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Showing papers in "The International Journal of Advanced Manufacturing Technology in 2017"


Journal ArticleDOI
TL;DR: In this article, the authors summarize the developments in the joining of Al alloys over the recent years and provide guidance for the industry and researchers dealing with joining of these alloys.
Abstract: The mass saving potential of light-weight materials, such as Al alloys, is beneficial for fuel economy and reducing CO2 emissions. However, the wide-spread use of these alloys has been long hindered due to the difficulty in fusion joining as well as their high cost. Welding of Al alloys, which are considered to be difficult to weld through conventional arc welding, is now possible by either of low heat input arc welding, high-power density fusion joining, such as laser beam welding and electron beam welding, or friction stir welding. Particularly, friction stir welding can be successfully applied to these materials owing to the fact that no melting takes place in the weld nugget. The aim of this overview is to summarize the developments in the joining of Al alloys over the recent years. This study is also intended to provide guidance for the industry and researchers dealing with joining of these alloys.

301 citations


Journal ArticleDOI
TL;DR: In this article, the authors applied additive manufacturing for tooling up a stamping process on the automotive industry for the production of body panels, which enabled the manufacturing of stamping inserts using similar high performance alloy steel as in conventional tooling, without losing tool mechanical properties.
Abstract: Automotive industry faces new challenges every day, new design trends and technological deployments from research push companies to develop new models and facelifts in short term, requiring new tools or tool reshaping. Concerning the current world economic scenario, decreasing time for tooling up becomes as important as decreasing time-to-market. Such scenario opens up the horizons for new manufacturing approaches like additive manufacturing, in this case, applied for tooling up a stamping process on the automotive industry for the production of body panels. This approach enables the manufacturing of stamping inserts using similar high performance alloy steel as in conventional tooling, therefore, without losing tool mechanical properties. The stamping tools produced were tested by an automotive company in order to determine tool behaviour under real operating conditions, considering the high level demands of the stamping process. The results obtained enabled to conclude that metal additive manufacturing provided tools for the stamping process with excellent performance with a significant decrease on time-to-tooling.

208 citations


Journal ArticleDOI
TL;DR: In this article, a combination of sustainability and risk factors was considered for third-party reverse logistic provider (3PRLP) evaluation, and fuzzy step-wise weight assessment ratio analysis (Fuzzy SWARA) was applied for weighing the evaluation criteria.
Abstract: Third-party logistic provider (3PLP) companies play a major role in supply chain management (SCM) by carrying out specialized functions—namely, integrated operation, warehousing, and transportation services. Taking sustainability issues into consideration makes reverse logistics even more significant. In this paper, a combination of sustainability and risk factors was considered for third-party reverse logistic provider (3PRLP) evaluation. Initially, fuzzy step-wise weight assessment ratio analysis (Fuzzy SWARA) was applied for weighing the evaluation criteria; then, Fuzzy multi-objective optimization on the basis of ratio analysis (Fuzzy MOORA) was utilized for ranking the sustainable third-party reverse logistic providers in the plastic industry in the second step. Findings highlight that quality, recycling, health, and safety were the most important criteria in economic, environmental, and social dimensions of sustainability, respectively. Also, operational risk was found to have the highest weight among risk factors.

188 citations


Journal ArticleDOI
TL;DR: In this paper, the current state and development of self-piercing riveting (SPR) process is reviewed and the influence of the key process parameters on joint quality is discussed.
Abstract: Self-piercing riveting (SPR) is a cold mechanical joining process used to join two or more sheets of materials by driving a rivet piercing through the top sheet or the top and middle sheets and subsequently lock into the bottom sheet under the guidance of a suitable die. SPR is currently the main joining method for aluminium and mixed-material lightweight automotive structures. SPR was originated half century ago, but it only had significant progress in the last 25 years due to the requirement of joining lightweight materials, such as aluminium alloy structures, aluminium-steel structures and other mixed-material structures, from the automotive industry. Compared with other conventional joining methods, SPR has many advantages including no pre-drilled holes required, no fume, no spark and low noise, no surface treatment required, ability to join multi-layer materials and mixed materials and ability to produce joints with high static and fatigue strengths. In this paper, research investigations that have been conducted on self-piercing riveting will be extensively reviewed. The current state and development of SPR process is reviewed and the influence of the key process parameters on joint quality is discussed. The mechanical properties of SPR joints, the corrosion behaviour of SPR joints, the distortion of SPR joints and the simulation of SPR process and joint performance are reviewed. Developing reliable simulation methods for SPR process and joint performance to reduce the need of physical testing has been identified as one of the main challenges.

176 citations


Journal ArticleDOI
Lian Chen1, Yong He, Ying-xin Yang1, Niu Shiwei1, Ren Haitao1 
TL;DR: In this article, a brief review of development courses of additive manufacturing technology and summarizes the development status and the application fields of additive Manufacturing technology, then, according to the manufacturing methods, it focuses on the principles and characteristics of several main additive manufacturing technologies.
Abstract: The paper first presents a brief review of development courses of additive manufacturing technology and summarizes the development status and the application fields of additive manufacturing technology, then, according to the manufacturing methods, it focuses on the principles and characteristics of several main additive manufacturing technologies. This paper also analyzes the existing problems and challenges of additive manufacturing technology and its future development trend. This paper aims to provide references for the development direction of additive manufacturing technology in developing countries.

168 citations


Journal ArticleDOI
TL;DR: In this paper, the authors have reviewed the current state of the art in MQL with a particular focus on drilling, turning, milling and grinding machining operations and concluded that MQL has huge potential as a substitute for conventional flood cooling.
Abstract: Government legislation and public opinion are the main drivers behind the movement of manufacturing companies towards sustainable production. Fundamentally, companies want to avoid future financial penalties and the industry is therefore under pressure to adapt new techniques and practices in order to become environmentally friendly. The cost efficiency of metal cutting operations is highly dependent on accuracy, excellent surface finish and minimized tool wear and, to this end, has traditionally made abundant use of cutting fluid in machining operations. However, these cutting fluids have been a major contributor to environmental and health issues. In recent years, an enormous effort to eradicate these adverse effects has been made with one important focus being the implementation of minimum quantity lubrication (MQL). In the present work, the authors have reviewed the current state of the art in MQL with a particular focus on drilling, turning, milling and grinding machining operations. Overall, it is concluded that MQL has huge potential as a substitute for conventional flood cooling.

155 citations


Journal ArticleDOI
Xun Xu1
TL;DR: In this article, the authors describe some of the key and desired characteristics of Machine Tool 4.0 such as Cyber-physical Machine Tools, vertically and horizontally integrated machine tools and more intelligent, autonomous and safer machine tools.
Abstract: The widespread use and continuous improvements of machine tools have had a significant impact on productivity in manufacturing industry ever since the Industrial Revolution. At the dawn of the new era of industrialization, the need to advance machine tools to a new level that accords to the concept of Industrie 4.0 has to be recognised and addressed. Muck like the different stages of industrialisation, machine tools have also gone through different stages of technological advancements, i.e., Machine Tool 1.0, Machine Tool 2.0 and Machine Tool 3.0. Industrie 4.0 pleads for a new generation of machines—Machine Tool 4.0. This paper describes some of the key and desired characteristics of Machine Tool 4.0 such as Cyber-physical Machine Tools, vertically and horizontally integrated machine tools and more intelligent, autonomous and safer machine tools.

152 citations


Journal ArticleDOI
TL;DR: In this article, a comprehensive literature review on machining of natural fiber reinforced composites (NFRCs) is discussed with focus on drilling operation, which identifies the factors that affect the quality of the machined feature and provides general recommendations for the selection of process parameters.
Abstract: In the recent years with greater emphasis on the environmental and sustainability aspects of engineering materials, natural fiber reinforced composites (NFRCs) are gaining more importance because of their numerous advantages. Several researchers have developed NFRCs using various natural fibers as well as matrix materials. However, real-world applications of NFRCs require some secondary operations in order to complete the assembly of the components or parts. Very few researchers have discussed issues related to the machinability of these NFRCs. In this paper, for the first time, a comprehensive literature review on machining of NFRCs is discussed with focus on drilling operation. The paper also reviews the studies on milling and turning of NFRCs. The distinct feature of this review is that it identifies the factors that affect the quality of the machined feature and provides general recommendations for the selection of process parameters so as to generate better quality holes during drilling. In addition, the review also discusses the challenges that hinder machining of NFRCs which is a significant contribution to the field of NFRCs.

140 citations


Journal ArticleDOI
TL;DR: In this article, the effects of material hardness and high-pressure coolant jet over dry machining are evaluated in respect of surface roughness and cutting temperature using Taguchi L36 orthogonal array.
Abstract: In this article, the effects of material hardness and high-pressure coolant jet over dry machining are evaluated in respect of surface roughness and cutting temperature using Taguchi L36 orthogonal array. The experimental data was analyzed using empirical cumulative distribution function and box plot with respect to material hardness and machining environment. Afterward, optimization of the quality responses is performed using signal-to-noise ratio. As part of Taguchi optimization, the “smaller is better” was adopted as optimization principle; the design of experiment was used for parameters orientation, and the analysis of variance was used for determining the effects of control factors. For the present experimental studies, three types of hardened steels (40 HRC, 48 HRC, and 56 HRC) were turned by coated carbide insert at industrial speed–feed combinations under both dry and high-pressure coolant jet. Depth of cut, being a less significant parameter, was kept fixed. The high-pressure coolant jet was found successful in reducing cutting temperature, surface roughness, and tool wear. The statistical analysis showed that work material hardness is the most significant factor for both cutting temperature and surface roughness. However, for surface roughness, other variables exerted somewhat similar contribution, while in determining the cutting temperature, the environment demonstrated crucial role. The confirmation tests showed 15.85 and 0.28 % error in predicting surface roughness and cutting temperature, respectively.

138 citations


Journal ArticleDOI
TL;DR: In this paper, the performance of injection molding (IM) tools with conformal cooling channels has been evaluated using numerical modeling software originally developed for conventionally cooled mould designs, with a focus on material properties of tool steels.
Abstract: Additive manufacturing (AM) techniques such as selective laser melting (SLM) can enable the construction of injection moulding (IM) tools with conformal cooling channels that significantly improve performance through higher cooling uniformity and reduced cycle times. Design of IM cooling systems is typically achieved using commercial IM numerical modelling software originally developed for conventionally cooled mould designs. However, the accuracy of IM modelling software in predicting the performance of SLM manufactured tools with conformal cooling, across a range of moulding materials and processing conditions, has not been thoroughly evaluated in the literature. Furthermore, the SLM manufacturability and mechanical properties of tool steels typically applied in IM, such as AISI H13, are not well documented. This work addresses these deficiencies through the following: quantification of SLM H13 material properties, in particular fatigue strength which has not been previously reported; design and manufacture of a mould tool with easily exchangeable conventionally and conformally cooled inserts; and subsequent experimental validation of IM simulation software predictions under a range conditions. Result of mechanical testing showed SLM H13 parts to offer lower mechanical properties in the as-built condition compared to conventional materials; however, these increased substantially following residual stress reduction with heat treatment. Evaluation of the temperature prediction accuracy of IM numerical models showed generally high accuracy for conformally cooled SLM tools, although marginally lower when compared to conventionally cooled moulds. The outcomes of this work offer designers typical material property data for SLM manufactured H13 tooling, as well as an indication of the expected prediction accuracy of current commercial IM simulation software when applied to conformally cooled SLM tooling.

135 citations


Journal ArticleDOI
TL;DR: In this paper, a group of cubes were fabricated using different process parameters from Invar 36 powder using a selective laser melting machine, and the density, microstructures, and surface features of these cubes were measured.
Abstract: Invar 36 has gained considerable popularity in many industries, including the aerospace industry, because of its low coefficient of thermal expansion. In this paper, a brief overview for the research needs in metal additive manufacturing is presented. A thorough study for the influence of process parameters on the quality of the parts produced is presented. This study is beneficial for the long-term growth of the additive manufacturing industry. The paper aims to select the process parameters that can be used to fabricate dense parts from Invar 36 (UNS K93600) using the selective laser melting process. In this research, a group of cubes was fabricated using different process parameters from Invar 36 powder using a selective laser melting machine. The density, microstructures, and surface features of these cubes were measured. Experimental observations were drawn from the results of the preliminary analyses. The influence of the process parameters on the density of the parts produced is discussed in this paper.

Journal ArticleDOI
TL;DR: In this article, the state-of-the-art in several aspects including the generation reasons of residual stresses, the factors influencing distortion during machining, the measurement methods of residual stress, the prediction and controlling methods of distortion are summarized.
Abstract: The distortion in machining aeronautical aluminum alloy parts (AAAPs) is one of the serious challenges in the aviation industry, and the residual stresses produced in multimanufacturing steps are the main cause. In order to get a comprehensive understanding of the problems about residual stresses and distortion in machining AAAPs, the state-of-the-art in several aspects including the generation reasons of residual stresses, the factors influencing distortion during machining, the measurement methods of residual stresses, the prediction and controlling methods of distortion are summarized in this paper. The generation mechanism of the bulk residual stress inner materials and the machining-induced residual stresses, as well as the factors affecting two kinds of residual stresses are stated. Also, the influences of residual stresses and machining process conditions on distortion are analyzed. Furthermore, the common residual stress measurement methods and its application scope are summarized. Significantly, the differences, advantages, and disadvantages of various prediction methods are analyzed. The methods of controlling distortion before and after machining are summarized. Finally, the paper gives out further research on the distortion in machining AAAPs in aeronautical manufacturing.

Journal ArticleDOI
TL;DR: This study proposes a new approach for CCSOS problems, the so-called hybrid artificial bee colony (HABC) algorithm, which employs both the probabilistic model of Archimedean copula estimation of distribution algorithm (ACEDA) and the chaos operators of global best-guided artificialbee colony to generate the offspring individuals with consideration of quality of service (QoS) and CMfg environment.
Abstract: With the advent of cloud manufacturing (CMfg), more and more services in CMfg platforms may provide the same functionality but differ in performance. In order to insure the manufacturing cloud to match the complicated task requirements, composited CMfg service optimal selection (CCSOS) is becoming increasingly important. This study proposes a new approach for such CCSOS problems, the so-called hybrid artificial bee colony (HABC) algorithm, which employs both the probabilistic model of Archimedean copula estimation of distribution algorithm (ACEDA) and the chaos operators of global best-guided artificial bee colony to generate the offspring individuals with consideration of quality of service (QoS) and CMfg environment. Different-scale CCSOS problems are adopted to evaluate the performance of the proposed HABC. Experimental results have shown that the HABC can find better solutions compared with such algorithms as genetic algorithm, particle swarm optimization, and basic artificial bee colony algorithm.

Journal ArticleDOI
TL;DR: A structured and integrated decision model for evaluating sustainable suppliers in the context of telecom industry by combining analytical hierarchy process (AHP) and improved grey relational analysis (IGRA) approaches is proposed.
Abstract: Supplier selection is one of the critical problems in supply chain systems. Within the last decades, by the emergence of sustainability concept, companies have been motivated to enhance their supplier’s sustainability and move toward sustainable development. This paper proposes a structured and integrated decision model for evaluating sustainable suppliers in the context of telecom industry by combining analytical hierarchy process (AHP) and improved grey relational analysis (IGRA) approaches. The proposed model employs AHP for calculating sustainability criteria weights and IGRA for ranking suppliers. Moreover, a sensitivity analysis is also performed to demonstrate the robustness of the model. In this research, the sustainable supplier selection problem of the telecom industry in the southern part of Iran was investigated, showing the effectiveness and applicability of this proposed integrated approach.

Journal ArticleDOI
TL;DR: In this paper, the effects of process parameters including laser power, scan velocity, hatch distance, and scan strategy that produce various solidification cooling rates and thermal gradients during the process, which also contribute to the resultant microstructure, have been analyzed.
Abstract: Laser powder bed fusion (L-PBF) as an additive manufacturing process produces nearly fully dense nickel alloy 625 (IN625) parts with complex features. L-PBF generates surfaces and microstructure through directional solidification that can be controlled by scan strategies and selection of process parameters. This study provides experimental investigations on microstructure formation including sizes of cellular grains and growth directions of columnar grains on the nickel alloy 625 test coupons. The effects of process parameters including laser power, scan velocity, hatch distance, and scan strategy that produce various solidification cooling rates and thermal gradients during the process, which also contribute to resultant microstructure, have been analyzed. Optimization studies are conducted on several objectives to improve the productivity while controlling the process effects on the resultant microstructure using response surface regression, desirability functions, and multi-objective genetic algorithm optimization.

Journal ArticleDOI
TL;DR: In this article, a review on the resistance spot welding (RSW) of Al/Al alloys, Al alloys/steel, Al/Mg alloys and Al/Ti alloys with focus on structure, properties, and performance relationships is presented.
Abstract: This paper presents a review on the resistance spot welding (RSW) of Al/Al alloys, Al alloys/steel, Al/Mg alloys, and Al/Ti alloys, with focus on structure, properties, and performance relationships. It also includes weld bonding, effect of welding parameters on joint quality, main metallurgical defects in Al spot welds, and electrode degradation. The high contact resistance, induced by the presence of oxide layer on the surface of Al alloys, and the need for application of high welding current during RSW of Al alloys result in rapid electrode tip wear and inconsistency in weld quality. Studies have shown that cleaning the oxide layer, sliding of a few microns between sheets, enhancing the electrode force, and the application of a low-current pre-heating can significantly reduce the contact resistance and improve joint quality. For Al/steel dissimilar RSW, the technique of resistance element welding, the use of optimized electrode morphology, the technique of RSW with cover plates, and the use of interlayers such as Al-Mg, AlSi12, and AlCu28 alloys were found to suppress the formation of brittle intermetallic compounds (IMC) and improve the joint quality. The employment of pure Ni foil, Au-coated Ni foil, Sn-coated steel, and Zn-coated steel interlayers was also found to restrict the formation of brittle IMCs during RSW of Al/Mg alloys. Furthermore, the techniques of RSW with cover plates and RSW under the influence of electromagnetic stirring effect were found to improve the weldability of Al/Ti dissimilar alloys.

Journal ArticleDOI
TL;DR: In this paper, the effect of both cryogenic and dry machining of AZ31 magnesium alloy on temperature and surface roughness was examined, and it was found that the cryogenic machining was able to reduce the maximum temperature at the machined surface to about 60%.
Abstract: In this study, the effect of both cryogenic and dry machining of AZ31 magnesium alloy on temperature and surface roughness was examined. Cryogenic machining experiments were conducted by applying liquid nitrogen at the cutting zone. The cutting parameters (cutting speed, depth of cut, and feed rate) were varied, and their effect on the results was identified. It was found that the cryogenic machining was able to reduce the maximum temperature at the machined surface to about 60% as compared with dry machining. A finite element model was developed to predict the temperature distribution at the machined surface. The simulated results showed good agreement with the experimental data. After analyzing the temperature distribution, the model also suggested that the cryogenic-assisted machining removes heat at a faster rate as to that of the dry machining. An arithmetic model using the response surface method was also developed to predict the maximum temperature at the surface during cryogenic and dry machining. The analysis pointed out that the maximum temperature was greatly affected by the cutting speed followed by feed rate and depth of cut. Cryogenic machining leads to better surface finish with up to 56% reduction in surface roughness compared with dry machining.

Journal ArticleDOI
TL;DR: In this paper, the simultaneous effect of part building orientation (along the X, Y, and Z axis) and raster angle (0°, 30°, 60°, and 90°) on surface roughness, tensile strength, flexural strength, consumption of model, support material, and building time of acrylonitrile butadiene styrene (ABS) test specimens fabricated by FDM process was investigated.
Abstract: The present study investigates the simultaneous effect of part building orientation (along the X, Y, and Z axis) and raster angle (0°, 30°, 60°, and 90°) on surface roughness, tensile strength, flexural strength, consumption of model, support material, and building time of acrylonitrile butadiene styrene (ABS) test specimens fabricated by fused deposition modeling (FDM) process. Mechanical properties and surface roughness show a strong anisotropic behavior for the parts. For parts built with the X or Y orientations and 30° or 60° raster angle, pulling of fiber and a small amount of necking along with tearing are observed, which are responsible for higher strength. Post-built treatment of the parts with cold vapors of dimethyl ketone resulted in an immense improvement in surface finish. Exposing the parts in cold vapors turns the surfaces to a soft/mushy-like state due to the weakening of the secondary bonds, and the minor flow of polymer layers fills the cavity region between the adjacent layers and helps in improving the surface finish after the treatment.

Journal ArticleDOI
TL;DR: In this paper, the authors present a review of the available literature on benchmark artifacts for evaluating the geometrical performance of additive manufacturing processes and propose a summary of guidelines to design benchmark artifacts.
Abstract: In recent years, additive manufacturing (AM) has undergone a rapid growth, therefore several processes based on different working principles (e.g. photopolymerization, sintering, extrusion, material jetting, etc) are now available and allow to manufacture parts using a wide range of materials. Consequently, the so-called benchmark artifacts are necessary to assess the capabilities and limitations of each AM process or to compare the performance of different processes. This paper focuses on the benchmark artifacts for evaluating the geometrical performance of AM processes and proposes an extensive review of the available literature, analyzing the design of such test parts in detail. The investigated test parts are classified according to the process aspect that they are able to evaluate (dimensional/geometrical accuracy, repeatability, minimum feature size) and the combination AM process/materials for which they have been used. In addition, the paper draws a summary of guidelines to design benchmark artifacts for geometrical performance evaluation.

Journal ArticleDOI
TL;DR: In this paper, the use of a projector-based spatial augmented reality system in an industrial quality assurance setting to highlight spot-weld locations on vehicle panels for manual welding operators is presented.
Abstract: This paper presents the use of a projector-based spatial augmented reality system in an industrial quality assurance setting to highlight spot-weld locations on vehicle panels for manual welding operators. The aim of this work is to improve the precision and accuracy of manual spot-weld placements with the aid of visual cues as a proactive step by the automotive manufacturer to enhance product quality. The prototype system was deployed at General Motors (GM) Holden plant in Elizabeth, Australia on the production line building Holden Cruze vehicles. Production trials were conducted and techniques developed to analyse and validate the precision and accuracy of spot-welds both with and without the visual cues. A reduction of 52 % of the standard deviation of manual spot-weld placement was observed when using augmented reality visual cues. The average standard deviation with-AR assistance (19 panels and 114 spot-welds) was calculated at 1.94 mm compared to without-AR (45 panels and 270 spot-welds) at 4.08 mm. All welds were within the required specification and panels evaluated in this study were used as the final product made available to consumers. The visual cues enabled operators to spot-weld at a higher degree of precision and accuracy.

Journal ArticleDOI
TL;DR: In this article, carbon fiber-reinforced plastic parts were manufactured by sandwiching carbon fibres between upper and lower ABS layers made by a 3D printer using fused deposition modelling.
Abstract: Carbon fibre-reinforced plastic parts were manufactured by sandwiching carbon fibres between upper and lower ABS layers made by a 3D printer using fused deposition modelling. Carbon fibre-reinforced plastic tensile specimens were manufactured, and the strength of the specimens was measured. The strength is not increased only by sandwiching of the carbon fibres, and thermal bonding between the fibres and layers is required. The strength for the small diameter of the nozzle is higher than that for the large diameter. The thermal bonding operation is simplified by using a microwave oven.

Journal ArticleDOI
TL;DR: In this article, the performance modeling of hard milling to attain an optimum parameter setting for the minimum cutting force and surface roughness was performed by adopting Grey-based Taguchi method and composite desirability function.
Abstract: The present work focuses on the performance modeling of hard milling to attain an optimum parameter setting for the minimum cutting force and surface roughness. Furthermore, it was attempted to compute the minimum quantity lubricant flow rate precisely, besides the cutting speed and table feed rate, by adopting Grey-based Taguchi method and composite desirability function. The experimental data was collected by end milling of hardened AISI 4140 steel using carbide cutter under dry and minimum quantity lubrication conditions according to Taguchi L 16 orthogonal array. The predictive model of the responses was formulated by using response surface methodology. The analysis of variance revealed that the table feed has the maximum influence on cutting force, and the flow rate of lubricant has the highest effect on surface roughness. The parameter setting at lower table feed, higher cutting speed, and 150-ml/h lubricant flow yield the minimum value of the responses. Finally, the results of confirmation test verified the adequacy and supremacy of the optimization models; however, Grey-based Taguchi method induced a better optimization.

Journal ArticleDOI
TL;DR: In this paper, the state-of-the-art state of the art of uncertainty quantification and uncertainty management for additive manufacturing processes is reviewed, with a focus on laser powder bed fusion AM.
Abstract: One of the major barriers that hinder the realization of significant potential of metal-based additive manufacturing (AM) techniques is the variation in the quality of the manufactured parts. Uncertainty quantification (UQ) and uncertainty management (UM) can resolve this challenge based on the modeling and simulation of the AM process. This paper reviews the research state of the art and discusses needs and opportunities in the UQ/UM of the AM processes, with a focus on laser powder bed fusion AM. The major methods and models of laser powder bed fusion AM process are summarized first. The current research work in UQ of AM processes is then reviewed. Based on the review of AM process models and current UQ approaches for the AM process, this paper presents insights into how the current state of the art UQ and UM techniques can be applied to AM to improve the product quality. Future research needs in UQ and UM of AM are also discussed. Laser sintering of metal nanoparticles, which is part of the micro-AM process, is used as an example to illustrate the application of UQ and UM in the AM.

Journal ArticleDOI
TL;DR: In this article, the cooling performance of conformal cooling channel in plastic injection molding (PIM) is numerically and experimentally examined, and it is found from the numerical result that the cooling quality of the conformal channel is much improved compared to the conventional cooling channel.
Abstract: In this paper, cooling performance of conformal cooling channel in plastic injection molding (PIM) is numerically and experimentally examined. To examine the cooling performance, cycle time and warpage are considered. Melt temperature, injection time, packing pressure, packing time, cooling time, and cooling temperature are taken as the design variables. A multi-objective optimization of the process parameters is then performed. First, the process parameters of conformal cooling channel are optimized. Numerical simulation in the PIM is so intensive that a sequential approximate optimization using a radial basis function network is used to identify a pareto-frontier. It is found from the numerical result that the cooling performance of conformal cooling channel is much improved, compared to the conventional cooling channel. Based on the numerical result, the conformal cooling channel is developed by using additive manufacturing technology. The experiment is then carried out to examine the validity of the conformal cooling channel. Through numerical and experimental result, it is confirmed that the conformal cooling channel is effective to the short cycle time and the warpage reduction.

Journal ArticleDOI
TL;DR: In this paper, the lifetime, width and depth of the pools of molten powder material are analyzed for different beam powers, scan speeds and line energies in experiments and simulations, and a thermal finite element simulation tool is used to simulate the temperature distribution in the selective electron beam melting process.
Abstract: Selective electron beam melting of Ti-6Al-4V is a promising additive manufacturing process to produce complex parts layer-by-layer additively. The quality and dimensional accuracy of the produced parts depend on various process parameters and their interactions. In the present contribution, the lifetime, width and depth of the pools of molten powder material are analyzed for different beam powers, scan speeds and line energies in experiments and simulations. In the experiments, thin-walled structures are built with an ARCAM AB A2 selective electron beam melting machine and for the simulations a thermal finite element simulation tool is used, which is developed by the authors to simulate the temperature distribution in the selective electron beam melting process. The experimental and numerical results are compared and a good agreement is observed. The lifetime of the melt pool increases linearly with the line energy, whereby the melt pool dimensions show a nonlinear relation with the line energy.

Journal ArticleDOI
TL;DR: A detailed literature review on the current research of incremental sheet forming relating to deformation mechanism, modelling techniques, forming force prediction and process investigations is presented in this paper, where several potential hybrid incremental sheet-forming strategies are discussed.
Abstract: This paper presents a detailed literature review on the current research of incremental sheet forming relating to deformation mechanism, modelling techniques, forming force prediction and process investigations. First, a review of the fundamental deformation mechanism and formability in incremental sheet forming (ISF) is provided. Subsequently, the modelling techniques for ISF are reviewed and categorised into two approaches: analytical modelling and finite element modelling. Special interest is given to a critical review regarding the forming forces analysis and prediction during the process. Then, previous publications related to geometric accuracy, surface finish and forming efficiency in ISF are reviewed. Finally, several potential hybrid incremental sheet-forming strategies are discussed. This leads to a statement of conclusion which may act as an inspiration and reference for the researcher.

Journal ArticleDOI
TL;DR: In this paper, a real-time lightweight AM machine condition monitoring approach is proposed, where acoustic emission (AE) sensor is used, and the original AE waveform signals are first simplified as AE hits, and then segmental and principal component analyses are applied to further reduce the data size and computational cost.
Abstract: Machine condition monitoring is considered as an important diagnostic and maintenance strategy to ensure product quality and reduce manufacturing cost. However, currently, most additive manufacturing (AM) machines are not equipped with sensors for system monitoring. In this paper, a real-time lightweight AM machine condition monitoring approach is proposed, where acoustic emission (AE) sensor is used. In the proposed method, the original AE waveform signals are first simplified as AE hits, and then segmental and principal component analyses are applied to further reduce the data size and computational cost. From AE hits, the hidden semi-Markov model (HSMM) is applied to identify the machine states, including both normal and abnormal ones. Experimental studies on fused deposition modeling (FDM), one of the most popular AM technology, show that the typical machine failures can be identified in a real-time manner. This monitoring method can serve as a diagnostic tool for FDM machines.

Journal ArticleDOI
TL;DR: In this paper, the authors provide a state-of-the-art review on the investigations into the residual stresses in metallic structural materials generated by grinding, including steels, titanium alloys, and nickel-based superalloys.
Abstract: This paper provides a state-of-the-art review on the investigations into the residual stresses in metallic structural materials generated by grinding. The materials covered include steels, titanium alloys, and nickel-based superalloys. The formation mechanisms of the residual stresses and their impacts are specifically discussed. Some major influential factors on the residual stresses formation in grinding, such as grinding wheel characteristics, dressing techniques, grinding parameters, cooling conditions, and properties of workpiece materials, are analyzed in detail. These include experimental measurement, modeling, simulation, knowledge-based monitoring, and fuzzy analysis. Finally, the paper highlights some important aspects of grinding-induced residual stresses for further investigation.

Journal ArticleDOI
TL;DR: In this article, three different correction strategies are discussed for the correction of porosity during the selective laser melting (SLM) of 18Ni300 maraging steel, and the results indicate the capacity of improving the part density and reducing the part roughness effectively.
Abstract: One of the most critical defects in selective laser melting (SLM) is the porosity formation. Optimization of process parameters for reducing the porosity levels to lower than <1% is possible in most of the cases. Susceptibility to porosity formation can be higher for different alloys as function of chemical composition due to higher spark generation and molten pool instabilities. On the other hand, the probability of porosity formation increases in larger components due to an extended processing time. Powder recoater wear, increase in thermal load, and accumulation of particles in the processing chamber become more relevant as the processing time increases. Hence, the use of integrated monitoring and correction strategies becomes crucially important. In this work, three different correction strategies are discussed for the correction of porosity during the SLM of 18Ni300 maraging steel. The main aim is to develop a possible correction and prevention scheme to be used within a fully monitored SLM process. The 18Ni300 maraging steel is susceptible to high levels of porosity due to the empirically observed melt-pool instabilities as well as high spark and vapor generation. The correction methods consisted of remelting of the defected layer employing different scan strategies namely “double pass,” “soft melting,” and “polishing.” As a preventive strategy, preheating at 170 °C was also evaluated. At an initial stage, all the strategies were tested throughout the part built in order to assess their general capacity in improving the part density. Surface roughness, geometrical error, and material microhardness were also evaluated to assess the impact of the strategies on the other quality aspects. The results indicate the capacity of improving the part density and reduce the part roughness effectively.

Journal ArticleDOI
TL;DR: In this article, the machinability characteristics of hard-to-machine material MMCs are evaluated and the optimum machining parameters vital to maximizing tool life whilst producing parts at the desired quantity and quality.
Abstract: Metal matrix composites (MMCs) are materials which have been widely used in the aerospace and automobile industries since the 1980s and have been classified as hard-to-machine materials. During the intervening years, only a limited amount of research has been conducted into the cutting action of MMCs. As with traditional materials, it is important to understand the wear mechanisms that contribute to tool wear which reduces tool life. The objective of this research is to evaluate the machinability characteristics for these hard-to-machine material MMCs. This review will also establish the optimum machining parameters vital to maximizing tool life whilst producing parts at the desired quantity and quality.