Machining Of Compacted Graphite Iron Research Articles

A chip formation mechanism taking into account microstructure evolution during the cutting process: Taking compacted graphite iron machining as an example

Compacted graphite iron (CGI), a prototypical heterogeneous material, potentially demonstrates distinctive cutting deformation behaviours attributed to the random distribution of graphite and performance differences between graphite and the matrix, which have not yet received adequate attention. This study focuses on the influence of the microstructure characteristics of CGI on the formation of serrated chips. The morphology of the serrated chip segments during the orthogonal turning of CGI was observed in detail, the microstructures of the chip roots were characterised and analysed using various techniques, and a finite-element cutting simulation model considering the microstructural characteristics of CGI was developed. Results suggest that the formation of serrated chips in CGI is influenced by periodic and aperiodic brittle fractures, referred to as quasi-periodic brittle fractures, which are controlled by the distribution of graphite in CGI. This results in variations in the morphology and dimensions of the serrated chips in CGI. Plastic deformation is concentrated in a triangular deformation zone (TDZ) near the tool-chip interface, which is broader than the conventional secondary deformation zone. The experimental and simulation results revealed the reasons for the formation of the TDZ and emphasized the critical role of graphite in the formation of serrated chips in CGI. The graphite particles near the tool-chip interface promoted plastic deformation along the interface owing to the principle of minimum energy and restricted deformation perpendicular to the interface due to its structure, leading to the formation of the TDZ. The influence of graphite on material flow and the formation of the TDZ during the formation of serrated chips in CGI is a novel discovery. The microstructure evolution of the pearlite matrix in CGI caused by cutting deformation was analysed. The results demonstrate that the distinctive deformation behaviour of CGI contributes to the fragmentation of the pearlite structure, grain refinement, and increased dislocation density in the TDZ. Finally, the influence of the serrated chip formation mechanism on chip morphology and cutting force in CGI was discussed. These findings offer significant scientific insights and contribute to the fundamental understanding of the chip formation process in CGI.

Sustainability assessment and optimization for milling of compacted graphite iron using hybrid nanofluid assisted minimum quantity lubrication method

The climate change packages have strict regulations to reduce fuel consumption, costs, and carbon emissions in vehicles. Automobile manufacturers tend to utilize compacted graphite iron (CGI) in vehicle engine parts due to these regulations and rising engine performance needs. However, the difficulty of CGI machining and the sustainability problem during machining are barriers to its broad application in the automobile sector. In this study, nano molybdenum disulfide (nMoS2) reinforced nanofluid-assisted MQL (nMoS2-NMQL), multi-walled carbon nanotube (MWCNT) reinforced nanofluid-assisted MQL (MWCNT-NMQL) and nMoS2/MWCNT reinforced hybrid nanofluid-assisted MQL (HNMQL) cutting conditions were used for the first time in the milling of CGI material and machining performance was investigated in terms of cutting forces, cutting temperature and surface roughness. In addition, for the first time in the milling of CGI material, sustainability assessment and optimization in terms of carbon emissions and total machining cost have been carried out using non-dominant sequencing genetic algorithm II (NSGA-II) and technique for order of preference by similarity to ideal solution (TOPSIS). Using the MWCNT-NMQL cutting condition reduced the cutting temperature, resultant force, surface roughness, carbon emissions amount, and total machining cost by 38.2%, 54.5%, 57.6%, 7.6%, and 24%, respectively. The sustainability optimization conclusion was that MWCNT-NMQL cutting condition, cutting speed values between 90 and 93 m/min, and feed values between 0.11 and 0.117 mm/rev should be used in order to obtain the values closest to the optimum result for an improved and sustainable CGI milling process.

Design and fabrication of new oblique gradient cemented carbide tool material for inhibiting the initiation of thermal crack

Compacted graphite iron (CGI) is the preferred material for engines at present. However, in the process of intermittent cutting CGI, the tool is prone to produce thermal cracks, resulting in tool chipping failure. The initiation of thermal crack must be inhibited to solve this problem fundamentally. Therefore, a new idea of designing oblique gradient tool was presented, including selecting appropriate gradient tool material and designing accurate gradient direction angle. According to the proposed design criteria of the tool, five layers of WC-Al2O3 gradient tool materials were designed, so that the thermal conductivity and thermal expansion coefficient of gradient materials were increased along the direction of thermal crack propagation, thus effectively alleviating the concentration of thermal stress. According to the thermal crack initiation area of the tool for milling CGI, the gradient direction angle of the tool was accurately designed to be 71.6°. The accurately designed oblique gradient tool can inhibit the initiation of thermal cracks by reducing thermal stress concentration on the tool, thus preventing the tool breakage failure. The new designed oblique gradient cemented carbide tool TDA-X with excellent cutting performance was successfully fabricated, and the inhibition effect of TDA-X on thermal crack initiation was verified by experiment. The result showed that TDA-X remarkably inhibited the initiation of thermal cracks in the tool much better than the non-oblique gradient tool TDA and the commercial coated carbide tool, thus avoiding the tool chipping, greatly prolonging the tool life and ensuring the quality of machining surface. The successful fabrication of this tool was of great significance to the efficient machining of CGI, and opened up a new idea for the research and development of tools with high cutting performance.

Tool-chip contact characteristics during micro-cutting of compacted graphite iron (CGI) with textured tools

During the machining of compacted graphite iron, there will be strong friction at the tool-chip interface. The iron matrix is easy to bond with the rake face, which will affect the processing quality and efficiency. Processing micro-texture on the tool surface is an effective method to improve the performance of the cutting tool. In this paper, the micro-pit texture is prepared in the bonding area and the sliding area of the tool surface for cutting experiments to explore the influence of texture location on tool-chip contact characteristics, based on the wear area of the non-textured carbide tool surface. The optimal ranges of texture parameters are determined based on the response surface methodology. The cutting experiment results show that the position of micro-texture determines the performance of the micro textured tool. The micro-texture can change the contact status of the tool-chip, improve the anti-adhesion, and reduce the friction of the tool. The predictions of the statistical model showed that the distance from cutting edge has a great influence on cutting performance. The optimized micro-texture is positioned at a distance ranging from 40 to 52 μm from the cutting edge, and the spacing of texture is 47–70 μm.

Modulation-assisted machining of compacted graphite iron with coated carbide tool in dry condition

Compacted graphite iron (CGI) is a new material replacing conventional gray cast iron (FGI) for diesel engine block applications due to its superior mechanical properties. However, widespread adoption of CGI is hindered by its poor machinability, which is reflected by the rapid tool wear especially at higher cutting speeds. In current industrial practice, CGI is usually machined with coated carbide tools at low to medium speeds (< 200 m/min). This study investigates the effect of modulation-assisted machining (MAM) on tool wear in dry turning of CGI with coated carbide tool. A new MAM turning setup is implemented for conducting the longitudinal turning experiments. Tool wear, cutting forces and tool temperature are characterized for both conventional machining (CM) turning and MAM turning at three cutting speeds: 150, 250 and 350 m/min. The results show wear reduction by MAM is not significant at the low cutting speed (150 m/min), but it is quite significant at the higher cutting speeds (250 and 350 m/min). The cutting force and temperature results can be well correlated with the wear results, revealing the dependency of the forces and temperature on the tool wear and the severity of iron adhesion. This study demonstrates the potential of MAM in enhancing the productivity of machining CGI with the coated carbide tool. The results are also useful for better understanding the wear mechanism in cutting CGI with the coated carbide tool.

Wear Study of Cubic Boron Nitride (cBN) Cutting Tool for Machining of Compacted Graphite Iron (CGI) with Different Metalworking Fluids

Due to its desirable mechanical properties, compacted graphite iron (CGI) has been used to replace conventional gray cast iron (CI) in various applications, such as automotive engine blocks and cylinder heads. However, the poor machinability of CGI can lead to excessive tool wear and consequently high manufacturing costs. Various strategies have been developed to improve the machinability of CGI, including optimizing machining parameters and the development of novel metalworking fluids. In this study, machining of CGI was conducted using cubic boron nitride (cBN) tools under different cutting speeds, with both soluble and full-synthetic water-based metalworking fluids at different levels of sulfur addition and water dilution. The effects of the metalworking fluids on the tool wear behavior were examined. Results showed that at 200 m/min cutting speed, the soluble metalworking fluid at 4% dilution and 0.3% sulfur compound exhibited the best performance, with a cutting distance reaching 23.8 km. In contrast, the least effective soluble metalworking fluid at 9% dilution and 0.3% sulfur compound resulted in a 28.6% decrease in the cutting distance (17.0 km) compared to the best one. At a higher speed (300 m/min), the cutting distance for all metalworking fluids dropped to less than 6.0 km, with the full-synthetic metalworking fluid showing the shortest cutting distance of 4.8 km.

Machinability improvement of compacted graphite irons in milling process with supercritical CO2-based MQL

Compacted graphite iron (CGI) has become one of the most potential and promising materials for diesel engines contributing to automotive industry applications because of its outstanding mechanical properties over flake graphite iron (FGI). However, the poor machinability of CGI has hindered it to be widely employed in potential automotive industry. In this paper, a supercritical CO2-based MQL technique was introduced to improve the machinability of CGI. The machinability of CGI was systematically evaluated considering the cutting force, cutting temperature, surface integrity and tool wear under various cutting parameters (cutting speed, feed rate, depth of cut) and machining atmospheres (i.e., dry, supercritical carbon dioxide (ScCO2), supercritical CO2-based minimum quantity lubrication with oil-on-water droplets cutting fluid (ScCO2-MQL)) compared to FGI and nodular graphite iron (NGI) in the milling process. The results show that among three machining atmospheres, the lowest values regarding cutting force, cutting temperature, and surface roughness values are obtained under the ScCO2-MQL atmosphere. Furthermore, the tool wear mechanisms were revealed to be abrasion wear and adhesion wear. The ScCO2-MQL exhibited excellent superiority in cutting force and temperature, surface integrity, and tool life compared to dry and ScCO2 conditions due to its outstanding cooling and lubricant effects. The results demonstrated that using the advanced ScCO2-MQL technique can substantially improve the machinability of the compact graphite cast irons.

Research on different cooling methods in the machining of CGI and GCI

Gray cast iron (GCI) is the most common material used in diesel engine blocks. Compacted graphite iron (CGI) is a new material for high-power diesel engine blocks, which can allow an increase in the cylinder-pressures and achieve better fuel economy and a higher power output. However, the difficult machinability of CGI seriously hinders its large scale production. At high-speed machining, the tool life of machining GCI is 10–20 times that of GCI. To improve the tool life of machining CGI, this work focuses on the influence of uncooled, cutting fluid cooled and liquid nitrogen (LN2) cooled methods in the machining of CGI and GCI. The results indicate that LN2 cooled method can effectively reduce the highest temperature and temperature diffusion in the processing. Furthermore, for machining CGI, LN2 cooled method increases the tool life by 192.6% and 66.7% compared with uncooled and cutting fluid cooled methods, respectively. However, for machining GCI, LN2 cooled method plays a negative role. For CGI and GCI, the wear modes of the tools are similar, which are mainly material adhesion, coating wear and adhesion and built-up edge.

A strategy to improve tool life by controlling cohesive failure in thick TiAlN coating during turning of CGI

Beside machining condition and parameters, coating properties is one of the main factors affecting tool performance and wear pattern. These properties include coating hardness and elastic modulus, adhesion to substrate, roughness, defects, and most importantly residual stress. In general, the properties of a physical vapor deposition (PVD) coating can be controlled by adjusting deposition parameters such as substrate bias voltage and nitrogen pressure. Therefore, a coating can be tailored to withstand a specific wear mode which is dominant in machining the workpiece material. In this work a strategy is suggested to decrease adhesion wear and formation of built-up edge during machining of compacted graphite iron (CGI). This strategy involves deposition of thick TiAlN coating with low residual stress in order to promote cohesive failure within the coating. For this purpose, monolayer Ti40Al60N PVD coatings with high thickness (5–10 μm) were deposited under various deposition parameters. A comprehensive coating characterization was done using scanning electron microscope (SEM), X-ray diffraction (XRD), nanoindentation, and scratch test. Tool life of selected coatings were then tested under dry finishing of compacted graphite iron, and wear pattern was investigated with optical and scanning electron microscope. The results showed that coating under low compressive residual stress is successful in reducing sticking and built-up edge formation. This phenomenon happens with gradual cohesive failure of the coating under adhesion wear, resulting in a higher tool life under adhesive wear.

Research on machining compacted graphite iron under oil-on-water cooling and lubrication conditions based on modified material model

Oil-on-water (OoW) techniques, including external OoW sprayed to both the rake face and flank face (EOoWrf), as well as cryogenic air mixed with OoW (CAOoW), improve the machinability of compacted graphite iron (CGI). This paper proposes a modified material model for RuT400 CGI cutting, based on flow softening and weak thermal softening effect, as observed during split-Hopkinson pressure bar tests. Employing a modified material model and Cock-Latham damage model, a thermo-mechanical coupled finite element (FE) model, for RuT400 cutting, is presented. The simulations, considering dry cutting, EOoWrf, and CAOoW, are conducted for the purpose of revealing the causes for the RuT400 difficult-to-cut property and for establishing how the mechanism of OoW can improve cutting performance. The results show that the effective stress, required to form chip segments in RuT400 machining, is much lower than in hardened steel, so RuT400 is more likely to form a serrated chip. In dry cutting, the chip bottom surface is subject to high strain and temperature, leading to the work-material phase transformation, followed by aggravating adhesive and abrasive wears. Although EOoWrf has little influence on chip morphology and effective stress, it reduces the temperature and strain on chip bottom surface by reducing friction, thus suppressing the occurrence of phase transformation. Due to low friction and high heat exchange, CAOoW produces the lowest tool-chip interface temperature and minimal adhesive wear. For high-speed cutting of RuT400, compared to dry cutting, EOoWrf and CAOoW can effectively reduce cutting forces and maintain the tool temperature in a lower range, where low friction on tool-chip interface plays a key role. The proposed FE model can be used in the future to improve CGI’s machinability, by changing cooling parameters, tool geometry/material, and other machining variables.

Investigation of Drilling Machinability of Compacted Graphite Iron under Dry and Minimum Quantity Lubrication (MQL)

Compacted graphite iron (CGI), which is used as a potential material in the auto industry, is a hard-to-machine material for the different minor elements and for the geometry of graphite with grey cast iron. The machinability of CGI in the drilling process was investigated with a 4-mm diameter fine-grain carbide twist drill under four lubrication conditions, dry (no compressed air), dry (with compressed air), MQL 5 mL/h, and MQL 20 mL/h in this paper. The maximum flank wear, types of wear, and cutting loads were studied for identifying the wear mechanism in drilling of CGI. The tool life in the four experiments of CGI drilling is 639 holes, 2969 holes, 2948 holes, and 2685 holes, respectively. The results showed that the main wear mechanism in drilling of CGI is adhesion and abrasion. Carbon, which originates from the graphite of CGI, can improve the lubrication in the drilling process by comparing with MnS in drilling grey cast iron. The thrust force and torque are more than 1000 N and 150 N*cm after 2700 holes in CGI drilling. Drilling of CGI under dry conditions (with compressed air) and MQL 5 mL/h is feasible.

Effects of cutting fluid with different pressures and jetting paths on machined surface integrity in cutting compacted graphite iron: An experimental study

Compacted graphite iron is one of the existing structural materials for automobile engines that is difficult to machine using the conventional machining method. This article focuses on the effects of cutting fluid with different pressures and jetting paths on machined surface integrity in the machining of compacted graphite iron. The machined surface integrity is compared between dry cutting and 6 MPa wet cutting at cutting speeds of 100–500 m/min and the influences of the cutting fluid jetting paths (pouring, 2–6 MPa) along the tool flank face and rake face on the machined surface integrity are evaluated. Microstructure, roughness, work hardening, and residual stresses of the machined surface are also analyzed. The results suggest that cutting fluid can reduce surface defects and improve the machined surface finish. Of note, the roughness reduction effect decreases with an increase in fluid pressure; the roughness Ra of 6 MPa wet cutting with the cutting fluid jetting along the flank face is 0.2–1.56 µm lower than that seen with dry cutting in the cutting speed range of 100–500 m/min. The degree of hardening in 6 MPa wet cutting is 11%–19% lower than in dry cutting, and cutting fluid enhances the formation of residual compressive stress in the machined surface which reaches its maximum at 3 MPa.

Investigation of the performance of ceramic tools of alumina doped with magnesium oxide in the dry machining of compacted graphite iron

In the search for materials to serve the automotive industry, mainly in the application in engine blocks, the most interesting material is the vermicular cast irons, which must have superior physical and mechanical properties. However, one of the disadvantages for the industry is the difficulty of machining this class of materials, due to its microstructure. It is important for the process of machining to understanding the relation between the cutting tools and the process parameters. as their rapid wear and crash of the cutting tool causes many machine stops, which is directly impact the high production costs. The research for viable alternatives to improve the machinability of compacted graphite iron (CGI), the ceramic inserts are in highlighted. The objective of this study was to dry turning the vermicular cast iron of class 450 with a ceramic cutting tools of alumina doped with magnesium oxide, developed on an experimental scale for machining. For the machining test, the following conditions was used: cutting speeds (Vc) of 200 and 500 m min−1; feed rate (f) of 0.1 and 0.3 mm/rot−1 and depth of cut (doc) of 0.5 and 1.0 mm. For the process of machining was used a CNC machining center and compare the variables: flank wear (cutting tool), roughness Ra and Rt (workpiece). The wear of the cutting tools was analyzed using a scanning electron microscope (SEM) equipped with (EDS). This work obtained the best results using the condition: Vc of 200 m min−1, f 0.1 mm, doc 1.0 mm showed the lower value of flank wear and roughness. The main wear mechanism observed was abrasion for all the conditions analyzed.

Effect of coating thickness on the tool wear performance of low stress TiAlN PVD coating during turning of compacted graphite iron (CGI)

Compacted graphite iron (CGI), with its superior mechanical properties, is a promising candidate to replace grey cast iron in the automotive industry. However, the low machinability of CGI compared to grey cast iron, has made this transition difficult. Built-up edge formation, combined with abrasive and adhesive wear is the main problem of CGI turning at moderate cutting speeds. In this study, a low compressive residual stress PVD coating was developed using newly introduced super fine cathode (SFC) technology. The main advantage of low compressive residual stress SFC coating, is the possibility of increasing its thickness compared to the commercial range of arc coatings (usually with a thickness within 1–5 µm) without any process induced spallation of the coating layer. Therefore, three different low compressive residual stress Ti40Al60N coatings with thicknesses of around 5, 11 and 17 µm were deposited. The coatings were characterized by X-Ray diffraction, scratch test, ball crater test and nanoindentation. Furthermore, the cutting performance of the coated inserts was investigated in finish turning of CGI. An improvement of around 35% tool life is achieved for the cutting tool with the low residual stress thick coating compared to the commercial benchmark. Progression of flank wear was studied by means of TEM, SEM-EDS, optical microscopy and 3D wear measurement. Chip undersurface morphology as well as cross-sectional studies of the chip structure were performed. This was combined with analysis of the workpiece surface. Evaluation of the results obtained would help to achieve a better understanding of the wear mechanism and built-up edge formation of the studied coatings. According to the recorded data, coating thickness significantly affects cutting tool wear behavior and the mechanical properties of the coatings. A certain thickness range, specifically within 10 µm was found to be optimum.

Changes of cutting performance under different workpiece removal volume during normal speed and high speed milling of compacted graphite iron

Compacted graphite iron (CGI) possesses good mechanical properties and thermal properties in comparison to gray cast iron (GCI) and spherical graphite spheroidal cast iron (SGI). However, the machinability of CGI is poor, and the cutting tool wear is very fast during the machining of CGI, which can lead to the changes of the cutting force and the machined surface integrity. The present study investigates the influence of workpiece material removal volume (Q) on the cutting tool wear, cutting force, machined surface roughness, and morphology under normal (V = 134 m/min) and high cutting speed process (V = 800 m/min). The result shows that Q had a more obvious effect on the value of cutting forces when the cutting speed was 800/min, while the effect was slight when the cutting speed was 134 m/min. However, the effect of Q on the direction of the resultant cutting force was small, and the direction of the resultant cutting force was more likely to be affected by the increase of cutting speed. The effect of Q on the machined surface roughness Ra and Rz was different between normal and high cutting speed process. Dark and bright areas can be found on the machined surfaces obtained under the normal speed cutting process, and the ratio of dark area to total area P can be used as a parameter to measure the machined surface quality. The flank wear of the cutting tool used for normal speed cutting process can be divided into brighter cemented carbide region and darker coating wear region due to the low wear rate, while only the brighter cemented carbide wear region was found on the tool used for high cutting speed process. Cracks could be found on the cutting tool used for both normal cutting speed process and high cutting speed process. However, the crack propagation appeared faster under high cutting speed process, chipping was formed near the crack. The depth and width of the crater wear under normal cutting speed process were larger than that under high cutting speed process.

Effect of cryogenic high-speed milling of compacted graphite iron using indirect spray system

Compacted graphite iron (CGI) is replacing conventional cast iron (CI), especially in the automotive industries for the manufacture of a high-performance and light-weight diesel engine due to its outstanding mechanical properties as compared to the conventional CI. Nevertheless, the pace of replacement is still slow because of the low machining performance encountered by the industries during high-speed machining of CGI. Thus, in this study, the effect of various cooling-lubrication strategies in high-speed machining of CGI using uncoated carbide inserts was investigated. Results showed that the combination of indirect cryogenic cooling and minimum quantity lubrication (MQL) improves the tool life by 26% compared to conventional flood coolant strategy. The result has been clarified by monitoring the cutting force and the sound pressure for each cooling/lubrication strategy.

Dry and minimum quantity lubrication high-throughput drilling of compacted graphite iron

ABSTRACTThis research studies the sustainable and high-throughput drilling of compacted graphite iron (CGI), a high strength, lightweight material for automotive powertrain applications. CGI drilling experiments were conducted using a 4 mm diameter coated carbide drill at 26.5 mm/s feed rate. In two repeated tests under three lubrication conditions: dry, dry with through-the-drill compressed air, and through-the-drill minimum quantity lubrication (MQL), the drills were able to produce a maximum of 1,740, 3,150 and 2,948 holes, respectively, before the breakage of the drill. The Joule–Thomson effect due to the expansion of high pressure air from through-the-drill holes at the drill tip, chip shape, chip size and chip speed are investigated. Flank wear of the drill cutting edge is measured and results are correlated to drill life. Results indicate that dry machining of CGI is technically feasible. Chip evacuation and advanced tool cooling are important factors that affect drill life for high-throughput sustainable dry drilling of CGI.

Effects of high-pressure cutting fluid with different jetting paths on tool wear in cutting compacted graphite iron

Compacted graphite iron (CGI) is one of the structural materials of internal combustion engines. CGI is very difficult to fabricate by machining. In this paper, on the one hand, dry cutting and cutting fluid with different fluid pressures (pouring, 3–6MPa) are used in machining of CGI to investigate the effects of fluid pressure on tool wear at different cutting speeds (100–300m/min). On the other hand, cutting fluid is jetted in different directions (along rake face and flank face of cutting tool) to investigate jetting path's influences on the wears in the rake face and flank face of cutting tool. Wear morphologies of the cutting tool are analyzed with a 3D display system and scanning electron microscopy (SEM). Wear-reducing effect of the high-pressure (6MPa) cutting fluid is compared with those in the dry cutting, pouring fluid cutting, and low-pressure fluid cutting (3MPa). Influences of fluid pressure variation on cooling and lubricant of cutting fluid in machining are discussed in the final. Results show that the high-pressure cutting fluid has excellent effect on reducing tool wear for both jetting along flank face and rake face of cutting tool. The wear-reducing of cutting tool will be more obvious with the increase of the fluid pressure. Compared with the jetting along rake face, the cutting fluid jetting along flank face can more effectively reduce flank wear. Wear-reducing effect of high-pressure cutting fluid at higher cutting speed is more remarkable than that at lower cutting speed. Crater wear is the main mode on rake face and adhesive and abrasive wear on flank face due to high cutting temperature and hard particles in CGI. The high penetration ability which increases workpiece-coolant contact area and the high convective heat transfer coefficient due to forced heat convection process of the high-pressure cutting fluid enhances its cooling and lubrication effect in machining.

A Preliminary Machinability Study of Flake and Compacted Graphite Irons with Multilayer Coated and Uncoated Carbide Inserts

Compacted graphite iron (CGI) is considered to be one of the most promising materials for many automotive applications and has adopted by some automotive companies. Comparing to widely used flake graphite iron (FGI), CGI has superior physical and mechanical properties. The main drawback of this material is known to be its poor machinability. A preliminary study on flank and crater wear was conducted by dry turning experiments with both FGI and CGI using uncoated WC tools and multilayer coated tools. Confocal Laser Scanning Microscopy (CLSM) was used to investigate worn areas of the cutting tools. Despite of the reported poor machinability of CGI, our turning experiments showed that both flank and crater wear were higher for FGI compared to CGI when using uncoated WC tools at the cutting speed of 150, 250 and 350 m/min. An unexpected adhesion layer on the flank side of carbide inserts was observed when turning CGI, which believe to protect the flank surface and reduce flank wear. The adhesion on rake face concentrated on the cutting edge when turning CGI while the sporadic attachments of work materials are observed throughout the rake interface with FGI. In contrast, no adhesion layer was presented when both FGI and CGI were turned using multilayer coated tools, which yielded more flank and crater wear when turning CGI.

Influence of Lead Angle Variation on the Coated Carbide Inserts Wear when Milling CGI and Modeling by Artificial Neural Networks and Regression Analysis Method

The aim of this research is to investigate the influence of lead angle, cutting speed and the maximum chip thickness on tool wear in face milling process of compacted graphite iron. Tool failure modes and wear mechanisms for all cutting tools were examined in respect of various cutting parameters and were evaluated on the base of the flank wear. SEM analyses of the cutting inserts were performed and experimental results have been modelled with artificial neural networks (ANN) and regression analysis. A comparison of ANN model with regression model is also carried out. Predictive ANN model is found to be capable of better predictions for flank wear within the range used in network training. The R2 values for testing data were calculated as 0.992 for ANN and 0.998 for regression analysis, respectively. This study is considered to be helpful in predicting the wear mechanism of the coated carbide insert in the machining of compacted graphite iron.