TiAlN-coated Inserts Research Articles

Effect of materials and process parameters on machinability of stainless steels

Stainless steels, recognized for their corrosion resistance attributed to a minimum of 11 % Chromium, encompass a variety of alloys with distinctive microstructures and properties. Machinability significantly varies among these alloys. Austenitic steels such as SS303 and 304 present challenges, demonstrating poor surface finish and high power consumption. This study, employing a central composite design, investigates the machinability of AISI 303, 304, 316, AISI 416, and AISI A36. Turning tests with PVD TiAlN-coated inserts revealed optimal parameters for cutting speeds (90.5256–244.411 m/min), feed (0.0635–0.4826 mm/rev), and depth (0.00016–0.00187 m.). Surface finish analysis identified AISI 316 as the best, closely followed by AISI 303. From a power consumption standpoint, AISI 303 performed the best, and concerning fragmented chip morphology, AISI 303 also excelled. The superior performance of AISI 303 is attributed to 2 % Manganese and 0.15 % Sulfur, proving to be the most effective combination compared to the other four steels, resulting in a higher percentage of MnS2, optimal for improving machinability. The depth of cut emerges as the most influential factor affecting dimensional accuracy. These findings hold practical significance in the selection of stainless steels and corresponding process parameters across various industries, including the manufacturing of heavy earthmoving equipment. By shedding light on the optimal composition and machining conditions, this study contributes valuable insights for enhancing performance and efficiency in stainless steel applications.

Evaluation of Cutting Temperature and Optimization in Milling of GGG60 Cast Iron

Spheroidal graphite cast irons have increased ductility, tensile strength, and toughness compared to other cast irons. Additionally, it can be mentioned that choosing spheroidal graphite cast iron over steel material has a better machining feature. In this study, Face milling operations were carried out using GGG60 material and different inserts, feed, and depth of cut. The Taguchi method was used for the experimental design, and 27 experiments were carried out. During the experiments, a thermal camera measured the temperature from the cutting zone. Experimental results were evaluated with analysis of variance and graphics, and cutting parameters were optimized. As a result of the optimization, optimum parameters for minimum temperature, TiAlN coated insert, 300 m/min cutting speed, 0.30 mm/tooth feed rate, and 0.5 mm depth of cut were found. According to the results obtained from the study, the most influential parameter affecting the temperature was the cutting speed. In addition, the TiAlN-coated insert has been observed as the most suitable coating type for minimum temperature.

Understanding the Relationship between Surface Quality and Chip Morphology under Sustainable Cutting Environments.

Although chip morphology changes according to the machining method and related cutting parameters, chip formation affects the quality of the machined surface. In this context, it is very important to understand the relationship between chip morphology and surface quality, especially in materials that are difficult to machine. In the presented study, the changes in chip morphology, surface morphology, and surface quality criteria (Ra and Rz) that occurred during the milling of precipitation-hardened steel in different cutting environments were analyzed. Milling experiments were carried out in dry, MQL (minimum quantity lubrication), nano-MQL (graphene), nano-MQL (hBN), Cryo, and Cryo-MQL environments using TiAlN-coated inserts and three different cutting speeds and feed rates. While the highest values in terms of Ra and Rz were measured in dry machining, the minimum values were obtained in a nano-MQL (hBN) cutting environment. Due to the lubrication and low friction provided by the MQL cutting environment, chips were formed in thinner segmented forms. This formation reduced the chip curve radius and thus provided a more stable surface morphology. On the other hand, Cryo-ambient gas could not effectively leak into the cutting zone due to the intermittent cutting process, but it increased the brittleness of the chips with the cooling effect and provided a similar surface morphology. The values of minimum Ra and Rz were obtained as 0.304 mm and 1.825 mm, respectively, at a 60 m/min cutting speed and 0.04 mm/rev feed. Consequently, the use of nano-MQL cutting medium is seriously recommended in terms of surface quality in milling operations of difficult-to-machine materials.

Machinability improvement investigation in face milling of Ti–3Al–2.5V alloys using TiAlN coated carbide insert under dual nozzle minimum quantity lubrication cooling environment

This research presents the machinability analysis in face milling of Ti–3Al–2.5V alloys using TiAlN-coated carbide insert under dual nozzle minimum quantity lubrication (MQL) cooling conditions. The TiAlN-coated insert has several favorable characteristics like superior wear resistance, greater hardness, and high chemical stability at elevated temperatures. The performance capability of this cutting insert was assessed using machinability responses such as surface roughness, tool wear, and cutting temperature results. The improved quality finish was found with maximum Ra (0.823 µm) while the improved accuracy of flatness (0.044) was obtained even though the rotational speed of the face mill cutter ( N) was highest (1500 r/min). Likewise, an acceptable range of flank wear (0.058–0.118 mm) and a lower range of cutting temperature (65 °C–106.8 °C) was found due to the superior thermal characteristics of TiAlN coating, effective cooling, and lubricating capability of the dual nozzle MQL system in face milling to this alloy. Further, by using the entropy coupled multi-objective optimization ratio analysis method, the optimal value of milling parameters was computed as coolant flow rate ( Q) 50 ml/h, feed speed (vf) 200 mm/min, and rotational speed of the face mill cutter ( N) 500 r/min. At this optimal setting, the optimum Ra, VBc, and T were found as Ra = 0.596 µm; VBc = 0.058 mm, and T = 65 °C, respectively.

Experimental investigation of microtextured cutting tool performance in titanium alloy via turning

This study aimed to prevent the harmful consequences of the turning process. The use of micro-textured cutting inserts with a femtosecond laser an innovative efficient method to decrease chip adhesion to cutting of edge tools during titanium alloy (Ti6Al4V) turning was studied. Additionally, the effects of different micro-pattern geometries and sizes on the machining capacity of coated WC/Co cutting inserts in turning experiments with titanium–aluminium–nitride (TiAlN) were investigated based on various lubrication processes. The surface states of the micro-patterned TiAlN-coated inserts were analysed using scanning electron microscopy and optical microscopy. Subsequently, machining and measured tests on the titanium alloy were performed using the developed cutting tools. Tungsten carbide tools with textured cutting surfaces and different microstructures were fabricated, and their behaviours were compared with those of conventional coated tools. Thrust, cutting, and feed cutting force values were measured during machining using a three-component dynamometer. Based on the present investigation, the cutting tool with a cross texture exhibited greater reduction of machining forces, friction coefficients, and tool wear.

Simulation Analysis of the Influence of Coating on the Cutting Temperature Distribution inside the Insert

The coating on carbide insert surface can effectively reduce the transfer of cutting heat to the inside of the insert, improve the surface wear resistance and cutting performance, and ensure the service life. In this paper, the influence of coating on the heat conduction inside the insert is analyzed by two-dimensional heat transfer model, and the temperature distribution is quantitatively described. The simulation models of TiAlN-coated and -uncoated inserts are established, and the simulation results are compared. It is found that the cutting temperature of TiAlN-coated insert decreased by about 5% compared with that of uncoated cutting tools. The coating effectively reduced the conduction of cutting heat to the matrix, and the internal temperature of the matrix was significantly lower than that of uncoated cutting tools.

OPTIMUM FLANK WEAR OF TiAlN-COATED TOOL: TOWARD PRODUCTIVE ROUGH CUTTING OF INCONEL 625

Long tool life and high material removal rate (MRR) are the two essential requirements in rough cutting of materials. The rapid rate of the flank wear propagation in machining of nickel-based superalloys has induced the utilization of low cutting parameters when the goal was set to maximize the tool life based on the machining time or cutting length. However, this method may not provide an effective rate for the material being cut. This work presents two mathematical models to find the optimum cutting parameters results for the minimum flank wear and maximum MRR. Experimental tests were carried out based on the central composite design (CCD) in rough cutting of Inconel 625 by using TiAlN-coated insert. Maximum flank wear was measured to determine the tool wear propagation. The wear mechanisms which contribute in the tool wear were analyzed by using scanning electron microscope (SEM) to evaluate the effects of cutting parameters on the flank wear propagation. The results showed that cutting speed and depth of cut had the most significant effect on the tool wear. However, optimum cutting condition was achieved by reducing the cutting speed when feed rate and depth of cut maintained at the highest level. This was associated to the interaction of cutting speed and depth of cut, and predominant of abrasion and notching at their highest levels, respectively.

An Investigation on Surface Roughness and Tool Wear in Turning Operation of Inconel 718

This paper investigates the influences of three different input parameters, such as feed rate, insert nose radius, and insert coating methods, in the turning operation of Inconel 718. The coating methods were selected as medium temperature chemical vapor deposition (MT-CVD) and physical vapor deposition (PVD) and in addition to coating methods, the role of various coating materials was discussed since the inserts were coated with multi-layers of TiCN/Al2O3/TiN and single-layer of TiAlN on carbide substrates. The results were discussed in terms of wear behavior of cutting tools and surface quality of the workpiece, which is indicated by surface roughness. A full factorial experimental design was employed in the present work and the results were evaluated using main effects plots. Furthermore, the analysis of variance (ANOVA) method was applied to specify both reactive and non-reactive effects of experimental parameter reactions. The results showed that surface roughness is reduced using low feed rates and large nosed inserts in the operations. Furthermore, TiAlN-coated inserts with PVD method provided better surface finish than with MT-CVD method. It was also found that surface roughness increases as the wear rate of inserts increases.

PVD-CrAlN and TiAlN coated Si 3 N 4 ceramic cutting tools —1. Microstructure, turning performance and wear mechanism

Abstract In this work, CrAlN and TiAlN coatings were produced on silicon nitride cutting inserts via physical vapor deposition. The microstructure and hardness of the coatings, as well as the adhesive strength between the coating and the substrate were studied using a scanning electronic microscope, a micro hardness tester and a scratch tester, respectively. Continuous turning tests of the obtained CrAlN and TiAlN-coated silicon nitride cutting inserts were performed on gray cast iron to evaluate the cutting performances and the machining quality. The results show that the surface hardness of the Si 3 N 4 cutting inserts could be improved by 87% and 50%, respectively, when applying the CrAlN and TiAlN coatings, thereby enhancing the abrasion resistance of the cutting inserts. At different tested cutting speeds, abrasive wear under compressional deformation and adhesive wear were identified as the main failure mechanisms for the two cutting inserts during continuous turning of gray cast iron. The machining quality of the gray cast iron workpieces machined using the uncoated, the CrAlN- or the TiAlN-coated inserts increased with the increment of the cutting speed.

Performance evaluation on high speed machining of custom 465 steel

Custom 465 steel is a martensitic, age-hardenable alloy having a superior combination of strength and corrosion cracking resistance, which are commonly used in aerospace industries. When machining Custom 465 steel, tool-work interface temperature and tool wear are the major parameters which influences the machinability factors at a greater extend. Even though, researchers have performed many operations based on this subject, no significant data’s were available regarding the Custom 465 steel.A dry machining operation known for its ecological desirable and cost effective process was implemented to experimentally investigate the tool wear and tool-work interface temperature when machining Custom 465 steel using uncoated, TiAlN and TiCN coated carbide cutting tool inserts with a cutting speed of 100 m/min and 200 m/min and also the effects of cutting speed on tool wear and tool-work interface temperature were also determined. The highest tool life of 6.15 minutes was recorded for TiAlN coated insert at a cutting speed of 2000 rotations per minute (rpm), feed rate of 200 mm/min and depth of cut of 0.5 mm. The maximum tool wear recorded for TiAlN coated insert was 0.25 mm and the maximum temperature on the tool-work impact was 142.43 degrees. In all cutting speeds, TiAlN coated insert outperformed uncoated and TiCN coated insert in term of tool life and temperature. For a cutting speed of 2000 rpm and above uncoated inserts are not suitable to be used for machining Custom 465 steel due to the rapid wear of cutting edge.

The effect of monolayer TiCN-, AlTiN-, TiAlN-and two layers TiCN + TiN- and AlTiN + TiN-coated cutting tools on tool wear, cutting force, surface roughness and chip morphology during high-speed milling of Ti6Al4V titanium alloy

Tool coatings can improve the machinability performance of difficult-to-cut materials such as titanium alloys. Therefore, in the current work, high-speed milling of Ti6Al4V titanium alloy was carried out to determine the performance of various coated cutting tools. Five types of coated carbide inserts – monolayer TiCN, AlTiN, TiAlN and two layers TiCN + TiN and AlTiN + TiN, which were deposited by physical vapour deposition – were employed in the experiments. Tool wear, cutting force, surface roughness and chip morphology were evaluated and compared for different coated tools. To understand the tool wear modes and mechanisms, detailed scanning electron microscope analysis combined with energy dispersive X-ray of the worn inserts were conducted. Abrasion, adhesion, chipping and mechanical crack on flank face and coating delamination, adhesion and crater wear on rake face were observed during high-speed milling of Ti6Al4V titanium alloy. In terms of tool wear, the lowest value was obtained with TiCN-coated insert. It was also found that at the beginning of the machining pass TiAlN-coated insert and at the end of machining TiCN-coated insert gave the lowest cutting force and surface roughness values. No change in chip morphology was observed with different coated inserts.

MACHINING PERFORMANCE OF ALUMINUM ALLOY 6061-T6 ON SURFACE FINISH USING MINIMUM QUANTITY LUBRICATION

This paper presents an experimental investigation of coated carbide cutting tool performance on the surface roughness of aluminum alloy 6061-T6 machining through end mill processes using the minimum quantity lubrication technique. Process parameters including the cutting speed, depth of cut and feed rate are selected. The central composite design method is used for design of experiments. Two types of coated carbide tool are used in this experiment – an uncoated tungsten carbide insert and TiAlN+TiN-coated carbide insert. The analysis of variance method is utilized to validate the experimental data and to check for adequacy. The response surface method was used to develop the mathematical models and to optimize the machining parameters. Second-order regression models are developed based on the surface roughness results. It is observed that the surface roughness depends significantly on depth of cut and feed rate, followed by spindle speed for both the coated carbide inserts. The performance of the dual-layered coating of TiAlN+TiN is competent as compared to the surface quality obtained with TIAlN-coated inserts. The results can be used as an example of MQL applied to the machining of aluminum alloys, providing economic advantages in terms of reduced lubricant costs and better machinability.

Orthogonal cutting of hardened AISI D2 steel with TiAlN-coated inserts—simulations and experiments

This paper presented a finite element simulation model for the analysis of AISI D2 steel turning with TiAlN-coated inserts. In this study, material constitutive model of hardened AISI D2 steel (HRC62) was built based on power law relationship, which was used in the FEM codes to describe the effect of strain, strain rate, and temperature on the material flow stress. A damage model was employed to predict the chip separation. Cutting edge radius and thickness of TiAlN coating were obtained by micro-optical system and SEM, respectively. The average friction coefficients were obtained by ball-on-disk friction test using UMT-2 high-speed tribometer. Numerical simulations of AISI D2 steel turning were performed using AdvantEdge™ software. The simulated results of forces and chip morphology showed good agreement with the experimental results, which validated the precision of the process simulation method. The shear stress on the interface between coating and substrate of cutting tool was analyzed. And the maximal shear stress between coating and substrate was found on the cutting edge roundness near the flank face of cutting tool.