Showing papers in "The International Journal of Advanced Manufacturing Technology in 2004"
TL;DR: In this article, a benchmark model is designed to assess the fused deposition modeling (FDM) process for creating sacrificial investment casting (IC) patterns, and an indirect approach toward producing wax patterns via silicone rubber molding is investigated.
Abstract: Investment casting (IC) offers an economical method for mass producing complex, shaped metal parts. However, high tooling cost and lead times associated with the fabrication of metal moulds for producing IC wax (sacrificial) patterns result in cost justification problems for customised single casting, small- and medium-quantity production. Rapid prototyping (RP) techniques can reduce the costs associated with single-part or small-quantity production as they can be applied to the fabrication of sacrificial IC patterns containing complex and intricate designs with significant cost and lead-time savings. In this project, a benchmark model is designed to assess the fused deposition modelling (FDM) process for creating sacrificial IC patterns. In addition, an indirect approach toward producing wax patterns via silicone rubber moulding is investigated. Cost and lead time comparisons between the two IC pattern production methods were carried out and presented. The dimensional accuracies of metal castings generated from the RP-produced patterns are also presented.
148 citations
TL;DR: The use of the Petri net reduction approach is proposed to simplify very big PNMs so as to make necessary calculations easily in order to obtain an optimal deadlock prevention policy for FMSs.
Abstract: In a flexible manufacturing system (FMS) with multiple products, deadlocks can arise due to limited shared resources, such as machines, robots, buffers, fixtures etc. The development of efficient deadlock prevention policies, which can optimise the use of system resources, while preventing deadlocks from occurring, has long been an important issue to be addressed. In [1], an optimal deadlock prevention policy was proposed, based on the use of reachability graph (RG) analysis of the Petri net model (PNM) of a given FMS and the synthesis of a set of new net elements, namely places with initial marking and related arcs, to be added to the PNM, using the theory of regions. The policy proposed in [1] is optimal in the sense that it allows the maximal use of resources in the system according to the production requirements. For very big PNMs, the reachability graph of the PNMs becomes very large and the necessary computations to obtain an optimal deadlock prevention policy become more difficult. In this paper, we propose the use of the Petri net reduction approach to simplify very big PNMs so as to make necessary calculations easily in order to obtain an optimal deadlock prevention policy for FMSs. An example is provided for illustration.
146 citations
TL;DR: In this article, the authors proposed a define-measure-analyse-improve-control (DMAIC) approach to improve the sigma level of the screening process through the definemeasureanalyse improve-control approach.
Abstract: Since the early 1990s, six sigma has been sweeping the business world, driving greater manufacturing and service quality than has ever been seen before. Statistical quality techniques are one of the decisive factors contributing to the success of the six-sigma implementation. Applying statistical quality techniques is especially important in the manufacture of surface-mounted printed circuit boards (PCB). As any defect in the solder joint can lead to circuit failure, the screening process is regarded as the most critical process in PCB manufacturing. According to the current process capability study of a PCB company, the capability of the screening process is under 1.33—the company requirement. That is to say, the current printing process cannot reach a four-sigma level. Therefore, the objective of this study is to improve the sigma level of the screening process through the define-measure-analyse-improve-control (DMAIC) approach. At the early stages, process capability analysis (PCA) and statistical process control (SPC) were used to measure and analyse the current printing performance of the screening machines. During later stages, design of experiment (DOE) was conducted to determine the optimal settings of the critical-to-quality factors in the screening process. By using these optimal settings, six-sigma performance can be achieved.
96 citations
TL;DR: In this paper, a plan of experiments based on the methodology of Taguchi, was established considering turning with prefixed cutting parameters in the PEEK GF30 workpiece, and the analysis of variance (ANOVA) was preformed to investigate the cutting characteristics of PEEKGF30 using a polycrystalline diamond (PCD) and a cemented carbide (K20) cutting tool.
Abstract: Polyetheretherketone (PEEK) is a relatively new technical thermoplastic material, which has excellent physical properties. By this reason exits a strong need to understand the issues associated with the machining of this thermoplastic. The major concern of this paper is the study of the cutting parameters (cutting velocity and feed rate) under power (Pc), specific cutting pressure (Ks), surface roughness (Ra) and International dimensional precision (IT) in PEEK reinforced with 30% of glass fibre (PEEK GF30). A plan of experiments, based on the methodology of Taguchi, was established considering turning with prefixed cutting parameters in the PEEK GF30 workpiece. The analysis of variance (ANOVA) was preformed to investigate the cutting characteristics of PEEK GF30 using a polycrystalline diamond (PCD) and a cemented carbide (K20) cutting tool.
91 citations
TL;DR: The importance of coordination in supply chain is emphasised and a general architecture of agile supply chain management is presented based on a multi-agent theory, in which the supply network is managed by a set of intelligent agents for one or more activities.
Abstract: In a worldwide network of suppliers, factories, warehouses, distribution centres and retailers, the supply chain plays a very important role in the acquisition, transformation, and delivery of raw materials and products. One of the most important characteristics of agile supply chain is the ability to reconfigure dynamically and quickly according to demand changes in the market. In this paper, concepts and characteristics of an agile supply chain are discussed and the agile supply chain is regarded as one of the pivotal technologies of agile manufacture based on dynamic alliance. Also, the importance of coordination in supply chain is emphasised and a general architecture of agile supply chain management is presented based on a multi-agent theory, in which the supply chain is managed by a set of intelligent agents for one or more activities. The supply chain management system functions are to coordinate its agents. Agent functionalities and responsibilities are defined respectively, and a contract net protocol joint with case-based reasoning for coordination and an algorithm for task allocation is presented.
90 citations
TL;DR: In this paper, the influence of cutting conditions on surface finish during turning of Al/SiC-MMC was investigated using a fixed rhombic tooling system using an orthogonal L27(313) array.
Abstract: This paper presents an experimental investigation of the influence of cutting conditions on surface finish during turning of Al/SiC-MMC. In this study, the Taguchi method, a powerful tool for experiment design,is used to optimise cutting parameters for effective turning of Al/SiC-MMC using a fixed rhombic tooling system. An orthogonal L27(313) array is used for 33 factorial design and analysis of variance (ANOVA) is employed to investigate the influence of cutting speed, feed and depth of cut on the surface roughness height Ra and Rt respectively. The influence of the interaction of cutting speed/feed on the surface roughness height Ra and Rt and the effect of cutting speed on cutting speed/feed two factor cell total interaction for surface roughness height Ra and Rt are analysed through various graphical representations. Taking significant cutting parameters into consideration and using multiple linear-regression, mathematical models relating to surface roughness height Ra and Rt are established to investigate the influence of cutting parameters during turning of Al/SiC-MMC. Confirmation test results established the fact that the mathematical models are appropriate for effectively representing machining performance criteria, e.g. surface roughness heights during turning of Al/SiC-MMC.
89 citations
TL;DR: In this paper, a disassembly cell is composed of several sub-systems, each of which is dedicated to the planning and execution of one type of task, and a computer vision system is employed for the recognition and localisation of the product and each of its components.
Abstract: In this article, a personal computer disassembly cell is presented. With this cell, a certain degree of automatism is afforded for the non-destructive disassembly process and for the recycling of these kinds of mass-produced electronic products. Each component of the product can be separated. The disassembly cell is composed of several sub-systems, each of which is dedicated to the planning and execution of one type of task. A computer vision system is employed for the recognition and localisation of the product and of each of its components. The disassembly system proposed here also has a modelling system for the products and each of its components, the information necessary for the planning of tasks, generating the disassembly sequence and planning of the disassembly movements. These systems co-operate with each other to achieve a semi-automatic disassembly of the product.
88 citations
TL;DR: In this article, the dimensional errors resulting from tool deflection in the high-speed milling of hardened steel surfaces are measured as the difference between the theoretical surface and the high speed milling machined using ball-end mills.
Abstract: The present paper looks at the dimensional errors resulting from tool deflection in the high-speed milling of hardened steel surfaces. These errors are measured as the difference between the theoretical surface and the high-speed milling machined using ball-end mills.
88 citations
TL;DR: In this paper, a plan of experiments based on the Taguchi method was designed for hot turning operations and the results showed that cutting speed and feed rate were the dominant variables on multiple cutting performance characteristics.
Abstract: This paper presents an investigation on the optimisation and the effect of cutting parameters on multiple performance characteristics (the tool life and the workpiece surface roughness) obtained by hot turning operations. A plan of experiments based on the Taguchi method was designed. M20 sintered carbide as tool and the high manganese steel as workpiece material were used in experiments. The workpiece material heated with liquid petroleum gas flame was machined under different settings of feed rate, depth of cut, cutting speed and workpiece temperature on a lathe. The results showed that cutting speed and feed rate were the dominant variables on multiple cutting performance characteristics. An optimum parameter combination was obtained by using statistical analysis.
86 citations
TL;DR: In this article, a new technique of the oscillatory vibration assisted drilling of GFRP composites in order to minimise the damages is presented, and the cutting performance is analyzed through online studies such as the measurement of force, power and A.E. monitoring and through the measurement tool wear as an offline technique.
Abstract: Glass fiber reinforced plastic (GFRP) composites are finding their way into high technology applications. The machining of GFRP composites is needed to produce near nett-shaped components. Damage free machining is necessitated for the longer inservice life of composites. The present study attempts a newer technique of the oscillatory vibration assisted drilling of GFRP composites in order to minimise the damages. For comparison, conventional drilling also has been carried out. The cutting performance is analysed through online studies such as the measurement of force, power and A.E. monitoring and through the measurement of tool wear as an offline technique.
84 citations
TL;DR: In this article, the compliance effect of a high-speed ball-screw feed-drive system is modelled in this work and a topology structure optimisation method is proposed to reduce the moving weight.
Abstract: The compliance effect of a high-speed ball-screw feed-drive system is modelled in this work. A mechanical model of a ball-screw feed drive system including the motor, ball-screw, coupling, supporting bearing, linear guide and machine structure was developed. It was found that at high acceleration, the mechanical compliance caused a significant contouring error. Smoothing the acceleration and deceleration control input command did improve the transient deviation in the contouring error. However, the steady state error caused by the elastic elongation in the mechanical elements was not improved. It was also shown that the inertia force of the slide and saddle comprised the dominant loading on a high speed machine tool drive mechanism. A topology structure optimisation method is proposed to reduce the moving weight. This method can help the designer efficiently reduce the moving weight of a machine tool axis in a systematic way. More than a 30% weight reduction was demonstrated in a spindle carrier structural design.
TL;DR: A multi-objective evolutionary search algorithm using a travelling salesman algorithm and genetic algorithm for flow shop scheduling is proposed in this article, where the weights are randomly generated for each generation to enable a multi-directional search.
Abstract: A multi-objective evolutionary search algorithm using a travelling salesman algorithm and genetic algorithm for flow-shop scheduling is proposed in this paper. The initial sequence is obtained by solving the TSP. The initial population of the genetic algorithm is created with the help of a neighbourhood creation scheme known as a random insertion perturbation scheme, which uses the sequence obtained from TSP. The proposed algorithm uses a weighted sum of multiple objectives as a fitness function. The weights are randomly generated for each generation to enable a multi-directional search. The performance measures considered include minimising makespan, mean flow time and machine idle time. The performance of the proposed algorithm is demonstrated by applying it to benchmark problems available in the OR-Library.
TL;DR: In this paper, the authors studied the bulging effect of aluminium solid cylinders, varying the frictional conditions at the flat die surfaces, and established a relationship between the various bulge parameters including new hoop strain, hydrostatic stress, geometrical shape factor, and stress ratio factor.
Abstract: Friction plays a major role in all bulk metal forming processes, except in a few isolated cases such as die-less wire drawings, etc. In upset cold forging, the existence of frictional constraints between the dies and the work-piece directly affect the plastic deformation of the latter. When a solid cylinder is compressed axially between the top and bottom platen, the work piece material in contact with their surfaces undergoes heterogeneous deformation resulting in “barrelling” of the cylinder. The friction at the faces of contact retards the plastic flow of metal on the surface and in its vicinity. A conical wedge of a relatively undeformed metal is formed which suffers high strain hardening and bulges out in the form of a barrel. This experimental work has been undertaken to study the bulging effect of aluminium solid cylinders, varying the frictional conditions at the flat die surfaces. Flat dies of different surface finish were produced by different machining processes like grinding, milling, electro-spark machining, and lathe turning and finishing with ‘0’ grade emery paper. Experiments were conducted for two aspect ratios. The radius of curvature of bulge was measured and found to conform to the calculated bulge using experimental data. The calculations are made with the assumption that the curvature of the bulge followed the form of a circular arc. A relationship was established between the various bulge parameters including new hoop strain, hydrostatic stress, geometrical shape factor, and stress ratio factor, considering the dissimilar frictional conditions.
TL;DR: A multi-criterion genetic optimization for solving distribution network problems in supply chain management and provides more control for decision-makers on the determination of the optimization solutions, and gains more information for a better insight into the distribution network.
Abstract: This paper develops a multi-criterion genetic optimization for solving distribution network problems in supply chain management. Distribution problems deal with distribution from a number of sources to a number of destinations, in which various decision factors are closely related and influence each other. Genetic algorithms have been widely adopted as the optimization tool in solving these problems. This paper combines analytic hierarchy processes with genetic algorithms to capture the capability of multi-criterion decision-making. The proposed algorithm allows decision-makers to give weightings for criteria using a pairwise comparison approach. The numerical results obtained from the new approach are compared with the results obtained from linear programming. The result shows that the proposed algorithm is reliable and robust. In addition, it provides more control for decision-makers on the determination of the optimization solutions, and gains more information for a better insight into the distribution network.
TL;DR: In this paper, a hybrid of GA and simulated annealing (GSA) is used to determine optimal machining parameters for milling operations, and the results indicate that GSA is more efficient than GA and GP in the application of optimisation.
Abstract: The selection of optimal machining parameters plays an important part in computer-aided manufacturing. The optimisation of machining parameters is still the subject of many studies. Genetic algorithm (GA) and simulated annealing (SA) have been applied to many difficult combinatorial optimisation problems with certain strengths and weaknesses. In this paper, genetic simulated annealing (GSA), which is a hybrid of GA and SA, is used to determine optimal machining parameters for milling operations. For comparison, basic GA is also chosen as another optimisation method. An application example that has previously been solved using geometric programming (GP) method is presented. The results indicate that GSA is more efficient than GA and GP in the application of optimisation.
TL;DR: A real-time control algorithm based on Taylor’s expansion for implementing variable feed rate non-uniform rational B-spline (NURBS) curve interpolators using a digital signal processor for precision CNC machining is presented.
Abstract: This paper presents a real-time control algorithm based on Taylor’s expansion for implementing variable feed rate non-uniform rational B-spline (NURBS) curve interpolators using a digital signal processor for precision CNC machining. To efficiently compute the NURBS curve and its derivatives in real-time, an effective method is proposed. The variable feed rate NURBS curve interpolator can be used to realise the ACC/DEC before feed rate interpolation in which the ACC/DEC (acceleration/deceleration) planning on the feed rate command executes before the interpolation takes place, so that the path command errors caused by conventional ACC/DEC planning using the post feed rate interpolation can be effectively eliminated. To demonstrate the performance of the proposed algorithm, an
X-Y table driven by two servomotors is controlled to track command paths represented by multiple blocks of NURBS curves. Experimental results verify the effectiveness of the proposed method.
TL;DR: In this article, the authors used a 3-axis computer numerical controlled (CNC) machining center to produce a typical centrifugal impeller, and the results of verification proved the machining methodology and procedure to be successful.
Abstract: A clear trend shows that most products or mechanical components, especially those regarding aerospace applications, are designed to fit the requirements of free form surface features. When a 3-axis computer numerical controlled (CNC) machining centre is used to produce a typical centrifugal impeller, great difficulties, i.e., collisions between the cutting tool and impeller, need to be overcome. In this case, sophisticated five-axis machines have to be utilised. Presently, most commercial computer-aided manufacturing (CAM) systems for five-axis control are lacking generality, and functions for the rough tool-path generation are far less than required. The rough machining is recognised as the most important procedure influencing the machining efficiency and is critical for the success of the following finishing process. However, great difficulties are expected to arise in performing five-axis rough machining. The main objective of the present study is to overcome this problem by combining related machining technology. As a result, CL data based on the geometry model of blade and hub of the impeller are generated. Finally, the CL data is confirmed through software simulation. The results of verification prove the machining methodology and procedure to be successful.
TL;DR: In this article, the kinematic analysis of a new type hybrid serial-parallel manipulator is presented, which is based on two kinds of 3-UPU parallel mechanisms (PM).
Abstract: The kinematic analysis of a new type hybrid serial-parallel manipulator is presented. This manipulator is based on two kinds of 3-UPU parallel mechanisms (PM). Each 3-UPU possesses one platform, one base and three limbs, and hence has 3 degrees of freedom (DOF). Each limb comprises of universal (U), prismatic (P), and universal (U) joints in series. Therefore the hybrid manipulator has totally 6 degrees of freedom and has also an elegant structure. The moving platform (mid platform) of the first PM moves with pure translation with respect to the fixed base and the moving platform (end platform) in the second PM only changes its orientation with respect to the mid platform. In this paper, closed-form kinematic solutions are obtained for this type of mechanism and related theoretical results have been verified numerically.
TL;DR: In this paper, an attempt has been made to develop a new chip-thickness model for the performance assessment of silicon carbide grinding by incorporating the modulus of elasticities of the grinding wheel and the workpiece in the existing basic chip thickness model to account for elastic deformation.
Abstract: The chip-thickness models, used to assess the performance of grinding processes, play a major role in predicting the surface quality. In the present paper, an attempt has been made to develop a new chip-thickness model for the performance assessment of silicon carbide grinding by incorporating the modulus of elasticities of the grinding wheel and the workpiece in the existing basic chip-thickness model to account for elastic deformation. The new model has been validated by conducting experiments, taking the surface roughness as a parameter of evaluation .
TL;DR: In this article, the authors classified knowledge regarding man-machine interactions and provided a short survey of research in this area, where the interaction media are explained and a short review of the literature is provided.
Abstract: Continued development of modern machines and production equipment, supported by advanced control systems and based on recent achievements in computer and software technology, is necessary to fulfil client requirements. A significant number of manufacturing systems are able to work automatically with a limited contribution from employees. However, even in advanced manufacturing systems, one of the most important factors is still the human being. Usually overall system performance depends on human decisions, and the significance of such decisions is higher than it was in the past because of more complex and costly production systems. In such a situation, the efficient utilisation of manufacturing equipment via proper man-machine interaction is necessary. The paper deals with problems in man machine interactions and with an attempt to model human behaviour. The interaction media are explained and a short survey of research in this area is provided. The aim of the paper is to classify knowledge regarding man-machine interactions.
TL;DR: In this paper, an approach toward adaptive direct slicing with non-uniform cusp heights independent of CAD systems for rapid prototyping is presented, where the geometry model is imported into the adaptive direct slice system from CAD systems using the standard STEP format.
Abstract: Adaptive slicing varies layer thickness by taking the geometry change of the CAD model in the build direction into account to improve surface finish. Direct slicing generates exact slice contours from the original CAD model and avoids an intermediate representation, known as an “STL file”. At present, most direct slicing approaches are restricted to some CSG solids or some CAD systems. In this paper, an approach toward adaptive direct slicing with non-uniform cusp heights independent of CAD systems for rapid prototyping is presented. First the geometry model is imported into the adaptive direct slicing system from CAD systems using the standard STEP format. Using OpenGL graphics libraries, the solid model is then displayed and the user is prompted to specify the allowable cusp height for each highlighted surface. Lastly, the CAD model is sliced adaptively with different cusp heights (tolerance requirements) for different surfaces. With non-uniform cusp heights, adaptive slicing has a higher efficiency. Implementation details and results are also presented.
TL;DR: In this paper, an ant colony based optimization procedure was developed to optimise grinding conditions, viz. wheel speed, workpiece speed, depth of dressing and lead of dressing, using a multi-objective function model with a weighted approach for the surface grinding process.
Abstract: An ant colony based optimisation procedure has been developed to optimise grinding conditions, viz. wheel speed, workpiece speed, depth of dressing and lead of dressing, using a multi-objective function model with a weighted approach for the surface grinding process. The procedure evaluates the production cost and production rate for the optimum grinding condition, subjected to constraints such as thermal damage, wheel wear parameters, machine tool stiffness and surface finish. The results are compared with Genetic Algorithm (GA) and Quadratic Programming (QP) techniques.
TL;DR: In this paper, the authors proposed a novel analysis of the geometric errors of a machine tool using a ball bar test without using a complicated error synthesis model, and a statistical analysis method was employed to derive geometric errors using a hemispherical helix ballbar test.
Abstract: Machining accuracy is directly influenced by the quasi-static errors of a machine tool. Since machine errors have a direct effect upon both the surface finish and geometric shape of the finished workpiece, it is imperative to measure the machine errors and to compensate for them. A laser measurement system to identify geometric errors of a machine tool has disadvantages, such as a high cost, a long calibration time and the usage of a volumetric error synthesis model. In this study, we proposed a novel analysis of the geometric errors of a machine tool using a ball bar test without using a complicated error synthesis model. Also, a statistical analysis method was employed to derive geometric errors using a hemispherical helix ball bar test. According to the experimental result, we observed that geometric errors of the vertical machining centre were compensated by 88%.
TL;DR: In this article, single-point diamond turning experiments were performed to investigate the nanometric machining characteristics of single-crystal CaF2, and the effects of tool feed, tool rake angle, workpiece crystal orientation and cutting fluid were examined.
Abstract: Single-crystal CaF2 is an important optical material. In this work, single-point diamond turning experiments were performed to investigate the nanometric machining characteristics of CaF2. The effects of tool feed, tool rake angle, workpiece crystal orientation and cutting fluid were examined. It was found that two major types of microfracturing differing in mechanism limited the possibility of ductile regime machining. The critical conditions for microfracturing depend strongly on the tool rake angle and the type of cutting fluid. The results also indicate that one type of the microfractures is caused by thermal effect, and can be completely eliminated by using a sufficiently small undeformed chip thickness and an appropriate negative rake angle under dry cutting conditions. Continuous chips and ductile-cut surfaces with nanometric roughness were generated.
TL;DR: In this paper, a tabu search heuristic consisting of dynamic tabu tenure with a long-term memory mechanism is presented to solve the cell formation problem, which determines the decomposition of the manufacturing cells of a production system in which machines are assigned to these cells to process one or more part families.
Abstract: The cell formation problem determines the decomposition of the manufacturing cells of a production system in which machines are assigned to these cells to process one or more part families so that each cell is operated independently and the intercellular flows are minimised or the number of parts flow processed within cells is maximised. In this paper, a tabu search heuristic—TSCF—that consists of dynamic tabu tenure with a long-term memory mechanism is presented to solve the cell formation problem. Test problems adopted from the literature and generated randomly are used to evaluate the performance of the proposed algorithm. In addition, two methods for quickly generating the initial solutions are proposed, namely the group-and-assign (GAA) method, and the random approach. Computational results indicate that the GAA method, accompanied by the TSCF algorithm can produce optimal solutions in less than or equal to 0.005 s for all small- and medium-sized problems. The proposed algorithm should thus be useful to both practitioners and researchers.
TL;DR: In this paper, a genetic algorithm is used as the basic foundation for optimal tolerance allocation to help design and manufacturing engineers to overcome the shortcomings in the conventional tolerance stack analysis and allocation system.
Abstract: Conventional tolerance analysis is tedious and time consuming, which makes engineers resist doing it. Complex assembly problems are generally beyond the capabilities of most design and manufacturing engineers. In this paper, genetic algorithm, a kind of non-traditional optimization technique is used as the basic foundation for optimal tolerance allocation to help design and manufacturing engineers to overcome the shortcomings in the conventional tolerance stack analysis and allocation system.
TL;DR: In this article, an experimental study is conducted to diamond-cut BK7 glass in ductile mode, where the authors present the feasibility of achieving nanometric surfaces and show that tool wear is a severe problem.
Abstract: Owing to brittleness and hardness, optical glass is one of the materials that is most difficult to cut. Nevertheless, as the threshold value of the undeformed chip thickness is reached, brittle materials undergo a transition from the brittle to the ductile machining region. Below this threshold, it is believed that the energy required to propagate cracks is larger than the energy required for plastic deformation. Thus, plastic deformation is the predominant mechanism of material removal in machining these materials in this mode. An experimental study is conducted to diamond-cut BK7 glass in ductile mode. As an effective rake angle plays a more important role than a nominal rake angle does, a discussion about this effective angle is carried out in the paper. The investigation presents the feasibility of achieving nanometric surfaces. Power spectral density (PSD) analysis on the machined surfaces shows the difference between the characteristics of the two modes. During the experiments, it is recognised that tool wear is a severe problem. Further study is in process to improve the cutting tool life.
TL;DR: In this paper, a collaborative research program aimed at investigating the use of quick EDM electrodes obtained via appropriate rapid prototyping techniques in finishing laser-sintered tools was described.
Abstract: This paper describes a collaborative research programme aimed at investigating the use of quick EDM electrodes obtained via appropriate rapid prototyping techniques in finishing laser-sintered tools. Two methods were employed in obtaining the EDM electrodes: copper coating of stereolithography models and copper coating of direct metal laser sintered (bronze) models. The amount of copper deposited on both electrode models proved problematic as the electroplating process was unable to deposit enough copper in the inner cavities of the electrodes, with very gradual reduction in copper layer thickness from the outer faces/surface to virtually no deposition in the inner walls and bottom face. Consequently, the electrodes were not suitable for the envisaged EDM process.
TL;DR: In this paper, the authors investigated the mechanisms of void generation and growth in the cross-wedge rolling process using specialised experiments and the explicit dynamic finite element model (FEM).
Abstract: Internal defects in the cross wedge rolling (CWR) process can lead to the catastrophic failure of products. Using specialised experiments and the explicit dynamic finite element model (FEM), this work investigates the mechanisms of void generation and growth in the cross wedge rolling process. Based on a combined numerical and experimental approach, the morphology of void generation is determined as a function of the workpiece material and three primary parameters in the cross wedge rolling process: the forming angle, α, the stretching angle, β and the area reduction, Δ
A
. Through the definition of a non-dimensional deformation coefficient, e, a method for predicting the likelihood of void formation is subsequently ascertained and discussed with respect to CWR tooling design and operating conditions.
TL;DR: This paper summarises the methods used for Web-based remote sensing and monitoring, the design and implementation of Web-enabled virtual instruments, the architecture of the collaborative maintenance platform, and the design for the mini-servers.
Abstract: Optimised maintenance can reduce operating costs by demanding less resources and avoiding equipment breakdown, hence ensuring that daily manufacturing and production will not be interrupted. Web-based maintenance is one of the most efficient methods for optimising maintenance. The Web-based maintenance system that we have developed uses virtual instruments, to provide remote sensing, monitoring, and on-line fault diagnosis for equipment, together with a collaborative maintenance platform for international experts to interactively share their experiences in maintenance. Moreover, Web-based maintenance is suitable for multi-tasking and multi-user types of industrial work environments. In this paper, we summarise the methods used for Web-based remote sensing and monitoring, the design and implementation of Web-enabled virtual instruments, the architecture of the collaborative maintenance platform, and the design for the mini-servers. Each mini-server is equipped with a conventional mini-Web-server and a data acquisition (DAQ) server. With the help of Web-based maintenance, local companies can be transformed into global companies providing services to their customers anywhere and at anytime.