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Nowadays, with the increasing demands for quality and precision in microelectronic packaging, the study and prediction of droplet parameters before packaging have become increasingly important. This paper aims to derive a predictive formula for droplet volume dispensing to improve packaging quality, optimize process parameters, reduce resource waste, enhance process control, and enhance product quality and reliability. Based on the needle transfer method for ultra-microdroplet dispensing, a droplet dispensing device that meets packaging requirements is established, and precise control of droplet volume is achieved by changing the factors that affect droplet formation. The droplets obtained from experiments are analyzed using pixel extraction, and a numerical fitting method is employed to establish a droplet volume model. It is found that the pixel method is a practical approach for determining droplet volume, with an average deviation of approximately 1.85%. By conducting droplet dispensing experiments with varying initial distances, the smallest droplet volume achieved is 24.33 pL, and it is concluded that larger initial distances result in smaller droplet volumes and reduced droplet contact area. Based on the droplet dispensing experimental data obtained by varying the initial distance, mathematical predictive models for droplet volume and droplet contact area are derived. The results show that the average difference rate between predicted and actual volumes is 0.51%, and the average difference rate between predicted and actual contact areas is 0.56%. [ABSTRACT FROM AUTHOR]

With the rapid development of precision micro-manufacturing technology, the connection and assembly processes of precision micro-devices have placed higher demands on the volume and precision of micro-dispensing technology. In the dispensing process, the adhesive dispensing volume is crucial to the bonding quality. In this paper, based on the analysis of the composition of critical contact force and the mechanism of action, a method was proposed to control the ultra-micro-adhesive dispensing volume at pL level. Firstly, a mathematical model describing the change of droplet size and critical contact force during the extrusion of adhesive was established, which provided a theoretical basis for analyzing the mapping relationship between contact force and adhesive dispensing volume. Then, the mathematical models describing the droplet initial volume, dispensing volume, and transfer ratio were derived. Based on this, a mechanism and method to control the volume of dispensing to the substrate by contact force control to trigger the liquid bridge pull-off action was developed. The critical contact force was detected in real time to determine the changing state of the process of adhesive contacting the substrate, and used as the basis for triggering the stretching stage of the liquid bridge, and then achieved the prediction and control of the adhesive dispensing volume. In this paper, a series of experimental studies were conducted on the method of controlling the adhesive dispensing volume through contact force by embedding a micro-force sensor with high resolution into the dispensing system. The experiments were conducted with the critical contact force in the range of 0.5–4.5 mN. The results showed that the increase of the critical contact force was approximately linear with the increase of the adhesive dispensing volume. The deviation rate of the dispensing volume under the same critical contact force was less than 1.7%, and the average deviation rate of the overall adhesive dispensing volume was about 0.6%, so it was basically possible to precisely control the adhesive dispensing volume at the pL level by changing the contact force. This study revealed the composition and variation mechanism of contact force, and the proposed method for controlling the adhesive dispensing volume have significant value and potential in the micro-assembly of viscous ultra-microfluids and other applications. [ABSTRACT FROM AUTHOR]

Due to gravity, a change in the welding position will significantly affect the flow of the molten pool, thus affecting the weld bead shape. An all-position welding process of low-power pulsed laser-MAG (metal active gas) hybrid welding was proposed to improve the welding efficiency and quality of all-position welding. This paper used the response surface method (RSM) to develop the weld bead geometry mathematical model. The analysis of variance confirmed the significance and accuracy of the model. The results show that the models can accurately predict the weld geometry, percentage errors for any models are less than 8.1%. Then, the effects of welding parameters and welding position on weld width, weld reinforcement, and weld penetration were analyzed. Finally, the optimal welding parameters at five positions of 0°, 45°, 90°, 135°, and 180° were obtained by numerical optimization with RSM. The study results can provide a reference for applying laser-MAG hybrid welding in all-position welding. [ABSTRACT FROM AUTHOR]

Electromagnetic clinching (EMC) is a high-speed connection technology that combines electromagnetic forming and mechanical clinching. The die structure significantly affects the mechanical properties of the joint. In this paper, an optimal method based on response surface methodology (RSM) and particle swarm optimization algorithm (PSO) is proposed to improve the mechanical properties of joints clinched by EMC. The mathematical models of die geometrical parameters and cross-sectional parameters of the joint are obtained by RSM and numerical simulation. Then, the die structure is optimized through PSO. Finally, the experiments are carried out using the optimized and standardized die. The results show small errors between the simulation and the experiment. The joint strength using a standardized die is 878 N, and energy absorption is 0.758 J. The joint strength using the optimized die is 1322 N, and energy absorption is 1.335 J. Compared with the standardized die, the joint strength and energy absorption of parts obtained by the optimized die are increased by 50.5% and 76.1%, respectively. [ABSTRACT FROM AUTHOR]

The whirl-machining process is a precise, efficient, and promising machine process for manufacturing workpieces over the milling process. At the same time, the roller-gear cam has advantages over the other cam-follower system. However, the whirl-machining process has not been applied to manufacture the roller-gear cam. Therefore, this paper proposes a novel method for roller-gear cam manufacturing using a whirl-machining process. Mathematical modeling is described for generating the roller-gear cam, roller, and whirl-milling tool surface. A novel CNC machine and its coordinate system are proposed. Cutting simulations for obtaining the surface topologies and normal deviations are conducted. Globoidal cam with different cylindrical rollers, globoidal cam with a conical roller, and cylindrical cam with a conical roller are taken as case studies, and results are discussed. A virtual cutting simulation was conducted using VERICUT. Some machining examples are shown to verify the benefits of the proposed method in roller-gear cam manufacturing. [ABSTRACT FROM AUTHOR]

Free-form milling is a flexible gear machining method that allows the use of general disc cutters to machine various gear types on a 5-axis machine tool. This paper proposes a two-dimensional simulation method for free-form milling of cylindrical gears with disc cutters. A mathematical model for free-form milling of cylindrical gears with disc cutters is constructed. By analyzing the spatial positional relationships between the cutter and the workpiece, the instantaneous contact line is derived and projected onto the gear end face; then, the intersection of the projected curves is used to obtain the final profile. This calculation method enables rapid simulation of the actual cutting conditions on the gear end face, which helps determine the machining interference and analyze the tooth profile accuracy during the gear machining process. The method proposed in this paper can also be used to analyze the sensitivity of geometric position errors of the machine tool axes. [ABSTRACT FROM AUTHOR]

Ultrasonic power plays an important role in ultrasonic surface rolling, and the maximum contact stress and springback generated by ultrasonic power during ultrasonic rolling also affect the surface quality of mechanical materials. In order to study the effect of different ultrasonic powers on the maximum contact stress and springback during the ultrasonic rolling process, in this paper, based on the elastic–plastic theory, a mathematical model for predicting the maximum contact stress and springback is proposed. In order to verify the mathematical model, the ultrasonic surface rolling experiment was carried out with 20 steel as the experimental sample. Through the analytical derivation of the mathematical model, and study other characteristic parameters of the model, such as rolling depth, Mises. And the ultrasonic surface rolling process is simulated numerically by ABAQUS. The results show that the mathematical model can effectively predict the maximum contact stress, rolling depth, Mises, and springback, and the average deviation is 10%. With the increase of ultrasonic power, Mises, pressure, and springback gradually decrease, and the rolling depth increases. [ABSTRACT FROM AUTHOR]

This paper proposes a topology modification method of generating gear grinding based on multi-axis linkage parameter optimization. In order to improve the accuracy of tooth flank modification in generating gear grinding and to reduce the transmission error of modified gear pair, a multi-objective optimization genetic algorithm is adopted to adjust machine movement. Firstly, according to the position and motion relationship among diamond wheel, worm wheel, and workpiece gear, the mathematical models of worm wheel dressing and generating gear grinding are established. The linkage relationships between motion axes are redefined to achieve topology modification. The radial feed F X 1 , tangential feed F Y 1 of worm wheel, and gear rotational angle φ g are defined as the fourth-order polynomial function of axial feed F Z 1 . Secondly, the transmission error model of modified gear is developed. And the polynomial coefficients of each axis are optimized with the objective of minimizing total tooth flank deviation and transmission error. Finally, the effectiveness of this method is verified by three numerical examples with different parameter groups. In addition, the diamond wheel and worm wheel used in the study are standard profile, which saves the cost of gear machining and improves the efficiency of production cycle. The research results could provide a theoretical reference for the improvement of generating gear grinding process. [ABSTRACT FROM AUTHOR]

Currently, the quality check of bike frame still heavily relies on human operation. In practice, an entire checking process usually takes more than 30 min to complete. To overcome this dilemma, this paper aims to develop a fast high-precision measurement system using robotic arm based on 3D geometry mathematical model. Instead of four points needed to find coefficients of a space sphere, only three investigation points are required to achieve the sphere axis coordinates for measurement. The personal computer (PC) works as a control core, which to perform the mathematical model and control robotic arm movement. The robotic arm combined with contact sensor (probe) is used to move to the desired inspection points in shaft length, internal diameter, verticality, and parallelism following up the designated path planning route. The experimental results confirm that the proposed system can accurately reach the measurement outcomes. The entire checking cycle can be completed in 3 min at the range of 0.15 mm error, effectively reducing the process time with a high precision. [ABSTRACT FROM AUTHOR]

This paper aims to study tasks' allocation problem in a single-station collaborative robot assembly system 4.0. Two products with identical demands are run in a system simultaneously in mixed mode to reduce the idle time and improve the system utilization. The idle time occurs due to balancing difficulties and particularly in this case restrictions in the task vs. robot-worker feasibility matrix. It is not allowed for the resources to assemble a same product simultaneously to avoid any direct contact between resources. Thus, the products are swapped between resources as needed to complete the assembly tasks. Two approaches, a novel mathematical model and the shortest processing time (SPT) rule, are propounded in this study to reduce the cycle and idle times and enhance the production rate of an assembly system. The two proposed methods rely on dividing the timeline of a station into unknown stages with unknown lengths. The performance of the proposed mathematical model and SPT rule are evaluated by two performance measures: the total number of stations and the % average station utilization. The obtained results are compared to the results of the modified COMSOAL heuristic. The findings revealed that the novel mathematical model dominated results. It guaranteed minimizing the cycle time and maximizing the production rate compared to the SPT rule and modified COMSOAL heuristic. However, many companies value a 1-s reduction in cycle time as valuable. This directly relates to the reduction of direct resources costs and the total number of stations. [ABSTRACT FROM AUTHOR]

Power skiving provides an effective solution and considerable machining efficiency for the machining of internal gears. The tool profile design and the reusability after resharpening is crucial in gear manufacturing. In this paper, a novel method of tool profile correction based on the inverse error-complement of involute profile is proposed. Firstly, the mathematical model of involute cutter with rake angle and relief angle is established. The profile error relative to the target gear is calculated by the mathematical model. Then, the distribution of the gear profile errors is fitted by a fifth-order multinomial. The fitted multinomial function is attached to the cutter profile. The maximum theoretical error of the target gear profile is in 10e-7 mm order of magnitude through the calculation of fewer iterations. Finally, the distribution of the multinomial coefficients along the resharpening direction is obtained by linear programming. The result shows that the cutter designed by the proposed method possess almost negligible error to the gear profile and good repeatability of resharpening. [ABSTRACT FROM AUTHOR]

Rotary-laser automatic theodolite (R-LAT) system is a distributed large-scale metrology system, which provides parallel measurement in scalable measurement room without obvious precision loss. Each of R-LAT emits two nonparallel laser planes to scan the measurement space via evenly rotations, while the photoelectric sensors receive these laser plane signals and perform the coordinate calculation based on triangulation. The accurate geometric parameters of the two laser planes play a crucial role in maintaining the measurement precision of R-LAT system. In practice, the geometry of the two laser planes, which is termed as intrinsic parameters, is usually unknown after assembled. Therefore, how to figure out the accurate intrinsic parameter of each R-LAT is a fundamental question for the application of R-LAT system. This paper proposed an easily operated intrinsic parameter calibration method for R-LAT system by adopting coordinate measurement machine. The mathematical model of laser planes and the observing equation group of R-LAT are established. Then, the intrinsic calibration is formulated as a nonlinear least-square problem that minimizes the sum of deviations of target points and laser planes, and the ascertainment of its initial guess is introduced. At last, experience is performed to verify the effectiveness of this method, and simulations are carried out to investigate the influence of the target point configuration in the accuracy of intrinsic parameters. [ABSTRACT FROM AUTHOR]

The die undergoing severe loads induces inevitable wear in the pressure forming process, and the wear of die arouses obsessions about the die's service lifetime. In order to predict the wear and lifetime for a pair of rollers in net-shape blade rolling process, this paper quantified the distributions and evolutions of the local wear over roller cavities based on the local contact load responses and predicted the lifetime which related to wear by a mathematical model. Firstly, the net-shape blade rolling process and the local contact load responses were summarized. Then, an improved wear model was provided based on the Archard formula, and the impact factors of the model were standardized by a regression analysis experiment. The transient wear distributions and evolutions over the roller cavities were enumerated, and the wear distribution for one rolling cycle was calculated based on wear accumulation effect. Finally, a lifetime prediction model was proposed to predict the service lifetime of the rollers according to the wear accumulation effect, and an experimental verification was carried out to validate the model. The results show that the wear model and lifetime prediction model can be used for investigating the wear and lifetime of the roller cavities for the net-shape blade rolling process. [ABSTRACT FROM AUTHOR]

In this paper, a six-degree-of-freedom (6DOF) error measurement system based on geometric optics is proposed for linear stages. This measurement system uses an additional linear stage that drags the sensor onto the stage so that the light spot projected on the sensor moves back and forth with the moving stage. This method achieves long-range 6DOF measurement. Compared with commercial laser interferometers, the proposed measurement system has the advantages of a lower cost, a simpler structure, and the capability of measuring 6DOF errors simultaneously. Zemax software was used to simulate the relationships between the 6DOF errors and the values of position-sensitive detectors. MATLAB software was then used to construct the forward and inverse mathematical kinematic models of the optical paths and simplify the models through curve fitting. Finally, to address installation and manufacturing errors, a reverse kinematic mathematical solution was obtained through the use of a six-axis Stewart platform. The proposed measurement system was experimentally implemented on a commercial linear stage to measure the 6DOF errors and verified against results obtained with a commercial interferometer and electronic level. [ABSTRACT FROM AUTHOR]

Due to the increase in the difficulty and diversity of tasks performed by robots, robot "hand-eye" collaborative operation has attracted widespread attention. This technology is widely used in aerospace, medical, automotive, and industrial fields. Recently, hand-eye calibration technology is developing towards high precision and high intelligence. However, it has much work to be done in terms of identifying robot and camera parameters. This article introduces in detail the methods and theories involved in hand-eye calibration. According to the structure of the algorithm and the type of the optimization method, this paper summarizes the hand-eye calibration method into four steps: camera pose, mechanical claw pose, mathematical model, and error metrics. The well-known open problems about hand-eye calibration are finally stated, and some new research interests are also pointed out. The results of this review are useful for robot technicians to choose the correct parameter identification method and for researchers to determine further research areas. [ABSTRACT FROM AUTHOR]

In order to further improve the control accuracy of thickness, crown and tension in hot strip finishing mill, a multivariable optimizing strategy based on inverse linear quadratic (ILQ) control theory is proposed in this paper. First, the state space model of hot rolling process is established based on the basic dynamic mathematical model of rolling process and measured data collected from a certain plant. Then, the new ILQ control strategy is designed for the thickness, crown and tension control system in the complex rolling process, and the response performance and anti-interference performance of ILQ controller and PI controller were tested. The results show that the proposed ILQ control strategy has excellent control performance with the maximal overshoot 24.13% smaller than that of PI controller when strip crown, thickness and tension step signals are added simultaneously, and the ILQ control strategy has certain guiding significance for the actual production of hot rolling. [ABSTRACT FROM AUTHOR]

The paper presents results of CFD parametric study of centrifugal compressor stage vane diffusers in the Ansys CFX. The results obtained will be used to build a mathematical model of vane diffuser in optimization design system. Objects of research are vane diffusers with external relative diameter (relative to the diameter of the impeller) equal to 1.5; vane inlet angle of 20°; relative vane heights of 0.025, 0.034, 0.045, 0.06, and 0.08; and vane profile curvature angles of 10, 15, and 20 °. The characteristics of polytrophic efficiency, loss coefficient, recovery coefficient, ratio of inlet and outlet velocities, and flow deviation angle versus incidence angle are set. The analysis of the flow structure in the vane diffuser channels is presented. Unlike with a straight vane cascade, the deviation angle in the circular rows of vane diffusers tends to increase with increasing row density. This may be due to the complex nature of the interaction of the active part of the flow with separation zones. In rows with almost straight vanes at a lower density, the separation zone on the pressure side decreases and even shifts to the very end of the suction side. [ABSTRACT FROM AUTHOR]

Kitting – meaning to supply assembly with components in presorted kits – is widely seen as beneficial for assembly quality and efficiency when there is a multitude of component variants. However, the process by which kits are prepared – the kit preparation – is labour-intensive, and kit errors are problematic at assembly processes. The use of robotics to support kit preparation has received some attention by researchers, but literature is lacking with respect to how collaborative robots – cobots – can support kit preparation activities. The purpose of this paper is to identify the potential of a cobot to support time-efficient batch preparation of kits. To address the purpose, the paper presents a mathematical model for estimation of the cycle time associated with cobot-supported kit preparation. The model is applied in a numerical example with experimental data from laboratory experiments, and cobot-supported kit preparation is compared with manual kit preparation. The findings suggest that cobot-supported kit preparation is beneficial with diverse kits and smaller components quantities per SKU (Stock Keeping Unit) and provides less variability of the outcome, when compared to manual kit preparation. The paper reveals several insights about cobot-supported kit preparation that can be valuable for both academics and practitioners. The model developed can be used by practitioners to assess the potential of cobots to support kit-batch preparation in association with assembly, spare parts, repair and maintenance, or business to business industry. [ABSTRACT FROM AUTHOR]

Due to the complicated deformation of the billet in roll forming process and the lack of the theoretical understanding, there are still no unified methods to design and optimize roll profiles. Theoretical analysis of the deformation in roll forming process based on mathematical method is efficient and necessary. A qualified roll profile optimization method should be based on the accurate calculation of the spatial configuration of the billet. However, the existing models for calculating the spatial configuration of the billet in roll forming process cannot calculate the springback of the billet. In this paper, according to the mathematical model established by the author for calculating the spatial configuration of the billet, a roll profile optimization method for high-strength V channel roll forming process was proposed by taking the maximum edge membrane longitudinal strain as constraint conditions. After optimization, the number of roll stands required for final V channels was reduced from 8 to 5. Through analyzing and comparing the deformation of the billet in simulation results of bending and roll forming process, it is found that bending tests can also be used to verify the feasibility of the roll profile optimization method proposed in this paper. The bending tests were carried out using the original and optimized process parameters, respectively. The results show that the shape of the V channel obtained by the optimized process parameters is much closer to that of the designed V channel. [ABSTRACT FROM AUTHOR]

Product design and development (PDD) involves various types of tradeoffs, for which multi-objective optimization has been a prevailing approach. Complex PDD optimization problems are associated with multidisciplinary decision makers and may encompass different levels of the design decision hierarchy. A practical concern is that many conflicting goals with diverse decision variables have to compete to arrive at equilibrium solutions, entailing a paradigm of leader-follower joint optimization (LFJO). In line with a typical decision chain of engineering optimization, comprising such consecutive stages as problem formation, optimization modeling, model solution, and optimization evaluation, this paper provides a state-of-the-art review of the LFJO problems that are widely observed in the PDD literature, along with a survey of LFJO mathematical modeling methods. Also reviewed is the status quo of bilevel programming (BLP) models for LFJO problems with focus on their engineering implications for PDD. The paper also reviews the prevailing algorithms for solving BLP mathematical models, as well as common practice of LFJO model evaluation in the PDD literature. Finally, the critical issues of LFJO problems and outlook for further research are discussed. [ABSTRACT FROM AUTHOR]

The sculptured surface has been widely used in aerospace and machinery manufacturing industries. CNC machining of sculptured surfaces is an important research area, and computation efficiency improvements are considered critical topics in this field. This paper presents a highly efficient method to generate smooth tool paths by establishing a mathematical model to describe the relationship between the relative curvature of sculptured surface and the machining strip width in five-axis machining. The method is improved from the middle-point error control method (MPECM) and the feasible tool position surface method (FTPSM), by changing the objective from the complete optimization for each drive point to the drive points' interpolation. The drive point with the narrowest machining strip width and some sample points is selected to interpolate the remaining points. Both theoretical analysis and test examples show the correctness of the proposed method. Under the same condition, compared with the MPECM and the FTPSM, the computing time of the new method decreases to 10% at least. Besides, the fluctuation of the tool path is reduced. The machining examples verified the superiority of the proposed method. [ABSTRACT FROM AUTHOR]

Variation propagation modeling of multistage machining processes enables variation reduction by making an accurate prediction on the quality of a part. Part quality prediction through variation propagation models, such as stream of variation and Jacobian-Torsor models, often focus on a 3-2-1 fixture layout and do not consider form errors. This paper derives a mathematical model based on dual quaternion for part quality prediction given parts with form errors and fixtures with N-2-1 (N>3) layout. The method uses techniques of Skin Model Shapes and dual quaternions for a virtual assembling of a part on a fixture, as well as conducting machining and measurement. To validate the method, a part with form errors produced in a two-stationed machining process with a 12-2-1 fixture layout was considered. The prediction made following the proposed method was within 0.4% of the prediction made using a CAD/CAM simulation when form errors were not considered. These results validate the method when form errors are neglected and partially validated when considered. [ABSTRACT FROM AUTHOR]

This paper studies the effects of geometrical errors on the repeatability of positioning of linear axes, based on theoretical modeling and an experimental study. Firstly, this paper elaborates on the mechanism of repeatability of positioning that is affected by motion pose of moving part. Secondly, a mathematical model is proposed between the geometrical error and motion pose of the moving part, based on point-by-point recursion. Subsequently, the influence of geometrical errors on the repeatability of positioning of the linear axes is obtained based on GA (genetic algorithm). Finally, the effectiveness of the proposed model is validated experimentally, and an assembly method for improving the repeatability of positioning is proposed. The method can provide designers and/or field engineers with informative guidelines for improving the repeatability of positioning in the design, manufacturing, and assembly processes. [ABSTRACT FROM AUTHOR]

Ultrasonic straight-blade tool is one type of effective tool for processing Nomex composites. As a system part, the ultrasonic tool, directly contacting the workpiece and providing the vibration, is an important acoustic element alongside the cutter. And the resonant frequency of ultrasonic processing systems, a key parameter of the vibration performance, is greatly influenced by the straight-blade tool changes when connected to the ultrasonic system. In the present paper, a mathematical model for calculating the resonant frequency was established for the ultrasonic straight-blade tools with variable cross-sectional areas. The relationship between the parameters of the straight-blade tool and the resonant frequency, as well as between the force and the vibration of the ultrasonic system, were presented and utilized to calculate the system resonant frequency change and the corrected horn value to hold the frequency. To solve the vibration equations, they were refined by fitting a trigonometric function combination. The errors of the vibration equations and the fitting were analyzed, showing the applicable scope of the vibration equations. According to the model and the common ultrasonic straight-blade tool sizes, four tools were manufactured for verification experiments. Results showed that the presented model could be well matched with the actual value. [ABSTRACT FROM AUTHOR]

Optimization of the end milling process is a combinatorial task due to the involvement of a large number of process variables and performance characteristics. Process-specific numerical models or mathematical functions are required for the evaluation of parametric combinations in order to improve the quality of the machined parts and machining time. This problem could be categorized as the offline data-driven optimization problem. For such problems, the surrogate or predictive models are useful, which could be employed to approximate the objective functions for the optimization algorithms. This paper presents a data-driven surrogate-assisted optimizer to model the end mill cutting of aluminum alloy on a desktop milling machine. To facilitate that, material removal rate (MRR), surface roughness (Ra), and cutting forces are considered as the functions of tool diameter, spindle speed, feed rate, and depth of cut. The principal methodology is developed using a Bayesian regularized neural network (surrogate) and a beetle antennae search algorithm (optimizer) to perform the process optimization. The relationships among the process responses are studied using Kohonen's self-organizing map. The proposed methodology is successfully compared with three different optimization techniques and shown to outperform them with improvements of 40.98% for MRR and 10.56% for Ra. The proposed surrogate-assisted optimization method is prompt and efficient in handling the offline machining data. Finally, the validation has been done using the experimental end milling cutting carried out on aluminum alloy to measure the surface roughness, material removal rate, and cutting forces using dynamometer for the optimal cutting parameters on desktop milling center. From the estimated surface roughness value of 0.4651 μm, the optimal cutting parameters have given a maximum material removal rate of 44.027 mm3/s with less amplitude of cutting force on the workpiece. The obtained test results show that more optimal surface quality and material removal can be achieved with the optimal set of parameters. [ABSTRACT FROM AUTHOR]

This paper presents a new decentralized/distributed decision-making (DDM) supply chain planning model. A supply chain is called decentralized when various decisions are made in different companies trying to optimize their own objectives. The proposed approach is applied to plan a wood supply chain network called Puya Wood Company. The supply chain network design problem discussed in this paper is an integrated multi-echelon, multi-product problem considering total costs of purchasing raw materials/returned product, transportation of raw materials, and inventory holding of raw materials. A coordination mechanism is designed to share information between the retailer model and the manufacturer model called centralized planning. The main contributions of this paper are summarized as follows: (1) presenting a decentralized (distributed) approach in order to address the production and distribution problem in supply chain including manufacturer and retailers and (2) proposing a coordination mechanism in order to handle problems related to production and distribution in a two-echelon supply chain network through a decentralized approach. The proposed model is tested using real case study. Sensitivity analysis is accomplished to find the effects of changing the parameter on the results. The proposed coordination mechanism provides high-quality solutions in reasonable number of iterations for the case study. This coordination mechanism can be applied in other supply chains such as natural gas and oil, water resource management, and crisis and disaster planning. [ABSTRACT FROM AUTHOR]

Increasing the cutter size to enhance its stiffness is of great significance for improving the machining efficiency and precision of deep and narrow channel parts. In this paper, the concept of cutter size critical sphere (CSCS) is presented, which is a specified sphere and tangent to several geometric constraints of tool accessible regions. With this concept, the complex multi-constraints of the workpiece can be transformed into several simple but precise geometric conditions to optimize the size and tool orientation of a conical cutter. The conical cutter generated by CSCS can reach a critical state with multi-constraints simultaneously. Firstly, the mathematical principle of the conical cutter generated by a cylindrical cutter is deduced based on the motion envelope theory. Secondly, the concept of CSCS is proposed based on the deduced mathematical principle and the calculation method of the CSCS with the general situation is provided. Thirdly, the CSCS with special situations is discussed and the calculation method is proposed. Fourthly, the mathematical model and solving algorithm for the max-size CSCS is given. The solving algorithm is designed based on the 3D Medial Axis Transformation (3D MAT) theory. Finally, the proposed method is verified by three simulation experiments and a comparison experiment. The results show that the proposed method can efficiently and accurately calculate the max size and tool orientation of the conical cutter simultaneously. The optimized conical cutter can be tangent to the multi-constraints of the workpiece but do no interfer with them. [ABSTRACT FROM AUTHOR]

This paper proposes an approach to the planning and optimization of quality inspections within a multistage manufacturing process based on quality costs and the value added to the production process by inspections. Inspection errors and the resulting costs of repair and scrapping are taken into account. In addition, the capability of the manufacturing process and of the inspection system is included. A mathematical model for calculating quality costs was developed with a focus on its practical application. [ABSTRACT FROM AUTHOR]

The present paper aims to describe the development of a FEM model for the simulation of a die-sinking micro-EDM process. A commercial FEM code specific for the simulation of thermo-mechanical forming processes was used. The developed model was based on the capacity of the code to simulate the removal process or the separation of the material through the mesh element deletion. The electrical discharges were simulated through a proper heat flux and the material melting temperature was set as a trigger for the element deletion. The heat flux was related to the EDM process parameters by means of mathematical models selected from the literature. In the first part of the present work, a model based on a single discharge analysis was developed; then, the model was extended to a sink EDM process characterised by repeated discharges. The model was validated in terms of machining time, top diameter and MRR by the execution of experimental tests. [ABSTRACT FROM AUTHOR]

Establishing a mathematical model that can reflect the relationship between temperature increase and thermal error during machining is the core of thermal error compensation technology for CNC machine tools. The collinearity between temperature-sensitive points and the correlation between temperature-sensitive points and thermal errors are important factors affecting the prediction accuracy and robustness of the thermal error compensation model. Based on the thermal error measurement experiments of the Leaderway-V450 CNC machine tool in different periods of the year, the principal component regression (PCR) modelling algorithm, which can eliminate the collinearity effect, is proposed to establish the thermal error compensation model of the machine tool on the basis of selecting the temperature-sensitive points by using the correlation coefficient. It is compared with the newly proposed ridge regression thermal error compensation modelling algorithm. The results show that the thermal error compensation modelling method proposed in this paper can basically control the Z-direction thermal error of the CNC machine tool spindle within 10 μm with only two temperature sensors and has higher engineering practicability. It is found that the thermal error compensation model of machine tools has a jump interval affected by the ambient temperature. This interval is called the temperature-sensitive interval, and a temperature-sensitive interval subsection point selection algorithm is proposed to build a subsection model on both sides of the segment point. The results show that the Z-direction thermal error of the spindle of CNC machine tools can be basically controlled within 5 μm with only two temperature sensors and that the model is highly robust and has great engineering application value. [ABSTRACT FROM AUTHOR]

With the outbreak of product miniaturization, the demand of micro-tools fabrication is increasing. Tungsten is a widely used material when fabricating micro-tools. However, tungsten is difficult to machine due to its high hardness. Electrochemical micro-machining (EMM) has many advantages over conventional machining processes, which makes it a potential method to manufacture tungsten micro-tools. This paper proposes a novel EMM fabrication method of high aspect ratio micro-tools with a reverse conical shape tip. During the machining process, a tungsten rod is passed through the electrolyte liquid membrane and makes a linear reciprocating motion. The anodic dissolution occurs only in the region where the rod and electrolyte are in contact. Comparing to the conventional method, this proposed method can improve the shape accuracy of micro-tools. A mathematical model is developed to predict the final diameter of the tool. Furthermore, the effects of main parameters, including electrolyte concentration, feeding rate, the thickness of electrolyte, and the position of the micro-tools, are investigated experimentally. Finally, optimum parameters are selected, and a high aspect ratio micro-tools with a reverse conical shape tip are successfully fabricated using these parameters. [ABSTRACT FROM AUTHOR]

Micro-hole drilling is experiencing a very rapid growth in precision production industries. The micro-drills play a critical role in manufacturing industry. There are many factors which influence the micro-drill performance including the drill point geometry, the drill material, and the workpiece material, among which the most fundamental factor is the drill point geometry. In this paper, a new micro-drill point geometry, termed the centering micro-drill point, is developed. A mathematical model for this new micro-drill point has been established. Micro-drilling tests in AISI 1045 steel are performed with different cutting conditions. By contrasting centering micro-drill and planar drill point micro-drill, the cutting performance of the centering micro-drill has been investigated. The results showed that, when the cutting speed is 35 m/min and the feed rate is 44 mm/min, the thrust force of the centering micro-drill reduces by 21.7% than that of planar micro-drill and the drilling hole amounts increase by 13.5%. The roundness of the thirtieth hole drilled by centering micro-drill is 1.02, and it is 1.08 by planar micro-drill; the centering micro-drill has better position accuracy than planar micro-drill, and further gets good size and shape accuracy. [ABSTRACT FROM AUTHOR]

The current paper attempts to develop a mathematical model to predict springback of thick sandwich panel made of steel/polyurethane (PUR)/steel in air bending process. Firstly, the behavior laws of sandwich panel components were experimentally obtained. Secondly, numerical simulations of the sandwich panel were conducted in bending process followed by springback for various process parameters. We found that the predicted springback agrees with experiment. Thirdly, three factors with three levels were considered in order to obtain a mathematical model to predict springback by using response surface method (RSM). Punch radius, die opening, and foam thickness are chosen as the main input parameters. The springback is considered as the output response. A relationship between the different factors and the response was obtained, and regression analysis has been done. The obtained results were analyzed with analysis of variance (ANOVA) in order to identify the factors' importance on the response. [ABSTRACT FROM AUTHOR]

Ultrasonic-assisted milling (UAM) has an outstanding performance in machining hard and brittle materials, such as glass. The cutting force which has been investigated both experimentally and theoretically is the key factor that affects the machined surface quality. This paper presents a mechanistic mathematical model for the axial cutting force in UAM of soda-lime glass. This model is based on the process mechanism of material removal and can be used to predict the cutting force without the need of performing actual experiments. The mathematical model is proposed taking into consideration two different material removal mechanisms, that directly affect the final material removed volume for the brittle material. The first model is the ductile model which is described by the ductile mechanism where the material is removed by the plastic flow, while the other is the brittle model described by the brittle mechanism where the material is removed due to the crack formation that cause material fracture. In the present models, the effects of both the rotation and ultrasonic vibration motion of the cutting tool were taken into consideration through their effects on the indentation volume, by each diamond grain, into the workpiece. The development of the model started by the analysis of the behaviour of a single diamond grain and obtaining the cutting force for an individual diamond grain first. The total cutting force then was derived by summing up the forces caused by all diamond grains taking part in the cutting process. From the developed models results, the trends of the predicted results from the ductile model agree well with the results determined experimentally at low feed rates and low depths of cut. However, the predicted results from the brittle model agree well with the results determined experimentally at high feed rates and high depths of cut. These results explain that the ductile mode of the material removal is occurring at low feed rates and low depths of cut. Then it changes to the brittle mode of material removal by further increasing of the feed rate and depth of cut. [ABSTRACT FROM AUTHOR]

In order to improve the quality of the tool path, different machining requirements have to be considered in the tool path generation process. The traditional tool path generation methods only consider one or a few requirements and ignore the others due to the lack of comprehensive mathematic framework. Tool path generated in this way normally is not fully optimized since different requirements could compete or even conflict with each other. Targeting at this issue, this paper presents a unified mathematic framework based on field theory to generate tool path for both planar and freeform surface, where the three most important factors in NC machining, i.e., the smoothness, evenness, and machining efficiency of tool path can be considered. In the proposed framework, a field-based cost functional and a gradient-field-based inequality constraint functional is established, so as to convert the multi-objective tool path computation into a functional minimization problem with inequality constraints. Then, a finite element method (FEM)-based numerical method is proposed to solve the multi-variable nonlinear optimization problem. After that, two smooth tool path generation methods are proposed with taking the step-over as constraint. To further improve the machining efficiency, this paper also provides a hybrid method that combines zigzag and spiral pattern tool path. Experiments on blade machining and simulation show that the proposed method can produce smooth tool paths, while the machining efficiency can be improved at the same time. In addition to the above advantages, the proposed mathematical framework is extensible by incorporating different machining requirements into it, making it possible to generate tool path when multi-objective is considered. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Assembly or disassembly sequence planning is a very hard combinatory problem while the assembly parts numbers become important. To reduce this difficulty, especially for the case of complex products, the subassembly identification concept can constitute an original way. It aims to decompose the complex assembly product into some subassembly entities containing a small number of parts. Consequently, the generation of assembly or disassembly sequence planning of parts becomes between the subassemblies and, in that case, can be determined relatively easily. Despite the prettiness of the subassembly method, the identification of subassembly from a computer-aided design (CAD) model remains a relevant research subject to be improved. In this paper, a subassembly identification approach is presented. The proposed approach begins with the exploration of the CAD assembly data to carry out an adjacency matrix. Then, to identify the subassemblies, the extracted matrix is transformed through three steps. The first step consists of idealizing this matrix by removing all connection parts identified by the Feature-Manager, which permits reducing its size. Afterward, based on the reduced matrix, an all-direction matrix is constructed to identify the base part of a subassembly. The third step consists of enriching the all-direction matrix by mounting conditions to construct the set of subassemblies. An example of a CAD assembly mechanism is presented in all sections of this paper in order to explain and discuss the steps of the proposed approach. [ABSTRACT FROM AUTHOR]

Electro-discharge machining (EDM) of thin deep features widens processing opportunities of difficult-to-cut materials, such as Ni-based alloys, towards attractive industrial applications. Conversely, the complex interaction between electrical, thermal, and chemical phenomena in EDM thwarts process modeling and prediction. As a matter of fact, recent experimental discoveries encourage setting forth a new theory of discharge ignition in the gap, based on the role of debris, which lays foundations for a recursive mathematical model showing a chaotic evolution. The paper reports on electro-discharge drilling of small deep holes in Inconel 718. Process performances are measured with varying electrode size and geometry, attesting a pivotal effect of gap pollution on productivity and on the onset of a secondary detrimental removal of material by intergranular corrosion. All findings support the emerging model for discharge ignition via debris bridges, and, most notably, debris chains are documented for the first time in the field of metals, second only to a previous case for a ceramic composite. On the whole, the paper provides conclusive validation of the role of debris in the ignition of discharges. [ABSTRACT FROM AUTHOR]

Vibratory finishing is a versatile process that is used in many industries globally for radiusing, brightening, deburring, fine finishing, cleaning, burnishing, and descaling of components. This state-of-the-art paper will discuss how vibratory finishing has evolved into what it is today and the advancements in technology. The development of mass finishing, the importance of vibratory finishing in aviation industry, the parameters involved in this process, and the patent landscape of the advancements in vibratory finishing will be elucidated. More importantly, the paper will dwell into attempts made to understand the science behind this arcane process. Empirical investigations, model developments, bulk and granular impact velocity studies, vibrostrengthening, and Almen strip characterization are the research efforts that will be discussed in particular. This work has identified gaps in the vibratory finishing process, some of them being media flow measurement and the need for a monitoring system to determine the frequency losses from motor vibrations to the media vibrations. Methods for calculating the frequency and amplitude of machine vibrations, the impact velocity of media, and the force of media striking the workpiece are still under research. Literature points out that more work can be done in terms of the quantification of process parameters, the relationship between them, and the effect they have on the surface finish. The industry is on the lookout for shorter cycle times with improved surface finishing quality, and thus various technological advancements in vibratory finishing, namely drag and spindle finishing, have come into existence. To the knowledge of the authors, there has been no comprehensive review work done on vibratory finishing. This paper attempts to serve the purpose of being a one-stop academic and industrial reference for scientific communities and professionals working in this field. The paper further endeavors to serve as a means to initiate the development of a next generation vibratory finishing system with real-time monitoring and surface finish measurements. [ABSTRACT FROM AUTHOR]

With the application of the 5-axis abrasive water jet (AWJ) machining center, some shape errors, such as cock tail striation, taper, etc., have been removed successfully, and the cutting precision has been improved greatly. However, the shape error located in the cut-in/cut-out region is still a big issue in AWJ cutting process. It often leads to the result that parts cut by AWJ becomes unacceptable. Based on theoretical analysis of the shape error in this region, it is found that the mathematical model used in 5-axis AWJ machining to compensate taper is often built on cutting data within normal cutting speed range. Therefore, the mathematical model becomes inaccurate in cut-in/cut-out regions, where very low cutting speeds are used. To solve this issue, a method of adding an extra nozzle tilting angle is proposed in this paper. This method has been proved to be effective through a series of experiments. With this method, the cutting precision could be improved not only in cut-in/cut-out regions, but also in corner regions where very low cutting speeds are used. [ABSTRACT FROM AUTHOR]

Modelling the thrust force of rotary ultrasonic drilling (RUD) is an important aspect for optimizing the process parameters and predicting the material cracking and edge chipping. Mainly, the material removal of brittle material occurs mainly through the brittle mode, while the ductile mode occurs in case of micro or nano-depth of cut. This paper introduces a mathematical model for thrust force based on the two material removal modes. The mathematical model correlates the thrust force with the material characteristics and the machining parameters as feed rate, spindle speed, ultrasonic amplitude, frequency and tool abrasive size, tip angle, and concentration. Complete hole drilling and scratch-drilling with depth of 10-μm experiments are conducted in soda glass to verify the model. Thrust force measurement and microstructure features are used to verify the model. The predicted model results agree with the experimental results. The model predicts that the range of feed rate and spindle speed produce the ductile mode cutting. [ABSTRACT FROM AUTHOR]

In the grinding of aspherical optical surface, an arc-shaped diamond grinding wheel is generally employed, whereas its profile errors greatly influence the form accuracy of ground workpiece. A high efficiency helical interpolation precision truing method for the arc-shaped diamond grinding wheel is proposed in this paper. Helical interpolation trajectory and decreasing interpolation radius with the wear of a rotary truing wheel ensure a constant contact length and a uniform wear of the diamond grinding wheel and truer. The mathematical models of tool setting errors and measurement error of truer diameter in the truing process were established firstly. The prediction models considering the wear of truer are coincided well with the truing experiment results. Based on the mathematical error models, an error compensation truing process was proposed. The profile accuracy of an arc-shaped diamond grinding wheel was improved to 5 μm (PV) effectively by the error compensation truing process. An ellipsoidal surface of a fused silica workpiece was ground by the well-trued diamond grinding wheel. A form error (in PV) below 4.5 μm was obtained after precision grinding. [ABSTRACT FROM AUTHOR]

It stands to reason that the additive manufacturing build orientation for the material extrusion process affects the support material requirements, processing time, surface finish, etc. This paper aims to study the influence of the build orientation on the optimal process parameter settings (bead width, overlap, and raster angle), the amount, and location of unwanted voids. This research shows that there are limited optimal solution alternatives over the large solution space explored. The layer by layer process parameters are not selected independently. Knowledge of a void location in one layer is utilized to select a process parameter set for the next layer, preventing void regions from being stacked in 3D, and avoiding creating an internal chimney. Material extrusion processes, with a wide selection of nozzle sizes (0.4 mm to 21 mm), are considered suitable candidates for this solution. To carry out this study, a literature review was performed to understand the influence of the build parameters. Then, an analysis of valid parameter settings to be targeted was performed for a commercial system. The mathematical model is established based on the component geometry and the available build options for a given machine-material configuration. A C++ program has been developed to select a set of standards (available) toolpath parameters to determine the optimal process variables. Case studies are presented to show the merits of this approach. The influence of the orientation on the optimal process parameters is illustrated as well as its impact on voids. As expected, it is statistically shown that the amount and location of the voids depends on the build orientation. The optimal solution for the void minimization may be suboptimal for other criteria such as support material usage; consequently, a comprehensive multi-objective optimization heuristic algorithm needs to be developed. The processing time is long and is unacceptable for industrial applications. This outcome also needs to be addressed. [ABSTRACT FROM AUTHOR]

This paper describes an approach for robust design of a mechanical joining process, semi-tubular self-piercing riveting, in real time. Using joining process simulations as a basis, a metamodel is constructed for this purpose, which is subsequently used to optimize the robustness. In this way, joining points can be designed so that there are no impermissible effects on the result quantities in terms of specified scatter input variables. [ABSTRACT FROM AUTHOR]

In the electroplastic wire drawing process, the drawing force is reduced with the application of an electric current. The drawing force drop is the result of a combination of various factors. The objective of this article is to build a theoretical formula between the electroplastic effect and the drawing force. Based on existing electroplastic effect theory and experimental results, the mechanical characteristics of the electroplastic wire drawing process are analyzed, and a mathematical model of the electroplastic drawing force is established. This calculation method takes into account both the influence of electroplastic effect on metal’s flow stress and the change of the wire temperature with an electric current applied. Finally, the results of experiment and theoretical calculations are compared and analyzed. The results of this paper will provide a reference for the theoretical calculation and simulation study of the electroplastic effect in engineering applications. [ABSTRACT FROM AUTHOR]

Automation can be a valid way to reduce production costs. Considering medium/low volumes and a wide set of different models, a mixed model assembly work cell is a proper automated production system. The authors have recently introduced a new class of flexible assembly systems (FAS), the F-FAS, in which highly flexible feeding systems are used to improve the flexibility and reduce the set-up times at batch change. Such systems, guaranteeing a higher level of flexibility than traditional automated FAS, show some limitations in terms of productivity, due to the stochastic process of feeding and reorientation of parts and to the time spent for image acquisition and processing. The aim of this paper is to introduce an innovative automated assembly work cell, called the hybrid flexible assembly system (H-FAS), that merges the traditional FAS bowl feeder utilisation with the innovative F-FAS feeding concepts. The paper analyses the main factors influencing the H-FAS design, productivity and cost. Moreover, through a comparative analysis between the different single cell assembly systems, it defines the working conditions in which they can be preferable. [ABSTRACT FROM AUTHOR]

Nonlinear partial differential equation of temperature distribution with material properties varying was linearized by choosing appropriate linearization coefficient and solved through Green's function and Fourier transform methods. According to these results deduced, analytical model of arc welding temperature distribution under material properties varying condition was obtained. To verify precision of the analytical model obtained, temperature distribution of semi-infinite body under moving spot heat source was calculated through three different methods, including analytical model with and without considering material characters varying and finite element model. By comparing weld pool size calculated through the three methods, results got from analytical model of this paper were found more close to which got from finite element method. Conclusion was that, by taking material properties varying into account, analytical model deduced in this paper had higher precision, especially near the area of weld pool where temperature gradient was very great in welding process. [ABSTRACT FROM AUTHOR]

Slicing is an important step for all layer-based additive manufacturing (AM) processes. This paper proposes an improved and robust slicing algorithm with efficient contour construction to reduce the slicing time and be able to slice a complex STereoLithography (STL) model with millions of triangles (resulting from high-accuracy STL files). Also, another important feature of the proposed method is it can identify outer and inner contours automatically. Test results to demonstrate the improvements in execution time and comparisons with results from published papers have been given to illustrate the algorithm efficiency. The robustness of this slicing algorithm is demonstrated by several complex models with large numbers of nested contours on each slice. [ABSTRACT FROM AUTHOR]

In this paper, the linear and nonlinear mathematical force models are presented for an end-milling process. The nonlinear force model is compared with the updated linear force model. The mechanistic identification of the cutting force coefficients for the linear and nonlinear force models of the end milling process is presented with experimental validation. The cutting force coefficients are determined for an end-milling process using two methods, the average force method and the optimization technique method. The average force method uses equations given by Altintas and Budak [-] for calculating the cutting coefficients of the linear force model. However, the equations for the nonlinear model are derived and used in this paper. The second method uses the optimization technique for identifying the cutting coefficients in the milling process by forming objective functions using the optimization technique to minimize the error between the experimental and the analytical forces. Moreover, this method produced a good force model that approximates the experimental force results, which compared with the average force method for both models. [ABSTRACT FROM AUTHOR]

This paper proposed a hybrid intelligent process model, based on finite-element method (FEM) and Gaussian process regression (GPR), for electrical discharge machining (EDM) process. A model of single-spark EDM process has been constructed based on FEM method, considering the latent heat, variable heat distribution coefficient of cathode ( f), and plasma flushing efficiency (PFE), to predict material removal rate (MRR) and surface roughness (Ra). This model was validated using reported analytical and experimental results. Then, a GPR model was proposed to establish relationship between input process parameters (pulse current, pulse duration, and discharge voltage) and the process responses (MRR and Ra) for EDM process. The GPR model was trained, tested, and tuned using the data generated from the numerical simulations. Through the GPR model, it was found that responses of EDM process can be accurately predicted for the chosen process conditions. Therefore, for the selection of optimum parameters, the hybrid intelligent model proposed in this paper can be used in EDM process. [ABSTRACT FROM AUTHOR]