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Abstract

In this study, tool wear and chip formation during the drilling process of AISI 1045 material using plasma-nitrided high-speed steel drill bits were experimentally investigated. Two uncoated and plasma-nitrided drill types were used in the experiments. First, commercial drill bits were subjected to the plasma nitriding process. Following this, the drilling processes were carried out at various feed rates and cutting speeds. A sensitive computer numerical control machine was used in the experiments. Tool wear was determined using scanning electron microscopy and chips obtained from the drilling process were observed under microscopy. Finally, the relationship between the chip cross section and tool wear was determined using statistical analysis. It was concluded that the mechanical properties of uncoated high-speed steel drill bits improve significantly through the plasma nitriding process. Less tool wear and a good chip formation were observed with the improvement of the mechanical properties. It was determined that there is a relationship between the chip section and wear.

Keywords

Drill bits plasma nitrided tool wear chip formation drill processing

Introduction

Drill bits have been used in the manufacturing industry due to geometrical, dimensional, and various other properties. Drilling performance, economical, and surface qualities are very important to the drill bits. Many important parameters such as drill bit material, coating, drilling conditions, workpieces, and drilling parameters determine the drilling performance. Coating is a very important parameter and has a significant effect on the tribological behaviors of the drill bits.^1–6

There are a limited number of studies concerning the drilling performance of drill bits in the literature. However, in recent years, the performance of drill bits coated with different coating types has been studied by various researchers. In one of these studies, Dasch et al.⁷ investigated the tool performance of aluminum-carbon-based coated tool in the dry drilling process. In the study, a better cutting performance was obtained from coated drills than uncoated drills. In a different study, Nouari et al.⁸ examined the effect of coating and drilling parameters in the drilling process of aluminum alloy material. At the highest cutting speeds, a better drilling performance was obtained from the drill bits coated with TiAlN+WC/C.

Zitoune et al.⁹ experimentally studied the cutting performance of coated and uncoated drill bits in the drilling process of aluminum composite materials. The cutting force and surface roughness of the coated drill bits were lower than those of the uncoated drill bits. Elhachimi et al.¹⁰ developed a mechanical model for the drilling process carried out at high cutting speeds. Force and drilling torque were estimated with this model. Analytical studies have shown that drilling parameters play an important role in the estimation of force and torque. Barshilia and Rajam¹¹ investigated the drilling performance of coated high-speed steel (HSS) drill bits. Type 304 stainless steel was used in the study, and the drilling process was carried out in coolant. The tool performance significantly increased in the drilling process carried out with TiN-coated HSS drill bits. Park et al.¹² investigated tool wear in the drilling of composite materials using carbide and polycrystalline diamond (PCD) tools. Using tungsten carbide (WC) versus PCD drill bits, drilling forces significantly increased with an increase in the number of holes in the drilling process. Bai et al.¹³ investigated the thermal stability in the dry drilling process using CrTiAlN-coated drill bits. Due to the CrTiAlN coating, the life span of the drill bits significantly increased in the dry drilling process. Audy¹⁴ conducted a computer-aided analysis regarding the effect of drilling geometry and coating surface on the power consumption and cutting forces in drilling operations. As a result, it was observed that cutting forces, power consumption, and torque play an important role in the determination of different model drilling geometries and coating surfaces. Wang et al.¹⁵ investigated the wear behavior and chip formation in drilling processes using a TiAlN-coated gun drill. In the study, an adhesive wear type was observed, and in addition, chip morphology that affected the state of wear. Kalidas et al.¹⁶ investigated the effect of the coating process on the hole quality in a drilling operation using TiAlN/TiN- and TiAlN-coated HSS drill bits. The coating process had no significant effect on the hole quality. In addition, the coating process had no significant effect on the temperature of the workpiece in the drilling operation. Lin and Shyu¹⁷ investigated the effect of coating on tool performance in a drilling process using TiN-, TiCN-, CrN-, and TiAlN-coated drill bits. In the study, TiN- and TiCN-coated drills were more suitable than CrN- or TiAlN-coated drill bits in a drilling process using stainless steel.

Nickel et al.¹⁸ examined the wear performance of plasma-nitrided and TiN-Coated HSS drill bits. It was observed that the pre-nitrided drill bits wore less and had longer life in the same processing time than the commercial drill bits. Yilbas and Nizam¹⁹ metallurgically investigated the wear behavior of TiN-coated AISI H11 and AISI M7 twist drill bits. They examined the wear behavior of plasma-nitrided (TiN-coated) drill bits. The nitriding process carried out before coating had a positive effect on the tool. Mandl et al.²⁰ recommended the plasma immersion ion implantation (PIII) method to improve the life of HSS drill bits. This method was applied in the drilling experiments. Less wear was observed in the drill bits when PIII was applied than when it was not applied. Tool life significantly increased with this method. Chip formation has not been examined in detail, and the relationship between wear and chip formation has not been determined in the studies conducted so far. However, in this study, chip formation and wear behavior of AISI 1045 material were experimentally investigated in a drilling process using plasma-nitrided drill bits. Wear and chip sections were determined in the drilling process. Finally, a statistical analysis between wear and chip sections was performed.

Experimental procedure

Plasma-nitrided process

First, the drill bits used in the cutting processes were subjected to plasma nitriding. Two different drill bits referred to as uncoated and plasma nitrided were used during the drilling process. Nitriding processes were carried out using an experimental setup. The schematic illustration of the experimental setup is shown in Figure 1. The plasma nitriding process was carried out at 450 °C, at a pressure of 5.6 mbar vacuum, in a 50% H₂ and in a 50% N₂ gas environment, for 5 h. After HSS drill bits were cleaned using pure alcohol, they were placed in a plasma chamber. After the air of the plasma chamber was discharged, hydrogen atoms were ionized as a result of the current flow carried out with the release of H₂ gas into the medium for 20 min during the process. Then, these ionized atoms were sprayed on the drills, which were first cleaned with alcohol. This process allowed an increase in the temperature of the workpiece to the temperature at which the nitriding process was to be carried out and the oxides to be removed from the surface of the workpiece. When the temperature reached the desired level, the HSS drills were subjected to the nitriding process for 5 h. A purple color radiation emerged with the start of the plasma nitriding. After the completion of the required time for nitriding, the system was shut down and the drill bits were kept in the chamber and allowed to cool to room temperature (1–2 h).

Figure 1.

Schematic illustration of the experimental setup.

The most important equipments of plasma nitriding are the vacuum pump, furnace, gas distribution system, and the control unit. The pressure in the furnace, in which the workpiece is to be nitrided, should be 0.1–10 mbar. Direct current voltage should be 100–1500 V and the current density 100–1000 Am⁻². Voltage is applied between the cathode (workpiece) and the anode (the furnace wall). The gases used are N₂+H₂, N₂+H₂+A or their hydrocarbon gas added mixtures depending on the purpose. Gas atoms and molecules are ionized in the plasma which emerges with electrical discharges between the cathode and anode. Positive ions collide with the workpiece, which is the negative pole, with great energy and diffuse inwardly from the surface; this way, the released energy heats the material. The temperature can be adjusted by varying the voltage and current. The processing time varies from 10 min to 20 h.²¹

DIN 338 HSS drill bits were used in the coating process. Table 1 shows the chemical composition of the drill bits used in the experiments. Figure 2 shows the optical microscope image of the sections of the plasma-nitrided HSS drill bit. In the image, a white nitride layer can be observed on the HSS drills. A flat nitride layer was formed on the plasma-nitrided metals. The thickness of the nitride layer which formed on the HSS drills as a result of plasma nitriding was 10 µm. The near-surface compound layer (white layer) of plasma-nitrided steels consists of single nitride layer [ε-Fe_2–3N or γ′-Fe₄N)] or double nitride layers (ε+γ′) depending on nitriding method, gas composition, and chemical composition of steels. The white layer becomes thicker and more brittle with increasing nitrogen in the gas mixture.²²

Table 1.

Chemical composition of the drill bits.

DIN 338 HSS	C	Si	Mn	P	S	Cr	Mo	Ni	V	W
	0.85	0.3	0.2	0.002	0.002	3.87	4.72	0.18	1.75	6.09

HSS: high-speed steel.

Figure 2.

Microscopy illustration of the plasma-nitrided HSS drill bit.

Microhardness of the HSS drills significantly increased following the plasma nitriding process. Microhardness was observed to increase fourfold following the plasma nitriding process. The microhardness of the outer surfaces (clearance and margin) of the coated and the uncoated drill bits were measured using a Micro-Knoop (Shimadzu HMV-2) with 25 g loads. The hardness tests were repeated 10 times for the coated and uncoated drill bits. The microhardness of the outer surface of the uncoated and coated drill bits was around 441 ± 18 and 2095 ± 38 HV_0.025, respectively. Microhardness measurements of the coated HSS drill bits were also carried out on the cross section from surface to interior along a line. The tests were repeated five times for each line. Microhardness distribution of the plasma-nitrided HSS bits is given in Figure 3.

Figure 3.

Microhardness distribution from surface to interior of the plasma-nitrided HSS drill bit.

Figure 4 illustrates X-ray diffraction (XRD) patterns of plasma-nitrided and uncoated drill bits. Figure 4 shows that Cr, α-Fe, and Mo phases occurred on the uncoated HSS drills, while hard nitride phases (CrN, Cr₂N, Fe₂N, Mo₂N) occurred on the nitrided drills. It was observed that the HSS drill bits were coated as a result of the plasma nitriding process.

Figure 4.

X-ray diffraction (XRD) patterns of the uncoated and the plasma-nitrided drill bits.

Experimental parameters

The TAKISAWA computer numerical control (CNC) machine was used during the drilling processes (Figure 5). The power of the machine was 3000 W, the maximum speed was 2000 r/min, and the accuracy was 0.001 mm. Two types of drill bits were used in the cutting experiments: uncoated and plasma nitrided. Drilling experiments were conducted with different cutting parameters (feed rate and cutting speed) using these drills. Experimental parameters used in the drilling processes are detailed in Table 2. Each drilling parameter was repeated 10 times, and therefore, the performances of the drill bits were determined. Totally, 20 coated and uncoated drill bits were used in the drilling process. AISI 1045 material was used in the drilling processes, and the dry drilling process was carried out. The drill depth is 30 mm. Table 3 shows the chemical composition of AISI 1045 steel. In the cutting experiments, drill bits of 8 mm diameter with DIN 338 standards were used.²³ The geometrical features of the drill used in the experiments are given in Figure 6.

Figure 5.

Illustration of the drill process in the machine.

Table 2.

Detailed experimental parameters used in the drilling processes.

Test no.	Drill bit type	Feed rate (f) (mm/min)	Cutting speed (V) m/min
1	Uncoated HSS	0.04	10
2	Uncoated HSS	0.06	10
3	Uncoated HSS	0.08	10
4	Uncoated HSS	0.04	15
5	Uncoated HSS	0.06	15
6	Uncoated HSS	0.08	15
7	Uncoated HSS	0.04	20
8	Uncoated HSS	0.06	20
9	Uncoated HSS	0.08	20
10	Plasma-nitrided HSS	0.04	10
11	Plasma-nitrided HSS	0.06	10
12	Plasma-nitrided HSS	0.08	10
13	Plasma-nitrided HSS	0.04	15
14	Plasma-nitrided HSS	0.06	15
15	Plasma-nitrided HSS	0.08	15
16	Plasma-nitrided HSS	0.04	20
17	Plasma-nitrided HSS	0.06	20
18	Plasma-nitrided HSS	0.08	20

HSS: high-speed steel.

Table 3.

Chemical composition of AISI 1045 steel.

AISI 1045	C	Si	Mn	P	S	Cr	Mo	Ni
	0.45	0.25	0.61	0.02	0.033	0.2	0.034	0.12

Figure 6.

Geometric properties of drill bits used in the experiments (mm).

Wear on the drill bits was determined by optical microscopy and scanning electron microscopy (SEM) analysis following the drilling processes. Figure 7 shows the wear mechanism on a drill bit. Maximum wear which occurred following the drilling process was obtained taking into account the two surfaces of the drill bit. The maximum wear is average of the wears of first (W_max1) and second (W_max2) cutting surface of the drill bits.

Figure 7.

Wear mechanism on a drill bit.

Chip formation after the drilling process was examined by SEM as well as by a sensitive micrometer (sensitivity 0.002 mm). Figure 8 shows the SEM image of the chip section obtained following the cutting process.

Figure 8.

SEM illustration of chip cross section.

Chip section indicated in Figure 8 was calculated as follows

C_{c s} = (\frac{C_{t 1} + C_{t 2}}{2}) C_{b}

(1)

where C_t₁, C_t₂, and C_b represent the thickness of the chip core, the thickness of the outer region of the chip, and the chip width, respectively. Following the drilling process, the thickness and width of each chip were measured from five different regions and averaged, and the chip section was obtained.

Results and discussion

Determination of tool wear

Drilling tests were repeated 10 times for each parameter. As a result of these repetitions, the wear performance of the drill bits was measured. Figure 9 shows the wear values, depending on the number of experiments, as a result of the drilling processes. With the increasing number of experiments, the wear of the uncoated and plasma-nitrided drill bits significantly increased. Following the plasma nitriding process, the hardness and wear resistance of the drill bits rose, and therefore, less wear occurred compared to the uncoated HSS drill bits.

Figure 9.

Drill bit wear values depending on the experiment numbers.

Figure 10 shows the maximum tool wear in the experiments conducted using different parameters. For every two drill bits, cutting speed significantly increased with the feed ratio. In addition, tool wear increased with a rise in the cutting speed. The number of chip cuts per unit of time increased with the increase in the feed ratio and cutting speed. With this increase, tool wear also increased. Maximum tool wear was obtained from the uncoated tools. Tool wear significantly decreased with the coating of the drill bits. One of the most important reasons for this is that the hardness of the drill bits subjected to the plasma nitriding process significantly rose. This led to an increase in the wear resistance of the drill. The coefficient of friction significantly decreased with the plasma nitriding process.^24,25 Tool wear significantly decreased with the increase in the coefficient of friction. Drill life was prolonged with up to 23% on average with the decrease in the wear of the drill bit.

Figure 10.

Wear values depending on feed rate and cutting speed.

The drill bits were examined in the SEM following the drilling process. Figure 11 shows the SEM image of the worn drill bits. As shown in figures, abrasive wear occurred on the drill cutting surfaces due to friction. In addition, major wear occurred on the lateral surface of the drill bits which carry out the cutting process. Maximum wear was observed on the uncoated drill bits, while less wear was observed on the plasma-nitrided drill bits. Maximum wear was observed toward the outer part of the drill bits. In the drilling process, more sections are cut toward the edges of the drill bits. Therefore, the thicknesses of the chips differ (in the inner and outer regions) and the wear increases toward the outer parts of the drill bits.

Figure 11.

SEM illustration of the worn drill bits.

Energy dispersive scanning (EDS) analysis was performed on the wear region of the plasma-nitrided cutting tool. Figure 12 shows the EDS analysis of the plasma-nitrided drill bits. EDS analysis of the worn region shows that the nitride layer was not totally worn. EDS analysis shows the presence of N composition in the nitride layer. Using the plasma-nitrided drill bit in the drilling process, it was observed that the wear depth did not fall below 10 µm, which is the coating thickness.

Figure 12.

Energy dispersive scanning (EDS) analysis of wear region in the plasma-nitrided drill bit.

Determination of chip formation

Figure 13 shows the average chip cross section dependent on the feed rate. The chip section significantly increased with a rise in the feed rate. The reason behind this is that the chip size cut per minute increased with an increase in the feed rate. For every two drill bits, maximum chip thickness values were obtained at 0.08 mm/min of feed rate. In addition, cutting speed was found to be an important factor in the determination of the average chip thickness. Chip thickness increased with an increase in the cutting speed. The drill carried out more cutting per unit of time with an increase in the cutting speed. In the cutting process, chips that are cut slide on the tool and move outward.²⁶

Figure 13.

Variation of chip cross section depending on the cutting parameters.

The analysis of the chip sections for both drill types indicates that the chip sections obtained with the plasma-nitrided drill bits have lower cross sections than the other chip sections. During the drilling process, when the drill bit starts cutting the workpiece, a considerable amount of heat is generated. The chip, which reaches very high temperatures momentarily, starts to cool, slides through the drill and comes to the surface. It is expected that the chip withdraws from the cutting media quickly, and this situation is related to the friction coefficient of the drill bit.²⁷ In the drilling process, the movement of the chip, which appears via the low friction coefficient, is facilitated.¹⁶ If the friction coefficient is high, the chip cannot move easily in the cutting medium and aggregation occurs. This aggregation significantly increases the chip section. When the friction coefficient is low, the chip slides more quickly on the surface and since there is less aggregation, the chip section decreases. Therefore, a small chip section was obtained in the drilling experiments conducted with plasma-nitrided drill bits, which have low friction coefficients.

Figure 14 illustrates the chip formation obtained using uncoated and plasma-nitrided drill bits. It was observed in all the experiments that the shapes of the chips obtained using the uncoated drill bit were very long and continuous, while those of the chips obtained using the plasma-nitrided drill bits were short and fractured. In a similar study, Heaney et al.²⁸ clearly determined that the coated tool cut with less burring produced many small uniform chips, while the uncoated tool created a large amount of burring producing only a few long continuous chips.

Figure 14.

Chip formation after the drill processes (v = 10 m/min): (a) 0.04 mm/min, (b) 0.06 mm/min, and (c) 0.08 mm/min.

The friction between the tool and the workpiece in the drilling process generates heat. This heat diffuses on the surface of the chip, the tool and the workpiece. However, in the coating process, the heat diffuses mostly on the chip and the workpiece. The coating process generates high thermal resistance on the drill bits; in other words, the coating serves as a thermal barrier.²⁹ The chip, which is subjected to more heat by the effect of the coating, cools instantly after it withdraws from the cutting zone and becomes brittle. Therefore, shorter chip sizes were obtained in the drilling process using plasma-nitrided drill bits. In the drilling processes using uncoated drill bits, lower temperature heat is released which diffuses mostly homogeneously on the workpiece and the chip due to the lack of a thermal barrier (Figure 15). These chips formed at low temperatures are long and spiral-shaped. Thermal conduction and the friction coefficient significantly affect chip formation.³⁰

Figure 15.

t_i₂ > t_i₁ tool–chip interface temperature, q_t₁ > q_t₂ heat flow to the cutting tool, q_c₂ > q_c₁ heat flow to the chip.²⁹

In addition, in the microhardness analyses, the microhardness value of the chip obtained in the cutting process using the plasma-nitrided drill bit was 401 HV_0.025 on average, while the microhardness value obtained from the uncoated drill bit was 343 HV_0.025. Here, it can be stated that a higher cutting temperature is generated in the drilling process using the plasma-nitrided drill bit, and the chip becomes brittle and its hardness increases as it cools instantly.

Relation between wear and chip cross section

A statistical analysis was performed between the wear and chip section. Figure 16 shows the wear-dependent statistical analysis of the chip section. For uncoated and coated drill bits, it may be said that there is a significant relationship between the drill bit wear and the obtained chip sections. For both drill bits, drill bit wear significantly increased with a rise in the chip section. In addition, the correlation coefficients of the uncoated and plasma-nitrided drill bits were 0.96 and 0.97, respectively. In the light of these results, it can be argued that there is a very strong connection between the chip section and drill bit wear.

Figure 16.

Relation between wear and chip cross section.

Conclusion

In this study, wear and chip formation in drill processes using uncoated and plasma-nitrided HSS drill bits of AISI 1045 material were investigated in an experimental study. Following the plasma nitriding process, the hardness of the drill bits increased significantly. Wear behaviors of the plasma-nitrided HSS drill bits were observed to be better than those of the uncoated drill bits with an increase in hardness. Wear increases with a rise in the feed rate and cutting speed for the uncoated and the plasma-nitrided HSS drill bits. Abrasive-type wear was observed in all the experiments. Wear increased due to the fact that it removed more chips per unit of time with an increase in peripheral speed and feed rate.

The chips in the drilling processes using plasma-nitrided drills were shorter and smaller than those in the drilling processes using uncoated drills. Following the coating process, the friction coefficient decreased, and as the coating served as a barrier for the tool, the chip withdrew from the cutting medium promptly during the drilling process. The chip sections significantly decreased with the prompt withdrawal of the chip. This had a positive effect on tool wear and chip section. In this study, a statistical evaluation of wear and chip section was made. It can be concluded that there is a strong relationship between wear and chip section. More wear was observed in the chips with large cross sections, while the amount of wear decreased with a decrease in chip section.

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship and/or publication of this article.

References

Murphy

Byrne

Gilchrist

. The performance of coated tungsten carbide drills when machining carbon fibre-reinforced epoxy composite materials. Proc IMechE, Part B: J Engineering Manufacture 2002; 216(2): 143–152.

Ertunc

Oysu

. Drill wear monitoring using cutting force signals. Mechatronics 2004; 14(5): 533–548.

Chen

Liao

. Study on wear mechanisms in drilling of Inconel 718 superalloy. J Mater Process Tech 2003; 140(1–3): 269–273.

Küçüktürk

. Modeling and analyzing the effects of experimentally determined torque and thrust force on cutting tool according to drilling parameters. Proc IMechE, Part B: J Engineering Manufacture 2013; 227(1): 84–95.

Kelly

Braucke

Liu

. Pulsed DC titanium nitride coatings for improved tribological performance and tool life. Surf Coat Tech 2007; 202: 774–780.

Lin

. Cutting behavior of a TiN-coated carbide drill with curved cutting edges during the high-speed machining of stainless steel. J Mater Process Tech 2002; 127(1): 8–16.

Dasch

Ang

Wang

. A comparison of five categories of carbon-based tool coatings for dry drilling of aluminum. Surf Coat Tech 2006; 200(9): 2970–2977.

Nouari

List

Girot

. Experimental analysis and optimization of tool wear in dry machining of aluminium alloys. Wear 2003; 255: 1359–1368.

Zitoune

Krishnaraj

Almabouacif

. Influence of machining parameters and new nano-coated tool on drilling performance of CFRP/aluminium sandwich. Compos Part B: Eng 2012; 43: 1480–1488.

10.

Elhachimi

Torbaty

Joyot

. Mechanical modeling of high speed drilling 1: predicting torque and thrust. Int J Mach Tool Manu 1999; 39(4): 553–568.

11.

Barshilia

Rajam

. Performance evaluation of reactive direct current unbalanced magnetron sputter deposited nanostructured TiN coated high-speed steel drill bits. Bull Mater Sci 2007; 30(6): 607–614.

12.

Park

Beal

Kim

. Tool wear in drilling of composite/titanium stacks using carbide and polycrystalline diamond tools. Wear 2011; 271: 2826–2835.

13.

Bai

Zhu

Xiao

. Study on thermal stability of CrTiAlN coating for dry drilling. Surf Coat Tech 2007; 201: 5257–5260.

14.

Audy

. A study of computer-assisted analysis of effects of drill geometry and surface coating on forces and power in drilling. J Mater Process Tech 2008; 204: 130–138.

15.

Wang

Yan

. The study on the chip formation and wear behavior for drilling forged steel S48CS1V with TiAlN-coated gun drill. Int J Refract Met H 2012; 30: 200–207.

16.

Kalidas

DeVor

Kapoor

. Experimental investigation of the effect of drill coatings on hole quality under dry and wet drilling conditions. Surf Coat Tech 2001; 148: 117–128.

17.

Lin

Shyu

. Improvement of tool life and exit burr using variable feeds when drilling stainless steel with coated drills. Int J Adv Manuf Tech 2000; 16: 308–313.

18.

Nickel

Shuaib

Yilbas

. Evaluation of wear of plasma-nitrided and TiN-coated HSS drills using conventional and micro-PIXE techniques. Wear 2000; 239: 155–167.

19.

Yilbas

Nizam

. Wear behavior of TiN coated AISI H11 and AISI M7 twist drills prior to plasma nitriding. J Mater Process Tech 2000; 105: 352–358.

20.

Mandl

Gunzel

Rauschenbach

. Characterization of drills implanted with nitrogen plasma immersion ion implantation. Surf Coat Tech 1998; 103–104: 161–167.

21.

Gunes

. Forming of complex coatings on the steels by plasma nitriding. Master Thesis, Afyon Kocatepe University, Afyonkarahisar, Turkey, 2006.

22.

Taktak

Gunes

Ulker

. Effect of pulse plasma nitriding on tribological properties of AISI 52100 and 440 C steels. Int J Surf Sci Eng 2014; 8(1): 39–56.

23.

Kaplan

. Effect to tool performance of coating in drilling process using drill bit of AISI 1045 material. Master Thesis, Afyon Kocatepe Üniversitesi, Afyonkarahisar, Turkey, 2012.

24.

Gunes

Ulker

Yalcin

. Effect of N₂+H₂ gas mixtures in plasma nitriding on tribological properties of duplex surface treated steels. Mater Charact 2008; 59: 1784–1791.

25.

Taktak

Ulker

Gunes

. High temperature wear and friction properties of duplex surface treated bearing steels. Surf Coat Tech 2008; 202: 3367–3377.

26.

Kim

Ahn

Kim

. Real-time drill wear estimation based on spindle motor power. J Mater Process Tech 2002; 124: 267–273.

27.

Stephenson

. Chip thickening in deep-hole drilling. Int J Mach Tool Manu 2006; 46: 1500–1507.

28.

Heaney

Sumant

Torres

. Diamond coatings for micro end mills: enabling the dry machining of aluminum at the micro-scale. Diam Relat Mater 2008; 17(3): 223–233.

29.

Ucun

Aslantas

. Numerical simulation of orthogonal machining process using multilayer and single-layer coated tools. Int J Adv Manuf Tech 2011; 54: 899–910.

30.

Kalss

Reiter

Derflinger

. Modern coatings in high performance cutting applications. Int J Refract Met H 2006; 24: 399–404.

Determination of tool wear and chip formation in drilling process of AISI 1045 material using plasma-nitrided high-speed steel drill bits

Abstract

Keywords

Introduction

Experimental procedure

Plasma-nitrided process

Experimental parameters

Results and discussion

Determination of tool wear

Determination of chip formation

Relation between wear and chip cross section

Conclusion

Footnotes

Declaration of Conflicting Interests

Funding

References