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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]

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]

In order to generate efficient tool path with given precision requirements, scallop height should be kept under a given limit, while the tool path should be as short as possible to reduce machining time. Traditional methods generate CC curves one by one, which makes the final tool path far from being globally optimal. This paper presents an optimal tool path generation model for a ball-end tool which strives to globally optimize a tool path with various objectives and constraints. Two scalar functions are constructed over the part surface to represent the path intervals and the feedrate (with directions). Using the finite element method (FEM), the tool path length minimization model and the machining time minimization model are solved numerically. The proposed method is also suitable for tool path generation on mesh surfaces. Simulation results show that the generated tool path can be direction parallel or contour parallel with different boundary conditions. Compared to most of the conventional tool path generation methods, the proposed method is able to generate more effective tool paths due to the global optimization strategy. [ABSTRACT FROM AUTHOR]

In a recent paper by Fattahi et al. (Int J Adv Manuf Technol 65:787-802, ), a mathematical model is presented for a two-stage assembly scheduling problem containing a hybrid flow shop and an assembly stage. Some constraints in the model are not valid. This note shows that some new constraints are proposed for the mathematical model. An example is proposed to present and prove this new model by executing mathematical software. [ABSTRACT FROM AUTHOR]

Minimum quantity lubrication (MQL) has been proposed as a promising alternative to conventional flood cooling to substantially reduce the lubrication usage while maintaining high surface quality. Residual stress induced by grinding process directly affects the surface quality of the final product. An analytical relationship between residual stresses and process conditions such as process parameters, material properties, and lubrication conditions could support process planning and optimization of MQL grinding. This paper has presented a physics-based model to predict residual stresses in grinding with consideration of the lubrication and cooling effects of MQL. Grinding force and temperature distribution in the workpiece are used to calculate the loading stresses imparted by MQL grinding. The loading stresses are then coupled into a rolling/sliding contact algorithm to solve for residual stresses. Experimental measurements of residual stress profile under and flood cooling conditions have been pursued to calibrate and validate the predicted results. [ABSTRACT FROM AUTHOR]

In a free-state condition, deformable bodies (or compliant parts) have a significantly different shape than their nominal geometry (CAD model) due to gravity loads and residual stress. Typically, the dimensional metrology of such parts requires a particular approach where expensive and specialized jigs are needed to constrain and follow the component during inspection. This paper proposes a new method to fixtureless inspect deformable bodies by adapting the coherent point drift (CPD) algorithm. This new approach combines the optimization of the smoothness regularization parameters of the CPD powerful non-rigid registration method alongside the Thompson-Biweight statistical test as an identification method to distinguish profile and localization process manufacturing defects from a part's deformation. In other words, a new 'flexible' registration approach that meets the specifications of compliant parts is proposed. The CAD model is smoothly modified to fit the scanned part by minimizing two criteria that belong to deformable bodies. The first criterion is the conservation of the curvilinear distance (isometric transformation). That is to say, the condition that the stretch difference between the original CAD model and the modified one should be very small. The second criterion is the usual minimization of the Euclidean distance between the modified CAD model and its corresponding scanned part. Many case studies were performed on a typical industrial sheet metal which presented profile and localization defects. The estimated values of the defects, as well as their positions, are much closer to their reference ones in most cases, thus reflecting the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Adaptable design has the potential to improve product competitiveness through meeting customers' needs in the product life cycle. Design of open-architecture products has been proposed using the adaptable design method with open and adaptable as well as standard interfaces. Effective tools are required for engineers to apply the concept and approaches of the adaptable design in their daily design processes. This research proposes an optimization method of the adaptable design for open-architecture products. Mathematical models and algorithms considering both adaptability and openness have been developed to identify an optimal design of the adaptable product configuration considering the existing modules and products. An integrated system framework and optimization methods have been implemented as a cyber-enabled tool for the adaptable design of open-architecture products to enable users and vendors to participate in the product development processes using open, adaptable, and standard interfaces. Design of an industrial product was carried out to verify the proposed methods and tools. The system usability, effectiveness, and efficiency were also evaluated. [ABSTRACT FROM AUTHOR]

The main purpose of the vehicle routing problem (VRP) is to deliver a set of customers with known demands on minimum-travel routes and terminating at the same depot. The vehicle routing problem with time windows (VRPTW) requires the delivery made in a specific time window for every customer and returning to the depot before a due time. Contrary to current research, an estimation of distribution-algorithm-based approach coupled with a simulation model is proposed and developed to solve the problem and implement the solution. The approach mentioned makes use of a Bayesian network as a probability model to describe the distribution of the solution space. Furthermore, the approach taken in this study combines the key advantages of both estimation of distribution algorithms (EDA) and simulation. The simulation is used to model the VRPTW environment, while the EDA is used to guide the overall search process to identify the best performing ones. Solomon's (Oper Res 35:254-265, ) instances served as input and test parameters in order to show that there exists a relationship and interaction between vertices and positions on the sequence of the VRPTW solution. A better position for each vertex on the sequence can be estimated through a Bayesian network. Experimental results show that the EDA performance was better in 70 % of the cases, as average, for the number of vehicles used in all the trails with respect the other algorithms proposed as a benchmark for comparison with the EDA scheme. [ABSTRACT FROM AUTHOR]

Disassembly systems obtain valuable parts from end-of-life products to remanufacture, reuse, or recycle them. This study deals with disassembly scheduling and presents a novel mixed integer programming model. Disassembly scheduling is the problem of determining quantity and schedule of items disassembled, held in inventory, sold, and disposed on capacitated resources over a planning horizon while satisfying at least a given service level. The model presented here includes a number of novelties including assignment of disassembly operations to parallel capacitated resources, consideration of costs to environment and demand for each level of items. We also present a problem testbed to be used for comparison of different algorithms and the generation mechanism. Results from a large experimental design using problem testbed are presented. [ABSTRACT FROM AUTHOR]

In gas tungsten arc welding (GTAW), the weld pool is the major source of information that can be used to assure the production of the desired weld penetration-the most critical factor determining the weld integrity. To meet this challenge, various sensing technologies, modeling methods, and control strategies have been studied, and artificial intelligence technologies were applied to improve system intelligence. The GTAW process analysis is given first. Then, a short introduction on weld pool sensing technologies is presented, where three-dimensional (3D) vision sensing is a very active orientation. Furthermore, weld pool description model and characteristic parameter model are also discussed, where intelligent algorithms were used generally. Besides, dynamic modeling and penetration control strategies, especially intelligent control strategies are presented. At last, the discussion about development of the GTAW penetration control product is analyzed briefly. [ABSTRACT FROM AUTHOR]

Managing geometric part deviations to control their effects on the product function and quality is an important task in the design of physical artefacts. Consequently, computer-aided tolerancing tools are widely applied in industrial practice to evaluate the effects of geometric part deviations on assembly and functional requirements. However, most established models and approaches for the representation of geometric part deviations, geometric tolerances, and geometric requirements in such tools lack of a realistic consideration of form deviations and are often not conform to international standards for the geometric product specification and verification. With the aim to provide a further step towards a computer-aided tolerancing theory employing variational part representatives in discrete geometry, approaches for the generation of such representatives, which conform to pre-defined tolerance specifications, are presented. These approaches ground on algorithms for the evaluation of geometric tolerances from point clouds and are essential for the tolerance analysis employing point based models. We highlight the usefulness of the presented methods for the tolerance analysis in a typical case study. [ABSTRACT FROM AUTHOR]

A novel micro-coordinate measurement machine (micro-CMM) is introduced as a viable device to be used with high precision and high accuracy measurement of part dimensions in micron scale. This design considers eliminating Abbé error, and is intended to achieve submicron accuracy for a work envelope of at least (100 × 100 × 100) mm. In this study, a prototype of the new micro-CMM was built; a mathematical measuring model to explicitly define the coordinate of the probe in x, y and z directions have been represented. An algorithm to find the workspace was implemented. The error model of the machine was created and the effect of structural errors on probe position was studied analytically. The significance of each geometric parameter was studied in order to minimize the measuring error and achieve the best machine design. Finally, the results of the analytical error model were confirmed through a Monte Carlo analysis. Moreover, the real measurements of the micro-CMM were compared with the error model. [ABSTRACT FROM AUTHOR]

A numerical study of the laser welding process is presented. The numerical model is based on a combination of the enthalpy method and the finite difference techniques applied to the heat equation that can bypass the manual enforcement of the jump condition at the phase-separating surfaces. Minimal application of the 'life and death of elements techniques' is required in order for the dynamics of the keyhole to be captured. This analysis results in the construction of the flowchart of a time-stepping algorithm, suitable for any software platform or computer language. [ABSTRACT FROM AUTHOR]