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The incorporation of bioactive glass (BG) into zirconia-based composite materials shows a feasible option to enhance the biological properties, reduce the sintering temperature, and resist the transformation of the tetragonal phase of zirconia. In this present work, the bioceramic composites, having the general formula [(100-x) (8 Mg-PSZ) – x (13–93 BG)] where x = 0 to 25 wt%, have been prepared and evaluated the effect of BG amounts on the machinability, mechanical and biological behavior of the composite material. The machining experiment is performed on an abrasive air jet machine (AAJM), and machinability is evaluated in the form of material removal rate (MRR), surface roughness (SR), and mechanics of material erosion (MME) at room temperature. The machinability results show that MRR decreases with enhancing the BG contents, and the SR follows the opposite trend of MRR. The MME indicates that the material is removed from the surface mainly due to the erosion crater and brittle fracture. Further, mechanical properties are evaluated, and it is found that the inclusion of BG frits and sintering temperature is substantially associated with the relative densities and the mechanical characteristics. Adding BG reinforcements increases the mechanical characteristics at lower sintering temperatures (1250 °C) while reducing the mechanical characteristics except hardness at higher sintering temperatures (1350 °C). Elastic modulus decreases with the addition of BG content up to 15 wt%; after that, it slightly increases up to 25 wt%. The in-vitro bioactivity and bio-degradation are tested in simulated body fluid (SBF), and both are increased by enhancing the BG contents up to 25 wt%. The in-vitro cell culture is performed on the MG-63 cell line. The biocompatibility increases with BG concentration (up to 25 wt%). Based on experimental results, it may be concluded that 8 Mg-PSZ/13-93BG bioceramic composites may be a potential choice for biomedical applications. [ABSTRACT FROM AUTHOR]

The demand for high-performance materials in aerospace, automotive, and power generation industries has led to the development and utilization of advanced superalloys. Nimonic C-263/263, a nickel-based superalloy, is widely employed in critical components of jet engines, such as combustion chambers, heat exchangers, reformer tubes, gas turbine power generation components like turbine discs, shafts, and blades, due to its exceptional high-temperature strength, corrosion resistance, and creep properties. However, the inherent hardness and toughness of this alloy pose significant challenges for conventional machining processes. Abrasive waterjet cutting (AWJC) emerges as a promising alternative for the efficient machining of such difficult-to-cut superalloy materials. This paper presents an in-depth investigation on the machinability of thick Nimonic 263 superalloy plate material using AWJC, aiming to provide insights into the effects of process parameters, cutting performances, and resulting surface integrity due to change in declination angle measurement. An examination was also conducted on the pattern of striation formation under varying process parameters, utilizing digital microscopic images. The goal of the study is to establish a link between the parameters of striation production and the angle of jet impingement. The results indicate that a decrease in striation during the water jet processing of Nimonic 263 superalloy is caused by an increase in the declination angle. [ABSTRACT FROM AUTHOR]

This paper investigates the impact of high-speed machining with heat-assisted machining (HAM) on the machinability of heat-treated SKD61 steel, utilizing alloy cutting tools. The study encompasses microstructure analysis, mechanical properties evaluation, chip color examination, surface roughness assessment and cutting force measurement during the machining process. Experiments are conducted under controlled conditions with advanced equipment. Findings indicate that at 200°C and 350°C, SKD61 steel's microstructure remains unchanged, while at 500°C, there's a superficial alteration of approximately 0.05 mm thickness. Material hardness remains consistent across temperatures. Unique chip color variations serve as temperature indicators. Cutting force consistently decreases with rising temperature, highlighting the intricate relationship between temperature, material behavior and cutting mechanics. Surface roughness improves with higher temperatures, emphasizing the potential benefits of HAM in precision manufacturing. [ABSTRACT FROM AUTHOR]

In today’s rapidly evolving manufacturing industry, researchers and engineers are constantly seeking innovative methods to improve machining processes. One such area of interest is the use of electrical discharge machining (EDM) for difficult-to-machine metals like SS316. This research compares the performance and economic aspects of traditional EDM and powder-mixed EDM when machining SS316 using copper electrode. Graphite powder dispersed in biodegradable palm oil is investigated as a dielectric media with the aim of enhancing EDM performance. According to the findings, the analysis of the cutting performance of different machinability aspects revealed that using graphite powder mixed with palm oil as a dielectric in EDM outperformed conventional EDM relating to material removal, surface finish, surface hardness, electrode wear rate and hole overcut. The flushing condition and unique properties of graphite powder and palm oil, such as cooling, and thermal conductivity, contributed to the improved performance observed in EDM processes. These findings highlight the potential of graphite powder mixed with palm oil as a promising alternative dielectric in EDM, offering enhanced machining capabilities and improved surface quality. The total machining expenditure per part under PMEDM (INR 505.50) is lowered by 9.2% than expenditure under conventional EDM (INR 525). The surface microhardness of the machined component attained using graphite powder-mixed EDM is enhanced in comparison to that achieved using standard EDM due to the creation of a carbon-rich re-solidified layer. [ABSTRACT FROM AUTHOR]

High-silicon cast steel exhibits good ductility and mechanical strength after microstructure transformation through an austempering heat treatment. The combination of these properties is outstanding in other steels, leading to emerging applications for high-silicon cast steel, such as in the railway sector. The Si content above 1.5% is a crucial factor for the formation of refined bainite and a dispersion of carbides in the matrix. This work involves the evaluation of the machinability of a steel alloy with 0.77% C and 1.77% Si using ceramic metal and ceramic tools. The alloy was cast, homogenized, austempered, and tempered. Subsequently, the high-silicon cast steel was characterized using scanning electron microscopy (SEM), hardness, tensile strength, and elongation. Machinability tests were conducted by turning and varying the cutting speed under dry cutting conditions with a constant feed rate. The analyzed output parameters were surface roughness, tool wear, and wear mechanisms. The increase in cutting speed directly influenced tool wear for all tools. The predominant wear mechanisms observed during the tests were abrasion and diffusion. The hard metal tool exhibited chipping on the cutting edge. [ABSTRACT FROM AUTHOR]

The application of super austenitic stainless steels (SASS) in the petroleum, chemical, and naval industries has gradually increased owing to their intrinsic properties, such as corrosion resistance and durability. Consequently, the low machinability of SASS is due to its high mechanical strength, low thermal conductivity, and high tendency to work hardening. The understanding of how cutting conditions impact the machining of this material remains limited, highlighting a deficiency in information regarding strategies to enhance its machinability. In this context, the present work analyzes the influence of different cutting and lubri-cooling conditions on machining forces, tool wear, surface roughness, and chip features produced during end milling of SASS 254 SMO. The results showed that depth of cut was the most influential parameter on static and dynamic machining forces, whereas the effect of cutting speed was low expressive. The nanofluid minimum quantity lubrication provided more stability in force values and lower tool failures on the peripheral cutting edge for the total machined length than in flood conditions. In comparison, dry machining resulted in higher tool failure and machining forces. Low roughness values were generated on the sample surface because the end-cutting edge did not exhibit substantial failures. The lubricating effect of NMQL also improves the surface quality of the machined workpiece. On the other hand, dry machining resulted in adhered materials owing to high temperatures in the cutting zone and flood milling in removing material particles from the surface due to work hardening. Furthermore, the generated chips corroborated the analysis of the lubri-cooling effects on the machinability of the material, highlighting the higher temperatures produced during dry cutting owing to changes in the surface color of chips. [ABSTRACT FROM AUTHOR]

Sustainable manufacturing has become a global and societal goal. Although its execution is much slower, the manufacturing sector is also slowing down the unsustainable practices. One of the difficulties in the implementation of sustainability is to re-engineer its evaluation for specific fields. This study brings sustainable manufacturing underpinned an overall performance index (OPI) by integrating machinability metrics, sustainability metrics, and their comprehensive sustainability evaluation. It involves quantitative and qualitative factors such as the operator's health, shop floor environment, air quality, chip removal, and surface quality of the product in this assessment process. In this attempt, the application of the framework is presented for the assessment of sustainability through a case study with different green and hybrid lubri-cooling technologies in machining processes. These technologies have the potential to contribute to cleaner production by reducing the consumption of cutting fluid, cutting tools, energy, and carbon emissions. Considering these state-of-the-art cooling technologies, this research aims to explore their advantages and promote their application in engineering fields, thereby opening new possibilities for sustainable manufacturing practices. [ABSTRACT FROM AUTHOR]

Due to its superior maximum strength/weight relation among titanium alloys and outstanding resistance to corrosion and fatigue, the Ti–5Al–5 V–5Mo–3Cr (Ti5553) alloy has been used in critical aerospace components, including landing gear parts and airframe structures for large modern aircraft. However, its high stress strength, low thermal conductivity, and ability to retain its mechanical properties at high temperatures contribute to its poor machinability. Several studies have indicated that Ti5553 alloy exhibits poorer machinability compared to Ti–6Al–4 V (Ti64), the most widely used titanium alloy at present. This paper presents a literature review of conventional machining of Ti5553, using tools with defined geometries and their performance using several materials for the tools, applying several coolant systems and heat-assisted machining. The Ti5553 performance was evaluated regarding tool wear, cutting efforts, chip morphology, and machined surface integrity. Notably, most researchers applied cutting speeds below 90 m/min and did not use cutting fluids. The best results achieved, in terms of tool wear, were applying high-pressure coolant (HPC) system, but cryogenic coolant can also be a good option. There are ongoing discussions regarding flank wear in Ti5553 machining, with tool wear predominantly influenced by adhesion and diffusion mechanism evidenced through crater wear. Ti5553 needs higher cutting efforts compared to the main titanium alloys, resulting in long, segmented chips with two well-defined shearing zones. Consequently, chip control through the cutting parameters is required. The machining parameters significantly impact the surface integrity and compressive residual stress after machining is required. Considering environmental considerations, future research trends emphasize the use of cryogenic and nanofluid cutting fluids, as well as the application of PCD tools and special carbide substrates and coatings. [ABSTRACT FROM AUTHOR]

In this study, metal matrix composite (MMC) materials were made with an aluminum matrix (AA7075 alloy) and reinforcement silicon carbide (SiC) elements using molten metal stir and indirect squeeze casting. SiC was used as a reinforcing element in the making of MMC material in different amounts (10%, 14%, and 18%) by mass. Electro Discharge Machining (EDM), cut depth (0.5 mm), three different pulse-on times, three different discharge current values, and a fixed pulse-off time (20 s) were used to machine MMC materials. The effects of machining parameters on machining time, average surface roughness, hole diameter, and material wear difference after machining were studied. As a result of the study, the composite material with 75 μ s pulse-on time, 6A current value, and 10% reinforcement element had the lowest machining time, the largest hole diameter, and the smoothest average surface. These machining parameters and materials also had the shortest machining time (5 min). Based on the signal-to-noise ratios, the best parameters for average surface roughness, hole diameter, Processing time, and material wear amount (MMC, discharge current value, and impact time) were found to be L 2 L 1 L 1 , L 3 L 1 L 1 , L 1 L 3 L 3 , and L 1 L 1 L 2 , respectively. Based on the ANOVA results, the R 2 values for the average surface roughness, hole diameter, machining time, and material wear loss value were 99.3%, 98.7%, 77.8%, and 97.3%, respectively. [ABSTRACT FROM AUTHOR]

In order to further research the effect of cryogenic cooling, the cooling capacity of LN2 jet was studied through the theoretical and experimental methods. Based on the boiling cooling mechanism of LN2, a set of predicted mathematical model considering the evaporating part before impacting, spreading adhesion, and impact spatter abilities was established. The effects of injection velocity and injection angle on the cooling speed, spreading area, and splashing state were analyzed. A series of milling experiments with LN2 impact cooling were executed. The results show that the smaller injection angle can cause a larger temperature difference, as well as achieving the easy nuclear boiling and improving the heat flux. At the same flow, the cooling effect is better at the condition of small milling depth following the smaller injection angle, as well as the excellent cutting quality. At large milling depth, the cooling effect at injection angle αn = 20° is not as good as that of 40°. Meanwhile, the relation between injection angle and feed is similar to that of milling depth. At small LN2 flow, the cooling rate will be less than the required speed at bigger cutting parameter; the processing area of the workpiece cannot be completely cooled, which causes the cooling effect, and cutting quality is not ideal. In addition, the cutting effect at angle αn = 40° is also better at large flow qf = 50 L/h. Furthermore, the smaller injection angle has the larger microhardness, and it is conducive to increase strain rate and rapidly reducing temperature, as well as the degree of high grain refinement. Ultimately, the small LN2 flow is followed small impact speed, the small injection angle 20° has the shortest cooling time with the strong cooling ability, and it is suitable for the cooling processing of small cutting parameters. Under the large flow, the injection angle of 40° can relatively increase the spreading time of LN2 and achieve full boiling heat transfer and can guarantee the complete cooling processing for large cutting parameters. [ABSTRACT FROM AUTHOR]

End-of-life management of fibre-reinforced thermoset composites is challenging due to the difficult-to-recycle reinforcements and the irreversibly polymerised thermoset matrix; therefore, researchers proposed the vitrimers as a sustainable alternative to thermosetting polymers. Although the early results of the material scientists are promising, the machinability of vitrimers has yet to be explored. Therefore, this paper aims to present a comparative machinability study of polyimine vitrimer, pentaerythritol-based epoxy (PER) and polycarbonate polymers through orthogonal machining experiments. Reflecting on the temperature-dependent properties of vitrimers, the starting temperature of the cutting tool was varied between room temperature and an elevated temperature above 155 °C. The cutting tool was heated by a 2000-W hot air gun until the surface temperature of the cutting tool, monitored by a VariocamHD thermographic IR camera (with Jenoptik IR 1.0/60 LW lens) and checked by a Fluke 51 II thermometer with a type K thermocouple, was permanently above 155 °C for 5 min. The cutting force was measured by a Kistler 9257B dynamometer, and the machined surface was characterised by a Mitutoyo Surftest SJ-400 surface roughness tester and Keyence VHX-5000 (with VH-Z20UT VH lens) microscope. The analysis of variances (ANOVA) results show that the sustainable vitrimer polymer is an appropriate substitute for thermosetting epoxy polymers, especially at low cutting temperatures. [ABSTRACT FROM AUTHOR]

This article discusses the effect of machining assistance on the machinability and surface integrity of titanium and nickel-based alloys for turning operations. The presented results are based on a literature review of the principal experimental work published by the French research laboratories within the framework of the Manufacturing 21 group. The work presented focuses on the assistances the most studied by the research group: cryogenic assistance and high-pressure assistance. This paper specifically addresses the experimental approaches used to determine the effect of the assistant on the cutting force, tool wear, chip formation, microstructural changes, and residual stresses generated on the workpiece machined surface. This literature review is completed by new results comparing machining tests on the Ti6Al4V titanium alloy using high pressure and cryogenic assistances. The results show that the assistances increase the tool life, as well as improve the surface integrity of the parts. However, these gains are not identical from one material to another. In particular, titanium alloys and nickel alloys show how a very different gains for a fixed assistance. The conclusions presented highlight current trends and research needs. [ABSTRACT FROM AUTHOR]

AbstractManufacturers confront considerable difficulties when machining titanium and nickel-based alloys due to concerns related to surface integrity, tool wear, cutting forces and temperature regulation. In order to tackle these difficulties, the prevailing method consists of utilizing cutting fluids to cool and lubricate the machining interface. Nevertheless, the persistent use of these fluids presents significant hazards to both human health and the environment. Hence, it is imperative to investigate novel methodologies that can reduce or eradicate the reliance on lubricants. Surface texturing has become a practical method in this situation since it improves the tribological properties of cutting inserts. The main factors that lead to the improvement of tribology are the capture of debris, decreased contact area, and increased lubricating capacity. These factors work together to lower cutting forces, tool deterioration and the surface roughness of the work material. This study provides an extensive analysis of the existing literature regarding the consequences of tool texturing in the process of machining titanium and nickel-based alloys. It scrutinizes techniques that utilize textured tools to enhance machining performance and assesses their influence on several machining parameters. The study explores various techniques for improving performance by analyzing the impact of textured tools on tool wear, thermal profiles, cutting dynamics and surface integrity in different scenarios. These scenarios include dry conditions, high-pressure cooling (HPC), the use of solid lubricants, the application of minimum quantity lubrication (MQL) with and without nanoparticles and the effectiveness of hybrid cryogenic/MQL techniques. This review also provides a comprehensive sustainability analysis, covering both the environmental and economic effects of using textured tools and lubricoolant techniques. Furthermore, this study provides valuable insights for future academic research, identifying areas that are ready for further investigation in this field. [ABSTRACT FROM AUTHOR]

Owing to its outstanding properties such as corrosion resistance, low density, relatively low cost, and stiffness, Al2024-T3 aluminium alloy has been widely applied in aircraft manufacturing. To perfectly assemble an aircraft, numerous high-quality holes are drilled into its structures employing conventional drilling processes. Conventional drilling poses some challenges such as thermal distortions, burr formations, and tool wear. Alternatively, abrasive water jet drilling (AWJD) is a thermal-free machining process that can be employed as an alternative to conventional drilling of aeronautical structures. Hence, in this work, the effect of abrasive water jet parameters, namely stand-off distance, water jet pressure, and abrasive mass flow rate, on hole-quality parameters was evaluated at traverse speed = 10 mm/min. Three parameters were stand-off distance = 1, 2, and 3 mm, abrasive mass flow rate = 200, 250, and 300 g/min, and water jet pressure = 1800, 2100, and 2600 bar. Using a 6 mm circular-movement diameter of the nozzle tip, optimal stand-off distance, water jet pressure, and abrasive mass flow rate obtained by multi-objective optimization were 2 mm, 250 g/min, and 2600 bar, respectively. The corresponding hole-quality parameters were Diameter = 6.232 mm, Kerf angle = 0.018°, Cylindricity = 0.051 mm, Perpendicularity = 0.033 mm, Circularity = 0.0041 mm and Surface roughness Ra = 2.909 µm. The results showed that water jet pressure had the greatest influence on Perpendicularity, Circularity; stand-off distance had the highest effect on Kerf angle; and abrasive mass flow rate has the largest influence on Hole diameter, Cylindricity and Surface roughness Ra, and Rz at the given value of traverse speed. The adopted optimization process for abrasive water jet of Al2024-T3 aluminium alloy was successfully verified through confirmation runs, clearly illustrating its benefits. [ABSTRACT FROM AUTHOR]

The urge to build a more environmentally friendly future has motivated researchers to examine composites outside of synthetic fiber and continue to consider natural fibre polymer composite. This present research, the hybrid bio composite was developed by bio fillers and natural fibres. The preliminary investigation was done to examine the possibility of using natural fillers (palm and coconut shell) in natural fibre (hemp and basalt) reinforced polymer (NFRP) composite for manufacturing application. In that way initially mechanical (tensile and flexural) properties testing were done on four different combinations of NFRP by using palm and coconut shell particles, to their influence on mechanical properties (tensile stress 278 MPa and flexural stress 330 MPa). It was found that 5% wt. palm + coco shell fillers combination hybrid composite presented good results in mechanical properties. Then 5% wt. palm + coco fillers was added in the matrix phase of NFRP composite was developed and study the machinability properties by using Abrasive Water Jet Machining (AWJM). NFRP machining in the relationships of material removal rate (MRR), kerf angle and surface roughness has been experimentally examined for various process parameters (nozzle pressure, distance stand and transverse speed). The research values for quality properties (MRR, Kt and Ra) were analysis-based on the trimming factors by developing the Taguchi method. The influence of optimized input process parameters on quality features were examined by utilizing experiential models. From this study, it is noticeable that, filler material in natural fiber composites reduces the kerf angle and the low and very high traverse speed leads the wide disparity in kerf inclination. For obtaining the good surface roughness and material removal rate medium traverse speed and medium stand of distance is the significant parameter respectively and moreover impact of jet pressure on surface finish is 3 times lower than the impact supplied to the surface finish by traverse speed [ABSTRACT FROM AUTHOR]

Purpose: This study aims to comparatively analyze the cut parts obtained as a result of cutting the Ni-based Inconel 625 alloy, which is widely used in the aerospace industry, with the wire electro-discharge machining (WEDM) and abrasive water jet machining (AWJM) methods in terms of macro- and microanalyses. Design/methodology/approach: In this study, calipers, Mitutoyo SJ-210, Nikon SMZ 745 T, scanning electron microscope and energy dispersive X-ray were used to determine kerf, surface roughness and macro- and microanalyses. Findings: Considering the applications in the turbine industry, it has been determined that the WEDM method is suitable to meet the standards for the machinability of Inconel 625 alloy. In contrast, the AWJM method does not meet the standards. Namely, while the kerf angle was formed because the hole entrance diameters of the holes obtained with AWJM were larger than the hole exit diameters, the equalization of the hole entry and exit dimensions, thanks to the perpendicularity and tension sensitivity of the wire electrode used in the holes drilled with WEDM ensured that the kerf angle was not formed. Originality/value: It is known that the surface roughness of the parts used in the turbine industry is accepted at Ra = 0.8 µm. In this study, the average roughness value obtained from the successful drilling of Inconel 625 alloy with the WEDM method was 0.799 µm, and the kerf angle was obtained as zero. In the cuts made with the AWJM method, thermal effects such as debris, microcracks and melted materials were not observed; an average surface roughness of 2.293 µm and a kerf of 0.976° were obtained. [ABSTRACT FROM AUTHOR]

A356 alloy is widely used in the automotive industry for applications such as cylinder heads, engine blocks and other components. Iron contamination is a major problem with this alloy. The use of recycled aluminum alloys has increased annually due to sustainable and energy issues involved in production. The presence of iron in Al–Si alloys enables formation of the β-Al5FeSi phase, which negatively affects mechanical properties and forming processes. In the present study, A356 alloy was cast with 0.2, 1 and 3% wt. of iron to reproduce a recycling process. Cooling rates of 1.17 and 1.81 °C/s were used. The material was submitted to thermal treatment by solubilization and artificial aging. The effects of iron contamination on cutting force during cylindrical turning were investigated using cutting speeds of 363 and 720 m/min, feed rates of 0.08 and 0.3 mm/rev and 1.5 mm depth of cut. In order to determine the influence of the parameters, ANOVA was performed at 5% significance. The results showed that cutting force increased by 185.8% at higher feed rates and declined 6.4% at greater cutting speeds. Greater presence of the β-Al5FeSi phase reduced cutting force by up to 5.6% when compared to the uncontaminated alloy, indicating that β-Al5FeSi formation can be beneficial when only cutting forces are analyzed, since its presence tends to minimize these forces. A slight change in the cooling rate affected the cutting force by 2.2%. Influences were also observed for combinations of two factors. [ABSTRACT FROM AUTHOR]

A comprehensive computational investigation has been carried out for YbPdH3 via first principles calculations for the first time. Structural, electronic and thermodynamic properties are obtained. The obtained lattice constant of YbPdH3 is in a good agreement with the existing literature. Subsequently, the elastic constants are obtained and used to compute several parameters such as anisotropy, hardness, Cauchy pressure, shear and Young modulus, machinability index and Poisson's ratio. According to Born stability criteria, YbPdH3 is mechanically stable material. Cauchy pressure and Poisson's ratio indicates ductile nature. The anisotropy factor indicates anisotropic nature almost in every direction for Young modulus, shear modulus, linear compressibility and Poisson's ratio. The machinability index (B/C44) is found to be 2.88 whereas Vickers hardness of YbPdH3 is computed via Chen's model as 2.965. The electronic band structure of YbPdH3 demonstrates metallic characteristics since there is no band gap between valence and conduction band. The thermodynamic properties such as Debye temperature, Debye vibrational energy, vibrational free energy, entropy, heat capacity and melting temperature of YbPdH3 are also obtained. The heat capacity seems to reach its Dulong-Petit limit at about 300 K. [ABSTRACT FROM AUTHOR]

Purpose: FeNi36 (Invar-36) alloy is widely used in the fabrication of molding tools in aerospace industries but there remains a need to improve its wear and friction performance due to its relatively low hardness. The formation of a heat affected zone (HAZ) on the surface of Invar-36 cut by wire electric discharge machining (WEDM) is promising to enhance its tribological properties. This study aims to investigate the tribological performance of WEDM-treated Invar-36 via a ball-on-disk tribometer in dry-sliding conditions. Design/methodology/approach: The untreated and WEDM-treated Invar-36 surfaces were reciprocated against an alumina ball at a sliding velocity of 40 mm/s, a stroke length of 10 mm and a sliding duration of 125 min under loads of 5, 10 and 20 N. The worn surfaces were characterized using a 2D profilometry and a scanning electron microscope equipped with energy-dispersive spectroscopy. Findings: The results showed that the WEDM-treated surface had a superior friction coefficient and wear resistance in comparison to the untreated surface, due to the grown HAZ. There was found to be a 9.3%–11.4% decrease in the friction coefficient and a 47%–57% reduction in the wear volume after the WEDM treatment. Both the untreated and WEDM-treated Invar-36 surfaces found abrasion and plastic deformation as the dominant wear mechanisms. Originality/value: Previous works have not focused on the tribological performance of the WEDM-treated Invar-36 extensively used for molding tools in aerospace industries. Our findings provide compelling evidence that the WEDM treatment improved the wear and friction performance of Invar-36 alloy because of the grown HAZ. [ABSTRACT FROM AUTHOR]

Aluminum alloys are widely used in many industries, including aerospace, automotive, civil, and electrical engineering. When compared to pure aluminum, most aluminum alloys have lower electrical and thermal conductivity, corrosion resistance, and weldability, as well as a low density and specific gravity. At the same time, the properties of aluminum alloys vary significantly depending on the group, which has a significant impact on their machinability. This review article is focused on the study of machining characteristics of aluminum alloys, such as machinability, surface integrity, tool wear and tool life, material removal rate (MRR), and chip morphology. The directions of increasing machinability by controlling cutting parameters, cutting environment, such as dry machining, conventional cooling systems, minimum quantity of lubricant (MQL), cryogenic lubrication (CL), with tool geometry, and textured tools, are also considered; tool materials include coating, vibration, thermally, and hybrid assisted machining. The article discusses the main types of machining, namely, turning, milling, drilling, and grinding. It shows ways to increase the machinability of machining on aluminum alloys, as well as the advantages and disadvantages. From the literature, it can be concluded that tool wear when machining aluminum alloys is 30–40% lower than when machining steel alloys due to their higher ductility and lower strength. Surface integrity, affected by the cutting parameters and cutting temperatures — which can reach between 200 and 400 °C — can vary by up to 15% in hardness and 20% in surface roughness. Cutting tool characteristics can enhance surface finish by up to 25% and extend tool life, reducing edge formation by up to 30%. Chip morphology, influenced by factors such as cutting parameters and tool material, can improve tool life by up to 35%. Vibration techniques can reduce thermal effects and improve surface finish by up to 40%, reducing cutting forces by around 30%. [ABSTRACT FROM AUTHOR]

As a new generation of chip-packaging materials, CaSiO 3 LTCC substrates have the characteristics of high frequency, low thermal expansion coefficient, and low dielectric loss. These materials are widely used in radar communication and other industries. However, in the condition of high heat density, it is difficult to adapt calcium silicate with a low thermal conductivity to the heat dissipation requirements. To improve the heat dissipation performance, high-aspect-ratio heat-dissipation microchannels must be prepared on the surface of the CaSiO 3 LTCC substrate. In this study, a new nanosecond laser and chemical milling-assisted micro-milling (NLCAM) method is proposed. The processing mechanism of the nanosecond laser ablation of CaSiO 3 is explored and the influence of the laser parameters on the depth of the etching groove, top width, and hardness of the residual modified layer are studied by establishing a laser energy superposition model and test method. The improvement of milling force and milling surface quality by laser is studied. The results demonstrate that the laser power has the most significant effect on the ablation depth and width of the top of the CaSiO 3 ; the excess heat diffuses outside the laser irradiation area, increasing the width of the top of the CaSiO 3 beyond the designed width. With an increase in the scanning speed and scanning distance, the ablation depth exhibited a decreasing trend, corresponding to the laser energy model. Nanosecond laser chemical milling (NLCM) can reduce the hardness of the material by 72.0–77.2%. The maximum reduction in the average axial milling force was 56.8%, and the fluctuation of milling force is reduced. Compared to pure micro milling, the tool wear area of NLCAM was reduced by 89.3% and the average roughness Sa of the bottom surface of the microgroove was reduced to 0.392 μm, which confirms the high-quality and efficient machining of the CaSiO 3 LTCC substrate. [ABSTRACT FROM AUTHOR]

The exceptional mechanical properties of titanium alloy and nickel-based high-temperature alloy make them extensively utilized in aero-engine blades. The machinability of these materials is poor due to their high material strength and low thermal conductivity which lead to technical difficulties such as cutting heat accumulation, tool wear, and poor surface quality during the machining process. This study commences with an investigation into the material properties and processing mechanisms of titanium alloy and nickel-based high-temperature alloy, with a particular focus on recent advancements in cutting dynamics, chip formation mechanisms, tool wear, and surface integrity. The important effect of reasonable setting of cutting parameters and machining conditions on the machining integrity is discussed. The future trend for high surface integrity machining of titanium alloy and nickel-based high-temperature alloy blade is finally predicted. [ABSTRACT FROM AUTHOR]

In the current study, Ti-6Al-4V (Ti64) and Ti-6Al-7Nb (Ti67) alloys were prepared by vacuum arc melting. The produced samples were then subjected to different heat treatment regimes. The evolved microstructures and their corresponding hardness were investigated. Computerized drilling tests using TiAlN-coated high-speed steel bits were performed to assess the machinability of the prepared specimen regarding cutting force, tool wear, and thickness of the deformed layer. It was observed that Ti64 specimens that were water quenched from either α/β or β range contained martensitic phase. In Ti67, samples showed martensite only when water quenched from the β-phase range (1070 °C). Formation of martensite resulted in higher hardness and hence led to higher cutting forces and increased tool wear during the drilling process. Machined samples with higher hardness formed a thicker subsurface deformation area (white layer) and increased burr heights. Surface roughness in Ti64 workpieces was generally higher compared to Ti67 specimens. The coat of the drilling bit was partially attacked in the as-cast specimens, which was evident by elemental N on the machining chips. The machining tool deteriorated further by increasing the workpiece hardness through martensitic formation, where elements such as Cr, V, Fe, etc. that came from the tool steel were detected. [ABSTRACT FROM AUTHOR]

On the way to the real industrial applications of the metal matrix composite foams, the machining issue is highly critical in terms of dimensional accuracy, surface quality, and design diversity. Therefore, especially for lightweight automotive and aerospace components, the drilling machinability properties of cellular glass‐added aluminum composite foams were examined in this paper, and this is the first initiative in the literature specific to millimeter‐scale glass and aluminum‐zinc matrix combination. To comprehend the drilling properties, the outputs of thrust force, cylindricity, material removal rate, specific cutting coefficient, circularity error, damage factor, surface roughness, and chip formation were measured elaboratively. The results showed that cylindricity and damage factor of foams elevated with the increased feed rates (from 0.05 mm×rev−1 to 0.2 mm×rev−1) and cutting speeds (from 25 m×min−1 to 100 m×min−1). Maximum thrust force value reached up to 150 N for 0.2 mm×rev−1 feed and 25 m×min−1 cutting speed. Besides, specific cutting coefficient values ranged between 360 MPa and 114 MPa. The highest surface roughness of 58.3 μm was obtained with the lowest cutting speed of 25 m×min−1, and the long/continuous chip structure converted into a separate/short structure based on rising feed and cutting speeds. [ABSTRACT FROM AUTHOR]

This study investigates the machining of FLC-4608 (designation by Metal Powder Industries Federation, standard 35) sinter-hardened steel compacts with 90% relative density during turning operation. The objective of the study is to analyze the effect of cutting velocity and feed rate on the cutting force component in the direction of cutting motion using chip characteristics. The results showed that the combination of high cutting velocity and low feed rate is the appropriate condition to obtain a low value of the cutting force component. The results also indicated that the machining configurations considered produce shear-localized segmented chips, also known as saw tooth chips, and that the chip formation process involves almost complete densification of the uncut chip material. Except for chip length, all the investigated chip characteristics, minimum and maximum chip thickness, shear band microstructure, and structure below the tip of the chip segment were consistent with the results of the cutting force component. As the feed rate increased, the minimum and maximum chip thickness increased, which was consistent with the increasing value of the cutting force component. Similarly, through the microstructure of the adiabatic shear band and the structure below the tip of the chip segment, increasing cutting velocity showed the dominance of the thermal softening effect over strain hardening and strain rate hardening, consistent with the decreasing value of the cutting force component. This approach is novel, as chip characteristics have received little attention in previous studies on the machining of PM materials. The present study is potentially helpful to the PM industry in achieving better machining process control through a thorough understanding of the results related to the cutting force component in the direction of the cutting motion. The future scope discussed in this report also has prospects for advancing the science of machining PM materials. [ABSTRACT FROM AUTHOR]

Ultrahigh-molecular-weight polyethylene (UHMWPE) is used in the defence industry mainly owing to its properties, such as excellent dimensional stability, excellent ballistic performance, and light weight. Although UHMWPE laminates are generally studied under impact loads, it is crucial to understand better the optimal machining conditions for assembling auxiliary structures in combat helmets or armour. This work analyses the machinability of UHMWPE laminates by drilling. The workpiece material has been manufactured through hot-pressing technology and subjected to drilling tests. High-speed steel (HSS) twist drills with two different point angles and a brad and spur drill that is 6 mm in diameter have been used for this study. Cutting forces, failure, and main damage modes are analysed, making it possible to extract relevant information for the industry. The main conclusion is that the drill with a smaller point angle has a better cutting force performance and less delamination at the exit zone (5.4 mm at a 60 m/min cutting speed and a 0.05 mm/rev feed) in the samples. This value represents a 46% improvement over the best result obtained in terms of delamination at the exit when using the tool with the larger point angle. However, the brad and spur drill revealed a post-drilling appearance with high fuzzing and delamination. [ABSTRACT FROM AUTHOR]

Due the importance of using commercially Zamak5 in a wide range in industrial applications, however, this study was focused on the enhancing its machining issues by adding pure copper, so the effect of the addition of (1 to 3)% Cu to commercially Zamak5 on its mechanical properties, microhardness, surface texture and corrosion resistance was investigated. A CNC machining tests, microhardness tests, corrosion test, compression test, and microhardness test were performed. It was found that there is an enhancement on the flow stress at 0.2 strain of about 19% for 3% Cu addition followed by 17% and 15% in the case of 2% Cu and 1% Cu respectively. There was an enhancement in microhardness of about 11.6% in the case of 3% Cu addition. The surface finish was improved by increasing the number of copper contents (1 to 3)% to the base material Za5. Polarization measurements revealed that 3% alloy specimen inhibit the corrosion by more than 70% compared with the blank sample. [ABSTRACT FROM AUTHOR]

In this paper, the authors present a comparative analysis of the thermomechanical properties of plastics intended for machining before and after the annealing process. The research included the dynamic properties, thermal analysis and a study of the surface after machining. The dynamic properties were tested using the DMTA method. The characteristics of changes in the value of the storage modulus E' and the tangent of the mechanical loss angle tgδ depending on the temperature and vibration frequency were determined. The thermal properties were tested using the DSC method, and a comparative analysis of the roughness parameters of the tested materials obtained from the profilometer was carried out. The presented studies indicate the extent of the impact of the annealing process on the machinability of structural polymer materials, taking into account the analysis of changes in the thermomechanical properties of the tested materials. [ABSTRACT FROM AUTHOR]

The paper investigates the influence of some 3D printing conditions on some physical–mechanical and technological properties of polycaprolactone (PCL) wood-based biopolymer parts manufactured by FDM. Parts with 100% infill and the geometry according to ISO 527 Type 1B were printed on a semiprofessional desktop FDM printer. A full factorial design with three independent variables at three levels was considered. Some physical–mechanical properties (weight error, fracture temperature, ultimate tensile strength) and technological properties (top and lateral surface roughness, cutting machinability) were experimentally assessed. For the surface texture analysis, a white light interferometer was used. Regression equations for some of the investigated parameters were obtained and analysed. Higher printing speeds than those usually reported in the existing literature dealing with wood-based polymers' 3D printing had been tested. Overall, the highest level chosen for the printing speed positively influenced the surface roughness and the ultimate tensile strength of the 3D-printed parts. The cutting machinability of the printed parts was investigated by means of cutting force criteria. The results showed that the PCL wood-based polymer analysed in this study had lower machinability than natural wood. [ABSTRACT FROM AUTHOR]

Tellurium treatment is used to control the morphology of manganese sulfide (MnS) inclusions, reduce the mechanical anisotropy, and improve the machinability of sulfur‐bearing steels, such as free‐cutting steels, super free‐cutting steels, medium‐carbon microalloyed steels, and die steels. The boiling point of tellurium is low, and it is mainly added to steel in the form of fine particles wrapped in a cored wire. In steels, tellurium mainly exists in the form of Mn(S, Te) inclusions or MnTe–MnS composite inclusions. The strength of MnS inclusions is increased through tellurium doping; thus, the aspect ratio of sulfide after hot working is significantly decreased through tellurium treatment. However, the tellurium content in steel should not be too high; otherwise, brittle compounds will form and cause embrittlement, particularly in high‐alloyed steels. The Te/S mass ratio is considered an important factor in tellurium treatment. When the Te/S mass ratio in steel is 0.2, the aspect ratio of the as‐cast sulfide could be controlled within the optimal range. During steelmaking, the yield of Te can be improved by reducing the basicity of the slag and decreasing the time of Te evaporation. Through data‐driven material design, Te treatment technology undergoes broader development. [ABSTRACT FROM AUTHOR]

Among the various renewable energy sources, wind energy offers an effective solution to the energy providers. Onshore wind turbines are generally designed for sites with low wind resources, while offshore wind turbines can be more efficient in producing energy thanks to their longer blades that provide more than 10 MW of rated power. Offshore wind turbine blades are subjected to significantly higher stresses and harsh environmental conditions. Therefore, hybrid composites composed of carbon and glass fibers can offer cost‐effective and long‐lasting solutions for wind turbine blade manufacturers. Turbine blades are connected with main spars through bolted connections and high interlaminar stresses occurring during the drilling process can cause to delamination in the composites. To prevent catastrophic failure related to defective machining, the drilling process must be performed meticulously and all machining‐related results must be analyzed step by step. In this paper, dry drilling properties of hybrid glass‐carbon fiber laminate epoxy matrix composites were examined experimentally in order to contribute to the wind energy sector. The results showed that the delamination factor could be decreased with higher cutting speeds or lower feed rates. Besides, higher feed levels caused higher thrust forces on the tool body. [ABSTRACT FROM AUTHOR]

The poor machinability of SiC f /SiC composites greatly limits its application and promotion. The laser-induced ablation products of SiC f /SiC composites are powdery, loose and porous. Milling of laser ablated samples demonstrated that the force and heat were almost negligible when milling ablation products. Accordingly, a laser ablation pretreatment milling (LAPM) process of SiC f /SiC composites was proposed. Under the LAPM process, after the laser ablation treatment with controllable depth, the cutting allowance could be achieved in only one pass, which greatly improved the machining efficiency compared with the conventional milling process. The material removal rate was greatly improved on the premise of ensuring the machining quality. Taking the milling of tensile specimens as an example, compared with conventional milling, the total processing time of the specimen was reduced by 31.29 % by LAPM process. Therefore, LAPM provides a potential feasible process scheme for greatly improving the machinability and machining efficiency of SiC f /SiC composites. [ABSTRACT FROM AUTHOR]

Steels for the production of frames for plastic molds frequently need to exhibit resistance to corrosion while at the same time requiring large amounts of machining. Machinability as a crucial property can be enhanced by the addition of sulfur, resulting in the formation of favorable sulfides, which in turn can deteriorate mechanical properties and corrosion resistance. The detrimental effect on mechanical properties is caused, among others, by the elongation of sulfides during rolling or forging. In a novel approach, a special wire treatment of the melt is performed, which results in improved spherical morphology and chemical composition of the inclusions, yet leading to even enhanced machinability (tested, among others, by means of milling). Milling tests reveal increased productivity compared to conventionally manufactured material, which means an improved lifetime of milling inserts even at the highest cutting speeds. In addition, orthogonal cutting trials are performed aiming at understanding differences in machinability. At the same time, mechanical properties, in particular toughness, are slightly improved, while corrosion resistance is not severely affected. [ABSTRACT FROM AUTHOR]

Due to the capability of maintaining excellent performance in mechanical properties and corrosion resistance at high temperatures, Inconel 718 superalloy (IN718) has been widely applied in aerospace. However, it is also a difficult-to-cut material because of these unique properties along with its low thermal conductivity. In order to improve its machinability and surface quality, dry and minimal quantity lubrication (MQL) cutting experiments were conducted in this study on solution heat-treated and aged IN718. Besides the analysis of tool wear and material deformation behavior was conducted to reveal the mechanism of MQL-assisted cutting, with an explanation offered for the difference in cutting results between solution heat-treated and aged IN718. As indicated by the experimental results, MQL-assisted cutting contributes to suppressing the generation of burrs, improves the finish of the machined surface, and reduces surface/subsurface damage. In addition, it also can effectively improve the tool-chip friction state and reduce the thermo-mechanical loads, thereby improving the tool life. The solution heat-treated IN718 demonstrated better machinability, the least significant tool wear under MQL-assisted cutting, as well as the best surface quality and chip breaking effect. The cutting response caused by the heat treatment state was different. The durability of the solution heat-treated IN718 was 56% higher than that of the aged, and the surface roughness was reduced by 6.1%. The flank wear of cutting solution heat-treated IN718 under MQL was the smallest, and the surface quality and chip breaking effect were the best. This study can provide a reference for hot and cold collaborative processing. [ABSTRACT FROM AUTHOR]

Undesired dough adhesion is still a challenge during the production of baked goods. There are various methods for determining the adhesive texture properties of dough. In the majority of scientific papers, dough stickiness is measured analytically by the force‐distance recording of dough detachment. In this study, we describe a new multi‐scale approach to compare dough adhesion phenomena in a laboratory, pilot sale and human sensory assessment. In it, the adhesive material properties of dough were investigated using a pilot scale toppling device representing dough adhesion behavior in the production process, in the laboratory by texture analysis with the Chen–Hoseney method and furthermore with a new, implemented non‐oral human sensory analysis. To simulate different dough adhesion behavior, the dough mechanical and adhesion properties were varied by applying dough‐modifying enzymes and different dough storage times. The structural changes in the different wheat dough system were compared by rheological characterization. By characterizing the different adhesion phenomena of the doughs, the sample with bacterial xylanase showed the highest values after 80 min of storage time in all three methods. Correlation analysis revealed a strong relationship between the detachment time (pilot scale) and human sensory assessment attributes (Force R = 0.81, Time R = 0.87, Distance R = 0.92, Stickiness R = 0.80) after 80 min of storage time. Even though human sensory assessment showed limits in the detectability of differences in dough adhesion behavior compared to the Chen–Hoseney method, it was better suited to predict machinability. [ABSTRACT FROM AUTHOR]

The impeller material FV520B-hardened stainless steel is a typical difficult-to-machine material. During the cutting process, the force and thermal load are large, and the chip breaking is difficult, resulting in poor processing quality and serious tool wear. Low temperature cooling can improve the machinability of materials by significantly reducing the temperature of the cutting zone. It is an important development direction of clean cutting in the future. In this paper, the effects of low temperature cooling (18 ~ − 196℃) on cutting machinability and chip morphology evolution of FV520B were systematically studied from macroscopic and microscopic aspects by setting triaxial milling and orthogonal turning experiments respectively based on low-temperature jet formed by mixing liquid nitrogen and compressed air. The experimental results show that liquid nitrogen cryogenic cutting can significantly improve the machinability of material FV520B and promote the formation of serrated chips. Under the condition of cutting speed of 80 m/min, axial cutting depth of 1 mm and feed per tooth of 0.25 mm/r, the cutting force, cutting vibration, and surface roughness of FV520B at − 100℃ are reduced by 30%, 62%, and 18% respectively compared with those at 18℃. When the cutting speed is 80 m/min, the axial cutting depth is 1 mm, and the feed per tooth is 0.1 mm/z, the tool life at − 100℃ is 43% higher than that at 18℃. With the increase of cutting speed and the decrease of jet temperature, the serration degree, pitch, and shear angle of chips increase and the deformation coefficient of chips decreases. [ABSTRACT FROM AUTHOR]

Wire and arc additive manufacturing (WAAM) technology has recently become attractive due to the fact of its high production capacity and flexible deposition strategy. One of the most prominent drawbacks of WAAM is surface irregularity. Therefore, WAAMed parts cannot be used as built; they require secondary machining operations. However, performing such operations is challenging due to the fact of high waviness. Selecting an appropriate cutting strategy is also challenging, because surface irregularity makes cutting forces unstable. The present research determines the most suitable machining strategy by assessing the specific cutting energy and local machined volume. Up- and down-milling are evaluated by calculating the removed volume and specific cutting energy for creep-resistant steel, stainless steel, and their combination. It is shown that the main factors that affect the machinability of WAAMed parts are the machined volume and specific cutting energy rather than the axial and radial depths of the cut due to the fact of high surface irregularity. Even though the results were unstable, a surface roughness of 0.1 µm was obtained with up-milling. Despite a two-fold difference in the hardness between the two materials in the multi-material deposition, it is found that hardness should not be used as a criterion for as-built surface processing. In addition, the results show no machinability difference between multi- and single-material components for a low machined volume and low surface irregularity. [ABSTRACT FROM AUTHOR]

This research focuses on wrought Ti-6Al-4V machining using coated carbide inserts under flood cooling to study the machinability characteristics. Machining parameters are optimized, and mathematical models are developed for correlations. Surface roughness lies between 0.215 μ m and 0.830 μ m and even below 1 μ m during machining. Flank wear lies within 0.033–0.16 mm which is below the 0.2 mm criteria of wear. Cutting temperature lies between 31∘C and 158∘C. The reduction of cutting temperature and chip serration under flood cooling and the subsequent transfer of heat from the shear zones help to generate good surface finish and may be due to the evolution of a lower wear rate. Abrasion, chipping, adhesion and built-up-edge are seen as major mechanisms of wear. The optimal conditions are found to be a depth of cut of 0.1 mm, 0.1 mm/rev feed rate and 70 m/min cutting speed. There is an improvement in results at optimal conditions of 38.42% for Ra, 60.86% for VBc and 27% for T , respectively, than initial parametric conditions. Further, grey relational grade has been improved by 0.263. Machinability models developed through quadratic regression are observed to be significant. [ABSTRACT FROM AUTHOR]

The state-of-the-art of high-strength fiber-reinforced polymer (HSFRP) textile composites exhibit a great strength to weight ratio and a high stiffness, durability, damping properties, and resistance to wear and corrosion. These properties of HSFRP textile composites have led to their applications in the aviation, defense, marine, biomedical, automobile, and many other manufacturing sectors. The major difficulties observed during the machining of fibrous polymer textile composites is the rapid wear of cutting tools, the deterioration of machined surfaces, the thermal damage, delaminations, and the fiber pull-out. This article is an extensive review of the machining and machinability of HSFRP textile composites, followed by their processing techniques, advantages, and applications. It can provide an insight into selecting manufacturing strategies for these composite materials. [ABSTRACT FROM AUTHOR]

Thermoelectric refrigeration is one of the mature techniques used for cooling applications, with the great advantage of miniaturization over traditional compression refrigeration. Due to the anisotropic thermoelectric properties of n‐type bismuth telluride (Bi2Te3) alloys, these two common methods, including the liquid phase hot deformation (LPHD) and traditional hot forging (HF) methods, are of considerable importance for texture engineering to enhance performance. However, their effects on thermoelectric and mechanical properties are still controversial and not clear yet. Moreover, there has been little documentation of mechanical properties related to micro‐refrigeration applications. In this work, the above‐mentioned methods are separately employed to control the macroscopic grain orientation for bulk n‐type Bi2Te3 samples. The HF method enabled the stabilization of both composition and carrier concentration, therefore yielding a higher quality factor to compare with that of LPHD samples, supported by DFT calculations. In addition to superior thermoelectric performance, the HF sample also exhibited robust mechanical properties due to the presence of nano‐scale distortion and dense dislocation, which is the prerequisite for realizing ultra‐precision machining. This work helps to pave the way for the utilization of n‐type Bi2Te3 for commercial micro‐refrigeration applications. [ABSTRACT FROM AUTHOR]

Preparation of lightweight polymer monoliths with highly thermo/electro conductivity for advanced thermal/electromagnetic interference (EMI) management in high-integrated and weight-sensitive electronics remains pending challenges. Here, lightweight porous exfoliated graphite/polyvinyl alcohol (EG/PVA) monoliths with locally layered structure are fabricated via a hypergravity induced self-assembly method (HGSA). Owing to the HGSA method resulting in formation of multiply robust EG networks, the monoliths show an exceptional thermal conductivity of 2.42–8.45 W/mK and a high electrical conductivity of 8.16–230.40 S/m at low density of 0.28–0.64 g/cm3, thus endowing itself with remarkable thermal/EMI management capability. To the best of our knowledge, this is probably first time to achieve high thermal conductivity (>5 W/mK) into porous polymer composites with such low density. Besides, an impressive specific compression modulus of 338.2–689.4 MPa cm3/g is achieved in the monoliths, which is basically comparable to most carbon foams after heat treatment. The results we provided in this research open new possibilities for fabricating lightweight polymer composites with multiple functions for advanced thermal/EMI management. [Display omitted] • EG/PVA monoliths had low density, high compression modulus, and high durability. • Thermal conductivity varied from 2.42–8.45 W/mK at density of 0.28–0.64 g/cm3. • An EMI shielding effectiveness of 77.51 dB was achieved in EG/PVA monolith. • EG/PVA monoliths showed exceptional thermal/EMI management capability. [ABSTRACT FROM AUTHOR]

The present study aims to enhance the hardness and wear resistance of AZ91 Magnesium (Mg) alloy using Equal Channel Angular Pressing [ECAP]. Specimens were initially prepared using the die casting technique and were homogenized at 420°C for 24 hours. Both homogenized and non-homogenized specimens were subjected to an ECAP single pass under different temperatures. A Scanning Electron Microscope was used to study the influence of die heating temperature on the microstructure of AZ91 Mg alloy. A reciprocating wear test was carried out using the weight loss method to analyse the importance of ECAP on wear resistance. Results revealed that the microhardness and wear resistance of AZ91 were found to have increased after ECAP. Homogenization of specimens showed improved properties compared to non-homogenized specimens. Grain refinement was observed in both homogenized and non-homogenized samples. Cracks were observed on the ECAPed specimen when the ECAP temperature was maintained at 435°C–455°C. Overall, ECAP caused grain refinement, increased hardness and wear resistance in the AZ91 Mg alloy. [ABSTRACT FROM AUTHOR]

The natural, glass, and carbon fiber reinforced polymer composites are currently being replaced conventional materials due to their lower specific weight and superior strength properties. Natural fiber-reinforced polymer composites (NFRPCs) have grown in importance in real world applications recently due to a growing focus on the environmental and sustainability elements of engineering materials. The difficulty of machining FRP composites, which results in dimensional errors, poor product quality, and material damage, is due to their inhomogeneity, ease of deformation, and anisotropic nature. Moreover, this review gives an insight regarding recent developments and challenges that will help for upcoming researchers. The nonhomogeneous properties and insufficient ductility of natural and synthetic fiber-reinforced composites have produced fracturing and discontinuous chips during the machining operations. The machinability of FRP composites depends on the constituents present in the composites. More delaminations were found in the natural fiber composites due to improper bonding and less compatibility with the polymer matrices, also the lower heat resistant property of the natural fibers causes serious problems during the machining process. Hence more studies are needed to decrease the thrust force and delamination damages in carbon, glass, and natural fiber reinforced polymer composites. [ABSTRACT FROM AUTHOR]

During machinability, the combination of machining process parameters and the material properties of the component to be machined plays an important role. Material properties depend upon the type of phase form present and the grain size of the formed phases, which in turn depends upon the prior treatment given to alter the initial room temperature types and form. Accordingly, spheroidization treatment was carried out on medium carbon steel (AISI1040) by altering the initial room temperature structure through normalizing and hardening treatment. Machinability experiments were performed on CNC machine by varying machining process constraints. Tool wear and surface roughness of the machined component obtained by turning were analyzed and correlated. Using Minitab and full factorial design, the ANOVA study was carried out. With the help of regression analysis, residual and main effect plots combined optimization (tool wear and surface roughness) was targeted. ANOVA result shows excellent machinability for the asbought-spheroidized condition where feed has a 67% contribution to tool wear (TW) whereas the depth of cut has a 71.91% contribution to surface roughness (SR). Also, the optimized regression values obtained for machining parameters are feed (0.39 mm/rev), depth of cut (0.6 mm), and spindle speed (780 rpm) with composite desirability of 0.8174. TW and SR experimental values for the optimized machining parameters are 0.039 mm and 2.89 µm, respectively, and the difference between the actual and optimized values is less than 5%. [ABSTRACT FROM AUTHOR]

An investigation was made on composites containing AA6082 as matrix and boron nitride/molybdenum disulphide (BN/MoS2) as reinforcement, which was a composite materials hybrid at 3 wt% of BN and 1% MoS2 and fabricated by stir casting methodology. Using electrical discharge machining (EDM) equipment, machinability studies were undertaken to achieve an optimal condition on process parameters. Taguchi (L27 orthogonal array)-based design of experiments was employed to examine the influence of process parameters like pulse on time (Ton), peak current (IP), and gap voltage (V) on material removal rate (MRR), circularity (CIRC), electrode wear rate (EWR), and cylindricity (CYLD). Multi-criteria decision-making (MCDM) methodology was employed for the process parameters while machining AA6082/3 wt% BN/1% MoS2 hybrid composites. An entropy-based objective weights method was integrated with the complex proportional assessment (COPRAS) approach to assess the most excellent optimal level of process parameters. The entropy (Wj) weights were 0.1285, 0.1002, 0.5707, and 0.2005 for MRR, EWR, CIRC, and CYLD. Optimal conditions are obtained from the COPRAS method of relative significance score, and quantitative utility assessment score in the nineteenth experiment having the 15 A, 50 μs, and 30 V with the relative significance score of 0.0735 and a higher quantitative utility score of 100% being achieved. Using an SEM, the machined surface is analysed for the micro-structural examination. At higher peak current (IP), micro-voids and craters with poor surface finish were located. [ABSTRACT FROM AUTHOR]

To evaluate the fracture toughness and brittleness of a newly developed CAD/CAM resin composite block and compare it with five other resin composite blocks and one polymer-infiltrated ceramic block. Fracture toughness was determined through single-edge notched beam (SENB) method according to ASTM D5045-14. Parallelepiped specimens (thickness × width × length = 1.8 × 3.6 × ∼18 mm) with a V notch (length = ∼1.8 mm) (n = 10) were made from block materials using a low-speed water-cooled diamond precision saw and razor blade. Brittleness index (BI) was calculated from Vickers hardness and fracture toughness. Data were analyzed using one-way ANOVA and post-hoc Tukey tests (p ≤ 0.05). The experimental block showed significantly higher fracture toughness than all commercial block materials (p < 0.001) and has a brittleness index similar to most commercial blocks (p > 0.05) which have significantly lower brittleness index than Vita Enamic (p < 0.001). A moderate or strong correlation was observed between fracture toughness and flexural strength (Pearson's correlation coefficient R = 0.66) or diametral tensile strength (R = 0.86) or filler loading (R = 0.66), and between brittleness and Vickers hardness (R = 0.87). The new composite block exhibited significantly higher fracture toughness and lower brittleness among the commercial CAD/CAM composite block materials tested, indicating a lower tendency to fracture and marginal chipping, and better machinability. The new composite block with higher fracture toughness and lower brittleness is suitable to use in the fabrication of CAD/CAM indirect restorations with potential long-term clinical success. [ABSTRACT FROM AUTHOR]

In the present work, the machinability of difficult-to-cut Inconel 718 aerospace superalloy is studied under vegetable oil-based minimum quantity lubrication (MQL) in consideration with different cutting tool materials. MQL environment is produced by supplying air-oil mist in which biodegradable sunflower oil is used. In comparison with uncoated carbide tool, performances of MT-CVD multi-layered TiCN-Al2O3-TiOCN coated and MT-CVD double-layered TiCN-Al2O3 coated carbide inserts are assessed during longitudinal turning of Inconel 718. Coating materials are characterized by average thickness of individual coating layer, elemental composition and frictional coefficient. With constant feed and depth-of-cut (0.1 mm/rev and 0.25 mm respectively), quantitative responses such as tangential cutting force, tool-tip temperature and width of tool flank wear are considered as machinability assessment criteria under varied cutting speed condition (v = 60, 80, 100 and 130 m/min). Notable reduction in tool-tip temperature (25.6% and 30.4%) and reduction in cutting forces (10.6% and 22.3%) are obtained for coated tool [T1] and coated tool [T2] respectively, when compared to uncoated counterpart. Detailed analysis on tool wear modes is carried out followed by chip's macro/micro-morphology. Apart from chip's micro-morphological parameters, morphologies of chip's back and free surfaces and chip microhardness are studied. [ABSTRACT FROM AUTHOR]

For the past few decades, cubic boron nitride (CBN) and ceramic tool inserts have been used in dry turning of heat-treated AISI D3 tool steel. But, when these inserts are used to achieve a high surface finish at a cutting speed beyond 200 m/min, they suffer from severe tool wear and generation of high temperature at the interface. To overcome these shortcomings, an attempt is made for dry turning of AISI D3 tool steel (heat-treated) by using ceramic insert, i.e., Al2O3 + Ti (C,N) with coated (TiN). The use of this hybrid insert has resulted in the improvement of the performance of the turning process by significantly reducing the tool wear and cutting forces requirement at a cutting speed of 175 m/min. In this study, a parametric analysis of the turning process is performed to develop a quantitative relationship between process variables and response characteristics using RSM. The process responses are optimized (at cutting speed 175 m/min, feed rate 0.12 mm/rev and depth of cut 0.1 mm) using a swarm-based intelligent algorithm, i.e., particle swarm optimization, and it is observed that the total cost of machining per part is USD 0.20 only for a tool life of 45 min. The confirmation run based on the optimized parameters setting reveals that the error is within 8%, as compared to the predicted results of optimization. A machining strategy based on parametric and chip morphology is proposed in this study. The main contribution of the paper is twofold: firstly, parametric analysis, optimization of turning process responses and cost analysis of turning process based on optimization results; secondly recommendation of machining strategies based on results of parametric analysis and chip morphology study. It is witnessed that our proposed methodology outperforms the state-of-the-art methods. [ABSTRACT FROM AUTHOR]

In this work, an alumina-yttrium aluminum garnet (Al2O3-YAG) cutting tool was developed and characterized aiming application in dry machining of nodular (spheroidal) cast iron. Ceramic powders containing 85 wt.% Al2O3 and 15 wt.% Y3Al5O12(YAG) were homogenized, compacted, and sintered at 1600 °C for 2 h at a heating rate of 5 °C/min. The sintered ceramic presented relative density of 98.3 ± 0.2%. X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed α-Al2O3 and YAG as crystal phases, both with equiaxed grains with average sizes of 1–4 μm (Al2O3 phase) and 0.7–1 μm (YAG phase). In addition, this ceramic composite presented Vickers hardness and fracture toughness of 15.2 ± 0.2 GPa and 4.6 ± 0.3 MPa.m1/2, respectively. The dry machining performance of the Al2O3-YAG cutting tool was compared with that of a commercial cemented carbide cutting tool using cutting speed (VC) of 200 and 500 m/min, feed rate (f) of 0.25 and 0.10 mm/rev, and axial depth of cut (ap) of 0.60 mm. The results showed that the best setting for the cemented carbide cutting tool was obtained at VC = 200 m/min and f = 0.25 mm/rev, which produced the best machinability with average surface roughness (Ra) of 3.516 μm, cutting length (LC) of 6000 m, and maximum flank wear (VBmax) of 0.58 mm. For the Al2O3-YAG cutting tool, the best setting was achieved at VC = 500 m/min and f = 0.10 mm/rev, which produced Ra = 0.848 μm, LC = 12,293 m, and VBmax = 0.54 mm. [ABSTRACT FROM AUTHOR]

The objective of the present study is to investigate the effect of chemical composition and microstructure on machinability, mechanical properties, and crack growth of GG-20 gray cast iron for brake drum application. The effects of a reduction in C and Si on microstructural parameters such as type, size, and aspect ratio of graphite particles, interlamellar spacing of pearlite, and the presence of MnS were investigated. In the following, the effect of different microstructures on mechanical properties and machinability of cast iron were studied. The fracture surface, crack growth, worn surface, chip formation and wear on cutting tools have been studied as well. The results showed that both tensile strength and hardness increased, and the machinability reduced by decreasing C and Si. By reducing the C content from 3.4% to 3.2%, the maximum hardness value and tensile strength were obtained to be 207HB and 286 MPa, respectively. Moreover, the Ra and Rz values were increased to 4.3 μm and 25.8 μm, respectively. With an increase in the length of graphite flakes, the distance between microcracks on the machined chips decreased. In the sample with the lower hardness value, delamination occurred extensively and led to the disappearance of cracks and pores on the worn surface. [ABSTRACT FROM AUTHOR]