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This study investigates the performance of deep cryogenically treated brass (CuZn25Al5) electrodes in the die-sink EDM process. Two different cryogenic treatment durations, 6 h and 12 h, were applied to 8 mm diameter electrodes, and their effects were compared to untreated electrodes. The machining tests were conducted under moderate and aggressive conditions. In the machining tests, the 6-h cryo-treated electrode exhibited a 16.8% increase in material removal rate (MRR) under moderate conditions and a 19.7% increase under aggressive conditions compared to the reference electrode. The 12-h cryo-treated electrode showed similar MRR values to the reference electrode but improved tool wear resistance by 9.4% under moderate conditions. The kerf angle was minimized, indicating better hole verticality, in the 6-h cryo-treated electrode group. The improvement in machining performance was attributed to the enhancement in electrical conductivity of the electrodes, which increased by 28% for the 6-h cryo-treated electrode and 20% for the 12-h cryo-treated electrode. X-ray diffraction (XRD) analysis revealed shifts in peak positions and possible phase transformations due to cryogenic treatment. Surface roughness measurements showed improved surface conditions in the cryo-treated electrodes under aggressive conditions. The results indicate that cryogenic treatment enhances MRR, reduces tool wear, and improves surface quality in die-sink EDM. These improvements are attributed to increased electrical conductivity and changes in the internal structure of the brass electrode. [ABSTRACT FROM AUTHOR]

Dicing and filling is the most commonly used method to fabricate the piezoelectric composite by replacing part of the piezoelectric ceramics with the polymer. The dicing quality affects the composite performance, and the dicing mechanism is not clear now. In this study, a theoretical dicing mechanism for PZT-4H ceramics is introduced and validated by the experiments. The results show that, along the dicing depth direction, the dicing surface goes through brittle removal, hybrid of ductile and brittle removal, and pure ductile removal modes. The high wheel speed and low feed rate can help to get the low surface roughness and edge chipping size (width and height) due to the material removal mode transition. The diced kerfs are in saddle shape due to the dicing force variation and wheel vibration in different locations. The composite with high dicing surface quality and consistent size of dicing kerf has low mechanical quality factors variation. The impedance and phase angle at the resonance and anti-resonance frequencies are sharp, which indicates the perfect superposition of the energy from a different pillar. The inconsistent dicing kerf ruined the impedance and phase angle curve after superposition, which shows poor performance. [ABSTRACT FROM AUTHOR]

Wire electric discharge machining (WEDM) is a famous machining process for manufacturing intricate and 3D complex geometries on tough difficult-to-machine superalloys and composites. Stainless steel 304 (SS 304) alloy has excellent corrosion resistance and forming faces which is used in aerospace, chemical, petrochemical industries, etc. The present work focuses on WEDM of SS 304 using a brass wire electrode of ϕ 0.25 mm with rough cut trailed by trim cuts to improve the machinability. WEDM experiments were conducted as per Taguchi's L9 experimental design with four-factor and three-level. The effect of pulse on time (Ton), pulse off time (Toff), current and wire offset during trim cuts on machinability characteristics, namely surface roughness, material removal rate (MRR), kerf width and microhardness, was analysed. Experimental results showed that trim cuts with varying wire offsets produced better surface finish, high MRR with hardness, and low kerf width compared with rough cut. Furthermore, surface characteristics of rough cut with trim cut surfaces were analysed using scanning electron microscope (SEM) images. Finally, grey relational analysis (GRA) was used to find the optimal input parameter combination and simultaneously optimize the selected machinability responses. [ABSTRACT FROM AUTHOR]

In this present study, the effect of processing parameters on cutting width (kerf), material removal rate (MRR), Ra (arithmetic mean deviation), Rq (root mean square deviation) and Rz (maximum height) values ​​as a result of wire electrical discharge machining (WEDM) of Ti-6Al-4V alloy was investigated. It is aimed to determine the optimum values of the cutting parameters to obtain the highest MRR value with the lowest kerf, Ra, Rq, Rz. Cutting experiments were carried out using three different voltages (46, 56, 66 V), three different dielectric fluid pressures (10, 12, 14 kg/cm2) and three different wire feed rates (8, 10, 12 m/min). The parameters used in the experiments were designed according to the Taguchi L9 (33) orthogonal array in order to reduce the experimental cost. Gray Relational Analysis (GRA), one of the multi-criteria decision-making methods, has been applied to optimize the machining parameters in the cutting process with the wire erosion machine. Analysis of variance (ANOVA) was used to determine the effect percentages of the processing parameters. By using the data obtained from the experiments, the prediction study of the experimental data was carried out with the Artificial Neural Networks (ANN) model. High correlation coefficients were obtained in the regression model created using the ANN technique, and it was observed that both models were suitable and usable to predict the answers. As a result of GRA, the most ideal sequence was determined as VG1LQ1WS1. Ideal conditions were determined as 46 V voltage, 10 kg/cm2 dielectric fluid pressure and 8 m/min wire feed rate. Using the optimum machining parameters, an improvement of 4.22%, 54.65%, 28.77%, 31.94% and 35.24% was obtained for kerf, MRR, Ra, Rq, and Rz, respectively. As for the results obtained from ANOVA the contribution rate of the voltage was 72.18%. However, the effect of wire feed rate and dielectric fluid pressure was not statistically significant. [ABSTRACT FROM AUTHOR]

In plasma arc cutting (PAC), the characteristics of the gas flow exiting the nozzle significantly influence the cut quality. The high-pressure jet in PAC forms complex shockwave structures when it is incident on the metal to be cut. In this study, the flow behavior inside the kerfs of various geometries derived from an actual PAC workpiece is assessed. The shape of the cutting front in the kerf varies with the changing cutting speed. A high cutting speed yields a curved cutting front, resulting in unwanted gas flow behavior and adversely influencing the cutting performance. In this study, a computational fluid dynamics simulation model was used to analyze the effects of a curved cutting front on the gas flow behavior during the PAC process. The gas flow patterns obtained from the numerical simulations were qualitatively compared with the Schlieren experiment results. The analysis results indicated that the curvature of the cutting fronts generated oblique shockwave structures that significantly reduced the flow velocity. In particular, the weak shock structures throughout the curved cutting front gradually decreased the flow velocity. The critical flow velocity was realized in the kerf with a highly curved cutting front, beyond which the vertical penetration of the material was not possible. The shear stress lines concurred with the striation patterns on the kerf walls, thereby validating the numerical analysis results. [ABSTRACT FROM AUTHOR]

Purpose: Inconel 718 (IN718) is a high-performance nickel-based superalloy with high oxidation-corrosion-temperature resistance, high strength (tensile, fatigue, creep and rupture), durability, toughness, hardness and dimensional stability, which is difficult to machine with traditional fabrication methods. To overcome these difficulties, wire electrical discharge machining (WEDM), one of the modern manufacturing methods, is used. Design/methodology/approach: Main performance criteria in WEDM; material removal rate (MRR), cutting speed, surface roughness, cutting width (kerf) and wire wear rate. In this study, the effect of processing parameters on kerf and MRR because of processing IN718 in WEDM was investigated. Machining parameters, voltage, wire feed rate and dielectric fluid pressure were determined. Deionized water was used as a dielectric fluid and 0.3 mm brass wire was used as wire in the experiments. Gray Relational Analysis (GRA), which is one of the multi-criteria decision-making methods, has been applied for the optimization of the machining parameters in the cutting process with the WEDM. Analysis of variance (ANOVA) was used to determine the effect percentages of the cut-off parameters. Findings: The parameter with the highest effect was determined as tension with a rate of 76.95% for kerf and 91.21% for MRR. Originality/value: The novel approach uses Taguchi-based GRA optimization as a result of cutting IN718 with WEDM, reducing cost and time consumption. [ABSTRACT FROM AUTHOR]

The novelty of EDM machining as a drilling operation for composite materials means that there is no consensus on the influence of the parameters that optimise the final quality. For these reasons, a characterisation of the EDM drilling process of a unidirectional composite material has been developed. The influence of several cutting parameters has been related to the quality of the final hole obtained. Thus, macrogeometric aspects in terms of conicity and final diameter and microgeometric aspects in terms of surface quality have been evaluated. In addition, the final state of the material and the wear of the electrode have been evaluated by visual inspection, allowing the range of cutting parameters that offer the best performance to be established. Finally, a series of contour diagrams based on predictive models have been obtained to establish a direct relationship between input and output variables. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to obtain strong materials with multiwall carbon nanotubes (MWCNTs) doped and investigate laser cut of MWCNTs also find the effect of the laser cutting parameters on composite materials. Design/methodology/approach: The laminated composite plates were manufactured by using a vacuum infusion process. The mechanical properties of the composite materials produced were determined according to American Society for Testing and Materials (ASTM) D3039M, ASTM D3171, ASTM D 792 and ASTM D2583. A 130 Watts carbondioxide (CO2) laser cutting machine was used for drilling the two different composite plates with a thickness of 1.6–1.5 mm. Three variables were considered as process parameters including laser power (in three levels of 84.50, 104.00 and 127.40 W), cutting speed (in three levels of 4, 6, 8 mm/s) and 14 mm fixed focal position. Findings: The fibers could not be cut due to insufficient melting in the experiments performed using 84.50 and 104.00 W laser power but the cutting was successfully completed when the laser power was 127.40 W. However, as the cutting speed increased, the contact time of the laser beam with the material decreased, so the kerf decreased, but the increased laser power created a thermal effect, causing an increase in hardness around the cutting surface. This increase was lower in MWCNTs doped composites compared to pure composites. It has been found that the addition of nanoparticles to layered glass fiber composite materials played an effective role in the strength of the material and affected the CO2 laser cutting quality. Originality/value: This study is a unique study in which the CO2 laser cutting method of MWCNT-doped composite materials was investigated and the machinability without cutting errors, such as delamination, splitting, distortion and burring using the most suitable laser cutting parameters was revealed. [ABSTRACT FROM AUTHOR]

In this study, the holes of glass fiber reinforced polymer (GFRP) and multi-walled carbon nanotubes (MWCNTs) doped GFRP composite materials were drilled using abrasive water jet (AWJ), CO2 laser cutting, orbital drilling, and punching methods; the effects of these methods on hole quality were determined. The hole entry and exit dimensions were obtained equal and in the desired size by orbital drilling; thus, kerf formation was prevented due to the lateral and face milling of the end mill. The surface hardness change was not observed in the hole circles obtained with the orbital drilling and punching methods. However, epoxy hardening was observed in the hole circles obtained by laser cutting due to the heat effect of laser beam. In AWJ method, matrix-fiber integrity was disrupted, and delamination was observed due to the effect of water pressure and kinetic energy; consequently an increase in material thickness was observed and surface hardness decreased. It was determined that MWCNTs additive increased the surface hardness of composites and maintained its hardness and durability in post-cutting measurements. Splintering and burring were not seen in any method, but fiber carbonization was observed in the inner parts of the hole due to thermal effects in laser cutting. [ABSTRACT FROM AUTHOR]

Magnetic field-assisted low-speed wire electrical discharge machining (MF-assisted WEDM-LS) is an effective technique to improve the surface quality of the workpiece. This paper presents a successive removing model to predict kerf width and the surface topography of nickel–titanium (Nitinol) shape memory alloy in different parameters. Firstly, the motion of an electron was calculated in the magnetic field. It could be obtained that if the length of the discharge channel path was the same with the condition that in traditional WEDM-LS, the width of the discharge gap was decreased because of the deflection of the electron trajectory caused by the magnetic field. Then, a modified gauss heat source equation was derived by calculating the incident angle of the discharge channel. Based on the principle of conservation of energy, the shape of the crater in different parameters was emulated. Moreover, an electrothermal coupling model was established to investigate the surface formation in the successive discharges process. The simulation results show that the average value of the surface roughness of the workpiece in WEDM-LS with magnetic field assisted was decreased by 12.3% compared with that in traditional WEDM-LS. Eventually, experiments of kerf and surface quality were carried out respectively. The experimental results showed that the kerf decreased from 376.2 to 361.7 μm in the magnetic field intensity of 0.4 T. The surface topographies of the workpieces showed good agreement with the simulation results, and the average relative error of surface roughness between simulated results and experimental results is 8.7%. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to optimize the surface roughness (Ra), delamination damage at the hole entrance (FdT) and at the hole exit (FdB) and kerf angle (K) in the drilling of aramid fiber-reinforced polymer (AFRP) composite material using abrasive water jet (AWJ) machining. Design/methodology/approach: The AFRP composite was produced by the vacuum infusion method. The drilling experiments were performed on an AWJ machine using a three-axis computerized numerical control system. Machine processing parameters were determined as water pressure (2,000, 3,000 and 4,000 bar), stand-off distance (2, 4 and 6 mm) and traverse feed rate (150, 250 and 350 mm/min). Optimization of processing parameters in the drilling experiments was carried out according to the Taguchi L27 (33) orthogonal array. In addition, gray relational analysis (GRA) was used to analyze the complex uncertainty affecting the results. Findings: Results of the drilling operations demonstrated that water pressure (P) was the most effective parameter, with 65.3%, 65.2%, 49.8% and 52.1% contribution rates for Ra, FdT, FdB and K, respectively. Practical implications: Reliable results have been obtained with Taguchi-based GRA while drilling AFRP composite material using AWJ. Significant results have been achieved to increase the hole quality in the drilling of AFRP composite material. Originality/value: The new approach is to present more detailed analysis by using Taguchi method and multi-decision Taguchi-based gray relation analysis in AFRP composite material drilling using AWJ. Thus, time and experiment costs are saved. [ABSTRACT FROM AUTHOR]

Porcine bone is often used as a substitute for human bone in forensic trauma studies, but little has been published on its comparative mechanical behavior. The factors affecting mechanical properties and therefore selection of bone models are complex and include the age of the animal at death, and physiological loading conditions, the latter being of particular relevance when using a quadrupedal animal as a human substitute. The regional variation in hardness of adult and infant porcine bones was investigated using Vickers' indentation tests and compared to published data for human limb bones to relate differences to inherent genetic effects and loading influences, and to examine the validity of the porcine‐human model. Significant differences in hardness were observed both along and around the adult porcine humerus and femur, but no significant differences were found along the length of the infant bones. Significant differences were found between the forelimb and hindlimb, but only in the infant specimens. The hardness values for porcine adult cortical bone from the femur (52.23 ± 1.00 kg mm−2) were comparable to those reported in the literature for adult human cortical bone from the fibula, ilium, and calcaneus. These data will help inform subject selection in terms of both species and bone type for use in future trauma studies. [ABSTRACT FROM AUTHOR]

I believe that laser power, laser cutting speed, position and CO2 pressure with which to cut S235 steel material of different thicknesses have a great contribution to be able to set the best parameters for laser cutting that influences the kerf. I did an experiment to optimize laser cutting with a 4020-watt laser. Three new steps were established to estimate a cutting profile deviation response (KPD) by estimating the total cutting area of the laser cut, characterizing these steps due to the difference between the resulting cutting profile and a straight cut. We concluded that the deviation of the kerf improved by 23.2 for the 2 mm sheet thickness, by 41.8 for the 6 mm sheet thickness, by 13.8 for the 10 mm sheet thickness, by 25.4 for sheet thickness of 15 mm. [ABSTRACT FROM AUTHOR]

WEDM (Wire electrical discharge machining) is a precision machining method for cutting electrically conductive materials. It is an unconventional machining process that produces precision parts that match the dimensional tolerances of our designs within the range of ±0.0001mm. As the residual stress results in premature failure of parts, the WEDM is preferred for hard to machine materials such as Inconel, Nickel, and other Super alloys. In the present paper, earlier and recent work was reviewed, segregated and evaluated on the effect of wire material, diameter, dielectric fluid, wire wear, pulse on and off times and machining characteristics such as kerf size, machining efficiency, material surface characteristics, etc. This paper also focused on hybrid and ultrasonic-assisted WEDM used for machining of different materials. This paper discussed the major research studies in WEDM. [ABSTRACT FROM AUTHOR]

Plasma arc cutting (PAC) process is widely used in metal cutting industries and modern fabrication units. Precise cutting of high strength material is still a challenging task to the industries. PAC process uses thermal energy to melt the material through highly energized plasma gas. Mostly, "hard-to-cut" type materials is used to cut through this process to meet the demands. The present work proposes an experimental investigation of PAC process of hardox 400 and abrex 400. Both the materials are high strength and high abrasion resistance in nature. Experiments were conducted based on Taguchi's L 2 5 orthogonal array design. The cutting parameters analyzed were arc current, cutting speed, stand-off distance and supply gas pressure whereas material removal rate, kerf and surface roughness were selected as responses. Also, a prediction model was developed to estimate the responses using multiple regression analysis. A comparison between experimental and predicted result shows the accuracy of the model. Analysis of variance (ANOVA) was used to verify the effect of each parameter on the surface quality to be assessed. [ABSTRACT FROM AUTHOR]

Demands on better control over the kerf dimension deviation, surface roughness, and corner accuracy are now on the increase for the two-piece aluminum metal composite mold tools. In this investigation, straight and triangular profile cuts attempted with wire electrical discharge machining (WEDM) on the aluminum 6061 self-lubricating composite-reinforced boron carbide (5–15 vol%) and hexagonal boron nitride particles (10 vol% hBN) fabricated using a stir casting method. Rational video measurement showed an increase in B4C particles reduces kerf width dimension deviation only at TON, TOFF and gap voltage (V) parameters. Optical microscope measurement showed an increase in the corner area inaccuracy increases with both low and high pulse-on duration conditions caused by insufficient material removal and a high order of erosion, respectively. There was a large reduction in corner area inaccuracy with increasing wire feed rate. Surface characteristics were examined using a scanning electron microscope (SEM) and XRD to enable observation of the structural damages and recast layers. Composite with 5% boron carbide showed a re-deposition layer over the machined surface, whereas 15% boron carbide composite went through uneven erosion causing the formation of craters and pits on the cutting surface resulting in higher surface roughness. [ABSTRACT FROM AUTHOR]

In this study, cutting of multi-walled carbon nanotubes (MWCNTs)-doped composite sheets by abrasive water jet machining (AWJM) and the effects of the water jet on cut composite materials were analyzed. The influence of MWCNTs doping to glass fiber-reinforced polymer composite plates was investigated. In addition, mechanical properties of doped composite and the effects of cutting by AWJM method were determined. It has been found that the addition of nanoparticles to layered glass fiber composite materials plays an effective role in the strength of the material and affects the abrasive water jet (AWJ) cutting quality. Additionally, composite materials were drilled using different water jet cutting parameters such as cutting speed, fixed nozzle diameter, cutting pressure and abrasive garnet. The entry–exit hole diameter, kerf, delamination, splintering, burring, thickness and hardness change were investigated. As the cutting speed increased, rotational slip, cutting start point, circularity and circular error increased. The thickness of the composites cut by water jet method increased and surface hardness decreased due to delamination. As the cutting speed increased, the hole inlet and outlet dimensions increased, which leads to an increased in size of the kerf. [ABSTRACT FROM AUTHOR]

This study supports the research in the field of laser cutting of steel sheets HARDOX400 (H400), a less well-known and analysed material. An H400 sheet with a thickness of 10 mm was used; a cutting plan was prepared according to Taguchi's method; the input parameters (laser power, assistant gas pressure and cutting speed) were varied according to a specific rule, producing nine pieces. The initial factorial experiment was replicated four times under the same conditions as the initial one. The values for the cutting width between the piece and the plate, the hardness, and the roughness of the 45 resulting pieces were measured. The results were interpreted for each measured parameter, and by using design of experiments (DOE) from the Statistics 7.0 software, we obtained the description of roughness (Ra) in terms of power and speed using Response Surface Method (RSM) for prediction and correlation formula. [ABSTRACT FROM AUTHOR]

The purification of laser keyhole and improving molten pool flow are important means to restrain the porosity of laser-MIG hybrid welding of aluminum alloy. In this paper, four kinds of kerf were prefabricated by four common gases (Argon, Nitrogen, Air, Oxygen), which are used for studying the effect of kerf remelted layer on weld porosity. The experimental results show that the porosity is affected by the composition and thickness of the remelted layer. The porosity of Argon-weld and Nitrogen-weld is low, and that of Air-weld and Oxygen-weld is high. It increased linearly with the thickness of remelted layer (d). Regardless of the types of kerf, when the d is less than 136 μm, the porosity is less than 2%. When the d is thin, the purification of laser keyhole avoids the adverse effect of remelted layer oxide on the molten pool and reduces the porosity. When the d is thick, the influence of oxygen on surface tension and molten pool flow driven by it starts to dominate. It makes the temperature coefficient of surface tension change from negative to positive, and the molten pool change from 'outward flow' to 'inward flow', which prevent bubbles from escaping and increasing the porosity. • The feasibility of the laser cutting-welding of aluminum alloy is proved. • The weld appearance is independent of the characteristics of kerf remelted layer. • When the oxide thickness is less than 136 μm, the weld porosity is less than 2%. • The purification of effect of laser keyhole reduces the weld porosity. • The influence of oxygen on the flow behavior is depended on oxide thickness. [ABSTRACT FROM AUTHOR]

The scribe line (also known as kerf or frame) is an area in the silicon wafer which is used to separate individual die at the end of wafer processing. The scribe line also contains features which assist in the manufacturing process but are not present in the final product. Examples of such features include lithography alignment and overlay marks, thickness measurement pads, and electrical test macros. The overall design of scribe line features can be drastically different from the die layout. In the chemical mechanical polishing process, regions of low pattern density have higher polishing rates compared to those of high pattern density, leading to overpolishing or “dishing”. The scribe line, with intermittent regions of low and high pattern density, is naturally more prone to dishing, an issue which is exacerbated by thickness variation at the wafer edge. In this work, we present examples of unforeseen defects caused by interaction between process variation and scribe line design, which can eventually lead to yield loss in the prime die. The findings in this paper pertain to “common platform” FINFET technology but can be extended to other technologies due to similar process steps employed in semiconductor manufacturing. [ABSTRACT FROM AUTHOR]

Origami-based sheet metal (OSM) bending is an extension of rigid origami technique, where the final 3D structure is created from a single 2D flat pattern by bending. The key aspect of OSM is material discontinuity (MD), which helps achieve a unique dieless bending process. MD is a feature along bend line of blank sheet and it can be fabricated using laser or water jet cutting. Even though a number of successful implementations of OSM bending have been found, these cases are limited only to product development and industrial application. The mechanics of OSM bending with respect to parameters that define MD, blank sheet, as well as the bending process have not been studied. Thus, this study identifies parameters and investigates the effect of identified parameters associated with OSM bending. Parameters studied in this work include design parameters and process parameters. Design parameters are kerf-to-thickness (k/t) ratio, web-to-width (w/b) ratio, and thickness of sheet (t). These are associated with MD design. The process parameters are related to OSM bending process, and they include punch placement (t+g), offset distance (s), and punch radius (RP). Finite element analysis (FEA) is performed to investigate the effect of these parameters on the OSM bending process. The simulated OSM bending cases resulted in successful bending without using a die. The general recommendation is provided for selecting parameters of OSM bending based on results. In addition, the shape of MD is an important factor when designing the OSM bending process. [ABSTRACT FROM AUTHOR]

In this study machinibility of hardox steel plates (welded by plasma and Mag welding) was examined in WEDM. Two different ampere values and two different feed rates were determined for the two different welding types. Depending on these factors ,micro structures, micro hardnesses and resistivity/conductivity values (varying according to heat output) were obtained at the HAZ and WM zones. Then, each of the samples taken from both HAZ and WM zones were cut in the WEDM by using 2 levelled four different parameters. The purpose at this stage is to examine the cutting width (kerf) and surface roughness (Ra) values at the HAZ and WM zones with respect to varying micro structure, micro hardness and conductivity values. At the end of the study, the lowest kerf was obtained with the plasma welded samples whereas the lowest Ra values were obtained with the Mag welded samples. The samples at WM zone are in general are the ones welded by high conductivity sample Mag welding. Whereas in the HAZ zone the samples are the ones welded by high conductivity plasma welding. [ABSTRACT FROM AUTHOR]

This paper attempts at investigation of the feasibility of imparting a swirling motion to abrasive particles by introducing internal threads in the nozzle. In this investigation, a novel internal threaded nozzle was introduced in the abrasive jet machine to make holes on the carbon fiber reinforced polymer composites with the objective of reducing the machining time. This is a unique attempt of its kind and this innovation has brought down the machining time considerably and, as a consequence, higher material removal rate was obtained. Carbon fiber reinforced polymer composites are inhomogeneous and coarse in nature, and hence, the ease of machining and the machining time are always challenging. A morphological study was also made using an optical microscope to find the kerf width and kerf angles. The effect of two different nozzles on machining time, material removal rate, and kerf analysis on the carbon fiber reinforced polymer composite was investigated. It was found that machining time was reduced by 92% with novel internal threaded nozzle. The nozzle with internal threads also reduced the kerf angle of the machined hole. [ABSTRACT FROM AUTHOR]

Composite materials have taken an imperative place in the material system because of their unique performance in various specialized applications. Fiber inclusion and the heterogeneous property of composites make it more difficult to machine with the conventional machining process. However, several nonconventional methods have been adopted for machining composites, in which abrasive water jet machining (AWJM) was proven to be more effective and a preferable technique in machining of fiber-reinforced composite material. This review article is intended to highlight and categorize the machining performance of the fiber-reinforced composites on machining with AWJM process. [ABSTRACT FROM AUTHOR]

This work presents a description of abrasive water-slurry jet machining (AWSJM) to improve machining capabilities of conventional abrasive water jet machine. This work proposes a novel approach of AWSJM, where the conventional abrasive water jet machine (AWJM) is equipped with a liquid (gelatin) polymer solution injection system and a programmable control valve for controlling abrasive flow rate (AFR) and polymer solution flow rate. Parametric study of gelatin enabled AWSJM reveals the improvements in machining performance. Experimental investigations have been performed by varying concentration of the gelatin, pressure of water jet, abrasive flow rate, and abrasive size. The present work identifies the optimal range of process parameters for AWSJM, with natural gelatin as binder, with the response parameters being material removal rate, kerf width, and depth of cut. Gelatin produces a coherent, three-phase, four-content beam of higher kinetic energy in comparison with AWJ and results in increased material removal rate and depth of cut, with reduced kerf width. [ABSTRACT FROM AUTHOR]

This study researched the effects of machining parameters on surface roughness and material removal rate in the wire electrical discharge cutting of high-density Al/B4C metal matrix composites produced via the hot pressing method. Wire tension, reinforcement percentage, wire speed, pulse-on time and pulse-off time were set as the control factors. The Taguchi L18 (21 × 34) orthogonal array was used in the experiment design and determination of the optimum control factors. Variance analysis was applied to determine the effects of the control factors on the surface roughness and material removal rate. The results showed the most effective parameters to be pulse-on time (30.22%) for surface roughness and wire speed (83.20%) for material removal rate, and the optimum levels of the control factors to be A2B1C2D1E1 and A2B2C3D2E2, respectively. Predictive equations were then developed by applying linear regression analysis, and the adjusted correlation coefficients were calculated as 0.61 for surface roughness and 0.785 for material removal rate. [ABSTRACT FROM AUTHOR]

Adverse childhood experiences increase the risk for a psychopathological development. Maltreated children have double, in some instances multiple odds of developing depression. They have an earlier onset, a more severe course, more comorbidities and frequently respond more poorly to fi rst-line treatments. Persons who are sensitive to social rejection also report more adverse childhood events. The current study quantifies the relationship between childhood adversities and course of depression as well as rejection sensitivity in a psychiatric clinic that includes an inpatient as well as a day care setting. The severity of depressive symptoms was evaluated for 48 patients with depression (including ICD diagnoses F31, F32, F33) at the beginning and the end of the treatment by self-assessment (BDI) and expert rating (HAM-D). Patients were interviewed during the treatment with the German version (KERF-I, short version) of the MACE (Maltreatment and Abuse Chronology of Exposure) scale and completed a questionnaire for rejection sensitivity (RSQ). Correlational analyses were used to test the hypotheses. Adverse childhood experiences were associated with depression severity measured by self-assessment (BDI) but not by expert rating (HAM-D). Patients with recurrent depression reported childhood adversities twice as much as patients with a single depressive episode. Inpatients reported triples of childhood adversities than patients in the day care treatment. Childhood adversities were also positively associated with higher rejection sensitivity and rejection sensitivity went along with a reduced treatment success. The association of adverse childhood experiences with depressive symptoms and rejection sensitivity suggests the development of negative cognitive schemata. The negative correlation of treatment success und rejection sensitivity allows a possible explanation for the less favorable course of depression in patients with many childhood adversities. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study on abrasive waterjet (AWJ) machining of the most commonly used titanium alloy, Ti-6Al-4V. Two types of machining operations, i.e. drilling (or piercing) and slotting, were conducted. For the drilling experiments, the influences of water pressure and drilling time were investigated. It was found that both the hole depth and diameter increased as drilling time increased but in a decreasing rate. An increase in the water pressure increased both the hole depth and the hole diameter. For the slot cutting, the influence of water pressure and the traverse speed were investigated. A slower traverse speed resulted in a deeper depth of cut. The kerf showed a taper shape with a wider entry on top, and the width decreased as jet cut into the material. At the bottom of the kerf, a pocket was generated. The variation of the depth of cut became insignificant when the traverse speed was increased. [ABSTRACT FROM AUTHOR]

Wire electrical discharge machining (WEDM) is a commonly used process in manufacturing industries to machine electrically conductive materials with complex shapes and varying hardness. The performance of any machining process is based on right selection of input variables. The selection of optimal parameters in WEDM is a difficult task as it is a highly stochastic process in nature. The present work deals with the development of empirical relationships for the output responses of kerf (cutting width) and wire wear ratio considering pulse-on time, pulse-off time, wire tension, dielectric flow rate, and wire feed as the input variables. Response surface methodology is used to find the quantitative relations. Subsequently, the developed mathematical models are used for optimization. A recently developed global optimization technique, harmony search algorithm, is applied to find the optimal set of input control variables. [ABSTRACT FROM AUTHOR]

Abstract: Jet impingement onto a kerf is considered in relation to laser cutting process. Flow and temperature fields are predicted using the three-dimensional modeling. In the simulations influence of kerf wall wedge angle on the Nusselt number and the skin friction at the surface of the kerf wall is examined. The RNG k−ε model is incorporated to account for the turbulence. A control volume approach is introduced to discretize the governing flow equations. It is found that the kerf wall wedge angle has considerable influence on the Nusselt number and the skin friction. [Copyright &y& Elsevier]

This paper reports the effect and optimization of eight control factors on material removal rate (MRR), surface roughness and kerf in wire electrical discharge machining (WEDM) process for tool steel D2. The experimentation is performed under different cutting conditions of wire feed velocity, dielectric pressure, pulse on-time, pulse off-time, open voltage, wire tension and servo voltage by varying the material thickness. Taguchi's L18 orthogonal array is employed for experimental design. Analysis of variance (ANOVA) and signal-tonoise (S/N) ratio are used as statistical analyses to identify the significant control factors and to achieve optimum levels respectively. Additionally, linear regression and additive models are developed for surface roughness, kerf and material removal rate (MRR). Results of the confirmatory experiments are found to be in good agreement with those predicted. It has been found that pulse on-time is the most significant factor affecting the surface roughness, kerf and material removal rate. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports on the research of wire electrical discharge machining (WEDM) as a cutting process for n-type high purity germanium (HP Ge). WEDM requires sufficient electrical conductivity of the work piece for discharges to occur. Owing to the very high material resistivity of HP Ge (32.8Ωcm), the electrical conduction is too low for WEDM to be efficient. To temporarily enhance the conduction, metals (aluminum and nickel) were deposited on the HP Ge on 1 or 2 sides with various thicknesses (1.0, 2.0, and 3.0μm) using sputter deposition. This shortens the path of conduction between the HP Ge and the WEDM ground and also serves to trigger the discharges. Machining experiments were performed to determine the correlation between the slicing rate and locally enhanced HP Ge through various discharge energies (potential voltage: 150, 200, 250 and 300V and capacitance: 1, 3.3, 5.5, 9.9 and 21.4nF). From the results, the obtained maximum slicing rate is 7.7mm2/min for Al coating (2 sides, 1.0μm thickness) at high energy (300V, 21.4nF), which is improved as much as 27 times over uncoated HP Ge. The fastest cutting without creating subsurface microcracks was measured as 1.12mm2/min performed at 150V and 9.9nF. Additional slicing experiments at reverse polarity (positive wire and negative work piece, uncommon polarity for WEDM) were performed at 150V and various capacitances. The experiment proved that there were rectifying contacts at the metal coating surface. It was found that under identical EDM settings, a faster slicing rate also showed a reduction in kerf size due to less lateral discharge energy. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) were used to investigate microcracks and to analyze surface impurities. [Copyright &y& Elsevier]

Abstract: In laser cutting process, an assisting gas is used to improve the mass removal rate from the cutting kerf and protect the kerf surfaces from the high temperature exothermic reactions, such as oxidation reactions, during the cutting process. Therefore, heat transfer rates from the kerf wall and the skin friction along the kerf surface are important for quality cutting. In the present study, jet emerging from a conical convergent nozzle and impinging onto the kerf surface is investigated in relation to the laser cutting process. The flow field in the kerf, the heat transfer rates from the kerf wall, and the skin friction along the kerf surface are computed for four average jet velocities at the nozzle exit and two kerf wall wedge angles. The ratio of the stand-off-distance (distance between the nozzle exit and the kerf top surface) to nozzle diameter is selected as H/D=2.2., where H is the stand-off-distance and D is the nozzle exit diameter. The kerf wall temperature is kept at 1500K to resemble the laser cutting process. It is found that the Nusselt number increases sharply at the kerf inlet and decreases towards the kerf exit for the kerf wall angle of 0°. However, it increases gradually in this region for the kerf wedge angle of 4°. The skin friction decreases along the kerf surface. [ABSTRACT FROM AUTHOR]

Analyses of saw marks in bone may yield important information about the class characteristics of saws used in postmortem dismemberments, yet little research has been directed at identifying saws' individualizing characteristics. This study adds to existing saw mark analysis methodologies by examining wear-related features of kerf walls using light- and environmental scanning electron microscopy. A crosscut saw and hacksaw were used to create sequences of 30 cuts in bone; these sequences reveal patterns of progressive loss of fine details of kerf wall morphology with increasing saw blade wear, because of the rounding of sharp points and edges. Nevertheless, diagnostic kerf wall features used to establish class characteristics persist despite these wear-related changes. Unsuccessful attempts at statistical analysis of wear-related changes, based on striae width and density, suggest these patterns are not readily quantifiable. Additionally, despite the scanning electron microscope's superior imaging capabilities, it provided few practical, methodological gains over traditional light microscopy. [ABSTRACT FROM AUTHOR]

Laser micro-cutting of Kevlar was carried out and the influence of laser cutting speed on the kerf size width and out-of-flatness is examined. A mathematical model was developed and incorporated to predict the kerf width size. It was found that laser cutting speed influenced significantly the kerf width and the out-of-flatness. with increasing laser cutting speed being seen to reduce the kerf width size and out-of-flatness. This was seen to be more pronounced at the front surface of the micro-cutting section. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates the slicing of germanium wafers from single crystal, gallium-doped ingots using wire electrical discharge machining. Wafers with a thickness of 350μm and a diameter of 66mm were cut using 75 and 100μm molybdenum wire. Wafer characteristics resulting from the process such as the surface profile and texture are analyzed using a surface profiler and scanning electron microscopy. Detailed experimental investigation of the kerf measurement was performed to demonstrate minimization of material wastage during the slicing process using WEDM in combination with thin wire diameters. A series of timed etches using two different chemical etchants were performed on the machined surfaces to measure the thickness of the recast layer. Cleaning of germanium wafers along with its quality after slicing is demonstrated by using Raman spectroscopy. [Copyright &y& Elsevier]

• PP laser cutting was based on a thermal ablation mechanism, accompanied by the formation of by-products such as propene and benzene. • The width of kerf was reduced to ∼22 μm for high cutting speed (250 mm/s). • Under low cutting speed (50 mm/s) and high repetition rate (120 kHz), large HAZ (∼42 μm) was generated due to heat accumulation. • Under the optimal manufacturing parameters, the minimum width of kerf (21.26 ± 1.8 μm) and HAZ (16.92 ± 0.4 μm) were achieved. As a rapid, convincing, and scalability technology, laser micromachining has been widely reported for achieving high-quality processing of polymers. This paper presents a study on improving the cutting performance of polypropylene (PP) film with nanosecond laser emitting at 355 nm (ultraviolet light). Various repetition rates, cutting speeds and repeat times were applied to modify kerf properties, including cut width, heat-affected zone (HAZ) morphology, and cross-section depth. The narrowest kerf width of 21.26 ± 1.8 μm and heat-affected zone (HAZ) width of 16.92 ± 0.4 μm were obtained when repetition rate was 100 kHz, cutting speed was 250 mm/s and repeat times of 4. The laser-treated samples were studied by Scanning Electron Microscopy and Raman spectroscopy. Furthermore, Py-GC–MS and thermogravimetric analysis were employed to revealed thermal decomposition behavior. The morphological and composition analysis showed that swollen HAZ were produced after laser irradiation, with the residues after carbonization and the generation of gases such as propene, 1-butene, etc. These experimental results and developed mechanism provided some insights into the laser processing PP film. [ABSTRACT FROM AUTHOR]

Abstract: Laser beam machining (LBM) is one of the most widely used thermal energy based non-contact type advance machining process which can be applied for almost whole range of materials. Laser beam is focussed for melting and vaporizing the unwanted material from the parent material. It is suitable for geometrically complex profile cutting and making miniature holes in sheetmetal. Among various type of lasers used for machining in industries, CO2 and Nd:YAG lasers are most established. In recent years, researchers have explored a number of ways to improve the LBM process performance by analysing the different factors that affect the quality characteristics. The experimental and theoretical studies show that process performance can be improved considerably by proper selection of laser parameters, material parameters and operating parameters. This paper reviews the research work carried out so far in the area of LBM of different materials and shapes. It reports about the experimental and theoretical studies of LBM to improve the process performance. Several modelling and optimization techniques for the determination of optimum laser beam cutting condition have been critically examined. The last part of this paper discusses the LBM developments and outlines the trend for future research. [Copyright &y& Elsevier]

Wire electrical discharge machining (WEDM) is extensively used in machining of conductive materials when precision is of prime importance. Rough cutting operation in WEDM is treated as a challenging one because improvement of more than one machining performance measures viz. metal removal rate (MRR), surface finish (SF) and cutting width (kerf) are sought to obtain a precision work. Using Taguchi’s parameter design, significant machining parameters affecting the performance measures are identified as discharge current, pulse duration, pulse frequency, wire speed, wire tension, and dielectric flow. It has been observed that a combination of factors for optimization of each performance measure is different. In this study, the relationship between control factors and responses like MRR, SF and kerf are established by means of nonlinear regression analysis, resulting in a valid mathematical model. Finally, genetic algorithm, a popular evolutionary approach, is employed to optimize the wire electrical discharge machining process with multiple objectives. The study demonstrates that the WEDM process parameters can be adjusted to achieve better metal removal rate, surface finish and cutting width simultaneously. [ABSTRACT FROM AUTHOR]

Zinc-coated steel sheets are important materials in the automobile and home appliance industries. Currently, lasers are the preferred tools for metal cutting because of their good cutting quality, flexibility and excellent features and results, as compared to traditional tools. The solid-state Nd:YAG laser has successfully replaced the gaseous CO2 laser for metal cutting; its small size and short wavelength makes it suitable for cutting bright and metal-coated materials, as well as being able to be transmitted via optical fibers and robots to cut complicated three dimensional and curved shapes. In this work, the Nd:YAG laser is used to cut 1 mm zinc coated steel sheets. We demonstrate the effects of different cutting parameters such as laser power, cutting speed, different gas types and pressures, and focus position on the cutting quality characteristics of attached dross, kerf width and cut surface roughness. Using a six axes robot, cutting speed was limited to 6 m/min because of the noticeable vibration at higher speeds. Results showed that the cutting surfaces achieved were very sharp and smooth. In cutting, Nd:YAG required less power and attained higher speeds than the published results of a CO2 laser, which makes Nd:YAG an economical alternative to cut zinc and metal-coated materials. In addition, laser cutting using robots provided efficient and consistent cutting quality, especially in the case of 3D and countered cutting. Apart from using low speed, robots proved to be more economical than costly, specially designed CNC tables. [ABSTRACT FROM AUTHOR]

Abstract: Although CO2 lasers have been widely employed for commercial sheet metal cutting operations, increased recognition of the processing benefits afforded by pulsed Nd:YAG lasers has recently fuelled interest in the latter. Pulsed Nd:YAG laser cutting differs from conventional continuous wave laser cutting as it involves overlapping of a series of individual spots generated by each pulse. In this paper, a typical cutting regime for pulsed Nd:YAG laser cutting of 1mm thick Hastelloy-X sheet has been constructed and explained in terms of extent of spot overlap. The characteristics of single holes drilled employing the same process parameters as those employed for cutting were investigated and correlated with the obtained processing regime. Additionally, the influence of key process parameters like pulse duration on the shift in the constructed processing regime was investigated. Cut quality attributes like kerf width, cut edge kerf profile and surface roughness were also studied and their dependence on process parameters has been discussed. [Copyright &y& Elsevier]

This paper presents an investigation on the effect and optimization of machining parameters on the kerf (cutting width) and material removal rate (MRR) in wire electrical discharge machining (WEDM) operations. The experimental studies were conducted under varying pulse duration, open circuit voltage, wire speed and dielectric flushing pressure. The settings of machining parameters were determined by using Taguchi experimental design method. The level of importance of the machining parameters on the cutting kerf and MRR is determined by using analysis of variance (ANOVA). The optimum machining parameter combination was obtained by using the analysis of signal-to-noise (S/N) ratio. The variation of kerf and MRR with machining parameters is mathematically modeled by using regression analysis method. The optimal search for machining parameters for the objective of minimum kerf together with maximum MRR is performed by using the established mathematical models. [Copyright &y& Elsevier]

Samples of 4130 steel were cut on a CO2 laser cutting system and the combined effects of power and feed rate on kerf width, surface roughness, striation frequency and the size of heat affected zone (HAZ) have been studied. Regression analysis was used to develop models that describe the effect of the independent process parameters on laser cut quality. For the range of operation conditions tested, it was observed that power had a major effect on kerf width and size of HAZ, while feed rate affects were secondary. On the other hand, surface roughness and striation frequency were affected most by feed rate. At low power levels, the smallest kerf width and HAZ are obtained and the effect of feed rate is moderate. Low feed rates gave good surface roughness and low striation frequency. For optimum cut quality, kerf width, HAZ and surface roughness are kept at a minimum. However, operating conditions that satisfy these requirements while maintaining high productivity could not be identified. [Copyright &y& Elsevier]

A laser-assisted high-speed shearing (LAHSS) method has been proposed for metal bars, which prefabricates equally spaced fracture-start kerfs by Nd:Yag laser to make stress concentration, and applies a high-speed load to complete fracture separation. Comparative tests were conducted for Q235, 40Cr, and 304 steel bars, and the effects of fracture-start kerfs and axial clearance were investigated on the fracture section. Moreover, the fracture behavior was demonstrated by numerical simulation, and the micro-fracture mechanism was revealed by fractographic analysis. The numerical simulation results show that the material damage concentrates along with the kerf tips with peak equivalent plastic strain, and the corresponding stress triaxiality drops to almost zero at the kerf tip, which reveals that the material is subjected to pure shearing at kerf tip; the Max. loading force is reduced by 15.2%–29.6%, and the impact energy is decreased by 29.8%–46.9% for the three types of bar material. The experimental results showed that the fracture-start kerfs effectively inhibited the plastic deformation stage, and higher precision blanks were obtained in the LAHSS test: roundness error improved from 2.7%–10.9% to 1.1%–2.6%, Max. bending deflection decreased from 1.3–3.4 mm to 0.4–1.0 mm, and flatness error dropped from 0.9–3.3 mm to 0.3–0.7 mm. The fractographic analysis reveals that the crack initiation is related to alternative V-shape micro-notches at the laser-affected zone; the predominant fracture mechanism involves mode II microvoid coalescence at the main fracture plane; smaller and less elongated dimples were formed in 40Cr steels due to higher number density of grains and pinning effect of second-phase particles compared to Q235 and 304 steel bars. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) laser cutting finds one of its most relevant applications in the processing of a wide variety of polymeric materials like thermoplastics and thermosetting plastics. Different types of polymeric materials like polypropylene (PP), polymethyl methacrylate (PMMA), low- and high-density polyethylene (LDPE, HDPE), are processed by laser for different household as well as commercial products in the industry. The reason is their easy availability and economical aspect in the market. The problems associated with laser cutting include heat-affected zone (HAZ) generated on the cut surface, kerf width (KW), surface roughness (SR), dross formation, and striations formation. Furthermore, other related problems include taper cutting for deep parts and high-power consumption. The primary purpose of this work is a comprehensive literature review in CO2 laser cutting of polymeric materials. The influence of parametric variation on the cut quality is also explained. Cut quality in terms of KW, SR, HAZ, dross formation, and striations formation is analyzed by optimizing cutting variables like laser power (PL), cutting speed (CS), assist gas pressure (Pg), pulse frequency, nozzle type and its diameter, and stand-off distance (SOD). The effects of the laser cutting on the properties of different thermoplastics/thermosetting materials are also reported. However, this topic requires further studies on exploring the range of polymeric materials, and their optimal parameters selection to improve the cut quality. Therefore, the research gaps and future research directions are also highlighted in the context of CO2 laser cutting for polymeric materials. [ABSTRACT FROM AUTHOR]

Recently, natural fiber-reinforced polymers (NFRPs) have become important materials in many engineering applications; thus, to employ these materials some final industrial processes are needed, such as cutting, trimming, and drilling. Because of the heterogeneous nature of NFRPs, which differs from homogeneous materials such as metals and polymers, several defects have emerged when processing the NFRPs through traditional cutting methods such as high surface roughness and material damage at cutting zone. In order to overcome these challenges, unconventional cutting methods were considered. Unconventional cutting methods did not take into account the effects of cutting forces, which are the main cause of cutting defects in traditional cutting processes. The most prominent unconventional cutting processes are abrasive waterjet (AWJM) and laser beam (LBM) cutting technologies, which are actually applied for cutting various NFRPs. In this study, previously significant studies on cutting NFRPs by AWJM and LBM are discussed. The surface roughness, kerf taper, and heat-affected zone (HAZ) represent the target output parameters that are influenced and controlled by the input parameters of each process. However, this topic requires further studies on widening the range of material thickness and input parameter values. [ABSTRACT FROM AUTHOR]

The axial splitting of thin-walled tube is usually considered as an efficient deformation mode to dissipate impact energy thanks to its large stroke ratio. However, the low crushing force and the unstable deformation process, such as crack merging and branching, significantly limit its application in crashworthiness design. In this paper, we propose to enhance the deformation stability through introducing initial kerfs on the inner and outer surfaces of the circular steel tube in its axial direction to guide the propagation of cracks during the splitting process, thus we can improve the crushing force via a significant increase in tube wall thickness. To demonstrate the feasibility of the proposed method, quasi-static compressive experiments on single tube (inner radius r = 55 mm, wall thickness t = 5 mm) and doubled tube (consisted of two tubes with wall thickness t = 5 mm) with kerf depth δ = 0.5 mm split by a radiused die are performed, which exhibit stable deformation processes and high steady-state compression forces (103.32 kN for single tube, and 216.44 kN for doubled tube). Then, finite element simulations are conducted to model the tested samples. It is found that the experimentally observed deformation processes are well captured by simulations, and the relative errors of numerical steady-state compression forces in comparison to experimental results are 0.39% (single tube) and 1.90% (doubled tube), respectively. Finally, based on the validated numerical model, the influence of tube and die dimensions on its crashworthiness performance is discussed. It is observed that the axial load significantly depends on kerf depth, crack number, and tube thickness. The curling radius is nearly not affected by kerf depth, but it almost linearly depends on die radius. Moreover, the tube with larger wall thickness has a higher specific energy absorption. • The crashworthiness of circular tube during axial splitting process is enhanced through introducing initial kerfs on tube surfaces. • Thicker steel tubes with initial kerfs are experimentally demonstrated to have stable splitting processes and high crushing forces. • The introduction of oblique notches significantly weakens the crushing peak force without losing steady-state force. • Effect of the tube and die dimensions on its crashworthiness performance is numerically investigated. [ABSTRACT FROM AUTHOR]

This paper reports the investigation results of CO 2 laser machining of Inconel 718 superalloy. Investigation on the effects of the two important laser parameters power and travel speed on machinability i.e. material removal rate, kerf wall inclination, and average surface roughness of Inconel 718 has been conducted. Increased kerf wall inclination has been found with slow travel speed and increasing power. Low power and high travel speed produced maximum material removal rate and minimum surface roughness. Premature state of fusion has advanced dross regime at a slow cutting speed of 3.3 m/min and leading to a surface roughness of 9.3 microns maximum. Dendrite structures were formed and changes in surface hardness were observed due to high travel speed. Therefore, based on the investigation, slow travel speed with appropriate laser power is recommended for the improved machinability and surface quality during laser machining of Inconel 718 superalloy. [ABSTRACT FROM AUTHOR]

Stainless steel (SS 304) is commonly employed in industrial applications due to its considerable corrosion resistance, thermal resistance, and ductility. Most of its intended applications require the formation of complex profiles, which justify the use of wire electrical discharge machining (WEDM). However, its high thermal resistance imposes a limitation on acquiring adequate surface topography because of the high surface tension of the melt pool, which leads to the formation of spherical modules; ultimately, this compromises the surface quality. Furthermore, the stochastic nature of the process makes it difficult to optimize its performance, especially if more than one conflicting response is involved, such as high cutting speed with low surface roughness and kerf width. Therefore, this study aimed to comprehensively investigate the interaction of SS 304 and WEDM, with a prior focus on simultaneously optimizing all the conflicting responses using the Taguchi-based grey relational approach. Analysis of variance (ANOVA) revealed that the current was the most significant parameter for cutting speed and kerf, whereas roughness, voltage (45%), drum speed (25.8%), and nozzle offset distance (~21%) were major contributing factors. SEM micrographs showed that optimal settings not only ensured simultaneous optimization of the conflicting responses but also reduced the number and size of spherical modules. [ABSTRACT FROM AUTHOR]