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The contact angle (CA) of a water droplet on the polished aluminum surfaces is usually between 60° and 90°. This paper discusses a tuned bulk micro-manufacturing approach for transforming the surface topology of aluminum simultaneously at the micro- and nano-length scales, thereby significantly influencing its wetting characteristics. The approach is cheap, easy to implement, and scalable. The treated aluminum surfaces appeared like roughly polished surfaces at the macroscale and were found to be robust and non-toxic. They exhibited a paper towel effect by showing extreme surface wettability (CA of zero) to many industrial liquids, i.e., wetting on these surfaces is only a function of the surface roughness but not the fluid type. This extreme wetting ability to multiple liquids (or ultra-omniphilicity) was generated by sequentially creating a sub-surface micro- and nano-cavity architecture with nano-cavities within the embryos of micro-cavities interconnected by a network of micro-grooves.

In order to manufacture functional parts using filament deposition modelling (FDM), an understanding of the machine’s capabilities is necessary. Eliciting this understanding poses a significant challenge due to a lack of knowledge relating manufacturing process parameters to mechanical properties of the manufactured part. Prior work has proposed that this could be overcome through the creation of capability profiles for FDM machines. However, such an approach has yet to be implemented and incorporated into the overall design process. Correspondingly, the aim of this paper is two-fold and includes the creation of a comprehensive capability profile for FDM and the implementation of the profile and evaluation of its utility within a generative design methodology. To provide the foundations for the capability profile, this paper first reports an experimental testing programme to characterise the influence of five manufacturing parameters on a part’s ultimate tensile strength (UTS) and tensile modulus (E). This characterisation is used to train an artificial neural network (ANN). This ANN forms the basis of a capability profile that is shown to be able to represent the mechanical properties with RMSEP of 1.95 MPa for UTS and 0.82 GPa for E. To validate the capability profile, it is incorporated into a generative design methodology enabling its application to the design and manufacture of functional parts. The resulting methodology is used to create two load bearing components where it is shown to be able to generate parts with satisfactory performance in only a couple of iterations. The novelty of the reported work lies in demonstrating the practical application of capability profiles in the FDM design process and how, when combined with generative approaches, they can make effective design decisions in place of the user.

In this paper, a characterisation of diamond abrasive grains of grinding tools using industrial X-ray computed tomography (XCT) is carried out. One of the most challenge tasks in the characterisation is extracting the diamond abrasive grains from the XCT volume data. Methods that are able to extract the grains are then developed and introduced in this paper. The first step is to create a triangular mesh surface from the reconstructed volume file using a gradient anisotropic diffusion filter. The second step is to convert the measured greyscale volume into a signed distance field using a global threshold value and then a localised method for grain segmentation. To validate the proposed method, three different types of grinding tool specimens are measured and analysed. Each abrasive grain is segmented and the distributions of grains (with both random and designed patterns) are then calculated, plotted and analysed. The quantitative analysis clearly shows the deviations between the measured distribution and the designed pattern of the grinding tool, which indicates that the proposed method can provide an accurate and comprehensive characterisation of the grinding tools.

The selection of printing parameters for 3D printing can dramatically affect the dynamic performance of components such as polymer spur gears. In this paper, the performance of 3D printed gears has been optimised using a machine learning process. A genetic algorithm (GA)–based artificial neural network (ANN) multi-parameter regression model was created. There were four print parameters considered in 3D printing process, i.e. printing temperature, printing speed, printing bed temperature and infill percentage. The parameter setting was generated by the Sobol sequence. Moreover, sensitivity analysis was carried out in this paper, and leave-one cross validation was applied to the genetic algorithm-based ANN which showed a relatively accurate performance in predictions and performance optimisation of 3D printed gears. Wear performance of 3D printed gears increased by 3 times after optimised parameter setting was applied during their manufacture.

Due to its excellent specific mechanical properties, carbon fibre-reinforced polymer (CFRP) composite is a widely used structural material in the aerospace industry. However, this material is difficult to cut, mainly due to its inhomogeneity and anisotropic features and because of the strong wear effects of its carbon fibres. In the scope of aerospace industrial uses of this material, thousands of holes have to be machined for purposes of assembly. Nevertheless, conventional drilling technology – even if special drilling tools are used – is only moderately able to manufacture good quality holes. Wobble milling is a novel advanced hole-making technology, which has been developed to minimize machining-induced geometrical defects like delamination or uncut fibres. The main objective of the present paper is to compare wobble milling, helical milling and conventional drilling technologies concerning unidirectional CFRPs. In addition, the kinematics of wobble milling technology is discussed in detail. In the scope of this paper, numerous machining experiments were conducted in unidirectional CFRPs: herein the impact of the type of cutting tool and of process parameters on the quality of machined holes are analysed and discussed (diameter of holes, circularity error and characteristics of uncut fibres). During these investigations, experimental data were evaluated with the help of digital image processing (DIP) and with the help of analysis of variance (ANOVA) techniques. Experimental results show that the amount of uncut fibres can significantly be minimized through the application of wobble milling technology.

Additively manufactured lattice structures are popular due to their desirable properties, such as high specific stiffness and high surface area, and are being explored for several applications including aerospace components, heat exchangers and biomedical implants. The complexity of lattices challenges the fabrication limits of additive manufacturing processes and thus, lattices are particularly prone to manufacturing defects. This paper presents a review of defects in lattice structures produced by powder bed fusion processes. The review focuses on the effects of lattice design on dimensional inaccuracies, surface texture and porosity. The design constraints on lattice structures are also reviewed, as these can help to discourage defect formation. Appropriate process parameters, post-processing techniques and measurement methods are also discussed. The information presented in this paper contributes towards a deeper understanding of defects in lattice structures, aiming to improve the quality and performance of future designs.

The present paper is focused on friction stir welding (FSW) of dissimilar aluminum alloys and steels, an area that is getting great concern recently. The promise of FSW joints lies in low welding heat input and its ability to minimize the extent of the formation of intermetallic compound (IMC) in dissimilar metals. The present paper assessed the status of FSW process of dissimilar aluminum alloys and steels, and to identify the opportunities and challenges for the future. The essential reason for the formation of the dissimilar Al/steel FSW joints with high quality is explained by super diffusion behavior. This paper will provide basis to designers and engineers to consider FSW for a wider range of dissimilar aluminum alloys and steels.

The method of combining simulations with experiments is used in this paper. Both traditional grinding and point grinding are considered as the research objects. The motion paths of grains in the point grinding process will completely differ from those in the traditional grinding process because of the non-zero inclination angle α. Thus, a coordinate transformation between the grinding wheel and the workpiece is performed. Then, a brand-new formation mechanism for a 3D workpiece surface is established by combining selected trajectories to simulate the formation of the surface. The interference trajectories are effectively screened by iterating over the cutting paths of all grains on the grinding wheel surface to improve the prediction accuracy for the machined surface. Both the surface features of the grinding wheel and the elastic-plastic deformation of the workpiece material are investigated and analyzed for the first time in this paper; they are considered in the motion trajectories of the abrasive grains to make the simulated grinding surface topography closer to that formed in the actual grinding process. The trend of the influence of the variable angle α on the surface roughness is obtained and analyzed. The comparison and analysis of the simulation and experimental results prove that the simulated surface quality of the grinding workpiece is consistent with that measured in a 3D microtopography analysis, and the curve shapes in the cross-section and surface roughness evaluations are also consistent. The surface quality of a grinding workpiece can be effectively predicted using this simulation method.

Sheet metal structures produced by bending are extensively used in a wide variety of industries. Rapid production of such workpieces is well sought after for low production volume demands. An effective and practical way to reduce springback is through compensating die dimensions, which has proved to be economic for large production scenario. However, in the environment of rapid production, part dimensions and/or material composition change frequently and hence new dies have to be designed and made to address these changes even if they are minor. Such situation inevitably incurs significant effort and high expenditure on determining appropriate die dimensions and fabricating new dies, and therefore imposes both time and financial burdens on producing angular sheet metal workpieces particularly at very low production volumes. This paper presents an effective and economic way of prototyping sheet metal workpieces with angular dimensional accuracy maintained, however without the need of creating new dies. The methodology extends from the author’s previous work on angular dimension improvement as reported by Li and Sekar (Proceedings of the 2016 Manufacturing Science and Engineering Conference, MSEC2016, 2016) to the rapid prototyping of sheet metal structures and process planning of bending-machining hybrid process. Three case studies are provided in the paper and the outcome shows that the methodology is capable of prototyping angled sheet metal workpieces with existing dies that are not designed nor compensated for the prototype models.

Slicing is the initial procedure in silicon wafer manufacturing process. The cost of slicing process is about 30% of the total cost of chip fabrication. The effective approaches to decrease slicing cost are to reduce the slicing kerf loss and to decrease the thickness and breakage ratio of sliced wafer. The resin-bonded diamond wire saw has the advantages of uniform of abrasive protrusion height and the manufacturing process less impact on the core wire strength. It is expected to achieve a narrow kerf and ultra-thin wafer slicing of silicon crystal ingot with resin-bonded diamond wire saw. The aim of this paper is to develop high-performance resin-bonded diamond wire saw. Based on the analysis of fabrication process of resin bond diamond wire saw, the device for resin-bonded diamond wire saw manufacturing is developed. The mold in the fabrication device ensures the consistency of the wire saw outer diameter and the uniform of abrasive protrusion height. A test device for constant force feed slicing is developed for the slicing performance evaluation of resin-bonded diamond wire saw. The components of the coating layer materials of resin-bonded diamond wire saw are investigated via orthogonal test. Choosing the material removal rate, wire saw wear rate, coating layer binding force, and sliced surface roughness as evaluation indexes, the performance of developed resin-bonded diamond wire saw is evaluated. The optimal component ratio of the coating layer materials of resin-bonded diamond wire saw is obtained, and the verification test of the optimal component ratio of the coating layer materials is performed. The results of this paper are useful for the development of smaller-diameter diamond wire saw and high-quality slicing of optoelectronic crystal ingot.

Incremental sheet forming is an advanced manufacturing technique where a piece of sheet is shaped into a product by a series of small incremental localized deformations. It has revolutionized sheet shaping for small-batch production since its inception in the 1990s, providing an economical and effective alternative to sheet stamping and pressing, which are cumbersome and expensive. However, the materials with poor overall ductility at room temperatures are difficult to be formed by conventional incremental sheet forming. Therefore, several heat-assisted incremental sheet-forming methods have been developed by researchers trying to improve the formability of such materials and overcome the low geometrical accuracy as well. The aim of this paper is to provide a state-of-the-art review on the development of heat-assisted incremental sheet forming. It is hoped that the knowledge provided in this paper can facilitate readers working in this field to obtain a comprehensive view and take a step forward for future incremental forming of hard-to-deform materials at elevated temperatures.

Given their rapid development, aerospace and other high-tech industries are in urgent need of process technology for large complex thin-walled shells represented by large thin-walled parts with ring inner ribs and curvilinear generatrix. To make up for the deficiency in existing forming methods, this paper presents a compound spinning process that integrates counter-roller spinning, multi-neck spinning, and hot spinning. The finite element models for the counter-roller spinning and multi-neck spinning forming of such parts are established, and these models can simulate the influences of different spinning process parameters on workpiece maximum equivalent stress and maximum ovality. The 2A12 aluminum alloy tube blank is used in this paper. The process parameters for obtaining the counter-roller spinning for such parts are as follows: a feed ratio of 1.0 mm/r and a roller nose radius of 8 mm. The process parameters of multi-neck spinning are as follows: a feed ratio of 3.0 mm/r and a roller nose radius of 80 mm; and the forming temperature of hot spinning is 200–250 °C. Verification by a compound spinning test found that the numerical simulation results are consistent with the process test results. The process parameters can be used for guiding the actual production of large thin-walled parts with ring inner ribs and curvilinear generatrix.

This paper investigates the effects of deep cold rolling (DCR) treatment on the fatigue life of C38500 brass alloy. Low cycle fatigue (LCF) and high cycle fatigue (HCF) tests were conducted according to Moore rotary bending instrument. The terms LCF and HCF are used here beyond the typical definitions in the literature and are used in this paper to distinguish between the two loading conditions. The DCR treatment was done for various rolling depths of 50, 75, 100, 125, and 150 μm and passes number to find the most effective conditions. The results showed that the rolling depth of 75 μm led to most improvement of the fatigue life near 20 and 302% for HCF and LCF regimes, respectively. Furthermore, DCR treatment was performed for the second pass which improved more the fatigue life by about 351 and 45% for LCF and HCF, respectively. Moreover, the effects of DCR parameters such as rolling depth, feed rate, number of passes, the ball diameter, and friction on distribution of residual stresses were evaluated numerically using ABAQUS commercial software. At the end, the finite element (FE) results were correlated with microscopic examinations and experimental findings.

Forging and casting are the commonly used manufacturing methods for the blank part of complex parts, such as the compressor blade and engine casing. Their geometric shapes are usually complex and difficult to measure or model. Besides, blank parts of different batches usually show slight difference in terms of shape and material consistency. Therefore, the axial cutting depth for the first sequence of rough machining is not fully decided. As a consequence, the rough milling process can only be planned with conservative feed rate, which leads to long machining time. Aiming at improving machining efficiency for roughing process, a feed rate optimization method by combining the monitored cutting force in the whole milling process with off-line optimization is developed in this paper. Firstly, the paper presents an analytical force model to calculate the instantaneous milling force and recognize the actual axial cutting depth, and a cutting force analysis method to recognize optimizable cutting segments of a trajectory. Secondly, a linear interpolation algorithm is applied to divide the optimizable cutting segments by interpolating a number of monitoring points. After that, the maximum feed rate of each monitoring point is calculated according to actual machining condition. The optimal feed rate is achieved after restraining with the constraints and smoothing with the least squares algorithm. To validate the effectiveness of the developed optimization method, a machining experiment with milling a designed blank part was conducted. Compared with the constant feed rate method, the developed method saved machining time by 19.83%.

This paper aims at modeling surface roughness and cutting force in finish turning of AISI 4140 hardened steel with mixed ceramic tool. For this purpose, an attempt is made to improve prediction by using Artificial Neural Networks (ANN) technique. The effects of the process inputs, namely cutting speed, depth of cut, feed rate, and tool nose radius on the output responses are evaluated using response surface methodology (RSM). Also, this paper provides a profound examination of the surface roughness through the bearing area curve analysis (BAC) of the three-dimensional topographic maps of the machined surfaces, where relevant criteria representing surface roughness are used. It was established that machining with larger nose radius and lower feed rate produces surfaces with better functional characteristics and that the undesired effect of feed rate can be reduced by increasing the cutting speed. Desirability function approach (DF) and the Non-dominated Sorting Genetic Algorithm (NSGA-II) coupled with ANN models are used to solve different multi-objective optimization problems. It is found that NSGA-II is more efficient than DF method and offers diverse sets of non-dominated solutions that satisfy the requirements of parts quality, productivity, and cutting force, which lead to better competitiveness. Furthermore, the NSGA-II coupled with ANN models allowed to predict minimal value of Ra much less than the values of the experimental data.

Electrical discharge machining (EDM) is an advanced non-traditional manufacturing technology that has many advantages over other machining methods. Many papers have discussed the machining mechanism and modeling of the EDM process. However, previous mechanism models have mainly been linear, which contradicts their precondition that EDM is a stochastic process. In this paper, a non-linear mechanism model is proposed for the EDM process. A threshold condition that leads to chaos is calculated using the Melnikov theory. The theoretical results indicate that the EDM system can generate varied chaos in the evolution of electrical discharge. To verify this conclusion, validation experiments are implemented. Several sets of complete EDM processes’ real-time series are analyzed by multiple chaotic numerical criteria, including power spectrum analysis, principle component analysis (PCA), correlation dimension analysis, and Lyapunov exponent analysis. The experimental results provide further qualitative and quantitative evidence that a complete EDM process has dynamical chaotic characteristics.

Thermal error modeling of the spindle plays an important role in predicting thermal deformation and improving machining precision. Even though the modeling method using temperature as the input variable is widely applied, it is less effective due to severe loss of thermal information and pseudo-hysteresis between temperature and thermal deformation. This paper presents a novel modeling method considering heat quantity as the input variable with theoretical analysis and experimental validation. Firstly, the change of thermal state of a metal part being heated is discussed to reveal the essence of the relationship between heat, thermal deformation and temperature, and the theoretical basis of the modeling method proposed in this paper is elaborated. Subsequently, the relationship between thermal deformation and heat quantity is further studied through modeling the thermal deformations of stretching bar and bending beam using heat quantity as the independent variable, and the stretching model is verified based on finite element method. Then, the thermal error models of the spindle are developed with the heat elastic mechanics theory and the lumped heat capacity method. In succession, the parameter identification of thermal error models is carried out experimentally using the least square method. The average fitting accuracy of these models is up to 91.3%, which verifies the good accuracy and robustness of the models. In addition, these models are of good prediction capability. The proposed modeling method deepens the research of thermal errors and will help to promote the application of relevant research results in the actual production.

© 2018, Springer-Verlag London Ltd., part of Springer Nature. This paper investigates the properties of titanium alloy (Ti6Al4V) lattice structures fabricated via selective laser melting (SLM). Response surface method (RSM) was used to design the experiments. Four factors were selected to determine its influence on the Young’s modulus and compressive strength. Detailed characterizations such as dimensional accuracy, surface roughness, microstructure analysis, and compression test were conducted and reported. The built structures have a Young’s modulus ranging between 0.01 and 1.84 GPa. The statistical method was used to find the relationship between factors and Young’s modulus and compressive strength. Porosity was comprehended to play a significant role in determining the Young’s modulus and compressive strength. The error of the developed model was in the range of 0.5 to 1.3% compared with experimental results. Meanwhile, all the four factors found not to affect the surface roughness significantly. The statistical method recognizes the trends of the factor effect on the Young’s modulus, yield stress, and surface roughness. This paper was made possible by NPRP grant# NPRP 8-876-2-375 from the Qatar National Research Fund (a member of Qatar Foundation). The findings achieved herein are solely the responsibility of the authors.

KDP (KH2PO4) crystal is an important functional crystalline material that can be used in the area of laser frequency conversion. As the first process of machining, the slicing process of the KDP crystal is of vital importance to the yield rate of wafers. While the KDP crystal often cracks in the slicing process by the traditional method of band saw because of its properties of high brittleness, low strength, and high thermal sensitivity, the cracks may lead to waste of the whole KDP crystal and should be avoided. Fixed abrasive wire saw slicing is considered a preferred method for KDP crystal slicing due to its advantage of low sling stress. In this paper, a finite element model in fixed abrasive wire saw slicing of the KDP crystal is established with respect to distributed slicing force and thermal stress. Distribution of slicing force and heat around the kerf area is deduced and applied to the finite element model. Based on the model, temperature field and stress field of the KDP crystal in the slicing process is obtained. The maximum principle stress caused by slicing force, thermal stress, and coupling of the slicing force and thermal stress is obtained. The maximum principle stress of different slicing parameters is analyzed; function equation between the maximum principle stress and slicing parameter is obtained by the least squares method. The critical slicing parameter at which cracks would not occur in the slicing is obtained. The simulation results in this paper are useful to avoid cracking in KDP crystal slicing with fixed abrasive wire saw.

International audience; This paper deals with design for manufacturing (DFM) approach for additive manufacturing (AM) to investigate simultaneously the different attributes and criteria of design and manufacturing. The integrated design approach is provided in the product definition level and it gradually maps the customer requirements to the final product model. The main contribution of this paper is an interface processing engine that is an interface between the product model and manufacturing model. This study uses the Skin-Skeleton approach to model the first definition of the product and model the material flow of AM technology as the manufacturing process. This engine is developed through analysis of all AM technologies and identification of their parameters, criteria, and drawbacks. In order to evaluate some product and process parameters, a multi-objective problem is formulated based on the analysis of all AM technologies; production time and material mass are optimized regarding mechanical behavior of the material and roughness of product. The approach is validated by a case study through a bag hook example. From its requirement specification to the proposed approach, this article defines an optimized product and its manufacturing parameters for fused deposition modeling (FDM) technology.

High-building multi-directional pipe joint is a complex structure. A novel technology, which is called wire and arc additive manufacture (WAAM), was used to manufacture a high-building 10-directional pipe joint in this paper. Because the intersecting areas of multi-directional pipe joint are space surfaces, the conventional planar slicing method of WAAM is hard to form space surface with high precision. According to the study of space surface slicing method and space path planning by WAAM, this paper used the outer cylinder surface of main pipe to slice other forming pipes of 10-directional pipe joint, and the intersecting surfaces could be divided into two kinds: smooth surface and curved surface with inflection point areas. Two different path filling schemes were proposed for different intersecting surfaces: The former was filled in rotating approaches, while the latter was filled in raster approaches. The dimensional errors of forming pipes were controlled about ± 1 mm, and the angle errors of intersecting pipes were less than ± 0.5°. Compared with the properties of the casting pipe joint, the tensile strength of 10-directional pipe joint increased by 12.4% and the impact toughness (20 °C) increased more than 100%. The microstructure mainly consisted of pearlite and ferrite, and average grain size was about 15 μm. Rare defects such as pores and cracks were found.

Electric discharge machining (EDM) is one of the leading edge machining processes successfully used to machine hard-to-cut materials in wide range of industrial applications. It is a non-conventional material removal process that can machine a complex shapes and geometries with high accuracy. The principle of the EDM technique is to use thermoelectric energy to erode conductive components by rapidly recurring sparks between the non-contacted electrode and workpiece. To improve EDM performance, the machine’s operating parameters need to be optimized. Studies related to the EDM have shown that the appropriate selection of the process, material, and operating parameters had considerably improved the process performance. This paper made a comprehensive review about the research studies on the EDM of different grades of titanium and its alloys. This review presents the experimental and theoretical studies on EDM that aimed to improve the process performance, including material removal rate, surface quality, and tool wear rate, among others. This paper also examines evaluation models and techniques used to determine the EDM process conditions. Moreover, the paper discusses the recent developments in EDM and outlines the progression for future research.

This paper based on the research of the different temperatures of AZ31 magnesium alloy by continuous variable cross-section direct extrusion (CVCDE) studied the effect of forming temperature on the deformation characteristics of magnesium alloy by CVCDE. It was found that the average size of grains and the proportion of large angle grain boundaries in microstructure increased obviously with the increase of forming temperature, which showed dynamic recrystallization has been relatively adequate. Because the dislocation density inside the grains was higher and the texture was weakened obviously at 623 K by compared with other temperatures, the yield strength and elongation increased at first and then decreased with the increase of temperature. This paper reveals the deformation mechanism of AZ31 magnesium alloy by CVCDE, which can provide scientific guidance for the development of magnesium alloy extrusion products with high property.

The continued development of high-speed rotating grinding wheels for grinding crankshafts has led to the use of high-performance materials such as carbon fiber matrix structures with abrasive segments bonded to them. The use of porous reinforcing centers in order to improve safety and increase rotational speed to gain the benefits associated with high-speed grinding is investigated. A 2-D finite-element model is developed which calculates rotational stresses and compares them with stresses predicted using closed-form solutions developed by Chree and Frost and Whitcomb for rotating rings. A 3-D finite-element model is developed for more complex grinding wheels that contain a porous reinforcing center that predicts stresses and deflections with remarkable accuracy. The paper also takes account of the strength of biaxially stressed brittle abrasive materials where the geometry of segments differs significantly from the prismatic geometry associated with flexural bending strength test pieces that are subjected to three-point loading conditions. Owing to lower design stresses and associated rotational speeds with high survival probability of ceramic abrasive structures (> 99.99%), it is assumed that the failure of abrasive segments is dominated by volume and/or surface flaws. The results predict accurate safety factors than previously calculated owing to the geometry of the abrasive segment loaded under plane stress conditions. The paper will be of interest to manufacturers who design and make such complex grinding wheel structures.

Metal additive manufacturing has employed several technologies and processes to advance from rapid prototyping to rapid manufacturing. Additive manufacturing technologies compete with traditional manufacturing methods through their ability to produce complex structures and customized products. This paper aims to study the characteristics of stainless steel 316L (UNS S31603) parts produced using a selective laser melting machine. In the aerospace industry, turbine blades are typically manufactured from nickel-based alloys, titanium alloys, and stainless steels. Several geometries typical of airfoil blades were examined. The main goal is to investigate the material characteristics and surface features of the airfoil blades. The study included the geometrical errors, surface microstructures, material compositions, material phases, and residual stresses of the samples produced. The characteristics of the parts produced were investigated based on experimental observations. The paper also discusses the influence of the part dimension and orientation on the profile error, surface microstructure, and residual stress.

Ceramic matrix composites of type C/SiC with superior properties have got increasing importance in many fields of industry, especially in the aerospace area. Rotary ultrasonic machining is a high-efficiency processing technology for these advanced materials. However, due to the inhomogeneity and anisotropy of these composites, the machining process is still challenging to achieve desired result due to the lack of understanding and control of material removal mechanism. In this paper, the maximum depth of penetration by diamond abrasives in workpiece material is proposed to quantify the material removal modes. A model of maximum depth of penetration for rotary ultrasonic face machining (RUFM) was developed based on the indentation theory. An experimental RUFM of C/SiC was carried out, and it revealed that the material removal mechanism transited from ductile mode to brittle fracture mode with the decrease of cutting speed. Similar transition was observed with the increase of feed rate and cutting depth. By comparing the measured cutting force with simulation, a critical depth of penetration for the cutting mechanism transition was defined at about 4 μm. The processed surface topography was studied, and the transition of material removal modes was identified by the sudden change of the 3D surface roughness map at the critical penetration depth. Thus, the maximum depth of penetration model developed in this paper can be applied to identify the ductile or brittle fracture removal mode in RUFM of C/SiC using the cutting parameters. This allows controlling the material removal mechanism to achieve desired machining efficiency and quality.

The paper presents the results of research into the influence of the process of grinding boron nitride dispersed cemented carbide (BNDCC) composite using diamond wheel with vitrified bond on the selected properties of this composite. Cutting tools of BNDCC composite were manufactured using several machining operations. At first stage, they were EDM (electrical discharge machining) wire cut from tablets and later on ground with diamond wheels (which removed the “white layer” produced by EDM cutting). Rake and flank faces of prepared cutting tools were examined by microscopic, topographic, and surface analytical techniques before and after grinding. The paper presents comparative results of BNDCC tools and tools made of H10S cemented carbide. Values of the grinding efficiency parameters, Q w , average material removal rate of grinding, Q′ w , average material removal rate per unit active grinding wheel for the two materials, were similar, indicating an insignificant effect of introduction of the harder BN phase into WCCo on these parameters. R a , surface roughness of flank face, was 0.040 μm for BNDCC composite and 0.51 μm for H10S after grinding, compared to 1.14 and 1.30 μm, respectively, before grinding. WC residual stress measurements in the flank faces of BNDCC tools were inconclusive; in the flank faces, the stresses were compressive, decreasing, e.g., from − 230 to − 1670 MPa after grinding. For the H10S tools, there was no comparable effect. The results also indicate that the vitrified bonded diamond abrasive wheel used is effective in grinding WCCo and BNDCC cutting tools.

This paper critically assesses the recent trends in aluminum-magnesium dissimilar welding and suggests a key design guideline to successfully improve the weld joint quality through addition of interlayer. First, the paper describes the main issue of incompatibility between these metals and considers the root cause of the problem, i.e., the Al-Mg-based intermetallic compounds (IMCs). It then reviews the recent trends of interlayer addition in various welding processes to mitigate Al-Mg IMCs. Focusing on laser welding, the paper finally proposes a 3-step design guideline in Al-Mg dissimilar welding through addition of an interlayer and presents a case study of using pure Ni foil as a proof of concept. The design guideline has shown to be an effective means to predict and prevent the formation of deleterious intermetallics.

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.

In the era of personalized medicine, three-dimensional (3D) printing is becoming an attractive process to manufacture bespoke medical devices for individual patients. However, 3D printing is in its initial stages of development and caution must be exercised before placing devices inside the body prior to exhaustive testing. This paper explores the current knowledge of 3D printing of materials that can be used inside and external to the body for the purposes of enhancing the quality of life. The paper explains the types of materials used for medical devices and their associated benefits. The paper then explains how advances in the laser sintering of medical materials are starting to benefit patients in improving their quality of life and concludes with statements associated with further works that need to be accomplished in order to make 3D printing the first choice process for producing personalized medical devices.

Thin-wall geometrical features are observed in many mechanical components, including micro-components such as blades of a micro-impeller and the walls of a micro-channel. Although several papers have already presented research studies regarding thin-wall development, there is still a lack of information regarding how thin a wall could be produced via micro-milling processes. This paper investigates thin-wall quality in terms of the shape and dimension, the problems faced by micro-milling technology in producing thin-wall features, and the feasibility of producing thin-wall components using a micro-milling process aluminum alloy 1100 (AA110). The minimum wall thickness of 11.71 μm was successfully machined in good condition. The actual deviation of the wall thickness, including the tool dimension incompatibility, was in the range of −4.69 to 3.48 μm. A 16-blade micro-impeller with average blade thickness of 11.96 μm was manufactured. Among the 16 blades, four cloven blades, nine deflected blades, and three blades were in good condition.

Micro electromechanical system (MEMS) shunt capacitive switches behave chiefly as a capacitor at both up and down states. Therefore, input-output matching for these switches is affected by varying the frequency. Although increasing the amount of capacitance at the up state reduces the actuation voltage, it deteriorates the RF parameters. This paper proposes a remedy for this problem in the form of two short high-impedance transmission lines (SHITLs) which are included at both ends of the MEMS switch. The SHITLs are implemented through adoption of a discontinued CPW transmission line. With this implementation, the switch can be modelled as a T circuit, neutralizing a capacitance behavior of MEMS switch at the up state. The paper also proposes an optimised fabrication process to realize a flat and planar bridge for the suggested RF MEMS switch. The measurement recorded by SEM and AFM shows that the proposed method significantly improves the planarity of the membrane. The RF and mechanical parameters of the fabricated switch are evaluated by Vector Network Analyser and Laser Doppler Vibrometer. At the up state, the switch has a return loss less than -20 dB in the entire frequency band (C-K). The isolation at the down state is better than 10 dB for the lower frequencies and increases to values better than 18 dB for the higher frequencies. The measured pull-in voltage is almost 20 V and the mechanical resonance frequency is 164 kHz.

In the electrical discharge machining (EDM) process, the aspects of the cutting performance such as material removal rate (MRR), surface roughness, crater geometry, and tool wear ratio are affected by the energy distribution. The difference in energy distribution during the EDM processing of Al6061, Inconel718, and SKD11 has been rarely studied. However, energy distribution is one of the most important parameters utilized in most existing models of the EDM process. In this paper, the energy distribution that occurs while processing these three materials is investigated by an experimental study under different EDM parameters, including current and pulse duration. Then, the relationship between the energy distribution and the specific discharge energy (SDE) is investigated. The results demonstrate that the discharge energy transferred to the above three kind of workpiece is small, and the fraction of energy distributed into the workpiece varies with discharge current and pulse duration form 7.998 to 12.005%, 2.879 to 3.485% and 2.976 to 3.716% for Al6061, Inconel718, and SKD11, respectively. These findings are consistent with previous studies. In addition, the optimization of the process parameters is investigated for these three materials, considering the MRR and the discharge energy efficiency simultaneously. This findings presented by this paper may be further used in existing thermal-physical models to improve the technological performance of such models.

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.

This paper aims to investigate the influence of defect morphology, defect size, and SDAS on the fatigue behavior of A356-T6 aluminum alloy. A 3D finite element analysis for specimens containing different pore morphologies—(i) spherical pore, (ii) elliptical pore, and (iii) complex pore—was implemented. The Chaboche kinematic hardening model embedded in Abaqus is used to characterize the material response during cyclic loading. Kitagawa diagrams for defective A356-T6 are simulated using the defect stress gradient (DSG) approach. A good agreement is found between experimental and numerical results for predicting fatigue limit in the case of spherical defects. The impact of defect morphology on the fatigue resistance is clearly demonstrated. This paper shows that aluminum fatigue resistance is strongly dependent on the defect size, SDAS, and the defect morphology. Therefore, a mathematical model that takes into account the impact of these three parameters is developed using response surface (RS) approach to predict fatigue limit of porous aluminum alloy. Moreover, the effects of defect morphology, defect size, and SDAS on fatigue response and their interactions under fully reserved tensile loading are investigated.

Roll forming has been used traditionally in the construction and housing industry for the production of longitudinal components but is now increasingly applied in the automotive industry for the manufacture of structural and crash components from ultra high-strength steel (UHSS); the incremental nature of this process allows these hard-to-form materials to be shaped with higher efficiency and less shape defects than observed in common sheet forming processes such as stamping. Tight dimensional tolerances are imposed on automotive components, and this can lead to problems when roll forming UHSS where the high material strength results in shape defect and forming problems. Recent work has therefore increasingly focused on developing process monitoring and control routines for roll forming to improve process robustness and part quality. In roll forming, the longitudinal edge strain is considered to be related to product defects such as bow, twist and end flare. Process and part shape parameters have been shown to significantly influence peak longitudinal edge strain, and the link between process and product parameters, longitudinal edge strain and shape defects needs to be understood for the roll forming of UHSS if routines for process monitoring and control are to be established. Previous studies were mainly focused on traditional roll forming materials used for building products and the like. In this paper, the effect of process and part shape parameters on the peak longitudinal edge strain, longitudinal bow and springback is experimentally and statistically investigated for three different advanced high-strength steel (AHSS) and UHSS commonly used in automotive manufacturing. The results show that there are significant differences in behaviour when forming UHSS and that forming trends differ from those reported for softer steel grades. The experimental data presented in this paper should contribute to the further development of advanced process monitoring and part shape quality control routines in the roll forming AHSS and UHSS.

External magnetic field (EMF) has a strong effect on the welding arc shape, droplet transfer, weld forming, microstructure, and properties of joint metal. This paper defines the types of external magnetic field and reviews the development of magnetically controlled arc welding process, particularly, the effect of external magnetic field parameters on the welding process. It is found that the welding productivity, the weld formation, the ductility, and toughness of welded metal can be improved; and the welding residual stresses, the chemical inhomogeneity, and the welding defects can be reduced. Finally, the development trend is discussed in the later sections of the paper.

This work discusses the Bayesian parameter inference method for a mechanistic force model for machining. Bayesian inference methods have gained popularity recently owing to their intuitiveness and ease with which empirical knowledge may be combined with experimental data considering the uncertainty. The first part of the paper discusses Bayesian parameter inference and Markov Chain Monte Carlo (MCMC) methods. MCMC method effectiveness has been further analyzed by (1) changing the number of particles in MCMC estimation and (2) changing the MCMC move step size. The second part of the paper discusses two example applications as nonlinear mechanistic force model coefficient identification. The Bayesian inference scheme performs prediction of the cutting force coefficients from the training data. Using these coefficients and input parameters to the model, the cutting force is predicted. This prediction is validated using experimental data, and it is demonstrated that with very few parameter updates the predicted force converges with the measured cutting force. The paper is concluded with the discussion of future work.

The materials and manufacturing processes are evolving very rapidly subject to today’s high performance, shorter lead times, and high part complexity needs. With over 80,000 materials, various manufacturing technologies (additive and traditional), diverse streams of application (aerospace, motor vehicles, health care, etc.), and high cost incurred due to manufacturability of the part, it has become essential to choose the right compromise of technology resource in early stages of design considering the Design for Manufacturing (DFM)/Design for Additive Manufacturing (DFAM) guidelines. The concerned literature to date focuses on manufacturing technology selection by being either part specific or application specific. As multiple criteria are involved for decision making, this paper provides a thorough review on the following questions: (1) What are the common design criteria used in literature for additive and traditional manufacturing technologies with respect to product-process integration? (2) What is the literature contribution for material and manufacturing process selection strategies with special focus on comparison of additive and traditional manufacturing technologies? The paper attempts to provide as a result a basic generic methodology for resource selection (RS) which will not only take into account all of the areas of application, DFM/DFAM guidelines, and three design criteria (function, cost, and environment), but will also discuss avenues for collaborative product development. A complex industrial case study is also presented to test the proposed methodology.

These days, miniaturized products have a lot of applications in biotechnology, information technology, environmental and medical industries, electric devices, miniaturized machines, and so on. Micro-electrical discharge machining (micro-EDM) is one the most efficient technologies among the nonconventional machining technologies for producing micro-components. Micro-EDM is able to machine tough die materials which cannot be machined by micro-milling. The micro-EDM method has the capability to machine electrical conductive materials with various hardness, strength, and temperature-resistant and complex shapes with accurate dimensions and fine surface roughness. Moreover, it is widely used to produce micro-scale components and structures such as micro-mold, micro-die, micro-probes, micro-tools, fuel nozzles, photo-masks, thin sheet materials, and complex 3D shapes with high accuracy. This paper presents a state-of-the-art review of micro-EDM process as well as the various kinds of micro-electrode and workpiece materials and dielectrics that have been used by previous researchers. In addition, this paper extensively describes and compares various micro-electrode and micro-tool fabrication processes in order to produce precise micro-products. This work is very helpful for the micro-EDM manufacturers and users to select suitable material, dielectric and fabrication processes in researches, and industry applications.

Flexible pocket-structures are widely used in engineering practice, especially in the aerospace industry. This paper presents a dynamic model which is suitable for predicting the chatter vibration during machining the thin bottom of flexible pocket-structures. The model is simplified as a three-degree-of-freedom (DOF) system, in which the cutter is considered to have two orthogonal degrees of freedom in its radial direction while the flexible component is considered to have one degree of freedom in the axial direction of the cutter. Modal analysis is implemented to obtain the system parameters. Thereafter, a semi-discretization method is used to plot the stability lobes. From the stability lobe, it is very easy to predict the appearance of the chatter vibration and thus decide the proper cutting conditions during milling the thin bottom of flexible pocket-structures. At the end of the paper, the developed model is demonstrated by a number of cutting experiments.

The improvements of surface quality and dimensional accuracy are critical for Wire and Arc Additive Manufacturing (WAAM). This paper highlights a multi-objective optimization process for Bainite steel additive manufacturing. The welding design matrix for conducting the experiments was made by using the Box-Behnken design of response surface methodology (RSM). The input process parameters were varied at three levels which result in 46 experimental trials. The responses were measured during or after conducting the experiments. A second-order response surface model was developed and then multi-objective optimization was performed to obtain the desired surface appearance. The acceleration and staggered deposition processes were used to decrease the head dimension of single weld bead. The results show that the optimized sample surface appearance is smooth which has little spatters and no visible defects. Compared with the traditional processes which rely on overlapping rate adjustment but weaken the single weld bead morphology optimization, the process of this paper has comprehensive considerations of droplet transfer, heat input, and shaping coefficient. It enables the capacity of fabricating metal parts with high accuracy and lays a good foundation for Bainite steel additive manufacturing.

To increase the performance of discharge ablation, a sintered diamond (SD) electrode is used as a machining electrode to achieve machining combined with high-efficiency ablation and mechanical grinding in this paper. A new constant pressure servo control method based on the SD electrode is proposed by gathering the mechanical grinding force during machining. Using Cr12 as the workpiece, we conducted five groups of comparative experiments in this study. They are mechanical grinding with SD electrode, inner jetted dielectric electrical discharge machining (EDM) with copper electrode, aerosol ablation with copper electrode, aerosol ablation based on voltage control with SD electrode, and aerosol ablation based on constant pressure with SD electrode. In this paper, we studied the mechanism, machining efficiency, and machining quality. The method based on constant pressure servo control with SD electrode can effectively grind the oxide layer and ensure the sustainability of machining. From these five groups of experiments, we concluded that the method based on constant pressure servo control can be efficient and stable during machining. The machining efficiency was 6.3 times that of the inner jetted dielectric EDM. The machining efficiency based on constant pressure servo control increased by 88% compared with that of the aerosol ablation with copper electrode and it increased by 62% compared with that of the aerosol ablation based on voltage with SD electrode which showed that the grinding effect of diamond based on constant pressure servo control was obvious. Compared with the other four methods, the method based on constant pressure servo control can obtain the best surface quality.

The paper discusses the problems of forming parts such as stepped shafts by cross wedge rolling (CWR). In industrial practice, this rolling process is performed at stages, i.e., in several passes, when large cross-sectional reductions are involved. The same can also be done using a different design of this forming process, namely, multi-wedge cross rolling (MWCR), in which the workpiece is simultaneously formed by several pairs of tools (wedges). This paper compares the above two methods with respect to forming a drive shaft. Wedge tools used in both forming processes are described, and the numerical results of the simulations performed to verify the adopted solutions are reported. The results demonstrate that the MWCR method offers more advantages than the classical CWR technique. Consequently, MWCR is then verified in experimental tests. The experimental results confirm that parts such as stepped shafts can be formed by the MWCR method.

During the machining process of large-scaled and thin-walled parts such as aircraft structural parts, the deformation is a relatively common phenomenon which seriously affects the machining quality of the parts and may lead the parts to be scrapped. In this paper, interim machining states of workpiece are considered in addition to final machining states for deformation control so as to improve the machining quality and part correct rate. It is very important for large-scaled and thin-walled parts to consider the interim machining states, as considerable deformation has always occurred in interim machining states. The difficulties of deformation control of interim machining states contain two aspects: (1) how to assess whether interim machining states can satisfy process requirements for further machining and (2) how to adjust the tool paths adaptively for further machining so as to make the final machining states correct. In order to address the above difficulties, an adaptive machining approach based on in-process inspection of interim machining states for large-scaled and thin-walled complex aircraft structural parts is proposed in this paper. The actual interim machining state is obtained based on in-process inspection of machining states during the machining process; the essential idea of this paper is that the final machining state of the workpiece can be guaranteed by adjusting the tool path based on the inspection of interim machining states, which is realized by coordinating the dimensional tolerance and geometrical tolerance. In order to realize the new idea, the criterion for determining whether the interim machining state is suitable or not for further machining and the concept of expected final state are introduced. Eventually, the large-scaled and thin-walled complex aircraft structural parts can be machined adaptively according to process requirements. A typical large-scaled and thin-walled complex aircraft structural part is used as a case to validate the proposed approach. The results show that the dimensional error is 0.10 mm and the profile error is 0.06 mm, which can meet the machining requirement of large-scaled and thin-walled complex parts.

A passive vision system based on image processing technology for automatic welding system is researched in order to enhance the efficiency for the tube-to-tubesheet welding of heat exchanger in this paper. To this end, the detection and extraction methods of the welding path are studied in tubesheet welding through the passive vision system. A calibration procedure is proposed for the vision system, and the positional relationships between the cameras and the robot are obtained. The Hough transform is used to extract the tubes’ position roughly through a camera that is fixed above the workpiece, and another camera is used to extract the feature of the tubes accurately one by one. A multiple iteration method of least squares is also proposed in this paper to remove the background noises. The edge of the inside tube circle is accurately extracted, and the welding path is obtained. Validation experiments are finally conducted to confirm the reliability and accuracy of this method.

This paper proposes an integrated method for process parameters optimization and objective analysis in the fiber laser keyhole welding based on Taguchi and finite element method (FEA). The Taguchi-FEA framework is established and applied for the objective of increasing the ratio of weld penetration to width (P/W) in the welded joints. Numerical simulations are incorporated into identifying the desired responses and the process parameters effects on the objective without consuming time, materials, and labor effort. To validate the effectiveness of the integration methodology, the fiber laser keyhole welding of the hot-dip galvanized dual phase sheet (GA-DP590) has been carried out in this paper. The three process parameters, laser power (LP), welding speed (WS), and focal position (FP), have been taken into consideration during the optimization process. The optimized results are confirmed, and trend of the objective variation near the optimal process parameters is analyzed by the numerical simulation. The corresponding microstructure, phase transformation and microhardness variation of the optimized weld bead are also calculated. The results demonstrate that the proposed method is reliable and effective for improving the quality of welded joints in the practical production level.

An undesirable factor that affects the dimensional precision and final shape of metallic parts produced in cold forming processes is springback phenomenon. In this paper, an analytical model is introduced to predict springback in U-shaped bending process of DP780 dual-phase steel sheet. It is based on the Hill48 yielding criterion and plane strain condition. In this model, the effect of forming history, the sheet thinning, and the motion of the neutral surface on the springback of U-shaped bending process is taken into account. The anisotropic nonlinear kinematic hardening model (ANK) is used to consider the impact of complex deformation, including stretching, bending and reverse bending. This model is able to investigate the Bauschinger effect, transient behavior and permanent softening. This model is used for the Numisheet2011 benchmark U-shaped bending problem. The effect of the sheet holder force, the coefficient of friction, thickness, material anisotropy, and hardening parameters on the sheet springback is studied. It can be seen that analytical model which presented in this paper has desirable accuracy in the springback prediction, and results are close to experimental data.

A cutting model is presented in the paper for multi-wire saw silicon rods with consolidated abrasive diamonds. The stress of single diamond particles is analyzed. Besides, the calculation formula of normal and tangential cutting force is found out by formula derivation and calculation. The paper uses ANSYS 15.0 to make finite element analysis for multi-wire saw silicon rods with consolidated abrasive diamonds by loading different process parameters, including wire-line speed and feeding force. Meanwhile, according to removing mechanism of brittle materials, when the maximum cutting depth of single abrasive diamond silicon is less than the critical cutting thickness, the cutting way of multi-wire saw silicon rods is plastic removal. Comparing the deformation by finite element analysis with the maximum cutting depth, the error is not more than 15 %. So the cutting model and calculation of cutting force of multi-wire saw silicon rods with consolidated abrasive diamonds are proven to be basically consistent. The results indicate that when the wire-line speed is constant, with the increase of the feeding force, the maximum cutting depth is also increased, and with the feeding force is constant, with the increase of the wire-line speed, the maximum cutting depth increases first and then decreases. Therefore, considering the maximum cutting depth, setting the wire-line speed to 900 m/min and the feed force to 725 N is the best cutting process parameters.

The forging force effect on resistance spot welding field is an ambiguity because it is believed to be just a mechanical force escalation in the classical theory. So far, the mechanically generated forging forces have been observed by many researchers and only the mechanical features have been considered for the investigation. Unfortunately, the journey of this exploration has not been continued after several superficial results were found for the past few decades. In real, there are still some cohesive existences of forces that have not been properly expounded yet, although it has frequently been noticed by other researchers. In this paper, the electrically generated forging force is introduced and also discussed for better realization. Several case studies for the fluctuation of electrode forces in terms of forces, vibrations, and acoustic emissions are primarily referred to support the classical concerns. With the inconstant and inaccurate force exertion, a computational analysis is derived as to distinguish the electrically generated forging forces with respect to the variation of process variables. Four types of metals are welded with two different electrode actuations and the corresponding force profiles are carefully measured. Only the stainless steel weld-based signals are presented in this paper to simplify the analysis because other materials too have similar phenomena. Experimental results show that the electrically generated forging forces are directly proportional to welding current, welding time, and compressing force but inversely proportional to electrode tips, provided the computation lies within welding lobe limits.