Showing papers in "International Journal of Computer Integrated Manufacturing in 2008"
TL;DR: A novel method for the production of body-fitting customized seat profiles utilizing the following digital methods: three-dimensional laser scanning, reverse engineering and rapid manufacturing (RM) is presented.
Abstract: The current paper presents a novel method for the production of body-fitting customized seat profiles utilizing the following digital methods: three-dimensional laser scanning, reverse engineering and rapid manufacturing (RM). Seat profiles were manufactured in order to influence the comfort characteristics of an existing ejector seat manufactured by Martin Baker Aircraft Ltd. The seat, known as the Navy Aircrew Common Ejection Seat (NACES), was originally designed with a generic profile. This paper shows the replacement of this profile with shapes captured from fast jet pilots. Pressure mapping of occupied seats, has shown that the pressure distribution under the buttocks can be influenced using body-fitting design and thus comfort is directly affected. The paper discusses the relevance of RM with respect to mass customization and personalization and, in addition, recognizes RM as a next generation manufacturing system (NGMS) capable of satisfying increasingly diverse products and lower volume production. A generic customization process is reviewed to identify areas of technical difficulty and key issues in the cost-effective customization of products.
148 citations
TL;DR: The authors propose that ubiquitous computing technology can be effectively used for the design and manufacturing of a product by proposing a new paradigm, called UbiDM® (Design and Manufacture via Ubiquitous Computing Technology).
Abstract: Since ubiquitous technology was introduced in the early 1980s, it has rapidly developed, and been applied to various domains mainly for the improvement of human life. In this article, the authors propose that ubiquitous computing technology can be effectively used for the design and manufacturing of a product by proposing a new paradigm, called UbiDM® (Design and Manufacture via Ubiquitous Computing Technology). The key aspect of UbiDM is the utilisation of the entire product lifecycle information obtained via ubiquitous computing technology for the design and manufacture of the product. The new paradigm can solve many of the problems that have not been properly handled by previous manufacturing paradigms. Specifically, it will address the concept of UbiDM by the following aspects: (1) why there is a need for UbiDM; (2) the essence of UbiDM; (3) enabling technologies; (4) application area; (5) worldwide RD and (6) the societal impacts of UbiDM.
85 citations
TL;DR: The effect of product modules structure on the corresponding globally distributed supply chain configuration is studied and an integer linear decision support model is developed to determine the optimal location of global supply chain nodes.
Abstract: 'Supply chain management' deals with the coordination and integration of the interactions among its members. It encompasses integration of functional and geographical considerations as well as tactical and operational decisions. In this paper, the effect of product modules structure on the corresponding globally distributed supply chain configuration is studied. The currency exchange rates affect the overall allocation cost (production, inventory, and transportation). An integer linear decision support model is developed to determine the optimal location of global supply chain nodes, by simultaneously considering the currency exchange rate at various sites and the optimal modular product structure to be used in order to minimise the total cost. An automobile wiper system was used to illustrate the use of the model and the effect of including the currency exchange rate, varying the product modular structure and employing postponement strategies in a global supply chain configuration. The application of this approach is also useful in managing the challenges arising from prevailing trade barriers, financial systems in different regions as well as protecting intellectual property.
79 citations
TL;DR: A framework, based on analysis grids and graphical representations, which help to better characterize collaborative strategies such as quick response, efficient consumer response, vendor managed inventory and replenishment is proposed.
Abstract: The current intense competition forces enterprises to pay attention to supply chain collaboration with their upstream and downstream partners. Different collaborative strategies such as quick response (QR), efficient consumer response (ECR), vendor managed inventory (VMI) or collaborative planning, forecasting and replenishment (CPFR) have already been proposed. The key to ensuring that the supply chain partners are progressing on the right track of creating the best-in-class practice lays in their ability to choose the appropriate strategy. The current paper proposes a framework, based on analysis grids and graphical representations, which help to better characterize these strategies. The analysis grids use several characterization criteria to express the collaboration nature and its extent. For a better understanding, this framework is then applied to the CPFR strategy.
64 citations
TL;DR: Application of the model to an industrial case study demonstrated its ability to assess, early in the system design and development stage, the probability of errors resulting from human involvement, which is critical in investigating different improvement opportunities to achieve lower levels of errors owing to human involved, and hence higher quality.
Abstract: The early assessment of the performance of responsive manufacturing systems contributes significantly to achieving their potential effectiveness. In most manufacturing scenarios, the human involvement is considered one of the critical elements affecting the system performance. In reconfigurable manufacturing systems (RMSs), the workers' tasks are expected to change frequently as the system is reconfigured. The ability to predict the probability of errors caused by human involvement can provide the system designer with insights as to the required skill levels, training programmes, job design, tasks assignment, work organization as well as options for modifying the system design to achieve better quality results. A model for assessing the probability of human errors in RMSs, based on tasks characteristics, work environment, as well as workers capabilities has been developed using the multi-attribute utility analysis. Application of the model to an industrial case study demonstrated its ability to assess, early in the system design and development stage, the probability of errors resulting from human involvement. This is critical in investigating different improvement opportunities to achieve lower levels of errors owing to human involvement, and hence higher quality.
64 citations
TL;DR: A multi-period reverse logistics optimisation model is developed based on a multiple start search algorithm where a heuristic method is performed in each iteration and two procedures for improving the quality of the generated solutions are proposed.
Abstract: The end-of-life (EoL) phase is a stage in every product lifecycle, where its management is affected by economical and environmental parameters. The main problem facing manufacturers is how to collect the EoL products and what to do with them in order to obtain the maximum economic benefits from their recovery and at the same time fulfilling the relevant legislations. By introduction of the European Union Directive on end-of-life vehicles (ELVs), the manufacturers are responsible for free take back and recovery of their vehicles. Implementing this Directive will impose new additional costs on manufacturers. In order to achieve an efficient management of the recovery process and minimising the costs, manufacturers should join with treatment facilities and hence creating a network. In this paper, these new cost drivers are established and then based on the number, location and the capacity of the collection centres, dismantlers and also the amount of materials flow between different facilities, a multi-period reverse logistics optimisation model is developed. A solution methodology has been developed based on a multiple start search algorithm where a heuristic method is performed in each iteration. Two procedures for improving the quality of the generated solutions are proposed. The first procedure is based on a sub-problem optimisation technique and the second one is a search algorithm.
63 citations
TL;DR: An ontology-based architecture for addressing the problem of semantic integration of SCM is proposed and a rule-based approach is presented to map semantically similar terminologies between SCO and application ontologies with the aim of enabling semantic interoperability among applications in supply chains.
Abstract: Efficient supply chain management (SCM) requires consistent exchange and sharing of information semantics, which is often hindered by semantic clashes among heterogeneous applications. This paper proposes an ontology-based architecture for addressing the problem of semantic integration. A supply chain ontology (SCO) is developed by using the skeletal method to capture concepts and relationships common to SCM. Moreover, it is formally defined in OWL DL, a web-based ontology language, to serve as an interlingua for an architecture enabling information integration of SCM. Syntactic transformation between XML Schema and OWL in the architecture is implemented by syntactic translators that are developed by using XSLT. Furthermore, a rule-based approach is presented to map semantically similar terminologies between SCO and application ontologies with the aim of enabling semantic interoperability among applications in supply chains. The mapping rules are represented by SWRL, a rule description language that is independent of the rule languages specific to inference engines. In addition, a case study of a printer supply chain is illustrated to demonstrate the proposed methodology. Finally, a prototype system is developed using the Java platform to implement the SCO-based approach to semantic integration of SCM.
62 citations
TL;DR: This paper presents the PPO model and the open IPPOP framework that instantiates this model and investigates how such a model with such a digital platform may interact with other services used to assist other phases of the product life cycle.
Abstract: The product-process-organization model, PPO, provides efficient assistance to collaboration during innovative design project. This model is dedicated to the development phase of new products for which product architecture is indeed not a priori defined and tasks will be set dynamically during the product development process. In an integrated design perspective, product behaviours must also be forecasted; that is achieved by assessing PPO behaviours. This paper presents the PPO model and the open IPPOP framework that instantiates this model. It investigates how such a model with such a digital platform may interact with other services used to assist other phases of the product life cycle.
60 citations
TL;DR: The aim of this research was to design a manufacturing knowledge model (MKM) and demonstrate its functionality through experimental software and presents requirements for a new MKM, proposes its structure and describes its design.
Abstract: A manufacturing model is an information and knowledge model that describes the manufacturing capability of a particular organization. This work contributes to the area of information and knowledge structure to support manufacturing decisions. The structures of the manufacturing model have been defined to achieve suitable access to, and maintenance of, the manufacturing knowledge. Emphasis has been made on investigating a suitable manufacturing model structure in order to readily access manufacturing knowledge related to process planning activities. The aim of this research was to design a manufacturing knowledge model (MKM) and demonstrate its functionality through experimental software. This paper presents requirements for a new MKM, proposes its structure and describes its design.
56 citations
TL;DR: A new method, which insures that any randomly generated chromosome will result in a feasible process plan, has been developed and the results showed that process planning for RMS would cost less, depending on the different cost indices.
Abstract: A new model for optimizing the manufacturing cost of process plans for reconfigurable manufacturing systems (RMS) using genetic algorithms is proposed. The model represents machines' configurations in the process plan representation string. It considers all process planning parameters simultaneously while simplifying the problem formulation and reducing the computational complexity by choosing the following parameters: machine assignment, machine configuration, operation sequencing, operation cluster sequencing and assigning the tools and tool approach directions (TAD) to the operations. A new approach is proposed, which guarantees that operations with specific constraints are clustered together. A string of continuous variables to represent a process plan is introduced. A new method, which insures that any randomly generated chromosome will result in a feasible process plan, has been developed. The problem formulation is presented and illustrated with two examples and the results are presented and analysed. The results showed that process planning for RMS would cost less, depending on the different cost indices. The presented optimal process planning method can also be used in aiding the part/machine assignment activities and in the initial design stage of reconfigurable manufacturing systems (RMS).
50 citations
TL;DR: The present paper aims to extend the universal description, discovery, and integration (UDDI) registry specification to include semantic descriptions about manufacturing services and to support reasoning of those descriptions for service discovery.
Abstract: Integrating distributed manufacturing systems is a longstanding dream of industrial engineers. The advent of internet technologies has provided opportunities to fulfill this dream, and has presented new challenges to overcome. Since most current internet technologies (e.g. SOA, web service) originated in business applications, it is difficult to apply them directly to manufacturing systems. The difficulties stem particularly from differences in meaning and usage of manufacturing terms and an inability to express semantic information about manufacturing services. The present paper aims to extend the universal description, discovery, and integration (UDDI) registry specification to include semantic descriptions about manufacturing services and to support reasoning of those descriptions for service discovery. Specifically, we provide OWL-based definitions for manufacturing service capability profiles and a description logic (DL)-based reasoning procedure for matching queries to service descriptions. An illustrative process is presented with a prototype implementation for a discrete part manufacturing case.
TL;DR: Owing to the increasing complexity of today's logistic systems, new planning and control methods are necessary and a complexity cube is derived in order to characterize production systems regarding their level of complexity.
Abstract: Owing to the increasing complexity of today's logistic systems, new planning and control methods are necessary. Autonomously controlled processes are a possible solution to cope with these new requirements. In order to verify this thesis, the development of an evaluation system is necessary which measures the logistic objective achievement, the level of autonomous control and the level of complexity. The current paper presents adequate operationalization of the complexity in production systems. For this purpose a complexity cube is derived in order to characterize production systems regarding their level of complexity. The different types of complexity in this cube are represented by vectors which allow measurement and comparison of different types of complexity for different production systems. The application of the complexity cube is illustrated using an exemplary job shop manufacturing scenario.
TL;DR: A novel STEP-NC compliant machine tool data model named STEP- NCMtDm has been developed to realiseSTEP-NC based process planning and manufacturing and to support the distributed manufacturing environment.
Abstract: STEP-NC-based manufacturing is a promising approach for digital manufacturing applications. However, as STEP-NC data are machine tool independent, when implementing STEP-NC-based process planning and manufacturing, a comprehensive machine tool database is required to provide machine tool data for generating machine-tool-dependent process plans. A novel STEP-NC compliant machine tool data model named STEP-NCMtDm has been developed to realise STEP-NC based process planning and manufacturing. The goals of STEP-NCMtDm are to meet the data requirements for implementing STEP-NC data model in process planning and scheduling, and to support the distributed manufacturing environment. EXPRESS language is used for constructing the data model, and a web-based data model is also built to support distributed manufacturing scenarios by using the corresponding extensible markup language (XML) schema. A milling machine tool is used to evaluate the proposed data model. It has been demonstrated that STEP-NCMtDm can provide adequate information for STEP-NC programming.
TL;DR: In this paper, the authors apply an association rule mining technique to deal with product and process variety mapping, which can be deployed to support production planning of product families within existing production processes.
Abstract: Today's manufacturers strive to design and produce a large number of customized products at low cost and quick turnround in order to survive market competition. The consequence of high product variety manifests itself through an exponentially increased number of process variants, which introduces significant constraints to production planning and control. Leveraging upon product and process families has been well recognized as an important area in which manufacturers can exploit mass production efficiency, wherein the linchpin of managing variety propagation from design to production lies in the mapping relationships between product differentiation and process variation. Taking advantage of knowledge discovery from historical data, this paper applies an association rule mining technique to deal with product and process variety mapping. The mapping relationships are embodied in association rules, which can be deployed to support production planning of product families within existing production processes. A case study of mass customization of vibration motors is presented to demonstrate how the association rule mining mechanism helps maintain the coherence between product and process variety. The performance of the association rule mining approach is further evaluated through sensitivity analysis.
TL;DR: The performance of the proposed dynamic routing strategy is benchmarked with a number of static and dynamic routing strategies including the shortest distance, round robin, widest shortest route and shortest widest route strategies.
Abstract: An agent-based dynamic routing strategy for a generic automated material handling systems (AMHS) is developed. The strategy employs an agent-based paradigm by which the control points of a network of AMHS components are modelled as cooperating node agents. With the inherent features of route discovery, route selection and fault management of these node agents, their performance is investigated through simulation study. A generic AMHS network is modelled with a simulation tool that represents a highly flexible material handling system in a typical distribution centre where simulation studies are performed under normal and exception operating conditions. The performance of the proposed dynamic routing strategy is benchmarked with a number of static and dynamic routing strategies including the shortest distance, round robin, widest shortest route and shortest widest route strategies. The results of the simulation experiments are presented and their performance compared under a number of performance indices including the cycle time, utilization and ability to balance network loading.
TL;DR: In this paper, the cutting accuracy is self-guaranteed to be less than the machining tolerance and the cutting speed is set to be as high as possible based on optimal cutter orientation and maximized step-over distance.
Abstract: This paper presents a three-dimensional configuration-space (3D C-space) machining method for 5-axis finish machining of tessellated surfaces. To maximize the step-over distance, the curvature matched method (CM2) is used to approximate the cusp height and the step-over distance. A 3D C-space is then built for each cutter contact point (CC point). Every configuration set in this 3D C-space guarantees that the cutter is gouge-free and that the cusp height is less than the machining tolerance. The inclination angle λ by which the cutter is rotated about LY, the yaw angle ω by which the cutter is rotated about LZ and the height δ by which the cutter is lifted along the normal of the surface are three variables used to build the 3D C-space. Next, the optimal cutter orientation is obtained in this corresponding 3D C-space via a special optimization process. The ideal 3D C-space set, the initial 3D C-space set and the objective function of the optimization process are based on machine tool kinematics. Boundary functions are determined by the geometry feature of the 3D C-space. The penalty function method is employed as the optimization method. In this paper, the cutting accuracy is self-guaranteed to be less than the machining tolerance. The cutting speed is set to be as high as possible based on optimal cutter orientation and maximized step-over distance.
TL;DR: This paper shows the application of a pheromone-based autonomous control method to a matrix model of a shop floor and compares the performance to an earlier developed method in different dynamic demand situations.
Abstract: Autonomous control means the decentralized coordination of intelligent logistic objects and the routing through a logistic system by the intelligent parts themselves. This paper shows the application of a pheromone-based autonomous control method to a matrix model of a shop floor and compares the performance to an earlier developed method in different dynamic demand situations. The discrete event simulations are analysed by comparing statistics on throughput time data resulting from the system's behaviour in dynamic order arrival situations.
TL;DR: The QFD methodology is extended by introducing a new group decision-making approach that takes into account multiple preference formats and fusing different expressions into one uniform group decision by means of fuzzy set theory.
Abstract: Quality function deployment (QFD) is a well-known planning methodology for translating customer needs into relevant design and production requirements. The intent of applying QFD is to incorporate the voice of the customer into the various phases of the product development cycle for a new product, or a new version of an existing product. The traditional QFD structure requires individuals to express their preferences in a restricted scale without exceptions. In practice, people contributing to the process tend generally to give information about their personal preferences in many different ways, numerically or linguistically, depending on their background. Moreover, collaborative decision-making is not an emphasized issue in QFD even though it requires the involvement of several people. In this study, the QFD methodology is extended by introducing a new group decision-making approach that takes into account multiple preference formats and fusing different expressions into one uniform group decision by means of fuzzy set theory. Moreover, a benchmarking procedure based on the Choquet integral is proposed to rate competing systems and find which dimensions need improvement.
TL;DR: This paper presents the impediments and issues arising from such incompatibilities and proposes a new framework to overcome these barriers in achieving interoperability in the CAD/CAM/CNC chain.
Abstract: Most manufacturing enterprises now employ compute numerical control (CNC) technology in their production chain. Improving the performance and flexibility of the computer aided design (CAD)/computer aided manufacturing (CAM)/CNC chain can therefore, have a significant effect on the competitiveness of such enterprises. Whereas hardware capabilities of these systems have increased proactively over the last few decades, the software components have been updated reactively to support the enhancements found on the newer generation of CNC machines. This passive approach has led to severe incompatibilities between the various CAD/CAM/CNC solutions. This paper presents the impediments and issues arising from such incompatibilities and proposes a new framework to overcome these barriers in achieving interoperability in the CAD/CAM/CNC chain. In the suggested framework different components of the CAD/CAM/CNC chain can exchange information with one another regardless of their native standards. The different elements comprising the framework are demonstrated by utilizing a test component in a dynamic manufacturing scenario.
TL;DR: The objective of the integrated technology roadmapping methodology STAR® outlined in this paper is to enable companies to align their technology acquisition programmes to meet their business objectives.
Abstract: The objective of the integrated technology roadmapping methodology STAR® outlined in this paper is to enable companies to align their technology acquisition programmes to meet their business objectives. STAR® has three phases: a preliminary phase involving the setting up of an enterprise framework; a technology data collection phase; and a project creation and assessment phase. STAR® utilises the analytic hierarchy process to rank company technology requirements, several non-financial factors to determine the alignment of proposed projects and visual representations to select a portfolio of projects. Project evaluations have demonstrated that statistically significantly different project selection outcomes arise from the additional non-financial factors included in STAR®. Elements of STAR® are being implemented at a major collaborator, and it is planned to implement the whole STAR® methodology within a year. An integrated enterprise level roadmapping methodology such as STAR® offers an objective way of selecting and evaluating projects and, later, of re-evaluating and improving the process.
TL;DR: In this paper, a methodology for the selection of AMT is presented to assist the decision maker in selecting technologies that meet their needs and is tested and validated using a real application from Saudi Arabian Industry.
Abstract: The problem of selection and justification of advanced manufacturing technologies (AMT) is a multi-attribute problem which involves both tangible and intangible factors. To select the best manufacturing technology that achieves most of the company requirements, it is necessary to use an appropriate selection approach that takes into consideration the different quantitative and qualitative factors of company objectives and AMT benefits. In this paper, a methodology for the selection of AMT is presented to assist the decision maker in selecting technologies that meet their needs. The suggested methodology combines two databases for the manufacturing company and AMT information, and multi-criteria decision making (MCDM) tools (analytical hierarchy process and fuzzy analytical hierarchy process). The developed methodology is tested and validated using a real application from Saudi Arabian Industry.
TL;DR: Based on the integrated product data model, the proposed procedure propagates engineering changes to product data views using the history of product structure changes to maintain consistency of product data during collaboration between various design, manufacturing and customer support departments, who have different productData views.
Abstract: The present paper proposes a comprehensive procedure for engineering change propagation in order to maintain consistency between various product data views. A product data model is also proposed for the propagation procedure, which integrates base product definitions for product design, and product data views for other manufacturing or customer support. The product data view in the proposed model enables manufacturing or customer support engineers to define their own product data views, without copying the existing product definition. Integrated with other components, the engineering changes in the data model provide structure-oriented change history, effectivity management for production, and integration with product configurations. Based on the integrated product data model, the proposed procedure propagates engineering changes to product data views using the history of product structure changes. The propagation procedure maintains consistency of product data during collaboration between various design, manufacturing and customer support departments, who have different product data views. Prototype database applications together with an example of illustrative change propagation are also presented.
TL;DR: An extended fuzzy parametric programming (FPP) approach to solve a dynamic cell formation problem considering the uncertain part demand and machine capacity and uses a simple strategy to extract all possible applicable solutions resulting from the core of the membership functions of the uncertain parameters.
Abstract: This paper proposes an extended fuzzy parametric programming (FPP) approach to solve a dynamic cell formation problem considering the uncertain part demand and machine capacity. The classical FPP approach gives the decision maker a number of alternative decisions for different grades of precision. Linear membership functions such as trapezoid, triangular and other piecewise forms have widely been used to express the uncertain parameters in the different engineering fields. Especially, to our best of knowledge, all researches related to the use of the fuzzy programming-based approaches for cellular manufacturing systems (CMSs) have been applied to the piecewise membership functions. In the case of lack of sufficient knowledge, there is a section in the piecewise forms called 'core', consisting of the fully included members (i.e. members with membership degree equal to one). This section, which represents the expert's ignorance, is not considered in the fuzzy programming-based approaches presented in the literature. In a highly cost-intensive production system, such as cellular manufacturing systems, the decision maker wants to know how big the changes of the cell configuration from one period to another are. These changes are caused by the fluctuations in some parameters of the system, such as part demand and machine capacity. However, when these parameters are uncertain as well as dynamic, the risk of decision making will increase significantly. On the other hand, in practice, a domain of uncertainty of data corresponds to a unique decision and hence the whole uncertainty in the system can be covered by only a few numbers of the alternative decisions, called 'applicable decisions'. This reduction in the decision space gives a better idea to the decision maker to make the final decision. The extended FPP proposed in this paper uses a simple strategy to extract all possible applicable solutions resulting from the core of the membership functions of the uncertain parameters. To verify the performance and applicability of the proposed approach, a comprehensive numerical example is solved and experimental results are presented.
TL;DR: The current paper identifies appropriate techniques for monitoring tool condition and surface anomalies in broaching, and presents results of the output signals obtained from multiple sensors such as acoustic emission, cutting forces, vibration, hydraulic pressure and table displacement.
Abstract: Process monitoring can be used for improving machining reliability and failure prediction. As manufacturing anomalies are a potential cause of gas turbine disc failure in aero-engines, engine life and performance can be improved by developments of manufacturing anomaly detection. The current paper identifies appropriate techniques for monitoring tool condition and surface anomalies in broaching, and presents results of the output signals obtained from multiple sensors such as acoustic emission, cutting forces, vibration, hydraulic pressure and table displacement. The results show that the signals obtained proved to be efficient in detecting surface deviations and anomalies. Tool wear was identified by the cutting force, pressure and table displacement signals. While the acoustic emission signals did not prove to be sensitive in detecting tool wear, they were efficient in detecting surface anomalies such as smearing, scoring and overheating.
TL;DR: This paper introduces a formal description and mathematical modelling of the personnel scheduling problem in the context of a paced multi-product assembly centre and validates and analyses the performance of the model through the optimal resolution of a small yet representative case using a commercial solver.
Abstract: This paper introduces a formal description and mathematical modelling of the personnel scheduling problem in the context of a paced multi-product assembly centre. The model explicitly takes into consideration the individual competencies; mobility and preferences of each worker, as well as the personnel and competency requirements associated with each assembly activity given both the current master assembly schedule and the line balancing for each product. The paper then validates and analyses the performance of the model through the optimal resolution of a small yet representative case using a commercial solver. For simplicity, we focus on the deterministic case; however the stochastic case will be discussed in the future research.
TL;DR: This special edition of the International Journal of Computer Integrated Manufacturing includes enhanced versions of unprinted papers selected from the papers accepted and presented at the 3rd International, CIRP sponsored Conference in Digital Enterprise Technology (DET’06), held in Setúbal, Portugal, in September 2006.
Abstract: The future of Manufacturing Industries and the development of the related service sectors of the economy depend on innovation for the rapid development of new products and services. The actual comp...
TL;DR: This paper proposes design of cam-follower velocity curve by using B-spline polynomials, which provides cam profile coordinates to manufacture a cam on computer numerical control (CNC) machines.
Abstract: This paper proposes design of cam-follower velocity curve by using B-spline polynomials. B-spline polynomials are smooth curves defined by control points. Curve shape can be modified by changing the control points. The traditional design method for improving the motion characteristics of the follower is to find an optimum displacement curve for which follower velocity, acceleration curves to be continuous and their peak values as small as possible (i.e. minimum jerk). B-spline polynomials of degree three and six control points are used in design of follower velocity curve. The B-spline curve is used to approximate the various basic curves which have better motion characteristics. A computer-aided design and computer-aided manufacturing (CAD/CAM) system is developed which generates follower motion curves, i.e. displacement, velocity, acceleration, jerk and cam profiles. An analysis is carried out on B-splines with basic curves for maximum accelerations to select the best cam follower motion. It also provides cam profile coordinates to manufacture a cam on computer numerical control (CNC) machines.
TL;DR: The proposed formalization combines a deterministic cash flow management model with a schedule management model using a mixed integer linear program (MILP) formulation to help high-level staff during operational planning and financial activities.
Abstract: The current paper shows the links and impact between physical flow and financial flow during the tactical planning process in a company supply chain. The target is to obtain optimal solutions during process operations preserving stock level, liquidity and satisfying customers. The proposed formalization combines a deterministic cash flow management model with a schedule management model using a mixed integer linear program (MILP) formulation. The benefits of this work are shown through a case study that illustrates the operational problem, modelled flows and necessary constraints to help high-level staff during operational planning and financial activities.
TL;DR: The current paper outlines the elements of remanufacturing and presents a tool in the form of a process model developed via the systems perspective using a practitioner-based research approach, which has a key advantage in reducing risk in re manufacturing by improving education, training and management in its operational processes.
Abstract: Remanufacturing, a process of returning used products to at least original performance specification from the customers' perspective and giving them warranties at least equal to that of new equivalents, is regarded as a vital strategy in waste management and environmentally conscious manufacturing. The practice is hindered by a lack of remanufacturing knowledge and a paucity of readily available remanufacturing tools and techniques. The current paper outlines the elements of remanufacturing and presents a tool in the form of a process model developed via the systems perspective using a practitioner-based research approach. Remanufacturers and academics examined the tool for replication logic and found it valid. The validation techniques used include the 'review method' and practical use in organizations. The assessment criteria were the tool's sufficiency, clarity and usability in addressing the needs of academics and remanufacturers. Its key advantage is in reducing risk in remanufacturing by improving education, training and management in its operational processes.
TL;DR: Experimental results show that the proposed rough-cut plan has significantly reduced the machining time when compared to the conventional, 5-axis-control-based, rough machining.
Abstract: This study presents an efficient, rough-cut path plan for the 5-axis, numerically controlled (NC) machining of an impeller. The hub and blade surfaces of the impeller are customarily machined by a 5-axis NC machine. Much of the machining time of the impeller is, however, consumed in the rough cutting where unnecessary stock materials are removed. Simultaneous, 5-axis, rough machining requires a considerably longer time than 3-axis machining because all the five axes have to be controlled at the same time at almost all cutter location (CL) points. Based on the characteristic curves of a blank and a finished impeller, a rough machining area can be partitioned into several unit machining regions (UMRs) by using the characteristic curves of an impeller and their projection graphs. Then, an UMR is machined by means of the simultaneous, 3-axis control of a 5-axis machine instead of simultaneous, 5-axis control. In each UMR, the rotating and tilting axes of a machine bed are fixed in advance to perform 3-axis machining. Finally, rough-cut CL data is generated based on the 3-axis machining plan at each UMR while avoiding the collision between the tool and impeller blades. An illustrative example is shown for a prototype impeller, and the final tool paths generated by the proposed method are verified by using the cutting simulation function of Vericut®. Experimental results show that the proposed rough-cut plan has significantly reduced the machining time when compared to the conventional, 5-axis-control-based, rough machining.