Showing papers in "Cirp Journal of Manufacturing Science and Technology in 2022"

A review on metal additive manufacturing for intricately shaped aerospace components

Abstract: Additive manufacturing (AM) is one of the fastest-growing industrial techniques, bringing many innovative solutions to different manufacturing problems. In AM, a sliced image of the 3D model is layered together to make a 3D object. The main reason for the exponential growth of AM is its numerous advantages over conventional methods, such as high-cost efficiency, less material wastage, a very high degree of freedom, and lesser material constraints. One of the biggest contributors to this growth is the aerospace industry. It is due to the ease of making complex structures and alloys with a very high strength-to-weight ratio (S:W). The authors have comprehensively reviewed the use of AM in the aerospace industry in this review. This review mainly focuses on the metal AM of complex components used in the Aerospace industry. The other topics in this review are an in-depth study of the different AM techniques, a classification of different AM processes, a comparison between conventional and AM techniques, an advantage of AM techniques, and the future scope of AM techniques. The material characterization and microstructure of the components and the different process parameters concerning the cost and irrespective of cost are also briefly discussed.

Effect of welding processes on mechanical and metallurgical characteristics of carbon steel cylindrical components made by wire arc additive manufacturing (WAAM) technique

Abstract: In recent decades, Additive Manufacturing (AM) has become a viable alternative to the manufacture of metal parts. Wire arc additive manufacturing (WAAM), a welding-based AM technique is an important research area since it permits the economical manufacture of large-scale parts with relatively high deposition rates. This article compares the effect of heat input on mechanical properties of carbon steel cylindrical components fabricated by Gas Metal Arc Welding (GMAW) and Cold Metal Transferred Arc Welding (CMTAW) processes. Firstly, the influence of heat input on the grain size was analysed. Subsequently, the effect of heat input on the tensile properties, impact toughness and hardness of the cylindrical components were studied along the building direction. The cylindrical component made by CMTAW process showed superior tensile properties and higher impact toughness than GMAW component. Similarly, CMTAW component exhibited higher hardness than GMAW cylindrical component. The variations in mechanical properties are mainly due to the appreciable variations that have occurred in the microstructural features and different grain sizes evolved at different heat input levels. The bottom and top regions of the fractured tensile and impact specimens of the components are characterised by dimple structures revealing the ductile fracture.

Enhancing EDM performance characteristics of Inconel 625 superalloy using response surface methodology and ANFIS integrated approach

Abstract: The objective of the present work is to find out the optimal level as well as the influence of the electrical discharge machining (EDM) process on material removal rate (MRR), surface roughness (SR), and tool wear rate (TWR). The machining is carried out on Inconel 625 superalloy by using a copper tool electrode in a kerosene submerged medium. The optimum level of input parameters such as current, pulse on time (Ton), pulse off time (Toff), and gap voltage are calculated to achieve maximum MRR and minimum SR and TWR. L27 orthogonal design is used to perform the experiments and optimum levels of MRR, SR and TWR have been obtained by the response surface methodology (RSM) and adaptive network-based fuzzy inference system (ANFIS) approach. Analysis of variance (ANOVA) is used to identify the significant and non-significant parameters. For implementing, RSM methodology, the Design Expert 13 software was used for the optimization and modelling of the experimental data. MATLAB R20b software was utilized for developing the ANFIS model. It is found that the pulse on time (Ton) and pulse off time (Toff) are the significant parameters for MRR and SR and more wire wear increases as the value of pulse on time (Ton) increases. The obtained quadratic RSM model is found significant for MRR, SR, and TWR. Similarly, ANFIS proved to be accurate for the optimization of output responses with model accuracy percentages noted as 95.55% for MRR, 90.35% for TWR, and 97.82% for SR. The obtained results show that the predicted values and experimental values are very well suited for the proposed objective. The obtained data can be utilized for the EDM industry during the machining of Inconel alloy.

Porosity management and control in powder bed fusion process through process-quality interactions

Abstract: Laser Powder bed fusion (L-PBF) has gained much attention for its ability to manufacture high-precision and high-complexity metal components for the aircraft and automobile industries. However, to a certain degree, the print quality (shape, GD&T, mechanical property) is difficult to predict and control due to the multi-variant processability. Recent research predominantly focuses on building a semantic/qualitative process relationship from the single/a few process parameters on the ultimate print qualities, such as thermal distortion failure/defect probabilities. However, such semantic/qualitative process relationships cannot reflect specific governing effects from process variables and provide an optimal selection of the parameters to ensure the build quality. Therefore, there is a strong need to develop a quantitative model within a process network and achieve a constant quality level by controlling the process parameter set. To address the aforementioned challenges, this research focuses on developing a multi-dimensional process-quality interaction model to predict and control the porosity of Titanium 6Al-4V in L-PBF. The process network is first derived from existing literature composing the potential, influential process parameters that can deviate the porosity level, such as laser power and scanning speed. Then the quantitative model is built based on a multi-dimensional quantitative modeling technique from a collection of experimental data. The multi-dimensional modeling provides an architecture that replaces the artificial neural network (ANN) or regression model to depict the mathematical relationship. The established quantitative process models analyze the intercorrelated effects from process parameters to the porosity. The printable zone can also be derived from such a quantitative model and visualized through a multi-dimension variable-control response graph to optimize the selection of process parameters. This would result in a comprehensive understanding of selecting the process parameters according to the desired porosity level and pave the path to fully control the metal L-PBF print qualities by adjusting the process variables. The experimental data also validate the proposed quantitative model to demonstrate its effectiveness and correctness.

WEDM machining of MoNbTaTiZr refractory high entropy alloy

Abstract: Refractory high entropy alloys (RHEAs) have shown great promise for a multitude of advanced engineering applications due to their high mechanical stability from cryogenic temperatures to 1600 °C. However, the low ductility they exhibit at room temperature limits their machinability when traditional machining techniques are used. Studies on the nontraditional machining of RHEAs, on the other hand, are very limited. In the present work, MoNbTaTiZr RHEAs subjected to wire electrical discharge machining (WEDM) were examined using electron microscopy, contact profilometry, and nanoindentation. Voids, microcracks, and recast material were observed on the machined surfaces. A transition from roughing to finishing decreased the amount of recast material, but the density of observable voids and microcracks on the surface increased. Optimal results were obtained by finishing, where the surface quality was improved by the removal of recast material remaining from prior passes. The brass wire electrode provided a smoother surface while the copper-core electrode provided minor heat-affected zone in the MoNbTaTiZr samples. In the roughing cuts, a 7.00% improvement in surface roughness was achieved using the copper-core electrode compared to the brass electrode. In the semi-finishing and finishing cuts, the brass wire electrode provided improvements of 13.68% and 22.68%, respectively, compared to the copper-core electrode. On the other hand, the wear of the brass electrode was as much as 20.98% higher than that of the copper-core electrode.

Dissimilar joining of the martensitic grade P91 and Incoloy 800HT alloy for AUSC boiler application: Microstructure, mechanical properties and residual stresses

Abstract: The presented study intends to analyze the microstructure and corresponding mechanical characteristics of P91 and Incoloy 800HT dissimilar welded joint (DWJ). The thermo-physical property differences between P91 and Incoloy 800HT arise due to their complex alloying composition, making their weldability difficult. Incoloy 800HT is difficult to weld due to its high susceptibility to solidification cracking. The recommended nickel-based filler metals for welding Incoloy 800HT were employed to weld P91 and Incoloy 800HT using conventional gas tungsten arc welding (GTAW). The welded joint morphology and characteristics were analyzed in as-welded (AW) and post-weld heat treatment (PWHT) conditions. The PWHT was performed to observe changes in microstructural inhomogeneity and residual stress relaxation in weld after the heat treatment. An electron probe microanalyzer (EPMA) was utilized to observe the distribution and segregation of elements in different weld regions. The deep hole drill technique was employed to find the distribution of bi-axial residual stresses in the weld fusion zone (WFZ) and heat-affected zone (HAZ) of base metals in both AW and PWHT conditions. The two nickel-based fillers, ERNiCr-3 and ERNiCrMo-3, were employed, and their weld characteristics were compared. The mechanical strength of ERNiCr-3 filler-based DWJ was found superior to ERNiCrMo-3 filler-based DWJ. The standard AW and PWHT ERNiCr-3 filler-based DWJ tensile specimen failed from Incoloy 800HT base metal with an ultimate tensile strength (UTS) of 570 ± 4 MPa and 650 ± 4 MPa, respectively. The ERNiCrMo-3 filler-based DWJ obtained the highest UTS of 679 MPa after PWHT in a subsize specimen. The microhardness for ERNiCrMo-3 WFZ was found to be higher than ERNiCr-3 WFZ microhardness, and PWHT successfully tempered the P91 HAZ. Further, the impact toughness for the ERNiCr-3 WFZ in AW condition was 86 ± 3 J and PWHT did not provide any significant improvements, while ERNiCrMo-3 WFZ had an impact toughness of 47 ± 10 J in AW state and 41 ± 10 J in PWHT state. Thus, a successful weld characteristic study of defect-free P91 and Incoloy 800HT DWJ was completed, and ERNiCr-3 filler was concluded to be an optimum choice of filler to make the DWJ between P91 and Incoloy 800HT.

Effect of build direction on the microstructure evolution and their mechanical properties using GTAW based wire arc additive manufacturing

Abstract: In recent years, welding-based wire-arc additive manufacturing has been enthusiastically accepted to fabricate different parts of structural materials. In this study, a gas tungsten arc welding-based wire-arc additive manufacturing setup was developed, and a low-carbon alloy steel ER 70S-6 filler wire was used to fabricate a geometry. To analyze the mechanical properties of the printed alloy, room temperature tensile test, hardness and Charpy toughness tests are produced. The microstructure reveals a mostly homogeneous ferrite phase as a matrix and a small amount of pearlite phase at grain boundaries, except for the last build surface. The grain size was found to be doubled from middle build to last build surfaces. The tensile test results show isotropic tensile properties in both directions. The observed morphological features of the fractured surfaces in both directions were found to be in good agreement with their tensile test results, confirming a higher ductility across the build samples. Large scatter was observed in the hardness tests concerning the building direction.

Wire arc additive manufacturing of functionally graded material with SS 316L and IN625: Microstructural and mechanical perspectives

Abstract: In the present study, functionally graded material (FGM) of Austenitic Stainless Steel-SS 316L and Nickel-based superalloy-Inconel 625 (IN625) was manufactured via Gas Metal Arc Welding (GMAW) based Wire Arc Additive Manufacturing (WAAM). WAAM processed FGM was well-formed without any defects and solidification cracking was not observed at the bi-metallic interface (IF) region. Microstructural features show a sharp transition at the IF with a discontinued dendritic structure. Energy-dispersive X-ray spectroscopy (EDS) examination confirmed the fine dissolution of elements at the IF and no major difference in the composition was observed. Electron Backscatter Diffraction (EBSD) maps confirmed that the grains are dominantly columnar while the IF revealed the smooth crystallographic growth along with large elongated dendrites in the< 001 >direction. The microstructure was mainly austenitic in the SS 316L layers with a lower fraction of ferrite while precipitates were noticed in the IN625 layers within the austenitic matrix. Yield strength (YS) and tensile strength (UTS) of SS 316L and IN625 were comparable with wrought ones. All the IF samples at 90° failed in the SS 316L region because of the lower UTS in comparison to IN625 and the mode of fracture was ductile. Microhardness measurements depicted the gradual change of hardness along the building direction. The present work highlights the potential of WAAM to fabricate FGM with required properties and is a viable manufacturing alternative to the traditional manufacturing techniques for producingFGM’s.

An investigation on mechanical properties of PA12 parts produced by a SLS 3D printer: An experimental approach

Abstract: Additive manufacturing methods such as Selective Laser Sintering (SLS) have attracted numerous scientists and different companies to print 3D parts. However, the mechanical properties of printed parts have been always the research area of many scientists. In this paper, the effects of SLS setting variables (laser power, scan speed, and hatch spacing) and scan length were investigated experimentally on key mechanical properties (strength, apparent modulus of elasticity, and elongation) of polyamide-12 printed parts using the response surface methodology. The results showed that the hatch spacing is the most effective variable on mechanical properties; the laser power and the scan speed are also important. By increasing the laser power and decreasing the hatch spacing and the scan speed, a higher strength part with a higher apparent modulus of elasticity and elongation can be printed. However, since a bigger hatch spacing and a faster scan speed are more desirable to have a more economical production, a challenging decision must be made for setting these variables to print parts with good mechanical behavior economically. If the hatch spacing, the laser power, and the scan speed are selected so that the laser energy density is too high, powders will burn and the printing process will fail. The scan length has a slight effect on the apparent modulus of elasticity and no significant effect on the strength and elongation. • Input variables: laser power, scan speed, hatch spacing, and scan length. • Mechanical properties: strength, modulus of elasticity, and elongation. • Effects of input variables on mechanical properties in the SLS process. • Determining effective inputs by experimental study and response surface methodology. • Predicting mechanical properties based on effective inputs and laser energy density.

Effect of the welding technique on mechanical properties and metallurgical characteristics of the naval grade high strength low alloy steel joints produced by SMAW and GMAW

Abstract: Naval grade, high strength low alloy (HSLA) steel is designed especially for shipbuilding applications due to its high strength to weight ratio. The conventional fusion welding processes of shielded metal arc welding (SMAW) and gas metal arc welding (GMAW) are employed widely for structural applications. This work reports the influence of welding processes on mechanical properties and metallurgical characteristics of fusion welded DMR249A grade steel. The evaluating tensile, impact, microhardness properties were correlated with microstructures. The maximum recorded transverse tensile strength value of SMAW and GMAW joints were 558 MPa and 578 MPa. The lower microhardness had obtained in the subcritical heat-affected zone than other regions. The weld zone microstructure consists of fine, elongated, and columnar grain structures. From this investigation, it has been concluded that GMAW joints displayed marginally better properties than SMAW joints. But most weld failures has been observed in the subcritical heat-affected region; due to grain deformation and subsequent softening in the weldment.

Cognitive digital twin: An approach to improve the maintenance management

Abstract: Digital twin (DT) technology allows the user to monitor the asset, specifically over the operation and service phase of the life cycle, which is the longest-lasting phase for complex engineering assets. This paper aims to present a thematic review of DTs in terms of the technology used, applications, and limitations specifically in the context of maintenance. This review includes a systematic literature review of 59 articles on semantic digital twins in the maintenance context. Key performance indicators and explanations of the main concepts constituting the DT have been presented. This article contains a description of the evolution of DTs together with their characterisation for maintenance purposes. It provides an ontological approach to develop DT and improve the maintenance management leading to the creation of a structured DT or a Cognitive Twin (CT). Moreover, it points out that using a top-level ontology approach should be the starting point for the creation of CT. Enabling the creation of the digital framework that will break down silos, ensuring a perfect integration in a network of twins’ scenario.

A systematic literature review for digital business ecosystems in the manufacturing industry: Prerequisites, challenges, and benefits

Abstract: Digitalization has disrupted how organizations collaborate and compete resulting in the development of new collaborative value-creation networks such as the Digital Business Ecosystem (DBE). A literature review shows that DBEs are being studied by various scholars from different perspectives in manufacturing. Digital Business Ecosystem is studied in many contexts in manufacturing, and it is creating both opportunities and challenges for manufacturing. By providing a systematic literature review of the prerequisites, challenges, and benefits of DBEs for manufacturing, this paper helps to alleviate this shortcoming and reveals how digital business ecosystems can dramatically impact the industry. A total of 149 research journal articles were included in this literature review, which uncovered nine prerequisites, eight challenges, and eight benefits for DBEs and led to five trends for future study. Also noted are practical issues that managers who work in manufacturing DBEs should address.

Application of a compressed air jet for cleaning of wheel surface in grinding nickel-based super alloy Inconel 718

Abstract: Grinding plays an important role in the production of fine finishing surfaces. However, generation of substantial amount of energy through rubbing, plowing and cutting actions in the grinding zone would result in the creation of micro cracks, surface damage, subsurface damage, surface burning as well as residual stress on the ground surface. Nickel-based super alloy Inconel 718 is widely utilized for the fabrication of workpiece, especially in aerospace industry and gas turbines according to their excellent oxidation resistance, fatigue resistance, thermal stability and superior corrosion. However, difficult-to-grind feature and tendency to adhere the wheel pores are considered as the main difficulties encountered in the production of workpiece with this material. Regarding the tendency to clog on the pores of wheel surface, the wheel would be dulled easily and immediately after shorter period of time. To avoid this problem as well as removing chips from the grinding zone and reducing the loading of the wheel, it is proposed to employ a compressed air jet nozzle under the incident angle of 30˚. The various parameters of surface roughness, tangential force, normal force, specific force, surface topography using Scanning Electron Microscopy (SEM) and profilometer, besides the evaluation of wheel loading using image processing toolbox by MATLAB are considered in this investigation. The obtained results reveal the best output parameters with the use of conventional cutting fluids along with a compressed air jet.

Development of friction stir powder deposition process for repairing of aerospace-grade aluminum alloys

Abstract: This paper presents development of a novel friction stir powder deposition (FSPD) process for potential repairing applications of aerospace-grade aluminum alloy AA6061-T6. Powder form of the deposition material was thermo-mechanically processed at a temperature below its melting point. Influence of various process parameters on thermal cycles, deposition quality, deposition height, microstructure, and mechanical properties have been studied. Higher degree of deformation resulted in a dynamically recrystallized fine-grained microstructure which gave better mechanical properties. EDS study revealed uniform distribution of the major alloying elements throughout the deposition. Best quality deposition showed maximum microhardness and wear rate 0.84 and 1.07 times respectively than the substrate AA6061-T6 alloy. FSPD process is found to be capable of depositing maximum height of 0.45 mm, maximum deposition efficiency of 22% with an energy consumption of 73.7 J/mm3 per unit deposition material consumption. Moreover, it used current in the range of 5-7 Ampere. This research shows that FSPD process can provide considerable cost and energy savings over fusion-based additive manufacturing processes making it a viable alternative for repairing aerospace-grade aluminum alloys.

Production of AA7075/ZrO2 nanocomposite using friction stir processing: Metallurgical structure, mechanical properties and wear behavior

Abstract: AA7075-T6 alloy has the highest strength among aluminum alloys, but the presence of relatively weak surface properties such as hardness and wear properties has limited its use in some industries. In this research, friction stir processing and the addition of ZrO2 nanoparticles have been employed to enhance the surface properties. The rotational speeds of 1000 and 1200 rpm and traverse speed of 40 mm/min were selected for the processing. Microstructural studies were performed using light and electron microscopes, and all the samples were subjected to hardness and tensile tests. Finally, the fracture surfaces of the samples were examined using x-ray diffraction test. Using appropriate variables led to the creation of defect-free macro and microstructures. Thanks to the grain refinement that occurred during the process and the presence of hard ceramic nanoparticles, the hardness and wear properties were improved. In total, with the addition of nanoparticles, it was observed that the microhardness increased up to 48%, and the wear rate decreased up to 62% compared to those of the base metal.

Effect of various post-extrusion tempering on performance of AA2024 tubes fabricated by shear assisted processing and extrusion

Abstract: • Extrusion speed of ShAPE for AA2024-T371 billets reaches 7.4 m/min. • The yield strength of the AA2024-T8510 ShAPE-extruded tube is 32% higher than typical ASM and minimum ASTM values. • The elongation at break of ShAPE-extruded AA2024-T8510 tubes is doubled than typical ASM and minimum ASTM values. Aluminum alloy 2024 tubes were extruded using the shear assisted processing and extrusion (ShAPE) method. Extrusions were produced at 7.4 m/min at 482 °C using the ShAPE technique which is more than doubles the previous highest extrusion speed for AA2024 using conventional extrusion methods. Standard T3510 and T8510 post extrusion heat treatments were applied to improve the mechanical performance of ShAPE extruded AA2024 tube. The ultimate tensile and yield strength of the AA2024-T8510 ShAPE-extruded tube are 522.0 ± 3.3 MPa and 510.7 ± 3.3 MPa, which are respectively 18% and 32% higher than typical ASM International and minimum American Society for Testing and Materials (ASTM) values. The elongation at break of ShAPE-extruded AA2024-T8510 tubes is two times higher than the typical ASM International and minimum ASTM values. This improved ductility is attributed to the refinement of grain size and secondary phases as well as the uniform dispersion of sub-micron strengthening precipitates formed during the ShAPE processing.

Design of serious games in engineering education: An application to the configuration and analysis of manufacturing systems

Abstract: Higher education has to cope with current trends in digital technologies, in particular in the field of industrial engineering, where digital competencies are required more and more. Digital technologies, combined with serious gaming, offer new opportunities for teaching engineering in higher education, with a twofold objective: 1) offering students a rich and realistic experience exploiting advanced digital tools; 2) supporting and complementing traditional education schemes by increasing participation and involvement via serious gaming, enhanced by digital/virtual technologies. Herein, we present a framework for the design of serious games in engineering education, with a specific focus on the definition of intended learning outcomes and the development of the corresponding game activities. This framework was applied to develop a serious game application for the design and analysis of manufacturing systems. The approach was tested thanks to the cooperation of 60 bachelor engineering students and the results extensively analyzed in both quantitative and qualitative terms.

Machining of micro features through µ-ECSM process and evaluation of surface integrity

Abstract: In the present experiment, micro features were fabricated on titanium alloy by means of the micro-electrochemical spark machining (µ-ECSM) process and the micro-electro discharge machining (µ-EDM) process, using similar electrical parameters. However, in case of the µ-ECSM, the types of electrolyte (KOH, NaOH, KOH+NaOH) and their concentration (0.5 M to 2.5 M) varied from that of the µ-EDM process. In course of the study, different machining output parameters, such as, material removal rate (MRR), recast layer (RCL) thickness, heat affected zone (HAZ) and surface topography, were analysed and compared. The results indicated that the µ-ECSM process produces higher MRR (7.29 times), RCL thickness (0.436 times) and HAZ (0.595 times) as compared to the µ-EDM process. Moreover, the mixed (KOH+NaOH) electrolyte at 0.5 M concentration, 25 V machining voltage, 15% duty factor and 10 kHz of frequency showed better machining performance as compared to the parent electrolyte and produced lower RCL thickness (3.54 µm) and HAZ (26.83 µm), respectively. The surface topography of the work piece, machined by the µ-EDM process, showed rough surface whereas the NaOH electrolyte-based µ-ECSM process produced smoother and clean surface.

An experimental investigation and neuro-fuzzy modeling to ascertain metal deposition parameters for the wire arc additive manufacturing of Incoloy 825

Abstract: Additive manufacturing is critical to repair, rebuild, and rapidly manufacture major components in today's manufacturing environment. Wire arc additive manufacturing technique using metal inert gas welding, which is a better way to produce large-scale parts at a subsidized cost was experimented on Incoloy 825 due to its many industrial applications in the construction of large structures. As bead deposition is vital for wire arc additive manufacturing, single bead depositions were performed. Metrological features of all deposited beads are evaluated using the CNC Video Measuring System by capturing the macrostructures. The effects of input parameters on bead geometry are statistically analyzed, and regression models are derived to forecast bead geometry. An adaptive Neural Fuzzy Inference System was implemented to predict geometrical characteristics, and the results were compared with experimental results. Subtractive clustering fuzzy inference model obtained the lowest percentage error difference in predicting deposited bead geometry as a function of process parameters. Further, the multi-objective optimization technique determined optimal input parameters for the best bead geometry. Finally, using identified optimum parameters, wire arc additive manufacturing of a single-pass multi-layer wall of Incoloy 825 was successfully constructed for validation, which revealed that the microstructure of the built structure was of appreciable quality without cracks and porosity.

Evaluation of nanocomposite structure printed by solid-state additive manufacturing

Abstract: Properties of polymer-metal hybrid structure printed by fed friction stir additive manufacturing (FFSAM) were evaluated. FFSAM is advanced solid-state additive manufacturing for the printing of macro-scale components for large stress-bearing situations. With the FFSAM, layer by layer printing of polymer and metal sheets convert to paste phase and join together as a uniform structure. With this process, during printing of hybrid structure, nanocomposite polymer is injected at the interface of base materials to fill voids and recover properties of the polymer matrix: polypropylene (PP) and stainless steel (SS) fabric selected as raw materials. During the printing process, Fe2O3 nanoparticles fed into the interface of PP and steel sheets. The mechanical and metallurgical characterization of printed [email protected]@Fe2O3 nanocomposite structure is evaluated. Macrostructure, tensile strength, hardness, and thermo-chemical properties of the printed structure were assessed and discussed. The result indicated that the In-situ feeding mechanism improves the physical and chemical properties of the printed structure. Reasonable properties achieved due to minimizing shrinkage gap in polymer side and improving sealing adhesion at interfaces of printed materials.

Double-sided friction stir welding of AA 2024-T6 joints: Mathematical modeling and optimization

Abstract: The heat-treatable AA 2024-T6 has been used widely in the aerospace and defense industry. In this paper, the effective parameters of the double-sided friction stir welding (DFSW) process of AA 2024-T6 were investigated by using Response Surface Methodology (RSM). Also, the optimal parameters have been obtained by using the Artificial Neural Network (ANN) and optimization algorithms. The most significant process parameters, i.e. rotational speed, welding speed, tilt angle, and tool pin length, were considered to predict the behavior of the response, i.e. ultimate tensile strength (UTS) and percentage elongation (% El). For this purpose, a central composite design, as well as analysis of variance, was used to investigate effective parameters. Also, an intelligent connection between the above parameters and responses was developed by using ANN. The optimal neural network was integrated with the whale optimization algorithm (WOA) to find optimal parameters and achieve desirable responses. The obtained result was verified by experiment. Results indicated that the tool pin length (h) factor has the highest contribution percentage between the parameters (14.95% and 9.59% for UTS and %El, respectively). Besides, the parameters of welding speed (v) and tilt angle (α) have a significant effect on the UTS and %El of DFSW joints, respectively. Using a rotational speed of 1250 rpm, welding speed of 80 mm/min, the tilt angle of 4°, and a tool pin length of 2.3 mm, as optimal parameters of the DFSW process, can be achieved the maximum of ultimate tensile strength and elongation.

Surface integrity studies on ZrB2 and graphene reinforced ZrB2 ceramic matrix composite in EDM process

Abstract: Zirconium diboride is a potential ceramic for high temperature applications because of its combination of properties, such as very high melting point, high hardness, elevated temperature strength, good thermal and electrical conductivity. Although the near net shape components are made from this material, machining is required to create additional features for the application requirements. This ceramic's high hardness and low fracture toughness make it very difficult to use the conventional processes for machining. The good electrical conductivity of this ceramic makes electrical discharge machining (EDM) the preferred machining process. This paper presents the surface and sub-surface modifications during Wire cut EDM (WEDM) and EDM of ZrB2 an ultra high temperature ceramic (UHTC) and ZrB2-GNP (ceramic matrix composite with 7 vol% Graphene Nano Platelets) along with the surface characterization of the copper electrode (EDM tool). Scanning Electron Microscope (SEM) with Energy Dispersive Spectroscopy (EDS) and Raman spectroscopy (for GNPs) were used to characterize the melt-solidified layer and the recrystallized region. The presence of micro cracks and pores was observed in the melt-solidified layer. Growing dendrites of ZrB2 were observed in the high magnification SEM images of the melt-solidified layer surface. Under the melt-solidified layer, a recrystallized fine grain structure was observed with reduced porosity compared to the rest of the bulk. After the WEDM of ZrB2-GNP (7 vol%), the stacks of cut GNP were retained, whereas GNPs were damaged after EDM The end surface of the copper electrode showed the partial deposition of ZrB2 and the formation of a micro scale pattern on it. The effect of peak current and pulse ON time on surface roughness (Sa), material removal rate (MRR) and relative tool wear (%) were studied for ZrB2-GNP (7 vol%) The results indicated that the surface roughness (Sa), MRR and the relative tool wear (%) increase with increasing peak current. The rise in pulse ON time also increases surface roughness (Sa) and MRR but reduces the relative tool wear rate (%)

Production of AA1050/silica fume composite by bobbin tool-friction stir processing: Microstructure, composition and mechanical properties

Abstract: In the present study, bobbin tool friction stir processing (BT-FSP) with a cylindrical pin was utilized to produce bulk processed AA1050 and AA1050/6.5 vol% silica fume (SF) composite at a rotation speed of 600 rpm using two travel speeds of 100 and 200 mm/min. The BT-FSP temperature was measured for both processed materials. Phase composition, relative density, macrostructure, hardness, ultimate tensile strength, and compressive strength were examined for the AA1050 base material, processed AA1050 and AA1050/SF composite. The results showed that the temperature of BT-FSP was increased with SF addition. The addition of fine SF resulted in a small crystallite size compared to the AA1050 BM and the processed AA1050. Moreover, the SF addition to the AA1050 matrix improved mechanical properties in terms of hardness, ultimate tensile strength, and compressive strength compared to AA1050 BM and processed AA1050. The bulk AA1050/6.5 vol% nano SF composite produced at 600 rpm and 200 mm/min showed remarkable enhancements in properties compared to AA1050 parent material; i.e. 50% in hardness, 11% in compressive strength, and 40% in ultimate tensile strength.

Double-sided friction stir welding of AA 2024-T6 joints: Mathematical modeling and optimization

Abstract: The heat-treatable AA 2024-T6 has been used widely in the aerospace and defense industry. In this paper, the effective parameters of the double-sided friction stir welding (DFSW) process of AA 2024-T6 were investigated by using Response Surface Methodology (RSM). Also, the optimal parameters have been obtained by using the Artificial Neural Network (ANN) and optimization algorithms. The most significant process parameters, i.e. rotational speed, welding speed, tilt angle, and tool pin length, were considered to predict the behavior of the response, i.e. ultimate tensile strength (UTS) and percentage elongation (% El). For this purpose, a central composite design, as well as analysis of variance, was used to investigate effective parameters. Also, an intelligent connection between the above parameters and responses was developed by using ANN. The optimal neural network was integrated with the whale optimization algorithm (WOA) to find optimal parameters and achieve desirable responses. The obtained result was verified by experiment. Results indicated that the tool pin length (h) factor has the highest contribution percentage between the parameters (14.95% and 9.59% for UTS and %El, respectively). Besides, the parameters of welding speed (v) and tilt angle (α) have a significant effect on the UTS and %El of DFSW joints, respectively. Using a rotational speed of 1250 rpm, welding speed of 80 mm/min, the tilt angle of 4°, and a tool pin length of 2.3 mm, as optimal parameters of the DFSW process, can be achieved the maximum of ultimate tensile strength and elongation.

Controllable shearing chain-thickening polishing process for machining of barium borate

Abstract: The functionality of nonlinear optics made from barium borate is significantly determined by its surface integrity. Nevertheless, it has been a challenge to control surface integrity precisely to prevent weak deliquescence. Here a novel finishing process - the Controllable Shearing Chain-Thickening Polishing (CS-CTP) - is proposed which provides a controllable discontinuous shearing effecting chain-thickening in a water-free slurry. Precise shearing control is applied to use the chain-thickening rheology for the material removal mechanism. Optimized conditions of the CS-CTP process enable to efficiently achieve ultra-smooth barium borate surfaces with ultra-low subsurface damage and high laser-induced damage threshold.

Dynamic Bayesian network-based disassembly sequencing optimization for electric vehicle battery

Abstract: The sharply increasing end-of-life (EOF) battery volume in the global complex energy market has created significant challenges for its recycling and reuse, to reduce environmental pollution and resource waste, and efforts have been focused on the disassembly process considering the uncertainty of electric vehicle (EV) battery pack categories and quality. Compared with traditional disassembly, the EV battery disassembly process needs to consider more uncertainty factors for each EOF battery pack to represent its disassembly structure, which significantly reduces disassembly production efficiency. Even though sequence optimization methods for the disassembly process have been developed to solve these problems, there are still two important challenges that remain: uncertain disassembly structure representation and optimal disassembly sequence selection. To address these challenges, this paper proposes a dynamic disassembly Bayesian network approach based on an EV battery disassembly graph model. This method offers dynamic process optimization to manufacturers to deduce the optimal disassembly sequences using the forward–backward algorithm and the Viterbi decoding algorithm. To validate the proposed method, an EOF battery is used to demonstrate the disassembly sequence selection, which indicates the possibility of massive EV battery disassembly prediction.

Energy consumption and performance optimisation of laser cleaning for coating removal

Abstract: Selective removal of coatings by lasers can facilitate the reuse of coated tools in a circular economy. In order to optimise and control the process, it is essential to study the impact of process input variables on process performance. In this paper, coating removal from tooling was carried out using a picosecond a pulsed fibre laser, in order to investigate the effects of laser pulse energy, pulse frequency, galvo scanning speed and scanning track stepover. A fractional factorial design of experiments and analysis of variance was used to optimise the process; considering cleaning rate, specific energy consumption and surface integrity as assessed by changes in surface roughness and composition of the tooling after laser cleaning. The results shows synergy between cleaning rate and specific energy with the laser pulse frequency and galvo scanning speed as the two most significant factors, while the laser pulse energy had the greatest contribution to changes in surface composition. Based on extensive experiments, the relationship between processing rate and system specific energy consumption was mathematically modelled. The paper contributes a new specific energy model for laser cleaning and provides a benchmark of the process energy requirements compared to other manufacturing processes. Additionally, the generic scientific learning from this is that the rate of energy input is a key tool for maximising cleaning rate and minimising specific energy requirements, while the intensity of energy applied, is a key metric that influences surface integrity. More complex factors, influence the surface integrity.

A systematic review of process uncertainty in Ti6Al4V-selective laser melting

Abstract: The adoption of Ti6Al4V-Selective laser melting (SLM) for direct manufacturing remains challenging in terms of quality as the resulting microstructures, mechanical properties, and overall performance of fabricated parts depend heavily on factors influencing the process. Although Ti6Al4V-SLM shows potential, the technology remains unstable and partially explored. This systematic review explores quality issues and uncertainty factors in the Ti6Al4V-SLM process. Using the Ti6Al4V-SLM, Quality, and Uncertainty as keywords, a search was performed on scientific databases. The findings demonstrate that laser power, scanning speed, and powder bed temperature significantly affect product quality and create various levels of uncertainty in Ti6Al4V-SLM.

Electric discharge assisted post-processing performance of high strength-to-weight ratio alloys fabricated using metal additive manufacturing

Abstract: Metal additive manufacturing (MAM) is a near net shape fabrication process intended for producing complex and intricate shaped metallic parts/components. The feasibility in batch production as well as minimal material wastage establish the potential of MAM over other manufacturing methods. MAM of high strength-to-weight ratio alloys such as AlSi10Mg and Ti6Al4V is gaining popularity nowadays owing to their never ending demand in aerospace, automotive and biomedical industries. Both the alloys mark the two extreme ends of commercially available MAM alloys in terms of contrasting material properties. However, the poor surface integrity achieved by AlSi10Mg and Ti6Al4V parts/components after MAM demands post-processing via laser energy, chemicals, abrasives, conventional cutting tools etc. A recently developed low energy wire electrical discharge polishing (WEDP) method showed promising outcomes in MAM post-processing over aforementioned methods. In the present study, the performance and feasibility of WEDP in post-processing AlSi10Mg and Ti6Al4V are investigated with reference to the contrary properties associated with the alloys. The significant difference in melting point, thermal conductivity and chemical affinity led to distinct outcomes for the two alloys after WEDP. The enhancement in surface finish (Sa) was ~79% and ~91% for AlSi10Mg and Ti6Al4V respectively. The excellent corrosion resistance offered by the alloys is found to be unaltered in case of AlSi10Mg whereas enhanced for Ti6Al4V after WEDP. Modification in subsurface microhardness was observed upto 300 µm depth from polished surface for AlSi10Mg, whereas absent in Ti6Al4V. The study also revealed that the WEDP induced bigger craters in AlSi10Mg as well as cracks and resolidified layer in Ti6Al4V can be minimized at lower settings of pulse on time (T ON ). Moreover, EDS and XRD analysis indicated the formation of an oxide layer over Ti6Al4V surface after WEDP. • Wire electrical discharge polishing of high strength-to-weight ratio alloys having contrasting physical properties. • An in-depth surface integrity and corrosion behaviour analysis. • Polished surface analysis through detailed characterization methods. • Improvement in surface finish by ~79% and ~91% fData availabilityor AlSi10Mg and Ti6Al4V, compared to the as-built samples.

Monitoring of in-process force coefficients and tool wear

Abstract: Mechanistic modeling of the milling forces is described by a set of cutting and edge force coefficients that characterize the shearing and ploughing actions of the metal removal process. The force coefficients are traditionally calibrated under a series of dedicated milling experiments. However, due to the force coefficients’ process-dependency, such an approach can become cumbersome if the machining conditions deviate from those of the milling experiments. In this paper, a method for monitoring the in-process force coefficients is proposed for toolpaths that exhibit varying radial immersions or feed rates. The proposed methodology was experimentally validated, and it is demonstrated that the edge force coefficients can be used to estimate the tool’s flank wear. In the absence of a force dynamometer, force coefficients as estimated under spindle current measurements were evaluated and also shown to be a viable solution for tool wear monitoring.