Showing papers in "International Journal of Computer Integrated Manufacturing in 1993"
TL;DR: The study of manufacturing systems has generated interest in IDEFO, a structured functional analysis technique for manufacturing as discussed by the authors, and a review of relevant published literature comprises a discussion of issues raised by the review, identifying general agreement that there is a need for such a technique and that it provides a basis for understanding and analysing manufacturing systems.
Abstract: The study of manufacturing systems has generated interest in IDEFO, a structured functional analysis technique for manufacturing. The paper comprises a review of relevant published literature. Four categories of publications have been identified: descriptions and reviews of the basic principles of IDEFO; performance evaluation and comparisons with other techniques; enhancements to the technique; and specific applications. The paper concludes with a discussion of issues raised ns a result of the review, identifying general agreement that there is a need for such a technique and that it provides a basis for understanding and analysing manufacturing systems.
163 citations
TL;DR: This paper briefly overviews the primary methods of the use of features through feature recognition and design by features, particularly in the process planning application area.
Abstract: The proper integration of the activities of computer-aided design (CAD) and computer-aided manufacture (CAM)is an objective that has become more urgent within the wider context of a total computer integrated manufacturing (CIM) environment. In seeking this integration it is recognized that the diversity of activities and consequent needs for data can best be served by a single representation for design, design analysis and manufacturing planning, and that a strong candidate for this descriptive role is a feature representation. This paper briefly overviews the primary methods of the use of features through feature recognition and design by features, particularly in the process planning application area.
82 citations
TL;DR: This paper explores some of the implications of the resulting requirement for multiple feature models in the engineering process from the viewpoints of the different processes occurring in the product life-cycle.
Abstract: The concept of form features originated in the process planning of machined parts. However, it is now perceived to have applications in many other phases of the engineering process, from initial design through to inspection and assembly, and, as in process planning, the use of form features appears to be crucial in the automation of these activities. From the viewpoints of the different processes occurring in the product life-cycle a given product has different characterizations in terms of form features. This paper explores some of the implications of the resulting requirement for multiple feature models. A designer will most naturally wish to generate a CAD model in terms of functional features, and the system should then be capable of transmuting the designer's feature model into the appropriate feature model for any desired downstream application. This appears to be a simpler process than that of automatic feature recognition from a pure geometric model, a currently popular but difficult rese...
44 citations
TL;DR: This paper addresses the problems of representing features in a form more suitable for feature transformation and the related feature reasoning mechanism and combines methodologies from both design and features and feature recognition.
Abstract: Feature-based modelling is an approach being studied for the next generation of intelligent CAD environments. In particular, feature mapping, i.e. how to support automatically the different ways specialists view the same object, has been identified as an important element in feature-based design systems. Consequently, feature representation and reasoning tools based on the representation are crucial issues. This paper addresses the problems of representing features in a form more suitable for feature transformation and the related feature reasoning mechanism. Our approach combines methodologies from both design and features and feature recognition. Geometric constraints are used within symbolic definitions of features and also to define their relative positions and orientations. A graph grammar parsing is combined with knowledge-based techniques to derive feature information and propagate constraints. The proposed approach can be used for the transformation of feature information and to facilitat...
40 citations
TL;DR: A feature-based model for describing component geometry and connectivity, and a hierarchical structure for form features definition and classification are presented, as are methods for representing the capabilities of machine tools.
Abstract: The aim of this paper is to report on some of our research findings in developing generative process planning systems. A feature-based model for describing component geometry and connectivity, and a hierarchical structure for form features definition and classification are presented, as are methods for representing the capabilities of machine tools. These models form the basis for decision making in our prototype process planning system GENPLAN. As an example, the paper reports on how the models are being used for reasoning about component geometry and the linguistic approach adopted for machine tool selection in process planning. The component and processing system models and the linguistic approach used for representing their information are proving useful for geometric reasoning and machine tool selection tasks in computer aided process planning.
38 citations
TL;DR: This paper re-evaluates the job-shop scheduling problem by showing how the standard definition is far more restrictive than necessary and by presenting a new technique capable of tackling a highly generalized version of the problem.
Abstract: This paper re-evaluates the job-shop scheduling problem by showing how the standard definition is far more restrictive than necessary and by presenting a new technique capable of tackling a highly generalized version of the problem. This technique is based on a massively parallel distributed genetic algorithm and is capable of simultaneously optimizing the process plans of a number of different components, at the same time a near-optimal schedule emerges. Underlying the evolutionary machinery is a specialized feature-based generative process planner.
36 citations
TL;DR: In this paper, a practical approach to the integration of process planning and production control business functions is presented, based on the discovery of time-dependent tasks within the process planning domain.
Abstract: Integration is often considered to be a tangible word. In fact integration is diffuse: it does not express in any detail how to conduct integration initiatives. On the other hand, integration docs represent a very efficient way of improving the operational characteristics of a manufacturing facility. The concepts provided for integration are derived from the discovery of time-dependent tasks within the process planning domain. When operating in dynamic environments it is important to separate static and dynamic controlled decision making and to provide architectures capable of providing the required dynamic knowledge at the time when the decisions are made. A natural expansion of this hypothesis is the development of an approach for process planning conducted concurrently with the other engineering activities within product life. This article introduces a practical approach to the integration of process planning and production control business functions. The approach outlines systematic methods t...
32 citations
TL;DR: It is reached that neither simple feature oriented design nor feature recognition methods alone will fulfil the requirements of advanced systems and satisfactory modelling of the interactions between features in a component is a prerequisite to progress.
Abstract: A major difficulty in the development of advanced and integrated CAD and CAPP systems lies in the difficulty of representing components. Here some of the problems that are often encountered are discussed and a composite component is used to demonstrate them. Possible approaches for solving some problems are proposed. The conclusion is reached that neither simple feature oriented design nor feature recognition methods alone will fulfil the requirements of advanced systems. Satisfactory modelling of the interactions between features in a component is a prerequisite to progress.
29 citations
TL;DR: In this paper, the principles of DFA are outlined and the role of features (especially feature-based design) in DFA is described, based on ongoing work in the BRITE project no. 4661 (DEFMAT) and the work of Hua Yang in assembly process planning.
Abstract: Design for assembly (DFA) is an important part of the concurrent engineering strategy for reduction of product manufacturing costs and lead times. In this paper the principles of DFA are outlined and the role of features (especially feature-based design) in DFA is described. An architecture for an integrated DFA/CAPP system is described, based on ongoing work in the BRITE project no. 4661 (DEFMAT) and the work of Hua Yang in assembly process planning.
28 citations
TL;DR: In this paper, three different concepts for describing parts and products are described including different types of features, skeletons and hierarchical models, and two approaches for linking CAD and CAPP, namely feature recognition and feature-based design, are discussed and compared with the problem of either integrating or interfacing design and process planning activities.
Abstract: This paper summarizes the reasons for considering new ways of modelling products and processes. Three different concepts for describing parts and products are described including different types of features, skeletons and hierarchical models. Two approaches for linking CAD and CAPP, namely feature recognition and feature-based design, are discussed and compared with the problem of either integrating or interfacing design and process planning activities. Results from a literature survey on feature-based design and feature definitions are described with the conclusion that feature definitions used are very different. A design-oriented manufacturing process database (MADED) and a feature-based CAD and CAPP system (DEPF), which currently are being developed at the Technical University, are presented.
28 citations
TL;DR: There is a requirement to characterize a richer set of shape properties on which search will be based, and Sequences of edges that are within the convex hull of a face (‘remnant’ loops’ and edge loops that are shared between several features add to the discriminating power of feature hunting techniques.
Abstract: Feature recognition from a solid model can be treated as a pattern-directed search for specific shape properties. However, to extend the range of features and of interacting situations in which it can be of use, there is a requirement to characterize a richer set of shape properties on which search will be based. Sequences of edges that are within the convex hull of a face (‘remnant’ loops’ and edge loops that are shared between several features add to the discriminating power of feature hunting techniques. These shape properties have been exploited in the implementation of a feature analysis system that operates on 2-5D object representations in a solid model and which derives a regional feature structure suited to three-axis machining. The motivation for its development was to provide a bridging link between a solid model representation and a knowledge-based, computer-aided, process planning system for prismatic parts.
TL;DR: This paper introduces to the reader a key element of the IDEM methodology, the integrated multi-view system description facility, and provides technical insight of the function view, information view and dynamics view of the facility.
Abstract: The global manufacturing challenge has forced many manufacturers to reorganize their factories in order to ensure long-term profitability or even survival. Modelling can play a crucial role in such an activity. A comprehensive methodology is being developed for factory modelling by the IDEM (Integrated DEsign and Modelling) project at Loughborough University. The purpose of this paper is to introduce to the reader a key element of the IDEM methodology, the integrated multi-view system description facility. Some light is shed on the IDEM project first. Emphasis is then placed on the discussion and presentation of the IDEM system description approach, the need for it and its scope. Finally technical insight is provided of the function view, information view and dynamics view of the facility, with typical intermediate results of an industrial case study demonstrated.
TL;DR: Petri nets are used to analyse flexible manufacturing systems (FMS) to achieve the following objectives: to derive a theorem for checking the buffer overflows in an FMS, and to detect the deadlock phenomenon by a corrected algorithm of the P-invariant theory for Petri nets.
Abstract: In this paper, we use Petri nets to analyse flexible manufacturing systems (FMS) to achieve the following objectives. The first objective is to derive a theorem for checking the buffer overflows in an FMS. The second objective is to schedule the earliest starting times for a sequence of operations in an FMS by the timed Petri net. The FMS may involve many part types, machines, pallets and so on. The third objective is to detect the deadlock phenomenon by a corrected algorithm of the P-invariant theory for Petri nets. This method will enable us to know whether there exists any deadlock in an FMS. The algorithm is implemented in the Turbo Pascal language. The fourth objective is to search for the optimal scheduling rule in an FMS. The search procedure is also implemented in the Turbo Pascal language¨ The optimal machine scheduling rule can result in a better throughput.
TL;DR: Two different approaches to the problem of identifying singly connected features and the closely related problem of defining what constitutes an inner-loop on a cylindrical surface are looked at and combined in an algorithm that can identify multiply connected depressions or protrusions and provide multiple interpretations of a 2·5D component's shape.
Abstract: This paper looks at two different approaches to the problem of identifying singly connected features and the closely related problem of defining what constitutes an inner-loop on a cylindrical surface. The two approaches are then combined in an algorithm that can identify multiply connected depressions or protrusions and provide multiple interpretations of a 2·5D component's shape.
TL;DR: This paper first maps the concepts of classical, general-purpose planning to the realm of manufacturing process planning and emphasizes the importance of having a planning strategy that explores the space of potential solutions.
Abstract: This paper first maps the concepts of classical, general-purpose planning to the realm of manufacturing process planning. Manufacturing features and processes are considered as mediators between design and manufacturing on a level of abstraction that supports the adequacy of representation of various kinds of process planning knowledge. It is shown how profound problems of planning theory manifest themselves in process planning and how the organization of domain knowledge around features helps to overcome these problems. Such a locality-based representation, however, requires that both part models and planning strategies have some new qualities, such as the possibility of causal reasoning from the geometric model and the ability to follow global objectives. The paper emphasizes the importance of having a planning strategy that explores the space of potential solutions. Finally, such a strategy, which uses a genetic metaphor, will be outlined
TL;DR: The control model presented in this paper consists of modules for Petri net generation, deadlock detection, and performance evaluation of manufacturing plans processed in a CIAC.
Abstract: A computer-integrated assembly cell (CIAC) plays an important role in modern manufacturing systems. To maximize cell utilization, multiple assembly jobs are often scheduled concurrently without consideration for the complex interaction between workstations. Sharing of assembly workstations among a set of concurrently flowing processes may cause deadlocks and conflicts, which are difficult to detect during programming of the cell's controller. This paper presents an overview of the control models developed for deadlock and conflict detection, and performance evaluation of manufacturing plans processed in a CIAC. Petri net formalism is used as the modelling tool for its ability to model concurrent and asynchronous activities, and for its well developed mathematical foundation for analysis and performance evaluation. The control model presented in this paper consists of modules for Petri net generation, deadlock detection, and performance evaluation. The control model may be applied to debugging con...
TL;DR: In this paper, a knowledge-based scheduler (KBS) for FMS which adopts the hierarchical approach and utilizes simulation techniques is developed, which is basically a rule-based system with a generic structure which allows tailoring to specific managerial and system needs.
Abstract: A knowledge-based scheduler (KBS) for FMS which adopts the hierarchical approach and utilizes simulation techniques is developed. It is basically a rule-based system with a generic structure which allows tailoring to specific managerial and system needs. The KBS schedules the loading of parts in the system based on global knowledge and dispatches parts to workstations based on local knowledge. It generates realistic schedules by satisfying a set of user-defined top and local goals and constraints. It is built on top of KEE, a hybrid AI environment and its use is demonstrated in a flexible printed circuit board assembly system.
TL;DR: In this article, the simulated annealing algorithm is applied to machine cell formation problems and two cooling schedules are adopted to detect the applicability of the algorithm to the problem of large-scale problems of cell formation.
Abstract: The application of the simulated annealing algorithm to machine cell formation problems is presented in this paper. This general algorithm is not influenced by the initial machine-component incidence matrix and has the potential of being extended to solve more complex problems. The concept of penalty costs is introduced into the objective functions to prevent the solution from violating given constraints. Two cooling schedules for the simulated annealing algorithm are adopted to detect the applicability of the algorithm to machine cell formation problems. The results show that the simulated annealing algorithm is able to find a near-optimal solution within a polynomial time even for the large-scale problems of machine cell formation.
TL;DR: This paper reports on two related investigations into the use of features and object concepts to integrate manufacturing intelligence into design and manufacturing and to provide a common integration path between design andManufacturing.
Abstract: This paper reports on two related investigations into the use of features and object concepts to integrate manufacturing intelligence into design and manufacturing and to provide a common integration path between design and manufacturing (Manufacturing intelligence is here used to mean data representations, that can encapsulate a range of data and other associated knowledge Features, objects and knowledgebase frames and rules are examples of such representations) The first investigation examined the feasibility of integrating manufacturing intelligence with CAD-based design by coupling an object-oriented methodology and a design-by-feature system In a pilot implementation, object-oriented concepts such as encapsulation, polymorphism and inheritance have been combined with features in an AutoLISP package which runs in conjunction with a design-by-feature (DbF) package The DbF package is based on a form of B-rep model and implemented in AutoCAD The benefits of combining CAD and objects are di
TL;DR: In this paper, a constraint modelling approach is used to detect errors in manufacturing processes, where the truth of the tolerance condition of the part is established using a constraint modeller and both the causes and corrective actions determined.
Abstract: A general approach to the use of features has shown that various different definitions can be created dependent upon the goals set. Within both design and manufacturing two distinct types can be established. Functional features allow higher levels of abstraction whilst geometric form features allow for rationalization. Within the manufacturing environment a similar division leads lo features defined in terms of process operations and those based on the geometric operations being executed, here termed manufacturing motion features (MMFs). An investigation into the communications between CAD systems and coordinate measuring machines has led to the adoption of MMFs to allow errors in manufacturing to be detected. This employs a constraint modelling approach in which the truth of the tolerance condition of the part is established. Through the investigation of errors, scenarios arc proposed and tested by the constraint modeller and both the causes and corrective actions determined.
TL;DR: In this paper, a short-term production planning (STPP) problem in flexible job shop manufacturing systems (FJSMS), which consist of computerized numerically, controlled (CNC) machines and dedicated machines, is discussed.
Abstract: Short-term production planning (STPP) problems in flexible job shop manufacturing systems (FJSMS), which consist of computerized numerically, controlled (CNC) machines and dedicated machines, are discussed here. Short-term production planning problems of FJSMS include part type selection, process selection, batch sizing and part family/ machine group formation. A proposed STPP system for FJSMS is developed for cases where production contents are frequently changed thus resulting in the physical machine layout being not justified. It mainly adopts a restricted-period planning approach, using a virtual cell's concept for solving the STPP problem. The planning goal of STPP is to satisfy quantity and due date requirements as determined by MRP/CRP, with due consideration to the features of NC machines and dedicated machines.
TL;DR: In this article, the role of features in machine planning for prismatic components is described, as are the methods used in the research to capture feature-specific data and feature-interaction data.
Abstract: Features research has been pursued for some years now as a key link between computer-aided design and computer-aided manufacture, with two main approaches being taken: design by features and feature recognition. This paper describes research into the integration of a machine planner, in a product model environment, which took a design by features approach. The role of features in machine planning for prismatic components is described, as are the methods used in the research to capture feature-specific data and feature-interaction data. The advantages and limitations of the approach taken are discussed together with directions for future research.
TL;DR: In this article, the authors compared two alternative production environments by allocating equivalent machining capacity to each one and found the equivalent capacity of each environment by minimizing the total daily production cost under each choice.
Abstract: Two alternative production environments are compared by allocating equivalent machining capacity to each one. Equivalent capacity of each environment has been found by minimizing the total daily production cost under each choice. SIMAN simulation language is used in determination of non-cost performance measures for each environment. This study assumes that lot sizes are fixed and cannot be reduced under the cellular option. Results support the recent findings that the cellular manufacturing or group technology method of production is not superior to traditional functional or job shop layout.
TL;DR: This paper identifies the steps involved in the development of such an off-line programming system for robotic spray glazing, and describes and evaluates various robot path specification methods and path-planning strategies.
Abstract: Off-line programming of robots is an important step in the effective integration of computer-aided design (CAD) and computer-aided manufacturing This paper identifies the steps involved in the development of such an off-line programming system for robotic spray glazing Various robot path specification methods and path-planning strategies are described and evaluated The basic methodology is to use the CAD representation of the component to determine a robot path that ensures good glaze coverage A CAD model of a sample robot work cell is created to simulate the spray-glazing operation, and to test the performance of the path specification methods Two path planning strategies are evaluated for this work cell, for two sample surfaces
TL;DR: The first attempts to use the modeller to automate the planning and machining process for NC machining of complex components are described and demonstrated.
Abstract: The full automation of the planning and control code generation for the NC machining of complex components is a commendable aim. Progress has been hindered by the lack of modeller systems capable of storing and providing access to a full product model. The ACIS modeller provides improved geometric modelling functionality, access to data structures and model attribute attachment mechanisms. This paper describes the first attempts to use the modeller to automate the planning and machining process. Initial strategies and algorithms are described and demonstrated. These cover: component validation; workpiece holding, including the use of vices, bolting and clamping; and the stability of the secured workpiece.
TL;DR: An intelligent decision system for a modern manufacturing system that integrates artificial intelligence, optimization techniques, and simulation to solve the problems of machine breakdown, rush order, etc.
Abstract: Due to the dynamic characteristic shown in manufacturing systems, production efficiency is not easily maintained as we plan, especially when an abnormal situation (e.g. machine breakdown, rush order, etc.) occurs. An intelligent decision system for a modern manufacturing system is presented in this paper. This system integrates artificial intelligence, optimization techniques, and simulation to solve the above-mentioned problems. Three modules are included in the system, namely a decision centre, decision support system and decision analysis module. Event graphs are adopted to describe the decision-making logic for the decision centre which is the core of the system. An example concerning machine breakdown is given.
TL;DR: In this article, the determination of computer integrated manufacturing (CIM) system flexibility involves the evaluation of three flexibility dimensions: (1) system dimension; (2) information dimension; and (3) production dimension.
Abstract: The determination of computer integrated manufacturing (CIM) system flexibility involves the evaluation of three flexibility dimensions: (1) system dimension; (2) information dimension; and (3) production dimension. Performance metrics for these dimensions are flow time, non-conformance ratio, mean number of products in queue, and machine utilization. Digital simulation modelling was used to emulate the CIM system production of six product styles. The design complexity in terms of assemblability was assessed using the metrics of percentage of manual assembly, part variety, part density, and total part count. The results indicated that the flexibility of the CIM system was sensitive to product design changes involving the touching parts and high percentage of manual assembly. Overall, CIM system flexibility decreased with increasing manual assembly.
TL;DR: In this paper, a model for aiding a large enterprise in decisions regarding consolidation and reconfiguration of its facilities to shared manufacturing facilities is described, which is the sharing of modern manufacturing technologies and management systems by different manufacturers with similar needs.
Abstract: A model for aiding a large enterprise in decisions regarding consolidation and reconfiguration of its facilities to shared manufacturing facilities is described. Shared manufacturing is the sharing of modern manufacturing technologies and management systems by different manufacturers with similar needs. The concept of shared manufacturing is extended to assess its usefulness to a large enterprise separated by wide geographic distances and focusing on re-manufacturing of products rather than original manufacturing. Production flow analysis was used to assess the technical feasibility of shared manufacturing by measuring the degree of similarity in processing of equivalent items at multiple facilities. Economic feasibility was assessed through development of a cost model that would directly compare savings incurred among factories. Practical feasibility was assessed through resolution of a variety of qualitative factors including the impact of capacity, quality, evolving technology, jigs and fixtur...
TL;DR: In this article, a methodological framework has been proposed to analyse comprehensively those multidimensional issues and an example from Indian industry has been explained using this methodology, which has been used to explain the success of computer integrated manufacturing systems (CIMSs).
Abstract: Implementing computer integrated manufacturing systems (CIMSs) is being attempted worldwide in many industries in recent times, but the process of justifying the adoption of a CIMS decides to a great extent the success of such attempts. The justification process involves issues which have both economic and non-economic dimensions. In this paper, a methodological framework has been proposed to analyse comprehensively those multidimensional issues. An example from Indian industry has been explained using this methodology.
TL;DR: In this paper, a feature-based B-rep solid modeller and process planning system have been integrated by using features in a common product model database, together with the commands available in the process planning toolkit to navigate and interrogate the feature model.
Abstract: A feature-based B-rep solid modeller and process planning system have been integrated by using features in a common product model database. A description of the feature hierarchy and organization is given, together with the commands available in the process planning toolkit to navigate and interrogate the feature model. The work is part of the ESPRIT-II project IMPPACT (2165) and is demonstrated in the sheet-metal shop of an aerospace company in Greece.