Showing papers in "International Journal of Computer Aided Engineering and Technology in 2011"

An integrated modelling approach in support of next generation reconfigurable manufacturing systems

Abstract: Dynamism and uncertainty are real challenges for present day manufacturing enterprises (MEs) Choosing and applying the best philosophies and techniques is very difficult as most MEs deploy complex and unique configurations of processes and resource systems to cope with changing product flows It follows that systematic methods of achieving model-driven reconfiguration and interoperation of component-based manufacturing systems are required to design, engineer and change next generation (NG) MEs This paper describes a novel systematic approach, namely an integrated modelling approach (IMA), designed to support next generation reconfigurable manufacturing systems (NGRMS) The IMA is helpful in creating coherent sets of models that facilitate the engineering of production planning and control (PPC) strategies Coherent multi-perspective industrial case study models are also presented that have facilitated process reengineering and associated resource system configuration Those models have a capability to enable PPC decision making in support of complex organisation design and change (OD&C)

Implementation of Six Sigma in Indian industries – a Delphi study

Abstract: A Delphi study was carried out to review and analyse the critical issues that affect Six Sigma initiatives in Indian context. This research is aimed at assisting Six Sigma management professionals, researchers and organisations to gain a better understanding of the critical factors that affect the successful implementation of the programme in India, and its future evolution. Consensus among experts has been arrived upon various issues related to implementation of Six Sigma. The expert opinions invited on various issues have been discussed in the context of present scenario. The main consensual issues as prioritised by the experts are top management commitment, developing an effective system for project selection, monitoring and selection of right people, with strong emphasis on training. The experts' priorities also focus on effective resource management and communication system. Based on the conclusion drawn from the study and literature reviewed, the effective implementation of Six Sigma also warrants the identification of the risk associated with it, and the development of an appropriate system to mitigate the risk at the earliest.

Partitioning and scheduling technique for run time reconfigured systems

Abstract: With tremendous improvement in FPGA technologies over the last decade, various high performances, low cost FPGAs are now available. This has enabled the development of cost effective, high speed reconfigurable boards called run time reconfigured (RTR) system. These boards, due to the abundant hardware resource available, enhance the amount of design parallelism by several magnitudes in comparison to ASIC designs of comparable cost. The advent of such high performance FPGA boards has brought a new research problem: the temporal partitioning problem. In the literature, the main objective of related algorithms in this field is to find the minimal execution time of the input graph on a fixed-size of area. However, this paper focuses on introducing a new temporal partitioning algorithm. It divides the input task graph into an optimal number of partitions and puts each task in the appropriate partition in order to decrease the transfer of data required between partitions of the design.

An improved scheme for online recognition of control chart patterns

Abstract: This paper proposes two alternative schemes for the online recognition of control chart patterns (CCPs), namely: 1) a scheme based on direct continuous recognition; 2) a scheme based on 'recognition only when necessary'. The study focuses on recognition of six CCPs plotted on the Shewhart X-bar chart, namely, random, shift-up, shift down, trend-up, trend-down and cyclic. The artificial neural network (ANN) recogniser used was based on multilayer perceptrons (MLPs) architecture. The performance of the schemes was evaluated based on percentage correct recognition, average run lengths (ARL) and average recognition attempts (ARA). The findings suggest that the online recognition should be made only when necessary. Continuous recognition is not only wasteful, but also results in poorer results. The methodology proposed in this study is a step forward in realising a truly automated and intelligent online statistical process control chart pattern recognition system.

A framework for fit manufacturing

Abstract: The near collapse of the global economy in 2008/2009 and the resultant losses in manufacturing jobs and capacities have unleashed a new wave of challenges and opportunities and created the need to re-think manufacturing strategies. In these turbulent times, manufacturing companies must look beyond improving manufacturing processes as a panacea to remain in business. The focus should now be on developing a new integrated manufacturing strategy that combines the strengths of leanness and agility with sustainability to deliver long-term fitness. Fit manufacturing offers a superior manufacturing model that leads to the development of fit enterprises capable of delivering sustainable benefits in an ever changing complex environment. The main objective of the paper is to present a framework for further development of fit manufacturing. The paper also discusses the concept of economic sustainability as it relates to manufacturing firms.

Automated design of fixtures based on FEM simulations

Abstract: With the aim of improving the availability and performance of machine tools, gentelligent® components for machine tools are developed at the Institute of Production Engineering and Machine Tools (IFW), Germany, starting with a fixturing system Being the interface between the machine tool and the workpiece, these systems allow a first evaluation of the potentials of a gentelligent production system This paper presents an approach for the design of the fixturing as a component of a sensing machine tool on the basis of finite elements simulations The fixture design is adapted to the workpiece geometry and properties as well as to the loads resulting from the machining process This is achieved by minimising the deformation of the workpiece and thus increasing the accuracy The method developed comprises five stages: the analysis of fixture elements, the preprocessing of input (G-code), reduction of input data for the sake of computation time, computation of subconfigurations and assessment and comparison of all subconfigurations

Queuing network modelling techniques for response time enhancement in electronics assembly

Abstract: The concept of quick response manufacturing points up that industrial manufacturing companies pressed to compete on speed by emerging competitor must change the management mind-set and reduce lead times throughout the organisation. As a factory's work-in-process, lead times and capacity are the result of complex dynamics in the production system, to predict whether a decision will improve lead times, it is necessary to be able to forecast both process and queue times. In this paper, a novel approach based on analytical techniques for queuing network modelling, called rapid modelling technology (RMT), is implemented via the MPX© software package for complex shop floor operations modelling. The main scopes of the MPX© utilisation are to evaluate the human and economic resources of a printed circuit board (PCB) producer company and to find solutions for the optimisation of the PCB manufacturing system performances.

Thermodynamic properties calculation in Ni-Cr-Co liquid alloys using FactSage

Abstract: The thermodynamic properties of liquid binary and ternary alloys in Ni-Cr-Co system, obtained by FactSage thermodynamic calculations, are presented. Thermodynamic calculations for three binary systems – Ni-Cr, Ni-Co and Cr-Co and ternary Ni-Cr-Co system, involved thermodynamic determination of activities, coefficient of activities, partial and integral values for enthalpies and Gibbs energies of mixing and excess energies at four different temperatures: 2,000 K, 2,173 K, 2,200 K and 2,273 K, as well as calculation of phase diagrams for the investigated binary systems.

Design concept and network reliability evaluation of ATM system

Abstract: This paper presents design concept, security analysis for customer satisfaction, performance ability, and software reliability of ATM system. Computerised telecommunication device as automated teller machines (ATMs) has altered the relationship between banks and their depositors, as well as the competitive relationships among banks. A simple ATM backbone network reliability model covering network connectivity and network performability has been presented based on reference architecture in a telecommunications network context. ATMs' problems are related to design of ATM, safety and security, reliability, comfortable operability, expansibility, and polyfunctionality. The comfortable operability is related to the universal design. We address the network reliability with respect to connectivity and performability in an ATM communication network context. The connectivity aspect refers to the availability of a path from a source node to a destination node. This paper describes the reliable design considerations, security modifications, and reliability models for excellent network connectivity and performability of the ATM system.

Manufacturing cell formation using artificial immune system

Abstract: The cellular manufacturing system is a well-known strategy which improves the production efficiency and cutting down the manufacturing cost. The main problem in designing cellular manufacturing system is cell formation, which is concerned with grouping parts with similar processing required into part families and associated machines into machines and minimises the exceptional elements. This paper presents the artificial immune system method to solve the manufacturing cell formation problems with the objective to minimise the exceptional elements. This method is applied to the existing datasets found in the literature and it is found to out performs other methods.

Effects of fibre content on the mechanical properties of short roselle/sisal fibre polyester hybrid composite

Abstract: In this paper, the mechanical properties of short roselle and sisal hybrid fibre reinforced polyester composite were analysed based on the wt% for constant length of the fibres. The fractured surfaces of the composite specimens were investigated using scanning electron microscopy (SEM). A positive hybrid effect was observed in tensile and flexural strength, while the fibre content increase. But a scatter and negative hybrid effect were observed in impact strength, while the fibre content increase. The results suggest that by using correct or optimum weight percentage of roselle and sisal fibres, one can get the better mechanical performance in short roselle and sisal fibre hybrid polyester composites.

An IEC 61499 distributed control concept for reconfigurable robots

Abstract: Current trends such as shorter product lifecycles, reduced time-to-market and mass-customisation require new paradigms and approaches for production lines and machines. In the long term, production and manufacturing companies will only be able to survive in the face of increasing globalisation if they can react flexibly and quickly to changing customer and market demands. New paradigms and approaches are waiting to fulfil these requirements, but their implementation requires completely new technologies. Reconfiguration, both at machine (physical) and control technology (logical) level is a promising candidate to achieve the flexibility required by these paradigms by technical means. This makes a shift from centrally controlled, highly interlinked, and often tightly interlocked production systems to distributed, modular, collaborative components essential. This paper describes the distributed control concept for a 6-DOF reconfigurable robot arm based on the IEC 61499 reference model as a demonstration platform for reconfigurable approaches.

Product mix and its optimisation in a paper mill according to the profitability computation of process measurements

Abstract: Conventionally, the calculation of the product profitability in the paper mills has been made according to a standard recipe, i.e., based on experience that comes from the knowledge and understanding of the process, however, not according to the actual process measurement data, which has been seen too inaccurate so far. We studied this issue by using, among other relevant variables, flow and consistency measurements of the raw materials. By applying a standard recipe, a consumption calculation is made according to assumed raw material percentages, but, instead, we estimated them on the basis of process measurements data, such as flow and consistency. To consider product profitability, the raw material consumption is first calculated and then the mutual profitability of products and ultimately the product mix are estimated noting production and sales limits. In order to optimise the product mix, which corresponds to the division of production into different products desired, we introduced a heuristic model which is simpler and easier to control than a linear model. On the basis of the results, we can discredit the belief that guessing by using the standard recipe could yield a better accuracy than using process measurements.

Swarm intelligence based system identification and controller tuning

Abstract: This paper presents an application of particle swarm optimisation (PSO) for system identification and tuning of the proportional integral (PI) controller in pH process. Two independent swarms are used sequentially for system identification and PI controller tuning. The proposed PSO utilises self tuning regulator to search for the changes in system parameters and to calculate the corresponding controller parameters. The self tuning regulator has a parameter identification function and requires neither prior knowledge nor training data for learning. Once the process parameters are identified, another PSO is applied to find the optimal controller setting. The performance of the proposed PSO approach is compared with the traditional Ziegler Nichols tuning and internal model control for various set point and trajectory response of the pH process. The simulation results show that the cascaded PSOs are very effective to adapt the controller to dynamic plant characteristic changes in pH process.

Investigation on the effect of hybridisation and weathering behaviour of natural fibre polymer composites

Abstract: The performance and behaviour of various natural fibres and their hybrids with synthetic glass fibre composites were investigated in this work. The composites were fabricated using moulding method. The tensile compressive and flexural strength of the fabricated composites were tested using universal testing machine (UTM). From the load-displacement graph obtained from UTM, the effect of fibres and its hybridisation with glass fibre on the ultimate stress and the displacement on loading were analysed. The impact strength of the un-notched composites was analysed using charpy impact tester. The water immersion tests were also conducted to ensure the weathering behaviour/suitability of this moulded composite under some moisture conditions. From the experimentations it was concluded that the natural fibres can become a best competitor to eliminate or decrease the use of conventional fibre reinforcement. In general, the hybridisation of natural fibre composites enhances the mechanical properties.

Behaviour and integration of service-oriented automation and production devices at the shop-floor

Abstract: Automation and manufacturing systems are changing in the direction of cooperative ecosystems with heterogeneous entities. An important feature that should be considered is the vertical integration from the business needs down to the shop-floor where the real action takes place. This paper analyses the integration of shop-floor devices into the IT-enterprise but maintaining also a certain degree of independence in terms of behaviour. Service-oriented paradigm is used as the main backbone due its proven merits in the business levels and recently also in automation and production systems. In the provided example, high-level Petri nets (HLPN) demonstrate a set of useful features, namely the partial behaviour description and analysis and some parameters in the integration. The resulting application leads to an easy integration of autonomous devices in the IT-enterprise, taking especially in account the requirements of the shop-floor level.

Experimental research of chip formation mechanism during high speed machining of hardened steel

Abstract: The development of chip morphology, critical cutting conditions of serrated chip formation and cutting forces were observed and measured by high speed machining experiment for 30CrNi3MoV hardened steel. Results show that the cutting speed and rake angle are leading factors to influence chip morphology and cutting forces. With the increase of cutting speed, the continuous band chip transforms into serrated chip at a certain critical value. As the rake angle is changed from positive to negative, the critical cutting speed significantly decreases, the cutting forces abruptly reduces when the serrated chip forms. The results from predicting critical cutting speed using the critical cutting condition criterion of adiabatic shear in metal cutting process show that the leading reason of serrated chip formation is that the adiabatic shear fracture repeatedly occurs in the primary shear zone.

Modelling and development of decision model for supplier selection in process industry

Abstract: The selection of appropriate supplier is one of the most critical decisions in the competitive business environment. In this study a decision support model has been developed for supplier selection using analytic hierarchy process by considering both qualitative and quantitative criteria. The proposed model is illustrated with a case study of an electroplating industry to demonstrate the effectiveness of this model. Through the proposed model, it is promising to effectively combine the specialised knowledge, experience and the quantitative data to select the best suppliers.

Smart connected and interactive production control in a distributed environment

Abstract: The European research project INT-MANUS embedded in the I*PROMS European network of excellence addresses the increasing demand for flexibility and adaptivity, which is summarised by rapid reconfiguration of complete factories, flexible reaction to new demands as well as related aspects in human computer interaction (HCI), software, and production systems. The project's main goal has been to develop a new technology for the production plants of the future: the Smart Connected Control Platform (SCCP). This platform allows controlling a factory with the help of an open distributed and learning agent platform that integrates machines, robots, and human personnel. It offers an enterprise service bus like concept for dynamic and decentrally controlled production systems, which flexibly connects machines and IT systems like robotic transport systems, terminals, mobile control systems, etc.

Towards an Auto-ID-enabled framework for manufacturing information sharing systems

Abstract: The current research on automatic identification (Auto-ID) boosts a broad spectrum of applications in manufacturing. In addition, Auto-ID technology provides a method for a product to retrieve its required information rapidly when it is transmitted through shop floors and the supply chain, during which the information generated by Auto-ID systems can facilitate the ubiquitous scenarios in manufacturing and initial stages of the product's whole lifecycle such as ordering, design, and production. This paper proposes a framework of the Auto-ID-enabled manufacturing information sharing system (AIDMISS) that allows the seamless and integrated access to manufacturing information (e.g., product information, design information, sales information), as well as the whole lifecycle management of products. Taking advantage of the Auto-ID system, information enhancement can be realised by using the proposed framework to enable the information sharing process in manufacturing activities across an enterprise. From the ca...

A new approach to nullify surplus parts in selective assembly

Abstract: Selective assembly is a generally accepted method for producing high precision assemblies from relatively low precision components. The mating parts are manufactured with wide tolerances. The mating part population is partitioned to form selective groups. The corresponding selective groups are then assembled interchangeably. The accuracy of selective assembly is mainly based on the number of selective groups (fixed before the assembly) and the range of selective groups. However, there are often surplus parts in some groups due to the imbalance of mating parts, especially in the case of undesired dimensional distributions. This paper presents a new approach to nullify the surplus parts in selective assembly.

Discovery of association rules from manufacturing data

Abstract: Manufacturing activities generate large quantities of data and it is no longer practical to rely on traditional manual methods to analyse these data. Data mining offers tools for efficient knowledge extraction, leading to significant improvement in the decision-making process. Association rule mining is one of the most important data mining techniques and has received considerable attention from researchers and practitioners. It aims to identify interesting relationships among a large set of data items. To date, little work has been done to exploit association rule mining tools in manufacturing. This paper presents the basic concepts of association rule mining and describes a number of its recent applications in manufacturing. The paper also presents a case study concerning the use of association rule mining in a steel bar manufacturing company.

Electricity market price forecasting using support vector machines

Abstract: Due to the electricity market deregulation, the techniques used for load forecasting have gradually improved over the years. Deregulation in the power system industry has caused rising requirement in planning, operating and controlling electric energy systems, which brings electricity load forecasting to a crucial level. Therefore, adequate techniques are desired for accurately predicting the load and hence assisting power companies in generating capacity scheduling, maintenance, energy planning and procurement, etc. An accurate forecast can greatly help power distribution companies to improve their electricity marketing strategies and avoid over or under unitisation of generating capacity and therefore optimises energy prices. But, to predict the load demand in real time requires a considerable amount of efforts. This paper presents a design methodology for a short term load forecasting useful for distribution companies, which are capable of interacting with users, gathering historical load data, performing a statistical analysis on the historical data and plotting graphs of the predicted load using the support vector machine (SVM). SVM is the chosen forecasting technique because many studies have concluded that SVMs produce the optimum accuracy as compared to other methods such as Naive Bayesian, but SVM has not been optimised for the domain.

Characterisation of delamination failure in composite wind turbine blade using refined delamination factor

Abstract: Wind turbine is now being used as a generic term for machines with rotating blades that convert the kinetic energy of wind into useful power. Utilisation of renewable wind energy in India increases in many folds from the last decade of 20th century. The wind turbine blades are fabricated using glass fibre reinforced composite materials. Wind turbine blades are complex section, since it includes the aerofoil section of varying thickness from leading to trailing edge, varying chord length from hub section to tip section, inclusion of blade twist angle and pitch angle along its length. In order to improve the strength of the blades under varying loading conditions, spars are embedded in it. The spars are fastened with the composite shells of the blades using bolted connections. In order to affect this fastening, holes of appropriate size were drilled in the composite laminates. Drilling is probably the machining process most widely applied to composite materials; nevertheless, the damage induced by this operation may reduce drastically the component performance. In order to establish the damage level, delamination is measured quantitatively using digital means. A comparison between the conventional (FD) and adjusted (FDA) delamination factor is presented. In order to quantify the delamination effectively, refined delamination factor (FDR) is proposed.

A network model for material handling with split loads using AGVS in machine modules

Abstract: The automatic guided vehicle system (AGVs) is an important element for material handling facility in the computer integrated manufacturing. The essential capability of an AGV is the ability to transfer loads to remote locations or through complex paths under computer control. They are used to move jobs between work stations on a factory floor. Research in this area is directed towards the development of a path layout design and routing algorithms for vehicle movement and control. The problem is to design a path layout and a routing algorithm minimising the distance travelled by AGVs considering sufficient but necessary conditions. Split loads concept is implemented for material handling for effective utilisation of AGVs. The capacity utilisation is analysed in terms of the distance travelled and the time required for AGVs to complete all pickup and drop-off jobs. Numerical results are presented to compare performance of the proposed model.

CFD simulation studies and experimental validation on a parallel plate heat sink

Abstract: The use of finned heat sinks in air cooled electronics components and assemblies increase the effective surface area for convective heat transfer, thereby, reducing the operating temperatures of these electronic devices. The objective of a heat sink is to achieve maximum heat dissipation, while restricting the consumption of valuable resources such as mass, fan power, pressure drop and space. Optimal design of the heat sink is a significant task. Therefore, preliminary studies on the heat transfer characteristics of a parallel plate heat sink have been carried. In this research work, the geometric parameters considered are fin height, fin thickness, base height and fin pitch. The simulation is carried out with a commercial computational fluid dynamics (CFD) package provided by Fluent Inc. Experimental validation of simulation results have been performed. In this study, the geometric parameters namely fin height, fin thickness, base height and fin pitch are found to be optimal at 48 mm, 3 mm, 4 mm and 3 mm respectively for an efficient heat sink design.

A multiple view product model for reflector and lens in automotive headlamps with reconfigurable tooling for manufacture

Abstract: While developing a product, product development groups involved create knowledge on selected attributes of the product from several functional perspectives. This process is highly iterative and the information models used for product development are to provide consistent and manageable solutions. That is, the knowledge available from upstream functions is transferred to the downstream teams for further processing. This leads to the concept of view as practised in industry and hence the relevance of multiple view information models. In product design context it is better known as multiple view product model. This paper tries to formulate a methodology for development of a headlamp for passenger cars as per the requirements of OEMs by a supplier. Headlamps in passenger cars are subjected to changes when the exterior of the car is modified. Major components subjected to change are the reflector and clear glass lens. The reflector and lens represent two different 'streams' of product lines based on their uniqueness in surface development. This is the basis for mapping of the products on to the manufacturing processes.

Automatic setup planning system using a neutral part data exchange format

Abstract: The task of automatic setup planning includes grouping machining features into setups, selecting setup datum and sequencing the setups. A feasible setup plan satisfies fundamental manufacturing constraints and assures that the part is machined to meet design specification. The objective of this work is to automatically generate and evaluate setup plans for complete machining of a given component while simultaneously considering the feature tolerance relationships, feature dependencies, general manufacturing rules, critical machine spatial constraints and fixturing feasibility. The methodology developed during the present work minimises the number of setups and machining tolerances, decides the setup sequence and generates the setups' information and the intermediate work piece geometry. The component geometry with identified machining features and their access directions is taken as input from a neutral part data exchange format STandard for the Exchange of Product data (STEP) model. The procedure for generation of setup planning results and visualisation of intermediate work piece model is presented and demonstrated with the help of case studies.

CAD utilisation at the concept design – a case study

Abstract: Generally for any new design initially a concept layout in 2D CAD is generated. But sometimes, if the geometry of the product becomes complicated, then 3D CAD model is preferred, because 3D CAD model can give us a complete all side view at a time like a real product, but in a virtual world. The present case study will show the utilisation of 3D CAD at the concept design stage of a complicated shaped product for a new system. This will also give an idea about cost and time comparison. This will also show how 3D CAD model can also helps to analyse the product. Thus, this paper will describe about the importance of 3D CAD tools for product development.

Implementation of genetic optimisation technique in small-scale industries

Abstract: The turning centre is so versatile that they find wide applications in all the manufacturing industries. Hence, it is desired to optimise the operating parameters of the turning process. Data collected from two different industries for two different components are used for optimising. Single optimisation procedure by genetic algorithm has been developed in this work which is applied for turning process. In this paper, we prove that an average of around 17.78% reduction in machining time is possible by applying genetic algorithm. Further, the same procedure can be applied to other production processes such as milling, grinding, welding and electrical discharge machining.