The mechanical ruling process using a diamond tool is an important method for fabrication of low-density diffraction gratings. In mechanical ruling, a deposited film of aluminum or gold is mechanically burnished by the diamond tool to form equally spaced and high-quality grooves. The goal of this work is to evaluate the effects of Al film properties and ruling tool loading conditions on the resultant groove formation. The microstructure of the Al film is first studied using scanning electron microscope (SEM) and X-ray diffraction (XRD). The mechanical properties of the Al film are measured by nano-indentation and scratch tests. Mechanical ruling experiments are then carried out on a 10.5 μ m thick Al film under various ruling loads ranging from 20 to 105 g. The groove geometry is investigated, and the tool wear of the diamond tool is inspected after the mechanical ruling tests. Finally, a three-dimensional (3D) thermomechanical-coupled finite-element (FE) model is developed to predict the deformation and temperature fields for the micron-scale groove formation by incorporating the Al film properties and a strain-gradient plasticity for modeling the size effect. Multiruling pass simulations are performed to analyze the groove formation under different loading conditions. Through comparison of simulation results with experimental measurement, this model is demonstrated as a useful numerical tool for modeling the mechanical ruling process using a diamond tool.

Increasing demands in profile manufacturing leads to a constant increase of the geometric complexity of the profile. Nowadays, lightweight design and load adaption are of huge importance and a need for new profile manufacturing technologies exists. In order to cope with this development, a new tube profile forming method was invented, the incremental profile forming (IPF). IPF allows the flexible manufacturing of profiles with varying cross section geometries along the longitudinal profile axis and offers therefore a high potential for the manufacturing of lightweight design parts. Due to the high degree of innovation, research work regarding the process fundamentals as well as the process limits is necessary. For this reason, the results of the first basic experimental and numerical investigations are presented. While in the experiments, the potential of the process is shown in feasibility studies, first analyses of the forming process, and the influence of different process parameters on the process were carried out in numerical investigations. In particular, it turned out that the tool infeed and tube dimensions have significant influence on the forming force, whereas the tool radius has a minor influence.

The purpose of this research is to perform an investigation of continuously dispensed material (or filament) deformation during dispensing. Depending on the material properties, and the process parameters the deformation behavior of the filament changes, so as the formation of the filament front (the front face of the filament, i.e., dispensing material). The focus of this investigation is the study of the evolution of the filament shape for Newtonian fluid experimentally and computationally. The experimental analysis has been performed with commercially available monomers with the help of a screw driven micro dispensing system installed on a high precision xyz translation stage. The imaging system consists of a high resolution CMOS camera. The developed computational model utilizes an adaptive quadtree spatial discretization with piecewise–linear geometrical volume–of–fluid (VOF) method for calculating the volume fraction for this multiphase problem. The model employs the continuum–surface–force model for formulating the surface tension, whereas the height function (HF) to estimate the curvature for tracking the evolution of the filament shape during the deformation. The computational model has been developed using an open source solver, Gerris Flow Solver. The considered governing and process parameters for this investigation are Froude number (Fr), Reynolds number (Re), gap ratio (GR), and velocity ratio (VR). The VR is the ratio of travel velocity to dispensing velocity. The GR is the ratio of filament height to filament diameter. Results have been presented as the interface contour for the filament front. The investigation shows that the results found from the developed model have a good agreement with experimental results, and the deformation phenomena is greatly influenced by the variation of the governing parameters.

Injection molding process is a widely used manufacturing technique to massively produce the components of mobile device with various sizes and complicated geometries. However, the final part quality, especially dimension or geometry, referring to the original design specifications is not often acceptable due to various reasons. This study aims at developing the numerical model to predict the final part quality and subsequently identifying the critical reasons for existing problems. moldflow and abaqus software have been simultaneously used to simulate the injection molding process and thermal deformation arising after ejection step from the mold. In order to validate the model, the deformation predicted by the developed model was compared with experimental results, and both results showed good agreement. We also carried out design of experiment (DOE) to investigate the effect of various processing parameters that affect the final deformation of injection molded product. The developed model and information derived from DOE are expected to provide useful resources to the initial stage of mobile device design.

Resistance spot welding (RSW) is a very complicated process involving electromagnetic, thermal, fluid flow, mechanical, and metallurgical variables. Since weld nugget area is closed and unobservable using experimental means, numerical methods are generally used to reveal the nugget formation mechanism. Traditional RSW models focus on the electrothermal behaviors in the nugget and do not have the ability to model mass transport caused by induced magnetic forces in the molten nugget. In this paper, a multiphysics model, which comprehensively considers the coupling of electric, magnetic, thermal, and flow fields during RSW, temperature-dependent physical properties, and phase transformation, is used to investigate the heat and mass transport laws in the weld nugget and to reveal the interaction of the heat and mass transports and their evolutions. Results showed that strong and complicated mass transport appears in the weld nugget and substantially changed the heat transport laws and, therefore, would be able to substantially affect the hardening, segregation, and residual stress of the weld. Compared with the traditional models which could not consider the mass transport, the multiphysics model proposed in this paper could simulate the RSW process with higher accuracy and more realities.

The thickness of recast layers produced during electrical discharge machining (EDM) is an important process performance measure as it may indicate an extent of crack propagation in a machined surface or thickness of a functional layer alloyed onto a machined surface. Thus, the availability of the recast layer thickness prediction models is needed to allow better control of machining outcomes, which becomes more vital for micro-EDM due to the microscale of machined features. The proposed numerical model, based on a multiple discharge approach for recast layer prediction, is developed to fill an existing gap in micro-EDM. The multiple discharge approach accounts for the overlapping nature by which craters are generated on the machined surface and considers the recast layer to be a combination of individual recast regions from individual craters. The numerical analysis, based on finite element methods, is used to determine the melting isotherms due to heat inputs on overlapping crater profiles. Then, a hemispherical-capped crater profile is estimated by applying a recast plasma flushing efficiency to the amount of molten material bounded by the melting isotherm. Finally, the recast region is defined to be bounded by the melting isotherm and crater profile. The model, developed for a peak discharge current of 1.45 A and pulse on time between 166 ns and 606 ns, predicted recast layer thicknesses of between 1.0 μ m and 1.82 μ m . It is then validated at pulse on time settings of 244 ns and 458 ns, which generated average recast layer thicknesses of 1.18 μ m and 1.56 μ m , respectively. Thus, the numerical model developed using the multiple discharge approach is suitable for estimation of recast layer thicknesses in micro-EDM.

This paper presents an in-depth experimental and numerical investigation of a split-ring test, which provides a simple yet effective benchmark for correlating forming and springback predictive capabilities with experimental measurements. The experimental procedure consists of deep drawing a circular 6111-T4 aluminum alloy into a cylindrical cup of 55 mm depth, crosscutting nine rings each of 5 mm wide from the cup, splitting the rings, and measuring their opening displacement, i.e., the springback amount. Experimental data obtained included punch force trajectories, drawn cup profile, thickness distribution after forming, and the ring openings after splitting. A numerical model is built to analyze the process, and both transversely isotropic and fully orthotropic yield criteria are investigated. Simulation results are validated against experimental data. A detailed numerical analysis is also conducted for stress distributions in each ring after each step and their relationship to the total springback amount. Stress and strain signatures suggested that the test is well suited for validating material models, such as anisotropic yield surface models and hardening models.

In practice of caliber rolling, it is highly desirable to obtain optimal processing parameters to achieve the best quality in a short time. A sophisticated and faster simulation model of caliber rolling is proposed, and then a global optimal searching method—simulated annealing algorithm (SA)—is applied to find the optimal processing parameters of caliber rolling. The simulation model of caliber rolling in this paper was established by the back-propagation neural network (BPNN) model, which replaces the complex numerical analytical model, proposed in an earlier paper. This replacement improved the speed of simulation significantly.

Considering the great impacts of the application sequence of multiclamps on the workpiece machining accuracy, this paper analyzes and optimizes clamping sequence. A new methodology that takes into account the varying contact forces and friction force during clamping is presented for the first time. A new analysis model is established to capture the effect of clamping sequence on contact force distributions and workpiece machining accuracy. It reveals that the historical accumulation of clamping steps influences heavily the final distribution of contact forces in the workpiece-fixture system. Therefore, the present contact forces in each clamping step are solved incrementally in terms of contact forces of the precedent step by means of the principle of the total complementary energy. Furthermore, based on the fact that the variation of contact forces from one step to another results in different workpiece deformations and position, a novel design model is formulated to select optimally the clamping sequence in order to minimize the workpiece deformation and position errors. Workpieces of low stiffness and high stiffness are investigated separately in order to simplify the modeling of clamping sequence optimization. Some numerical tests are finally demonstrated to validate the proposed model and method. Computational results are discussed and compared with experimental results available in the reference.

The concept for die-geometry design is shown to suppress void growth in multi-pass drawing. First, the void index to evaluate the void fraction in multi-pass drawing was newly proposed based on the well-known equation to predict the fracture limit in cold working. Using finite element analysis, the influence of die geometries on the void index was investigated and it was clarified that the extra-low-angle die is effective whatever reduction in area is adopted. Moreover, dies were designed to have the effect of suppressing void with the minimum die length. A series of experiments was then carried out that successfully verified the numerical results.

In any cutting processes, the temperature distribution in the cutting tool is intrinsically three-dimensional and very steep temperature gradient can be generated in the vicinity of the tool-chip interface. In this region, where the maximum temperature occurs, the effect of temperature dependent thermal properties may become important. The full three-dimensional nonlinear transient heat conduction equation is solved numerically using a control volume approach to study these nonlinear effects on cutting tool temperatures. The extremely small size of the heat input zone (tool-chip interface), relative to the tool insert rake surface area, requires the mesh to be dense enough in order to obtain accurate solutions. This usually requires very intensive computational efforts. Due to the size of the discretized domain, an optimized algorithm is used in the solution of the problem to significantly reduce the required computing time. This numerical model can be used for process development in an industrial setting. The effect of two different heat flux input profiles, a spatially uniform plane heat flux and a spatially nonuniform parabolic heat flux at the tool-chip interface, on the tool temperatures are also investigated in the present study. Some recommendations are given regarding the condition when these nonlinear effects cannot be ignored.

Investigations were carried out on the direct applicability of a set of grooves of multi-roll wire mills for different materials having different stress-strain curves. Special evaluation was made on the stability of the geometry among different materials when rolled under the same mill setting conditions. Influence of inter-stand tension generated by the change in roll force due to the difference in stress-strain curve was studied both numerically and experimentally. A group of three-roll and four-roll-type mills is superior to two-roll-type mill in getting rid of the time for mill setting.

Measured data taken from Coordinate Measuring Machines (CMMs) are in the form of Cartesian coordinates of points from a part surface. In order to interpret the data, a numerical analysis must be performed on them. Currently, data fitting techniques such as a least squares fit or a min-max fit are employed to compare the measured points to the design model. As the objectives of the various techniques differ, they often yield conflicting results. Since this discrepancy may lead to a different conclusions in the process dimensional inspection, it is critical that inspection procedures are based on well defined criteria that employ the appropriate technique to achieve the desired inspection goals. If tolerances are represented by tolerance zones, a zone fitting algorithm, introduced in this paper, provides a more consistent means of verify conformance to the tolerance zone. It determines whether a set of measured points fits into a specified tolerance zone. If the point set can fit into the zone, a rigid body transformation placing the points inside the zone is returned. The algorithm is numerically stable and addresses a general type of tolerance zone. The examples demonstrate that the zone fitting algorithm is more consistent compared to the least squares fit and the min-max fit in tolerance zone conformance verification. A subsequent paper (Part 2) addresses the determination of a minimum zone that extends inspection from a pass/fail mode to a quality analysis operation.

The concept of swept sections for flat-ended tools is revisited with the goal of improving the accuracy of calculations in five-axis tool path generation. Firstly, the notions of partial and total swept sections (distinct from traditional swept sections) are introduced. It is shown that partial and total swept sections provide a more accurate representation of the geometry of the moving tool compared to traditional swept sections. Next, geometric and numerical methods focused on calculating partial swept sections are presented. These methods are based on calculating plane-circle intersections. Finally, the calculated partial swept sections are compared to the traditional swept sections. Variations from the traditional swept sections are characterized to provide guidelines to the tool path programmer. [S1087-1357(00)71101-4]

The development of thermal stresses in ingots during the vacuum arc remelting (VAR) as well as specialized permanent mold casting (PMC) process was modeled via numerical solution of the two-dimensional, nonsteady-state heat conduction and stress equilibrium equations. The numerical analysis was carried out in conjunction with experimental studies of the mechanical properties and microstructure of a cracked VAR titanium aluminide ingot. Numerical solutions were obtained for different values of ingot diameter, crucible-ingot interface heat transfer coefficients, and lengths of the melted-and-resolidified ingot. For both VAR and PMC, model predictions revealed that the maximum tensile thermal stresses are developed at the bottom of the ingot; the magnitude of such stresses increases with ingot diameter and the magnitude of the interface heat transfer coefficients. The microstructural analysis of a cracked ingot indicated that the thermal cracking occurred in the temperature range where the alloy has very little ductility. The predicted development of large tensile stresses correlates well with observations of thermal cracking during VAR of near-gamma titanium aluminide alloy ingots. By contrast, the predicted thermal stresses developed during PMC are lower, thus suggesting an attractive alternative to VAR to obtain sound, crack-free ingots.

A theory employing the concept of potential flow and an easily implemented numerical method are developed. It can offer a preliminary prediction of the optimum blank shape with a little computational effort. The effects of the material anisotropy and the interfacial friction between the workpiece and blank holder on the material flow can be modeled by superimposing a “sink” or “source” term in the potential field. Variations in the cup wall thickness are considered. Both convex and non-convex punch profiles are studied. Generally speaking, the contours of the present theory are smoother than the solutions from the slip-line method. The discrepancy of the optimum blank contours between the plane strain and anisotropic cases is more significant for polygon and irregular cup drawing. The influence of friction on the optimum blank contour is not negligible.

In this paper, a summary of work performed in the area of modeling of the dynamic metal cutting process is presented. A general view of evolution of the dynamic cutting process models is depicted. Specifically four modeling approaches including analytical, experimental, mechanistic and numerical methods are critically reviewed. A brief assessment of future research needs is also given.

A number of methods exist for determining profiles of cutting tools that work by wrapping. Most of these methods are based on the envelope theory and almost inevitably require cumbersome analytical formulations not always easy to resolve. This work presents a new method for studying conjugated surfaces associated with rolling axodes. Originally devised in an analytical form in a previous work of the first author, a purely numerical method is developed here based on a theorem which we call “the theorem of the minimal distance.” The advantage is twofold: first, geometrical modeling of tool profile calculation is possible even for profiles which cannot be described analytically; second, a very useful tool is provided for the inverse problem—starting from the measured cutting edges profiles, one can calculate the effectively generated surface on the workpiece. Several examples are shown for rack, shaper, and rotational cutters.

A simplified numerical method is proposed in this article to predict strip profile. The mill is simulated by beams (rolls) on the infinite elastic half space (between rolls and strip). The roll deflection and indentation are calculated using the influence coefficients and Boussinesq’s equations respectively. The roll contours in the contact zone can be expressed in terms of the influence coefficient and indentation matrices. Compatibility equations are derived by matching two surface profiles in the contact zone. Equilibrium equations ensure force and moment balance of the strip and each roll. A complete linear system is established by assembling compatibility and equilibrium equations. The contact rolling pressure distribution and the rigid motion of the roll chocks can be solved. Roll surface contours and strip profiles can be further calculated accordingly.