Showing papers in "The International Journal of Advanced Manufacturing Technology in 2010"

Current status of machine prognostics in condition-based maintenance: a review

Abstract: Condition-based maintenance (CBM) is a decision-making strategy based on real-time diagnosis of impending failures and prognosis of future equipment health. It is a proactive process that requires the development of a predictive model that can trigger the alarm for corresponding maintenance. Prognostic methodologies for CBM have only recently been introduced into the technical literature and become such a focus in the field of maintenance research and development. There are many research and development on a variety of technologies and algorithms that can be regarded as the steps toward prognostic maintenance. They are needed in order to support decision making and manage operational reliability. In this paper, recent literature that focuses on the machine prognostics has been reviewed. Generally, prognostic models can be classified into four categories: physical model, knowledge-based model, data-driven model, and combination model. Various techniques and algorithms have been developed depending on what models they usually adopt. Based on the review of some typical approaches and new introduced methods, advantages and disadvantages of these methodologies are discussed. From the literature review, some increasing trends appeared in the research field of machine prognostics are summarized. Furthermore, the future research directions have been explored.

Study of mechanical properties of AISI 316 stainless steel processed by “selective laser melting”, following different manufacturing strategies

Abstract: Considering additive manufacturing (AM) as a field of major interest, this paper is focused on the study of the mechanical properties and their variability with manufacturing orientation (anisotropy) for a metallic alloy manufactured by AM, using the technology of selective laser melting (SLM). This study has been performed on an austenitic stainless steel—AISI 316 L—used for many industrial fields as chemical, cellulose, and medical, among them. Finally, the obtained properties have been analyzed and compared, for this steel, to those properties standardized and tested for “wrought” products. In this paper, previously published results are complemented, as the mechanical tests have been performed in all the possible directions of manufacturing by SLM and not only in two main directions. High mechanical values have been obtained, especially yield strength (significantly improved, compared with wrought or cast products) while keeping high values of ductility and notch impact resistance. For widespread industrial acceptance, AM parts need to be produced to high tolerances and with well-understood mechanical properties, and the aim of this paper is to contribute to this objective.

A review of machining monitoring systems based on artificial intelligence process models

Abstract: Many machining monitoring systems based on artificial intelligence (AI) process models have been successfully developed in the past for optimising, predicting or controlling machining processes. In general, these monitoring systems present important differences among them, and there are no clear guidelines for their implementation. In order to present a generic view of machining monitoring systems and facilitate their implementation, this paper reviews six key issues involved in the development of intelligent machining systems: (1) the different sensor systems applied to monitor machining processes, (2) the most effective signal processing techniques, (3) the most frequent sensory features applied in modelling machining processes, (4) the sensory feature selection and extraction methods for using relevant sensory information, (5) the design of experiments required to model a machining operation with the minimum amount of experimental data and (6) the main characteristics of several artificial intelligence techniques to facilitate their application/selection.

Application of soft computing techniques in machining performance prediction and optimization: a literature review

Abstract: Machining is one of the most important and widely used manufacturing processes. Due to complexity and uncertainty of the machining processes, of late, soft computing techniques are being preferred to physics-based models for predicting the performance of the machining processes and optimizing them. Major soft computing tools applied for this purpose are neural networks, fuzzy sets, genetic algorithms, simulated annealing, ant colony optimization, and particle swarm optimization. The present paper reviews the application of these tools to four machining processes—turning, milling, drilling, and grinding. The paper highlights the progress made in this area and discusses the issues that need to be addressed.

The economics of cell phone reuse and recycling

Abstract: There is widespread consensus that landfill of waste electronic and electric equipment is not an acceptable end-of-use management option. Diversion from landfill, either through voluntary or mandatory take-back and collection programs, overwhelmingly leads to the recycling of e-waste, which typically consists of the recovery of a limited number of metals. Cell phones are currently one of the few electronic products, if not the only one, that also have a thriving reuse market. In fact, more handsets are reused than recycled. Cell phones therefore offer the rare opportunity to compare closed-loop supply chains for e-waste reuse and recycling. In this paper, we examine the economics of cell phone reuse and recycling based on detailed primary data collected from reverse logistics, reuse and recycling operations in 2003 in the UK and in 2006 in the US. We show that while cell phone reuse has a healthy profit margin, handset recycling is currently a by-product of reuse.

Review of research work in sinking EDM and WEDM on metal matrix composite materials

Abstract: Metal matrix composites (MMCs) are newly advanced materials having the properties of light weight, high specific strength, good wear resistance and a low thermal expansion coefficient. These materials are extensively used in industry. Greater hardness and reinforcement makes it difficult to machine using traditional techniques, which has impeded the development of MMCs. The use of traditional machinery to machine hard composite materials causes serious tool wear due to the abrasive nature of reinforcement. These materials can be machined by many non-traditional methods like water jet and laser cutting but these processes are limited to linear cutting only. Electrical discharge machining (EDM) shows higher capability for cutting complex shapes with high precision for these materials. The paper presents a review of EDM process and year wise research work done in EDM on MMCs. The paper also discusses the future trend of research work in the same area.

Comparative study of different dielectrics for micro-EDM performance during microhole machining of Ti-6Al-4V alloy

Abstract: In microelectrodischarge machining (micro-EDM), dielectric plays an important role during machining operation. The machining characteristics are greatly influenced by the nature of dielectric used during micro-EDM machining. Present paper addresses the issues of micro-EDM utilizing different types of dielectrics such as kerosene, deionized water, boron carbide (B4C) powder suspended kerosene, and deionized water to explore the influence of these dielectrics on the performance criteria such as material removal rate (MRR), tool wear rate (TWR), overcut, diameteral variance at entry and exit hole and surface integrity during machining of titanium alloy (Ti-6Al-4V). The experimental results revealed that MRR and TWR are higher using deionized water than kerosene. Also, when suspended particles, i.e., boron carbide-mixed dielectrics are used, MRR is found to increase with deionized water, but TWR decreases with kerosene dielectric. Further analysis is carried out with the help of scanning electron microscope (SEM) micrographs, and it is found that the thickness of white layer is less on machined surface when deionized water is used as compared to kerosene. Also, a comparative study of machining time has been carried out for the four types of dielectrics at different machining parametric settings. Furthermore, the investigation on the machined surface integrity and wear on microtool tip have also been done in each type of the dielectrics with the help of SEM micrographs and optical photographs. Hence micro-EDM machining on Ti-6Al-4V work material with B4C-mixed dielectrics is performed in the investigation and reported the performance criteria of the process. It can be concluded from the research investigation that there is a great influence of mixing of boron carbide additive in deionized water dielectrics for enhancing machining performance characteristics in micro-EDM during microhole generation on Ti-6Al-4V alloy.

Micro-manufacturing: research, technology outcomes and development issues

Abstract: Besides continuing effort in developing MEMS-based manufacturing techniques, latest effort in micro-manufacturing is also in non-MEMS-based manufacturing. Research and technological development in this field is encouraged by the increased demand on micro-components as well as promised development in the scaling down of the traditional macro-manufacturing processes for micro-length-scale manufacturing. This paper highlights some EU funded research activities in micro/nano-manufacturing, and gives examples of the latest development in micro-manufacturing methods/techniques, process chains, hybrid processes, manufacturing equipment and supporting technologies/device, etc., which is followed by a summary of the achievements of the EU MASMICRO project. Finally, concluding remarks are given, which raise several issues concerning further development in micro-manufacturing.

Optimization of the EDM parameters on machining Ti–6Al–4V with multiple quality characteristics

Abstract: In this paper, parameter optimization of the electrical discharge machining process to Ti–6Al–4V alloy considering multiple performance characteristics using the Taguchi method and grey relational analysis is reported. Performance characteristics including the electrode wear ratio, material removal rate and surface roughness are chosen to evaluate the machining effects. The process parameters selected in this study are discharge current, open voltage, pulse duration and duty factor. Experiments based on the appropriate orthogonal array are conducted first. The normalised experimental results of the performance characteristics are then introduced to calculate the coefficient and grades according to grey relational analysis. The optimised process parameters simultaneously leading to a lower electrode wear ratio, higher material removal rate and better surface roughness are then verified through a confirmation experiment. The validation experiments show an improved electrode wear ratio of 15%, material removal rate of 12% and surface roughness of 19% when the Taguchi method and grey relational analysis are used.

Effect of machining parameters on surface roughness and tool wear for 7075 Al alloy SiC composite

Abstract: In the present study, an attempt has been made to investigate the influence of cutting speed, depth of cut, and feed rate on surface roughness during machining of 7075 Al alloy and 10 wt.% SiC particulate metal-matrix composites. The experiments were conducted on a CNC Turning Machine using tungsten carbide and polycrystalline diamond (PCD) inserts. Surface roughness of 7075Al alloy with 10 wt.% SiC composite during machining by tungsten carbide tool was found to be lower in the feed range of 0.1 to 0.3 mm/rev and depth of cut (DOC) range of 0.5 to 1.5 mm as compared to surface roughness at other process parameters considered. Above cutting speed of 220 m/min surface roughness of SiC composite during machining by PCD tool was less as compared to surface roughness at other values of cutting speed considered. Wear of tungsten carbide and PCD inserts was analyzed using a metallurgical microscope and scanning electron microscope. Flanks wear of carbide tool increased by a factor of 2.4 with the increase of cutting speed from 180 to 240 m/min at a feed of 0.1 mm/rev and a DOC of 0.5 mm. On the other hand, flanks wear of PCD insert increased by only a factor of 1.3 with the increase of cutting speed from 180 to 240 m/min at feed of 0.1 mm/rev and DOC 0.5 mm.

Producing of AZ91/SiC composite by friction stir processing (FSP)

Abstract: Friction stir processing (FSP) was used to fabricate SiC/AZ91 composite layer. Effect of process parameters such as rotational and traverse speeds, tool penetration depth and tilt angle on the formation of defects such as cracks, tunnelling cavity and also on sticking of matrix material to the tool was investigated. Also, effect of these parameters was studied on the mechanical properties and microstructures of specimens. Microstructure studies were carried out by optical and SEM. Results showed that FSP is an effective process to fabricate SiC/AZ91 composite layer with uniform distribution of SiC particles, good interfacial integrity and significant grain refinement. Increasing the rotational speed leads to a decrease in the grain size and an increase in the traverse speed leads to a decrease in the grain size. There are upper and lower limitations for these speeds which were determined. PD is a more effective parameter to produce sound surface layer. PD value was affected by traverse and rotational speeds and the tilt angle values. This study shows that by using 5 μm SiC particles, the stir zone grain size reduces from 150 to 7.17 μm and stir zone hardness increases from 63 to 96 Hv.

Reverse logistics network design using simulated annealing

Abstract: Reverse logistics is becoming more important in overall industry area because of the environmental and business factors. Planning and implementing a suitable reverse logistics network could bring more profit, customer satisfaction, and a nice social picture for companies. But, most of logistics networks are not equipped to handle the return products in reverse channels. This paper proposes a mixed integer linear programming model to minimize the transportation and fixed opening costs in a multistage reverse logistics network. Since such network design problems belong to the class of NP-hard problems, we apply a simulated annealing (SA) algorithm with special neighborhood search mechanisms to find the near optimal solution. We also compare the associated numerical results through exact solutions in a set of problems to present the high-quality performance of the applied SA algorithm.

Force prediction for single point incremental forming deduced from experimental and FEM observations

Abstract: The aim of the study was to establish practical formulae allowing to predict the forces occurring during the single point incremental forming process. This study has been based on a large set of systematic experiments on the one hand and on results of finite elements modeling simulations on the other. This led to analytical formulae allowing to compute the three main components of the force for five selected materials in function of the working conditions (sheet thickness, wall angle, tool diameter, and step down) with a good precision. Moreover, a general model has been deduced, allowing to compute an approximate value for the force for any material, based on knowledge of the tensile strength only.

A multi-objective genetic algorithm based on immune and entropy principle for flexible job-shop scheduling problem

Abstract: Flexible job-shop scheduling problem (FJSP) is an extended traditional job-shop scheduling problem, which more approximates to practical scheduling problems. This paper presents a multi-objective genetic algorithm (MOGA) based on immune and entropy principle to solve the multi-objective FJSP. In this improved MOGA, the fitness scheme based on Pareto-optimality is applied, and the immune and entropy principle is used to keep the diversity of individuals and overcome the problem of premature convergence. Efficient crossover and mutation operators are proposed to adapt to the special chromosome structure. The proposed algorithm is evaluated on some representative instances, and the comparison with other approaches in the latest papers validates the effectiveness of the proposed algorithm.

Handling WEEE waste flows : On the effectiveness of producer responsibility in a globalizing world

Abstract: This paper explores the present and future magnitude of global waste of electrical and electronic equipment flows, and investigates desirable changes in these flows from a sustainable development point of view. Quantitative estimates of present and future e-waste flows between global regions, generating, and processing waste are presented and their driving forces are analyzed. Global e-waste production by households exceeded an annual amount of 20 million tons in 2005. Domestic e-waste generation in China has already climbed dramatically, now equalling the amount generated in Japan. China is second in the world after the USA in landfilling and incineration of e-waste residues. Absolute volumes of recycled e-waste are largest in the EU, followed by Japan. After a period characterized by national disposal practices, a period of global low-level recovery practices has emerged. The paper analyzes exogenous factors, including legislating promoting extended producer responsibility, which are favoring as a next step regionalizing of (reverse) supply chains. Examples on a business level are discussed and critical success factors for applying regional high-level recovery are identified. The analysis shows that in the coming decades, two options will compete on a global scale: (1) a further expansion of the present low-level recovery system of e-waste recycling, and (2) a regional approach with higher level recovery applications. The authors argue that putting businesses, more specifically, the original equipment manufacturers, instead of legislators in the driver seat, will strengthen the opportunities for high-level recovery.

Study on tool wear and surface roughness in machining of particulate aluminum metal matrix composite-response surface methodology approach

Abstract: Metal matrix composites (MMC) have become a leading material among composite materials, and in particular, particle reinforced aluminum MMCs have received considerable attention due to their excellent engineering properties. These materials are known as the difficult-to-machine materials because of the hardness and abrasive nature of reinforcement element-like silicon carbide particles (SiCp). In this study, an attempt has been made to model the machinability evaluation through the response surface methodology in machining of homogenized 20% SiCp LM25 Al MMC manufactured through stir cast route. The combined effects of four machining parameters including cutting speed (s), feed rate (f), depth of cut (d), and machining time (t) on the basis of two performance characteristics of flank wear (VBmax) and surface roughness (Ra) were investigated. The contour plots were generated to study the effect of process parameters as well as their interactions. The process parameters are optimized using desirability-based approach response surface methodology.

An AHP model for selection of suppliers in the fast changing fashion market

Abstract: In the fast-changing fashion market, being flexible and adaptive is a key to survival. Therefore, supply chain strategy like quick response is important in the fashion or textile industry. Selection of suppliers to support such strategies is thus one of the most critical activities, but is not well studied. Traditionally, suppliers are selected usually based on quantity requirement and cost, which are not the only important issues in the operation of a textile supply chain nowadays. This study presents an example on solving the supplier selection problem in the apparel industry by using the Analytical Hierarchy Process (AHP), which takes the operational performance (for example, flexibility, cost, and delivery) into account for supporting supply chain strategies. The system was implemented with the aid of the commercial software package Expert Choice. Based on the results from the AHP model, benefits of implementing quick response in apparel supply chains can also be verified.

Electric hot incremental forming of Ti-6Al-4V titanium sheet

Abstract: Electric hot incremental forming of metal sheet is a new technique that is feasible and easy to control to form hard-to-form sheet metals. In the present study, Ti-6Al-4V titanium sheet was studied because it was wildly used in the aeronautics and astronautics industries. Although Ti-6Al-4V titanium can be well-formed in high temperature, the surface quality is a problem. In order to enhance the surface quality, it is very important to select the proper lubricant. At the same time, because Ti-6Al-4V titanium has a lively chemical property, it is very important to choose a processing temperature range in order to acquire excellent plastic property and to prevent oxidation. Various lubricants were selected in processing to compare the effect, and some workpieces were formed at different temperatures to find the best forming temperature. The results show that using the lubricant film of nickel matrix with MoS2 self-lubricating material, Ti-6Al-4V titanium workpiece was formed with high surface quality, and the optimum thickness of composite coating is 20 μm for Ti-6Al-4V titanium sheet of 1.0-mm thickness. In fact, the lubricant film also does help to prevent oxidation of Ti-6Al-4V titanium sheet. The appropriate temperature range of Ti-6Al-4V forming with slightly oxidized is 500–600°C in processing, and the maximum draw angle formed in this range was 72°.

Some recent advances in multi-material micro- and nano-manufacturing

Abstract: The increasing demand for micro-products and components can be met only partly by the lithography-based micro-electromechanical systems fabrication processes that originated from the silicon-based microelectronics revolution of the late twentieth century. In particular, such processes have limitations when applied to new micro-devices which require the use of a variety of materials and complex 3D microstructures with high aspect ratios. In this context, the paper presents technologies complementary to lithography-based processes for the manufacture of devices or components incorporating micro- and nano-scale features. More specifically, special attention is given to the main findings obtained over the last 5 years from the authors’ research programme on a range of micro- and nano-manufacturing technologies, namely, micro-electrodischarge machining, laser ablation, micro-milling, focussed-ion beam machining, micro-injection moulding, nano-imprint lithography, hot embossing and electroforming.

A multi-echelon reverse logistics network design for product recovery—a case of truck tire remanufacturing

Abstract: Due to increasing environmental deterioration, government regulations, social responsibilities, resource reduction, and economic factors, many companies are engaged in the product recovery business. Product recovery refers to the set of activities designed to reclaim value from a product at the end of its useful life. Due to the increasing number of vehicles in the country like India, large quantities of used tires are generated every year, and proper disposal of these used tires creates a significant problem in the day-to-day life. An alternative way to recover the value (tire remanufacturing also called retreading) from the used tire is proposed in this work. The implementation of such remanufacturing system usually requires an appropriate reverse logistics network for choosing the physical locations, facilities, and transportation links to convey the used products from customers to the remanufacturing facility and from there to secondary markets. The main objective of this work is to develop a mixed integer nonlinear programming model for maximizing the profit of a multi-echelon reverse logistics network and also to present a real-life case study of truck tire remanufacturing for the secondary market segment. The proposed model is solved using LINGO 8.0 optimization solver which provides the decisions related to the number of facilities to open, their locations, and also the allocation of the corresponding product flows. Finally, it is concluded that the choice of using retreaded tires is a profitable one by the way of cost reduction. Sensitivity analysis of the model is also presented to find the maximum allowable distance between the customers and initial collection points.

Process capabilities of Micro-EDM and its applications

Abstract: The micro-electrical discharge machining (micro-EDM) process has proved to be an appropriate nonconventional machining method for manufacturing accurate and complex three-dimensional structural micro-features which are difficult to be produced by conventional processes. However, the miniaturisation of the EDM process requests special requirements on the machining equipment. Pulse generators which can produce small input energy pulses and high precision systems are the two major requirements. In this paper, newly developed technologies regarding these aspects are explored with the aid of a commercial micro-EDM machine. By examining the pulses, innovative strategies implemented in the pulse generator are studied. Pulse measurements reveal the correlation between the discharge pulses and the machine parameters in order to provide an overview of process capability. Conclusions are applied on machining of a ceramic composite Si3N4-TiN and optimised machining settings for different machining conditions are achieved. Accordingly, applications of two- and three-dimensional micro-structures on different types of materials such as a stainless steel micro-compressor and a ceramic miniature gas turbine are demonstrated. By inspecting the machining geometry and surface integrity, process characteristics of micro-EDM are discussed.

A new multi-objective ant colony algorithm for solving the disassembly line balancing problem

Abstract: The disassembly line is the best choice for automated disassembly of disposal products. Therefore, disassembly line should be designed and balanced so that it can work as efficiently as possible. In this paper, a mathematical model for the multi-objective disassembly line balancing problem is formalized firstly. Then, a novel multi-objective ant colony optimization (MOACO) algorithm is proposed for solving this multi-objective optimization problem. Taking into account the problem constraints, a solution construction mechanism based on the method of tasks assignment is utilized in the algorithm. Additionally, niche technology is used to embed in the updating operation to search the Pareto optimal solutions. Moreover, in order to find the Pareto optimal set, the MOACO algorithm uses the concept of Pareto dominance to dynamically filter the obtained non-dominated solution set. To validate the performance of algorithm, the proposed algorithm is measured over published results obtained from single-objective optimization approaches and compared with multi-objective ACO algorithm based on uniform design. The experimental results show that the proposed MOACO is well suited to multi-objective optimization in disassembly line balancing.

Environmental and economical sustainability of WEEE closed-loop supply chains with recycling: a system dynamics analysis

Abstract: Nowadays, the worldwide production of electrical and electronic equipment (EEE) is consequently increasing, reducing both resources and landfills. In this manuscript, we investigate the significance of the factors that comprise the environmental sustainability strategies (environmental legislation and green image) and the operational features of the closed-loop supply chain (CLSC) (chain's features, products' features and economic parameters), their interactions and the type of their impact on the environmental (availability of natural resources and landfill availability) and economical sustainability of a WEEE CLSC. We use an extension of a System Dynamics-based model of a CLSC with recycling activities introduced by Georgiadis and Besiou [J Clean Prod 16(15):1665–1678, 2008]. The developed model is validated using data from a real-world CLSC of EEE in Greece. Extended numerical investigation provides insights to the managers of the WEEE CLSC and the legislators with regard to the actions which can lead to sustainability.

Multi-material microstereolithography.

Abstract: We have previously described the development of a microstereolithography (µSL) system using a Digital Micromirror Device (DMD) for dynamic pattern generation and an ultraviolet (UV) lamp filtered at 365 nm for crosslinking a photoreactive polymer solution. The µSL system was designed with x–y resolution of approximately 2 µm and a vertical (z) resolution of approximately 1 µm (with practical build limitations on vertical resolution of approximately 30 µm due to limitations on controlling UV penetration in z). The developed µSL system is capable of producing real three-dimensional (3D) microstructures, which can be employed in applications such as microfluidics, tissue engineering, and various functional microsystems. Many benefits will potentially be derived from producing multiple material microstructures in µSL, and one particular application area of interest is in producing multi-material microscaffolds for tissue engineering. In the present work, a method for multi-material µSL fabrication was developed using a syringe pump system to add a material to a small, removable vat designed specifically for the multi-material µSL system. Multi-material fabrication was accomplished using a material changeover process that included manually removing the vat, draining the current material, rinsing the vat, returning the vat to the system, and finally dispensing a prescribed volume in the vat using the syringe pump. Layer thicknesses of approximately 30 µm were achieved using this process. To demonstrate this system, several multi-material microstructures were produced to highlight the capability of this promising technology for fabricating 3D functional, multi-material microstructures with spatial control over placement of both material and structure.

Predictions of the optimized friction stir spot welding process parameters for joining AA2024 aluminum alloy using RSM

Abstract: The friction stir spot welding process (FSSW) is a variant of the linear friction stir welding process in which the material is being welded without bulk melting. The FSSW parameters such as tool rotational speed, plunge rate, plunge depth, and dwell time play a major role in determining the strength of the joints. A central composite rotatable design with four factors and five levels was chosen to minimize the number of experimental conditions. An empirical relationship was established to predict the tensile shear fracture load of friction stir spot-welded AA2024 aluminum alloy by incorporating independently controllable FSSW process parameters. Response surface methodology (RSM) was applied to optimize the FSSW parameters to attain maximum lap shear strength of the spot weld.

On the stability of high-speed milling with spindle speed variation

Abstract: Spindle speed variation is a well-known technique to suppress regenerative machine tool vibrations, but it is usually considered to be effective only for low spindle speeds. In this paper, the effect of spindle speed variation is analyzed in the high-speed domain for spindle speeds corresponding to the first flip (period doubling) and to the first Hopf lobes. The optimal amplitudes and frequencies of the speed modulations are computed using the semidiscretization method. It is shown that period doubling chatter can effectively be suppressed by spindle speed variation, although, the technique is not effective for the quasiperiodic chatter above the Hopf lobe. The results are verified by cutting tests. Some special cases are also discussed where the practical behavior of the system differs from the predicted one in some ways. For these cases, it is pointed out that the concept of stability is understood on the scale of the principal period of the system—that is, the speed modulation period for variable spindle speed machining and the tooth passing period for constant spindle speed machining.

Extension of VIKOR method based on interval-valued fuzzy sets

Abstract: Decision making is the process of finding the best option among the feasible alternatives. In classical multiple-criteria decision-making (MCDM) methods, the ratings and the weights of the criteria are known precisely. However, if decision makers cannot reach an agreement on the method of defining linguistic variables based on the fuzzy sets, the interval-valued fuzzy set theory can provide a more accurate modeling. In this paper, the interval-valued fuzzy VIKOR method is presented, aiming at solving MCDM problems in which the weights of criteria are unequal, using interval-valued fuzzy set concepts. For application and verification, this study presents a numerical example and builds a practical maintenance strategy selection problem to verify our proposed method. Moreover, a comparison is made between the interval-valued fuzzy VIKOR and other adapted MCDM interval-valued fuzzy number-based.

Recent development in finite element analysis of clinched joints

Abstract: Clinching is a high-speed mechanical fastening technique for point joining of sheet materials. Published work relating to finite element analysis of clinched joints is reviewed in this paper, in terms of process, strength, and vibration characteristics of the clinched joints. It is concluded that the finite element analysis of clinched joints will help future applications of clinching by allowing system parameters to be selected to give as large a process window as possible for successful joint manufacture. This will allow many tests to be simulated that would currently take too long to perform or be prohibitively expensive in practice.

Cryoprocessing of cutting tool materials—a review

Abstract: Cryoprocessing, a supplementary process to conventional heat treatment process, is the process of deep-freezing materials at cryogenic temperatures to enhance the mechanical and physical properties of materials being treated. The execution of cryoprocessing on cutting tool materials increases wear resistance, hardness, and dimensional stability and reduces tool consumption and down time for the machine tool set up, thus leading to cost reductions. The effects of cryoprocessing on tool steels and carbides, metallurgical aspects including reduced amount of retained austenite, precipitation of η-carbides, phase change in carbides, improvement in wear resistance, and applications are reviewed for manufacturing industry. Although it has been confirmed that cryogenic processing can improve the service life of tools, the degree of improvement experienced and the underlying mechanism remains ambiguous. The steps involved in cryoprocessing are critical enough to account for the significant incongruity in post-treated performance.

Grey relational analysis coupled with principal component analysis for optimisation design of the process parameters in in-feed centreless cylindrical grinding

Abstract: This paper investigates optimisation design of an in-feed centreless cylindrical grinding process performed on EN52 austenitic valve steel (DIN: X45CrSi93). The major performance characteristics selected to evaluate the process are surface roughness, out of cylindricity of the valve stem and diametral tolerance, and the corresponding centreless cylindrical grinding parameters are dressing feed, grinding feed, dwell time and cycle time. In this study, since the process is with multiple-performance characteristics, therefore, the grey relational analysis that uses grey relational grade as performance index is specially adopted to determine the optimal combination of centreless cylindrical grinding parameters. Moreover, the principal component analysis is applied to evaluate the weighting values corresponding to various performance characteristics so that their relative importance can be properly and objectively described. The results of confirmation experiments reveal that grey relational analysis coupled with principal component analysis can effectively be used to obtain the optimal combination of centreless cylindrical grinding parameters. Hence, this confirms that the proposed approach in this study can be a useful tool to improve the centreless cylindrical grinding performance of valve stem in in-feed centreless cylindrical grinding process.