. Sample 1, Plane B – the saw cut surface exhibited no internal porosity or other casting defects Figure 6. Sample 1, Plane C – the saw cut surface exhibited no internal porosity or other casting defects Figure 7. Sample 1, Plane D – the saw cut surface exhibited no internal porosity or other casting defects 35

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 a) As Polished, 90X b) As Polished, 90X Figure 8. Sample 1 – surface and core graphite microstructure consisted predominantly of Types I and II – minor levels of deformed graphite were found at the surface a) As Polished, 90X 36

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 b) As Polished, 90X Figure 9. Sample 3 – surface and core graphite microstructure consisted predominantly of Types I and II – minor levels of deformed graphite were found at the surface a) Nital Etchant, 90X 37

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 b) Nital Etchant, 90X Figure 10. Sample 1 – the core microstructure consisted of highly tempered low carbon martensite – the surface exhibits decarburization due to heat treatment in an oxidizing atmosphere a) Nital Etchant, 500X b) Nital Etchant, 500X Figure 11. Sample 1 – same as Figure 10 only a higher magnification image showing the spheroidized carbide particles in the matrix, which signify tempering at high temperature after hardening 38

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 a) Nital Etchant, 90X b) Nital Etchant, 90X Figure 12. Sample 3 – the core microstructure consisted of tempered medium carbon martensite – the surface exhibits decarburization due to heat treatment in an oxidizing atmosphere 39

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 a) Nital Etchant, 500X b) Nital Etchant, 500X Figure 13. Sample 3 – same as Figure 12 only a higher magnification image of the tempered medium carbon martensite – this structure is consistent with the requirements for 100-70-03 iron 2.3 Test Data’s and Figures On the test machine below rpm and pressure test had been applied, Table 1 Test Parameters Models RPM Brake Pressure m/min bar Sample 1 (Test 1) 955 45 Sample 3 (Test 1) 955 45 Sample 1 (Test 2) 550 35 Sample 3 (Test 2) 550 35 40

Sample 1 (Test 3) TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Sample 3 (Test 3) 350 30 350 30 Table 2 Test Results based with Wearing and Flatness Models RPM Brake Pressure Wearing Flatness m/min bar gr micron Sample 1 (Test 1) 955 45 0,055 0,012 Sample 3 (Test 1) 955 45 0,047 0,008 Sample 1 (Test 2) 550 35 0,048 0,01 Sample 3 (Test 2) 550 35 0,034 0,06 Sample 1 (Test 3) 350 30 0,038 0,078 Sample 3 (Test 3) 350 30 0,029 0,032 Figure 2: Peel stress distribution through the bond-line length (1) 3. CONCLUSION • Sample 3 was heat treated to a surface hardness of 271 and 277 HBW, which is within the expected range of 235 to 285 HBW. • Sample 1 was 198 and 198 HBW, while Sample 2 was 192 and 189 HBW. The hardness of these samples corresponds with both the 65-45-12 and 80-55-06 grades of ductile iron. This hardness is too low for 100-70-03. 41

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 Magnetic Particle Inspection per ASTM E709 Wet fluorescent particle inspection revealed no indications of near surface cracks or other casting defects. Examination of Internal Soundness Samples 1 and 3 (Figures 2 and 3) were sectioned into four pieces along two planes for the examination of internal soundness. Saw cut surfaces of sample 1 (Figures 4 to 7) revealed no internal porosity or other casting flaws. Overall soundness is considered equivalent to Radiographic Level 1 or better. Similarly, cut surfaces in sample 3 showed no porosity or other casting flaws. Hardness per ASTM E10 Surface hardness of the hubs was measured using the Brinell test method, employing a 10 mm diameter carbide ball and a 3000 kg-F test load. All parts were tested on the machined flats adjacent to the bolt holes. Results (Table I) showed that only Sample 3 at 271 and 277 HBW complied with the specified range of 235 to 285 HBW. Sample 1 was 198 and 198 HBW, Sample 2 was 189 and 192 HBW. This lower hardness matches both 65-45-12, at 156 to 217 HBW and 80-55-06 ductile iron at 187 to 255 HBW. Metallographic Examination per ASTM Methods Samples 1 and 3 were analyzed to determine the reason for the hardness differential. • Graphite microstructures (Figures 8 and 9) consisted primarily of Type I and II, Size 6 nodules, with Size 5 nodules from flotation on the cope side surface. Overall nodularity was visually estimated to be 95 percent minimum. Cast surfaces exhibited only a few scattered malformed shapes. The graphite in these samples is considered essentially identical. Overall quality of the graphite microstructure is good. • Matrix microstructure of Sample 1 (Figures 10 and 11) consisted of highly tempered low carbon martensite. This is a low hardness microstructure and is inconsistent with what is required to achieve 100-70-03 strength levels. • Matrix microstructure of Sample 3 (Figures 12 and 13) consisted of tempered medium carbon martensite. This microstructure is consistent with expectations for 100-70-03 ductile iron. • Surface decarburization in both samples reveal they were heat treated in a furnace that did not provide a neutral atmosphere. A summary of the microstructural findings is listed for reference purposes (Table II). REFERENCES [3] Özcanli M. and Serin H., (2011) \"Evaluation Of Soybean/Canola/Palm Biodiesel Mixture As An Alternative Diesel Fuel\", Journal of Scientific & Industrıal Research, vol.70, pp.466-470 42

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 [4] Gefen A. Consequences of imbalanced joint-muscle loading of the femur and tibia: from bone cracking to bone loss. In: Leder RS, editor. 25th Annual International Conference of the IEEE: Engineering in Medicine and Biology Society. Proceedings; 2003 Sep 17- 21; Cancun (Mexico): IEEE; 2003; p. 1827-1830. [5] Mow, V. C., Gu, W. Y. and Chen, F. H. (2005). Structure and Function of Articular Cartilage and Meniscus. In: Mow, V. C. & Huiskes, R. (eds.) Basic Orthopaedic Biomechanics & Mechano-Biology. 3rd ed. Philadelphia, USA: Lippincott Williams & Wilkins.Web-1: http://www.cjche.ca/submissioninstructions.htm, consulted 5 July 2009. 43

TOTOMAK AR-GE MERKEZİ YAYIN ÇALIŞMALARI 2020 ESKİŞEHİR TECHNICAL UNIVERSITY JOURNAL OF SCIENCE AND TECHNOLOGY A- APPLIED SCIENCES AND ENGINEERING 2020, 21(1), pp. 223 - 237, DOI: 10.18038/estubtda.648100 EFFECTS OF DIFFERENT CRYOGENIC TREATMENTS ON DRILLING PERFORMANCE OF HSS DRILLS Simge AVCI 1, *, Tugrul SOYUSİNMEZ 2, Onur ERTUĞRUL 1 1 Department of Materials Science and Engineering, İzmir Katip Çelebi University, İzmir 35620, Turkey 2 Totomak Makina ve Yedek Parça Sanayi ve Ticaret A.Ş., Ataşehir, 10002. Sk. No:4, 35620 Aosb / Çiğli / İzmir ABSTRACT Cryogenic treatment has been widely used in recent years to improve the properties of cutting tool materials. This process has been reported in the literature as it provides significant contributions to wear resistance and tool life of tool steels. This study presents the differences in tool performance between untreated and cryogenically treated M2 high speed steel (HSS) drill bits in terms of their tool wear, tool life, hardness and chip formation properties. Also, the effects of two different tempering temperatures (200 oC and 250 oC) in cryogenic treatment on tool performance are discussed. Drilling performances were studied on different workpieces of SAE 1050, lamellar cast iron and sphero cast iron, and the type of wear is characterized by a high resolution camera. Moreover, fracture tests were performed on a steel workpiece using a constant drilling speed of 1100 m/min and a feed rate of 0.5mm/rev. The microstructures of the samples were characterized using optical microscopy and SEM. The Vickers microhardness tests of the samples were performed using 100 g load. Microstructural studies showed that cryogenically treated samples exhibit better microstructure with finer and more homogeneous carbides which yields better tool wear and hardness properties. In paralel, cryogenically treated drills showed improved tool life than untreated drills during fracture tests. When tempering temperatures are compared, tempering at 250 °C resulted in better performance than 200 °C of tempering temperature. Also, the reduction in diameter values during drilling tests were consistent with the tool life tests. Keywords: Cryogenic treatment, Tempering temperature, M2 high-speed steel, Tool wear, Tool life 1. INTRODUCTION 1.1. High Speed Steels (HSS) High-speed steels (HSS) are high-carbon, high alloyed, and very hard steels in the tool steel family. They have a red hardness (hot hardness). They have high wear resistance and toughness thanks to their high alloying elements. These steels can be used for machining when high speeds are demanded. Therefore, they are mostly used as high-speed rotating component cutters and processors [1]. The main feature of high-speed steels, which are generally hardened and tempered, is the use of hard carbides such as chrome, molybdenum, vanadium and tungsten in the hot hardening matrix providing wear resistance [2]. AISI M2 steel is molybdenum based high speed steel in tungsten-molybdenum series. HSS M2 is a medium alloy HSS with good machining. HSS M2’s chemical composition provides a well balanced combination. M2 steels have good abrasion resistance, red hardness properties, and toughness. Thus, they have wide application areas such as twist drills, taps, end mills, saws, sharp objects such as knives [3]. 1.2. Wear On Tool Cutting tools fail due to following three cases, a. Fracture of tool because of ultra shock and force, b. Tool wears through plastic deformation or change in chemical of physical status of tool, and c. Gradual wear like flank wear, crater wear and others [4]. The type of wear on the side surface of the tool is called flank wear. It is the most major wear that seems on the flank surface parallel to the cutting edge. Abrasive/adhesive wear of the cutting edge most usually results from against the machined surface. It *Corresponding Author: [email protected] Received: 18.11.2019 Published: 31.03.2020 44

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 occurs due to reaching high temperatures between tool and work material. It consequences in the formation of wear layer. Wear layer formation is not always uniform along the major and minor cutting edge of the tool. Flank wear occurs by abrasion in the parts of built-up edge, that hit against the flank face of the tool [5]. Crater wear is caused by a chemical interplay between the rake face of a metalcutting insert and the hot metal chips flowing over the tool. The crater wear is mainly on account of diffusion and abrasion. They are frequently observed where the continuous chip is formed usually in the ductile material [6]. 1.3. Traditional Heat Treatment Of M2 Heat treatments are carried out in order to heat the material to the appropriate temperature and to keep it at certain temperatures and to improve the internal structure and properties by cooling it in various environments. [7]. Prior to forming and curing, all high-speed steels are softened by annealing for about 2-4 hours at 760-850 °C according to their composition, then cooled very slowly to 600 °C in the oven. They are cooled to the ambient temperature. The annealed structure consists of carbide beads dispersed in the perlite matrix [8]. Since stable carbides in the structure of high-speed steel have to be dissolved sufficiently before giving water, the quenching temperature is selected as 1200-1320 °C just below the solidus line. Rapid heating of the steel to a high temperature of 1200 °C causes distortions and cracking due to the low heat conduction coefficient. In addition, grain hardening and oxidation in the high hardening occurs. Also, grain growth and oxidation occurs at high hardening temperatures. For this reason, the steel is heated to this high temperature very slowly or gradually and mostly in a controlled salt bath [9]. With the rapid cooling of the steel in the cooling medium, the carbon is squeezed into the austenite phase, a rigid and stressed volume centered tetragonal structure is formed, called martensite. The martensite completion temperature falls below room temperature. Therefore, while austenitizing temperature is given to the steel, austenite is found in the structure without turning into martensite. This is called residual austenite. While the martensite in the structure is hardness and it is a structure which is stressed in the same way, it gives a fragility and due to the low hardness of the austenite, an unbalance in terms of hardness is observed. [10]. Another way to convert residual austenite to martesite in a structure other than tempering is to immerse high-speed steel cooled to room temperature in liquid nitrogen (-196 °C) by a process known as cryogenic processing [11]. Cryogenic treatment is an efficient method that improves the tool life-time and wear resistance of cutting tools. Cryogenic treatment enhances the wear resistance, toughness, hardness, tool life-time of not only steel based (HSS) but also carbide based cutting tools [12]. Significant parameters in cryogenic treatment that impress tool performance are cutting tool style, soaking period, soaking temperature, cooling speed and tempering process. The cryogenic process involves the steps of cooling the material at room temperature to -273 °C following the quenching process, keeping the medium in this environment until the structural change occurs throughout the material and then allowing it to warm to room temperature. [13-15]. 1.4. Literature Overview There are studies about cryogenic treatment in the literature. For example; In 2012, Adem Çiçek and his team investigated the effects of deep cryogenic processing (-196 ºC) on M35 HSS drills on tool life, tool wear, microstructure and microhardness. Three different cutting speeds (20, 25 and 30 m / min) were performed with constant progress (0.1 mm / rev) parameters. The cryogenic process was carried out in the vacuum furnace with protective atmosphere by the help of nitrogen in the gas phase. The cutting tools were gradually cooled from room temperature to -196ºC with a cooling rate of about 1.5 ºC/min and then stored at this temperature for 24 hours and then returned to room temperature with a heating rate of 1.5 ºC / min. Later on cryogenic treatment, the tempering process was carried out at 200 ºC for 2 hours. As a criterion for tool life tests, Nordtest NT Meche 038 standard is based on catastrophic failure recommended for HSS drills [16]. Another study was designed to evaluate the effects of different holding times of deep cryogenic treatment on tool wear in turning of AISI 316 austenitic stainless steel. 224 45

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 The cemented carbide inserts were cryogenically treated at (-145 ºC) for 12, 24, 36, 48 and 60 h. Wear tests were conducted at four cutting speeds (100, 120, 140 and 160 m/min), a feed rate of 0.3 mm/rev and a 2.4 mm depth of cut under drycutting conditions. The wear test results showed that flank wear and crater wear were present in all combinations of the cutting parameters. However, notch wear appeared only at lower cutting speeds (100 and 120 m/min). In general, the best wear resistance was obtained with cutting inserts cryogenically treated for 24 h. This case was attributed to the increased hardness and improved microstructure of cemented carbide inserts [17]. This study aims to observe the effects of cryogenic treatment in comparison to conventional heat treatment. The purpose was is to obtain maximum benefit from cryogenic processing in cutting tools and to find appropriate temperature in cryogenic process parameters and to increase tool wear resistance and tool life-time owing to progress in mechanical features. 2. MATERIALS AND METHODS 2.1. Cryogenic Treatment Chemical composition of the used M2 HSS drills are presented in Table 1. After heat treatment, the remaining austenite phase was converted to martensite by cryogenic treatment and hard carbide structures were formed [18]. To increase the hardness and wear resistance of the steel, the drills were kept at -196ºC for 24 hours, and with a cooling rate of 1ºC / min. Three drill groups were used as untreated drills (UT) with no additional treatment and cryogenic treatment with a 2h tempering at 200 ºC treated drills (CTT1) and 2h temper at 250 ºC treated drills (CTT2). The three group drill is shown in Figure 1. Table 1. Chemical composition of the used M2 drills (wt.%). Element Content % C 0.87 W 6 Mo 4.9 Cr 4 V 1.9 Si 0.4 Mn 0.2 Ni 0.2 Figure 1. Three different group of drills 225 46

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 2.2. Metallography and Hardness Studies The cutted samples were molded using bakelite. The molded samples were grinded with 150D, 500D, 800D, 1000D, 1200D and 2000D sandpaper respectively. The roughness of the sample surface was removed and made ready for polishing. At the polishing stage, the surface was polished and prepared for etching using 3 micron, 1 micron and 0.25 micron Diamond solution and lubricant. The etching step was carried out using a nital solution containing 0.2 nitric acid. The microstructure images were taken by optical microscope. SEM analysis of CTT1 and CTT2 drill bits were performed. Vickers micro- hardness tests were performed using 100 g load from the polished samples using six indentations, and the mean values and standart deviations have been calculated. The microhardness measuring instrument is shown in Figure 2. Figure 2. Microhardness measuring instrument 2.3 Drilling Processes and Tests Drilling experiments were performed on CNC drilling machine. Blind holes were drilled in normalized 1050 steel blocks, sphero and lamellar cast iron blocks. Hole dept was keept constant at 15mm, feed rate and cutting speed shown in the Table 2. Table 2: Drilling process parameters. Workpiece Cutting speed Feed rate Lamellar 900 m/min 0.084 mm/rev Sphero 900 m/min 0.07 mm/rev 1050Steel 840 m/min 0.05 mm/rev On steel, sphero and lamellar workpieces, untreated HSS, CTT1 and CTT2 drills were used to perform blind hole drilling with 10,20 and 30 specified parameters. After every 10 drilling operations, the type of wear is characterized by a high resolution camera. The appearance of wear on high resolution camera is shown in Figure 3. 226 47

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 3. High resolution camera image showing wear scars of “UT” drill bit 2.4. Fracture Studies For the drillings of the three groups used in the steel drilling tests, the fracture test was performed on the steel workpiece with a constant cutting speed of 1100 m / min and the constant progress 0.5mm / rev parameters. It is also used for microstructure and hardness inspection of drills used in fracture test. The steel workpiece with fracture testing and chip formation during drilling operations are shown in Figure 4 and Figure 5. Figure 4. Steel workpiece used for fracture testing Figure 5. Chip formation during drilling operations 227 48

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 3. RESULTS AND DISCUSSION 3.1. Metallographic Study As seen in Figures 6 and 7, the microstructure images of the UT drill bit have different sizes of white carbide particles in the microstructure. These particles were cryogenic and tempered, and then turned into a fragmented, smaller size and homogeneous structure. In addition, the residue has evolved into austenite, martenzite. The primary cause for developing fine carbide precipitation is supersaturation of martensite with decreasing temperature resulting to lattice distortion and thermodynamically uncertainty of martensite; for this reason, both carbon and alloying elements transmigrate to the nearby defects and set apart there which results in the formation of fine carbides on the after heating up or tempering [19]. The tempering after cryogenic treatment not only remove the thermal stresses of the treatment, but also provides finer carbide precipitation and improves the homogenity of carbide precipitation especially for tempering at 250°C (shown with arrows). This resultant microstructure is similar with the microstructures in previous studies [20-22] as the resultant precipitation of fine carbide particles and homogeneous structure of carbides improves mechanical properties such as hardness, toughness, dimensional stability, fatigue resistance, residual stress as well as tribological properties such as coefficient of friction and wear resistance which means tempering after cryogenic treatment is useful. (a) (b) (c) Figure 6. a) UT-500X, b) CTT1-500X, c) CTT2-500X (a) (b) (c) Figure 7. a) UT-1000X, b) CTT1-1000X, c) CTT2-1000X The SEM images are shown in Figure 8. It was observed that the particles were homogeneously distributed according to SEM images. Also the dimensions of carbide grains have improved in the way of homogenization. It can be understand that the grains have a homogeneous distribution, which affects the hardness and toughness positively. In addition, it is understood from the backscattered electron images that the atomic number of the elements in the light gray and bright regions were found to be higher than the elements in the main phase. Also, it was observed that light regions interacted with carbon and formed carbides according to elemental quantity. Cicek et al. [21] has claimed that by CTT2 the better wear resistance can be obtained as per most of the researchers there are only two main reason which increase the wear properties and hardness of the material which are the the phase transformation which takes place during cryogenic i.e from austenite to martensite, and the second is the precipitation of carbides in the matrix finer the carbide particles led to less wear of the drill. 228 49