Machining Conditions Research Articles

The Effect of High-Pressure Jet Cooling on Surface Roughness, Cutting Force and Chip Formation of Ti-6Al-4V ELI in High-Speed Turning

In the machining of difficult-to-machine metals, such as titanium-based alloys, the delivery of coolant with high pressure can increase machining efficiency and improve process stability through more efficient chip breaking and better cooling. Proper selection of machining conditions can also increase the productivity of the process by reducing cutting forces and tool wear rate. To investigate the effect of high-pressure jet cooling (HPJC) on cutting force, surface roughness, and chip formation of Ti-6Al-4V ELI in high-speed turning, Grade 5 Ti ELI turning tests were carried out under coolant pressure of 200 bar. A lower pressure of 6 bar was also used in this study to compare the results of the pressure change. In general, surface roughness increased as the feed rate increased at constant cutting speeds in experiments with both 6 bar and 200 bar coolant pressures. Even though 200 bar pressure provided a better cooling thus reduced cutting force, and tool wear rate; the surface roughness values ​​obtained from the experiments with 200 bar were relatively worse than the experiments with 6 bar pressure. It was also seen that 200 bar coolant pressure may result in instabilities in the turning process in terms of chip geometries and formations.

Towards understanding the cutting temperature in ultrasonic vibration-assisted drilling based on the dynamic contact characteristics between the cutting edge and workpiece

Compared with conventional drilling (CD), ultrasonic vibration-assisted drilling(UVAD) is experimentally proven a promising method to reduce the cutting temperature. But sometimes cutting temperature also becomes higher in UVAD than in CD. To further make clear the cutting temperature mechanisms in UVAD, this study aims to study the effect of tool’s ultrasonic vibration on the cutting heat generation and heat dissipation at a relatively micro level. Firstly, drilling experiments are designed to explore the variations of cutting heat under different ultrasonic vibrations. Then, to analyze the influence of ultrasonic vibration on the cutting heat theoretically, a kinematic model is developed to describe the dynamic contact between the cutting edge and workpiece in UVAD. Besides, a cutting heat analysis model based on the contact characteristics in UVAD is proposed to study and compare the variations of cutting heat generation. The effect of ultrasonic vibration on the cutting heat generation, heat dispassion, and the resultant cutting temperature under different machining in UVAD conditions are discussed. It is indicated from the theoretical analysis that more cutting heat tends to be produced due to the significantly increased sliding velocity on the cutting edge-workpiece interface when the ultrasonic vibration is applied. The analysis agrees with the experimental results that the cutting temperature in dry UVAD is higher than in dry CD. But on the other hand, ultrasonic vibration can also improve the lubrication and cooling effect under appropriate machining conditions, which is beneficial to the reduction in cutting temperature. The investigation shows the multifaceted influences of ultrasonic vibration on the cutting temperature in the drilling process in detail, which provides a reference for UVAD parameter optimization.

Characterisation of the Tensile and Metallurgical Properties of Laser Powder Bed Fusion-Produced Ti-6Al-4V ELI in the Duplex Annealed and Dry Electropolished Conditions

Metal additive manufacturing is becoming a popular manufacturing process in industries requiring geometrically complex components, part consolidation, and reductions in material waste. Metals manufactured via additive manufacturing processes such as laser powder bed fusion typically exhibit process-induced defects, material inhomogeneities, and anisotropy in terms of mechanical properties. Post-processing techniques such as heat treatments and surface finishing have been touted as approaches for improving these materials. Although various post-processing techniques have been proposed, the optimal post-processing route remains an active area of research. This research investigates Ti-6Al-4V ELI produced using laser powder bed fusion and post-processed via different routes. The materials in the stress-relieved and duplex annealed material conditions as well as dry electropolished and machined surface conditions were characterised. The duplex annealed Ti-6Al-4V ELI material showed improvements in ductility but at reduced strength when compared with the material in the stress-relieved condition. The microstructure of the duplex annealed material shows little evidence of process-induced defects and features and consists primarily of elongated and acicular α in a lamellar structure with intergranular β and exhibits uniform microhardness throughout the material. A reduced surface roughness due to surface finishing resulted in an improved reduction in area. This research highlights the effects of post-processing treatments and their ability to improve the properties of laser powder bed fusion-produced Ti-6Al-4V ELI.

A sensor-based monitoring approach to predict surface profile of vibration-assisted atomic force microscopy (AFM)-based nanofabrication

The vibration-assisted atomic force microscope (AFM)-based nanomachining offers a promising opportunity for low-cost nanofabrication with high tunability. However, critical challenges reside in advancing the throughput and the quality assurance of the process due to extensive offline experimental investigations and characterizations, which in turn hinders the wide industry applications of current AFM-based nanomachining process. Hence, it is necessary to create an in-process monitoring for the nanomachining to allow real-time inspection and process characterizations. This paper reports a sensor-based analytic approach to allow real-time estimations of the AFM-based nanomachining process. The temporal-spectral features of collected acoustic emission (AE) sensor signals are applied to predict the depth morphology of nanomachined trenches under different machining conditions. The experimental case study suggests that the most significant frequency domain information from AE sensor can accurately predict (R-squared value around 92%) the nanomachined depth profile. It, therefore, breaks the current limitation of characterization tools at the nanoscale precision level, and opens up an opportunity to allow real-time estimation for quality inspection of vibration-assisted AFM-based nanofabrication process.

Влияние деформаций инструмента и заготовки в направлении скорости резания на динамику обработки

Numerous studies were devoted to studying the dynamic cutting system considered in combination of the tool and the workpiece sub-systems interacting through a dynamic connection formed by the machining process. Dynamic coupling is simulated by the cutting forces represented in the system state coordinates, which determines the system properties. Several models were proposed to describe the dynamic connection reflecting various experimentally observed effects and contributing to the self-excitation. Regenerative effect of the tool trace left on the workpiece at the previous revolution was considered. The regenerative effect was studied on the basis of assumption that the retarding argument in the forces description was remaining unchanged. The paper studies the regenerative effect influence on dynamic properties of the cutting process taking into account (unlike the known works) the retarded argument dependence on the tool deformation displacement. This could fundamentally change properties of the system under consideration in the unity of stability and the attracted formed deformation displacement sets (limit cycles, invariant tori and chaotic attractors). Results of the mathematical simulation are presented taking into account the regenerative self-excitation, where the retarded argument is the state coordinates function. Bifurcation diagrams of attracting sets of the deformation displacements are considered, and conditions for formation of their superlow-frequency components of the complex spatial-temporal structure are discussed. Research results are aimed at determining the machining conditions based on requirements for ensuring the specified quality of parts manufacturing using the longitudinal turning example.

Investigation of machinability indicators during sustainable milling of 17-4PH stainless steel under dry and MQL environments

17-4PH steel, which has the perfect combination of corrosion resistance and high mechanical properties, is especially preferred in defense and aerospace applications, but its machinability is poor. Thus, an extensive research has been conducted on its milling under sustainable cutting regimes (dry and minimum quantity lubrication_MQL) to contribute to both more efficient use and sustainable machining. First, the changes in resultant cutting force ( Fr), the average surface roughness ( Ra), the mean roughness depth ( Rz) and total energy consumption ([Formula: see text]) were investigated after the experiments performed by applying the L18 orthogonal array. Subsequently, machining conditions were optimized for the minimization of machinability indicators with the Taguchi-based grey relational analysis technique. Finally, the predictive models for these indicators were developed by regression analysis. The order of importance for Fr and [Formula: see text] was the depth of cut and feed, while for Ra and Rz this ordering was found to be feed rate and cutting regime. Short curved chips formed in MQL cutting regime contributed positively to the minimization of the considered machinability indicators. Although the energy consumption due to spindle speed increased with increasing cutting speed in dry cutting environment, the decrease in material strength resulted in a decrease in [Formula: see text]. Since the cooling effect of MQL reduces the cutting temperature, material softening and thus the expected decrease in cutting resistance could not be achieved, so the decrease in [Formula: see text] was not as much as dry cutting. Optimum machining conditions were determined as MQL cutting regime, the cutting speed of 120 m/min, the cutting depth of 0.5 mm and feed rate of 0.05 mm/rev. The determination coefficients of the predictive models developed by regression analysis showed that these models can be used safely in up milling.

Simulation of Mechanical Response in Machining of Ti-6Al-4V Based on Finite Element Model and Visco-Plastic Self-Consistent Model

The predictions of mechanical responses (stress–strain variations) in the machining of Ti-6Al-4V alloy are important to analyze the deformation conditions of machining to optimize the machining parameters and investigate the generation of a machined surface. The selection of a constitutive model is an essential factor that determines the deformation behavior in the machining simulation model. In this paper, two constitutive models of a modified Johnson–Cook (JC) equation and visco-plastic self-consistent (VPSC) model were used to investigate the stress–strain evolutions in the machining process of Ti-6Al-4V. A finite element (FE) machining model was established, considering the influences of grain refinement and deformation twins, based on a modified JC equation. The VPSC model was fitted based on the macro-strain rate sensitivity of the JC equation. The prediction results of the stress–strain curves of two models were compared, and their validities were further proved. The results show that flow stress hardening and inhomogeneities are caused by multi-scale grain refinement during the machining process of Ti-6Al-4V. Five slip deformation modes and one compressive twinning mode were activated in the VPSC model to be consistent with the macro-deformation behavior predicted with the FE model. The validations show the effectiveness of the modified JC equation, considering microstructural changes and the fitted VPSC model, in predicting dynamic behavior in the machining process of Ti-6Al-4V. The results provide two aspects of macro-deformation and polycrystal plasticity to elucidate the stress variations that occur during the machining of Ti-6Al-4V.

Experimental investigation to optimize machining parameters for super duplex stainless steel in spark EDM using die-sinking and MQL system

The current experimental work discusses the electric discharge machining (EDM) of super duplex stainless steel with conventional die-sinking and minimum quantity lubrication (MQL) approach. The dielectric used in the conventional die-sinking EDM process is kerosene, and sunflower oil with air mixture is used in MQL-type machining conditions. The solid-type alpha brass electrodes of diameter 10 mm were used for machining. The most prominent input variables like pulse time (OFF and ON) and discharge current (varied at 3 levels) were selected, and Taguchi's L9 orthogonal array design was selected for experimentation. The responses like electrode wear rate (EWR), hole circularity (HC), material removal rate (MRR), and surface roughness (SR) were analyzed. The output results obtained from the experimental trials were analyzed using S/N ratios and analysis of variance (ANOVA). The most contributing input parameter affecting the responses like SR, HC, MRR, and EWR outputs were analyzed. The results showed that the optimum machining conditions were obtained at L3 and L9 levels for conventional die-sinking and MQL-type machining conditions, respectively. Out of three varying input parameters, pulse time (OFF) is the most contributing factor in deciding various responses. The same has been confirmed by ANOVA analysis. The theoretical prediction of experimental data was made using the Fuzzy logic approach, and the best optimal level is found out individually for all four responses.

Pareto Analysis of Machining Factors Significance When Turning of Nickel-Based Superalloy Inconel 718

Nickel superalloys occupy a reasonably broad niche in the industry. One of this group’s most common and well-known alloys is Inconel 718. Parts from Inconel 718 are used in aerospace, energy, automotive, and some other vital industries, which creates a demand for research and improvement of the machining conditions of this alloy. This article is devoted to the systematization and generalization of the accumulated experience of machining of Inconel 718 at turning operation. The research methodology is based on the Pareto distribution. In the study, more than 50 articles devoted to turning Inconel 718 were analyzed. The tool materials, methods, and types of coating used in turning Inconel 718 were analyzed. Finite element method modeling of processing processes has been considered. The trends in the selection of cutting parameters and the geometry of the cutting tool and finite element method modeling of processing processes have been considered. Lacunae for promising future research were formulated.

Study regarding the influence of process conditions on the surface topography during ultra-precision turning

During ultra-precision turning, the turned surface “copies” a large amount of turning process condition information. In this study, the path equations were combined with the turned surface topography equations, and the condition parameters were superimposed to develop theoretical surface topography models for ultra-precision turned end face, cylindrical, conical, and spherical surfaces influenced by turning condition parameters. The models were validated through a series of experiments. The turned surfaces were analyzed in the spatial frequency domain, and the corresponding relationship between the frequency information in the time domain and the spatial domain was obtained. The corresponding area power values were calculated to determine the quantitative impact of condition parameters on surface roughness. According to the calculation results, the surface roughness under the influence of process conditions was positively correlated with the amplitude of turning process condition parameters. The topography of the simulated surfaces was consistent with that of the experimental surfaces, and the trend of area power values corresponding to different turning process condition parameters in the simulated surface topography was consistent with the experimental results. It was proved that the established relational model, which determined the qualitative and quantitative influence of machining conditions on the machined surface, is tenable. This study established a mapping relationship between the machining condition parameters and their impact on surface topography, and also further provided a foundation for the digitization of ultra-precision machine tools.

An analysis of different cutting strategies to improve tool life when machining Ti-5Al-5V-5Mo-3Cr alloy

Ti-5Al-5V-5Mo-3Cr is a near-beta titanium alloy generally employed in the production of high strength parts. Its high tensile strength and light weight, compared to Ti-6Al-4V, make it a suitable choice for landing gear parts and advanced structural components. However, due to its high strength-to-weight ratio, mechanical strength at elevated temperatures, and oxidation resistance, the cutting zone experiences high cutting temperatures, which, combined with a low rate of heat transfer during the machining process, consequently, generates stress, causing premature tool failure. In this paper, several distinct experimental approaches were applied, different machining condition combinations (tools and coolants) were compared, cutting tool wear performance was diagnosed, and, finally, optimized cutting parameters were identified. The main objective of this research was to understand how these parameters affect tribological behavior when machining Ti-5Al-5V-5Mo-3Cr. One of the PCD tools possessed the longest life under high pressure coolant of 28 %–170 % longer than the other tool materials. The main wear mechanism was a combined abrasion, adhesion/attrition, diffusion, and oxidation. Optimizing cooling conditions can affect cutting forces substantially, minimizing residual stress, improving the surface roughness, and reducing the work-hardening during machining. Therefore, the results show that the combination of coolant and cutting tool material leads to longer tool life and improved surface integrity.

Influence of re-deposited nanoparticles on the surface elemental composition of femtosecond laser machined copper surfaces

Nanoparticles re-deposited during the laser machining process have been suspected to modify the intrinsic surface chemistry of machined metallic surfaces. However, only very few studies have focused on elucidating their effect. In this work, under two different machining conditions (laboratory air & controlled humid air), we fabricated laser-induced periodic surface structures, LIPSS, on polished Cu surfaces with three different amounts of re-deposited Cu nanoparticles to quantify how re-deposited Cu nanoparticles affect the surface chemistry of the machined samples. In carrying out these experiments, we demonstrate that the re-deposition of nanoparticles during laser machining is affected by the volume of the laser machining environment, which impacts the surface chemistry of laser-machined surfaces. Our results indicate that evacuation of the vacuum chamber before and after laser machining using a vacuum scroll pump did not affect the adsorption of carbonaceous molecules. Further, we present the effect of removing re-deposited nanoparticles through ultrasonic cleaning on the surface chemistry of the test surface. The cleaning exposes the LIPSS surface entirely to airborne carbonaceous species, resulting in a more significant increase in the total surface carbon content. Finally, we evaluated the quality of the nanoparticles generated during laser machining by assessing their stability to provide a first insight into the utility of those nanoparticles.

Reinforcing potential of MWCNTs on mechanical and machining performance of hot-pressed ZTA-MgO ceramic cutting inserts

A new generation cutting insert was manufactured by multi-walled carbon nanotube (MWCNT) reinforcement (0–0.25 weight percentage (wt%)) into zirconia toughened alumina (ZTA)- magnesium oxide (MgO) ceramic matrix using a powder metallurgy route. The hot-press sintering technique was used to compact the uniformly mixed ZTA-MgO-MWCNT powders, sintered at 1500 °C followed by morphological, mechanical and functional characterizations. The relative densities of the samples were between 98 % and 99 %. The mechanical properties of the matrix were improved up to 0.15 wt% MWCNTs. The highest microhardness was ~2366 HV0.5 for 0.15 wt% due to grain refinement by synergistic pinning between spinel (MgAl2O4) and MWCNTs. Similarly, the highest indentation fracture toughness was ~7.33 MPa.m1/2 for 0.15 wt% MWCNT content due to micromechanical interlocking mechanism from a combined effect of MWCNT size variation and inter-particle distance between MWCNTs featuring proper crack bridging and crack deflection. To function as a cutting insert, the sintered samples up to 0.15 wt% was selected and shaped according to SNGN120408 cutting tool geometry. For minimum cutting force with high surface roughness, the optimized parameters were observed as a cutting speed of 300 m/min, feed rate of 0.12 mm/rev and 0.2 mm depth of cut using the design of experiment technique while machining AISI 4340 steels. Furthermore, regression models were developed to correlate the machinability with machining conditions. The comparative study suggested that the significant improvement of cutting force (~26.4 %), surface roughness (~55.3 %) and tool life (~29.4 %) was achieved for ZTA-MgO-0.15 wt% MWCNT ceramic tool with respect to ZTA-MgO inserts depending upon self-lubrication phenomenon alongside with the retention of proper tool geometry for a longer tool life ~44 min. The morphological and Raman spectra analysis of the worn region justifies the self-lubricating phenomenon at the interface by breaking and rolling of MWCNTs.

Dynamometric cutting tool

The aim was to develop, manufacture and test a technically simple dynamometer for monitoring the cutting process during boring and turning. An S20R-SSSCR09 right-hand cutter was selected as a research object. To register the cutting force and vibration movements of the cutter tip in tangential and radial directions, the cutter was equipped with four KF5P1-10-400-A-12 strain gauges mounted according to a half-bridge scheme. The bending stiffness of the cutter in two directions was measured by a DOU-3-01 compression dynamometer and a DDP-10A dial indicator. The cutter natural frequency was determined by a vibrogram of damped bending vibrations. The dynamometric boring tool was tested on a DMG NEF 400 turning machine by turning a workpiece made of 20X steel, 79 mm in diameter with a 200 mm extension, at a spindle rotational frequency of 600 r/min, a cutting depth of 0.8 mm and a longitudinal feed of 0.103 mm/turn. According to the conducted review of modern turning dynamometers and their designs, strain gauging of cutting tools is the simplest technical solution when carrying out boring procedures. The bending stiffness of the cutter in tangential and radial directions comprised 0.6 and 1.058 N/μm, respectively. The conversion coefficients for displacements in these directions were 3.5 and 4.2 μm/V, respectively. The mutual influence of registration of radial on tangential and tangential on radial displacements was 7.7% and 2.8%, respectively. The obtained vibrograms showed that the turning process under the given machining conditions is accompanied by distinct auto-oscillations of the cutter with a frequency of 561 Hz. Therefore, strain gauging of cutting tools provides information in the form of vibrograms about the two most important parameters of the cutting process dynamics – force and vibration displacements. The main advantages of the presented dynamometric cutting tool include its design simplicity, possibility of manufacturing in laboratory conditions, low cost and insensitivity to temperature and axial feed force variations.

Propagation in Superconducting Niobium Rectangular Waveguide in the 100 GHz band

Rectangular waveguides that use superconducting materials for walls are expected to reduce transmission loss compared to normal metal waveguides. However, research on superconducting waveguides has been limited, particularly on the fabrication and measurement of physical models in the mm/sub-mm band. We attempted to fabricate a niobium (Nb) waveguide and measure its propagation. Because Nb is known to be a difficult-to-machine material, we searched for the best cutting tools and machining conditions. Consequently, we fabricated a waveguide with a surface accuracy of 0.3 µm rms using an end mill with a diameter of 1 mm. For the measurement of waveguide propagation, the resonator method was adopted, and the resonance characteristics were measured at room (298 K) and cryogenic (4.8 K) temperatures in the 100 GHz band. The resonance property at 298 K is consistent with the shapes predicted from literature-based conductivity. However, at 4.8 K, that of superconducting Nb is significantly changed. We used electromagnetic analysis to reproduce these properties, and the electrical conductivity and propagation loss were calculated. The conductivity and loss were computed as 1.8×1011 S/m and 0.05 dB/m, respectively. We observed a slight transmission loss and verified the effectiveness of the superconducting waveguides.

Performance evaluation of surface texturing on carbide tool under minimum quantity lubrication turning of aluminium alloy Al6061 using canola oil

Turning operation is considered an important material removal process and its performance depends largely on the machining parameters. This study presents the analysis of the effect of surface texturing on tool during MQL turning of Aluminium alloy Al6061 using canola oil. Minimum quantity lubrication possesses the benefits of flood lubrication as well as dry machining. Canola oil used in this study possesses good lubrication properties and its kinematic viscosity is 41 mm2/s at 40 °C. Tool texturing is in growing trend in the manufacturing industry and it has gained the attention of many researchers in the past few years. In this study parallel textured pattern is used in which the grooves are perpendicular to chip flow direction. Average surface roughness (Ra) and tangential cutting forces (Ft) are the responses measured. Chip patterns are also examined under different conditions. It is concluded that high spindle speed of 160 m/min along with low feeding rate of 0.2 mm/rev with MQL system using textured tool generates better results for tangential cutting force as well as average surface roughness in contrast with other machining conditions.

Компьютерное моделирование процесса сверления сложных пакетов титанового сплава и композиционного материала с использованием цифровых двойников

Complex packages of polycrystalline composite materials based on carbon fiber plastics and titanium alloys find wide ap-plication in the designs of machine-building products and become the main material in the production of high-speed modern transport modes. However, the technology of machining parts surfaces made of these materials, namely holes, is character-ized by insufficient knowledge, lack of standards for cutting modes and is based more often on the production experience of enterprises. When machining conditions and materials of complex packages change, the duration of technological prepara-tion of production causes a significant increase in the cost of manufacturing components and parts due to the need for com-petent selection of rational elements of the cutting mode. To exclude the empirical fit of rational elements of the cutting mode on machining facility, the possibility of using digital twins of drilling processes in workpieces made of these materials is studied. It also implies the introduction of ultrasonic field energy into new surfaces generation of geometry in order to improve the quality of the machining area production efficiency and reduction of technological preparation of production based on the selection of elements of the cutting mode instead of testing the selected machining conditions using the existing technological equipment. The LS-DYNA program was used in the simulation process. Preparation of models and data pro-cess was carried out in the LS-Prepost 4.8 program. In the course of research, an explicit simulation technique with pre-liminary validation was used. Studies proved that the developed finite element models allow simulating the technological processes of simultaneous drilling of packages of titanium alloy and composite material in a computer (digital twin) without conducting sufficiently complex and costly field tests. Generated by simulation, a calculation sheet was obtained containing the simulation process, the solution of which visually reflects the process of drilling holes in workpieces made of complex packages of titanium alloy and composite material, as close as possible to the real situation with chip removal. Since the use of digital twins for performing this stage of technological preparation of production in the conditions of existing enterprises is not associated with a long and expensive operation of machine-tool fleet, we should expect a significant reduction in the cost of manufacturing components and parts from similar materials in industry, primarily in small-scale or single-part pro-duction.

The machining parameter optimisation during the machining of the Cr-Mn austenitic stainless steel by the topsis method

The Cr-Mn stainless steel (austenitic) was dry turned in a lathe. A carbide tool (Indoloy) was used for the machining. The speed (v), feed (f), and depth of cut (DOC, d) were the input parameters. The experimental work was done following the Taguchi L 27 design plan. The chip reduction coefficients (CRC) and the von Mises stresses (VMS) were determined for all the experimental conditions. The TOPSIS (Technique for Order of Preference by Similarity to the Ideal Solution) method was used to optimise the process parameters. The optimal conditions were attainable at high speed (v = 100 m/min.), moderate feed (f = 0.1 mm/rev.), and moderate DOC (d = 1 mm). At optimized machining conditions, the VMS was 3429.5 MPa and the CRC was 1.6. The VMS was higher for the lower speed, and the VMS was lower for the higher speed. The higher VMS was attributed to the formation of strain-induced martensite (SIM). The lower VMS was due to the dynamic recrystallization (DRX) at the higher temperature for the higher speed. For the higher speed, the DRX and the dynamic precipitation (DP) occurred at the chip surface (under).

Effect of Copper Percentage in Copper Tungsten Electrode on Ti6Al4V by Electrical Discharge Machining

The aim of this study was to identify the optimal parameters for electrical discharge machining of Ti6Al4V titanium alloy using copper tungsten electrodes with tungsten compositions of 70% and 80%, respectively. The experiment involved varying current, pulse on time, and duty factor were determined using the Taguchi experimental method L-18 orthogonal arrays. The level of importance of each machining parameter on material removal rate (MRR) was determined using analysis of variance (ANOVA), and the optimal machining parameter combination was obtained using the analysis of signal-to-noise (S/N) ratio. The results showed that a Cu30/W70% electrode performed the best in terms of MRR, electrode wear, and surface roughness. The optimal machining conditions for achieving maximum MRR were found to be a current of 30 A, a pulse on time of 50 μs, and a duty factor of 40%.

Effect of Turning Parameter and Fiber Pullout on Machinability of Unidirectional EGFRP under Cryogenic Condition

The non-homogeneous and anisotropic nature of composites poses challenges during machining, requiring the use of specialized cutting tools. GFRP materials were selected for their excellent elasticity, corrosion resistance, and high strength, making them ideal for applications in the aerospace and automotive industries. In this work, the surface quality of UD-GFRP composite bars during CNC machining in diverse machining conditions (dry, wet, and cryogenic) was investigated while considering the fiber-pullout issue. The UD-EGFRP composite materials have been machined with a polycrystalline diamond tool. The Taguchi-L9 orthogonal-array technique is used to investigate and further analysis. Three independent-variables feed rate, rotational speed or cutting speed, and depth of cut have been taken into account for their optimal design to get better machinability of EGFRP. This study also investigates the delamination criterion in composites and establishes the correlation between its input parameters and output responses. The findings revealed that cryogenic machining led to a notable improvement of 25.21% in surface roughness compared to the other lubrication methods. Also, the reduction from 84 µm to 34 µm in fiber-pullout signifies that cryogenic cooling effectively mitigated the occurrence of fiber-pullout.