Model-based manufacturing integration: A paradigm for virtual manufacturing systems engineering

Current manufacturing system design methodologies produce multiple models of the eventual manufacturing system. These models reflect either the designers view of some subsystem, like materials handling, some level of abstraction, or some developmental stage in the design of the system. These models serve to break the complex system design into smaller, more manageable sized problems. This paper makes a case for the need to integrate these models before the physical system is constructed.     

Developing control and integration software for flexible manufacturing systems

The slow growth of computer-integrated manufacturing is attributed to the complexity of designing and implementing their control and integration software. This article expands on a methodology for designing and implementing this software that was introduced in [16]. The goal of this methodology is to build flexible and resuable control and integration software for computer-integrated manufacturing systems. It hinges upon the concepts of software/hardware components, their assemblages, a distributed common language environment, formal models, and generic controllers. Major sources of flexibility are obtained by decoupling process plan models from the model of the factory floor and by using a generic controller. Reusability is achieved by building selfcontained software/hardware components with general, possibly parametrized, interfaces. The interplay between simulated and actual hardware internals of software/hardware components is used as the basis of a testing strategy that performs off-line simulation followed by on-line testing.The methodology has been applied in designing and implementing the control and integration software of an actual Prismatic Machining Cell. The article also reports on the details of this implementation.The names of the authors appear in alphabetical order.     

CIM—the integration of manufacturing and information systems

The integration of computers within the manufacturing environment has long been a method of enhancing productivity. Their use in many facets of a manufacturing enterprise has given industries the ability to deliver low-cost, high-quality competitive products. As computer technology advances, we find more and more uses for new hardware and software in the enterprise. Over a period of time, we have seen many “islands” of computer integration. Distinct, fully functional hardware and software installations are a common base for many industries. Unfortunately, these islands are just that, separate, distinct and functional but non-integrated. The lack of integration within these information systems make it difficult for end users to see the same manufacturing data. We are finding the need for a “single image” real-time information system to provide the enterprise with the data that is required to plan, justify, design, manufacture and deliver products to the customer. Unfortunately, many industries have a large installed base of hardware and software. Replacement of current systems is not a cost-justified business decision. An alternative would be the migration of current systems to a more integrated solution. The migration to a computer-integrated manufacturing (CIM)-based architecture would provide that single image real-time information system.

The effort and skills necessary for the implementation of a CIM-based architecture would require active participation from two key organizations: Manufacturing and information systems (I/S). The manufacturing engineers, process engineers and other manufacturing resource would be the cornerstone for obtaining requirements. The ability to effectively use I/S is a critical success factor in the implementation of CIM. I/S has to be viewed as an equal partner, not just as a service organization. Manufacturing management needs to understand the justification process of integrating computer systems and the “real” cost of integration versus the cost of non-integrated manufacturing systems. The active participation of both organizations during all phases of CIM implementation will result in a effective and useful integrated information system.     

Structural optimization with manufacturing considerations

Product design has traditionally been done in a sequential fashion. This often requires extensive iteration between product and manufacturing engineers to insure manufacturability long after the initial product design. Simultaneous engineering attempts to reduce design time by considering both the product and process from the earliest design stage. Toward this goal, we have extended a structural optimization program by incorporating manufacturability requirements for thin-wall beam type members formed by stamping. This was implemented using a new two-piece beam design element which accounts for thinning of the sidewalls during combined stretch and draw forming. Multiple material types and stamping processes are considered. Simple formulae for forming strain and elastic springback after stamping allow us to evaluate the formability of each beam member. The new capability was tested using both simple beam structures and a complete automotive frame structure. Minimum mass designs were then produced while considering both structural and formability requirements. In general, the mass of the optimal designs was near the mass of the same structures designed without manufacturing considerations. This was possible because of the additional design freedom offered by including the sidewall thinning effects.     

Modelling manufacturing systems

The traditional approach of extrapolating past experience in order to predict the performance of manufacturing facilities has been found to be quite inadequate for automated manufacturing systems. The need to identify the key factors influencing performance has led to the development of both simulation and analytical models to help in design, operation and control. The basic approaches to the development of such models will be outlined and illustrated with examples pertaining to assembly lines, automatic transfer lines, and flexible manufacturing systems. The value of formal models will be demonstrated by examples of the insights which can be gained through their use. The paper will conclude with a discussion of current research needs in both model development and model application.     

Flexible manufacturing systems

Flexible manufacturing is an important new technology. The article explains the concept of flexible manufacturing, outlines its worldwide use, and comments on development trends.     

Flexible manufacturing systems in Europe

Flexible manufacturing systems can be classified as lines, networks, and cells. Current research efforts are concentrated on tool flow systems, process monitoring, and system control. To minimize economical and technological risks already in an early stage of system planning software for simulation and economic evaluation has been realized. The economy of different types of manufacturing cells are compared.     

Federated integration of networked manufacturing service platforms

Networked manufacturing is an advanced manufacturing pattern that was born of information technologies and suits the networked economic environment. Networked manufacturing service platforms have been widely established to support this new pattern. Since the island problems are retarding further development of networked manufacturing, integration of existing networked manufacturing platforms is in demand. A federated integration mode is proposed to integrate the existing networked manufacturing platforms and provide a large-scale distributed resource sharing and cooperative environment. The nature of federated integration is discussed, and the architecture of federated integration system was put forward along with a set of rules and three types of integration services. Two key issues in federated integration are discussed in detail. One is the federation management, including the hierarchy of federations, the basic states of federations and the state-keeping mechanism using factory/instance pattern. The other issue is the authentication, authorization and access control in across-platform applications. Finally, an implementation is presented.     

Designing Holonic manufacturing systems

This paper discusses the design of Holonic manufacturing systems (HMS), with emphasis on manufacturing control. First, it discusses the concept of a Holonic system. Second, it presents the HMS reference architecture for manufacturing control. Third, it addresses the overall design problem, i.e. designing both the holonic control system and the underlying manufacturing system. Finally, the paper addresses the design and development of the control software itself.     

Reconfigurable manufacturing systems: Key to future manufacturing

Presented in this article is a review of manufacturing techniques and introduction of reconfigurable manufacturing systems; a new paradigm in manufacturing which is designed for rapid adjustment of production capacity and functionality, in response to new market conditions. A definition of reconfigurable manufacturing systems is outlined and an overview of available manufacturing techniques, their key drivers and enablers, and their impacts, achievements and limitations is presented. A historical review of manufacturing from the point-of-view of the major developments in the market, technology and sciences issues affecting manufacturing is provided. The new requirements for manufacturing are discussed and characteristics of reconfigurable manufacturing systems and their key role in future manufacturing are explained. The paper is concluded with a brief review of specific technologies and research issues related to RMSs.     

The role of design for manufacturing in system integration

The costs of “over design” to build in recovery tactics for poor design-production match are substantial. Design for manufacturing can greatly improve the design-production match and enhance manufacturing system integration. A model of manufacturing integration is given which emphasizes three major parameters: (1) Corporate planning, (2) Capacity, and (3) Productivity. The model enables an assessment of overall manufacturing system integration. Methods for gathering the required data and analyzing the data to supply the system integration model metrics are given. Design for manufacturing is shown to significantly impact system capacity, production control, and effectiveness of manufacturing system integration.     

Functional integration in CAD systems

This paper examines the issue of integration in CAD systems and argues that for integration to be effective, it must address the functional aspects of a CAD system. It discusses the need for integrated systems and, within a structural engineering context, identifies several facets of integration that should be targeted. These include 2-D drafting and 3-D modelling, graphical and nongraphical design information, the CAD data structure and its user interface, as well as integration of the drafting function with other engineering applications. Means of achieving these levels of integration are briefly discussed and a prognosis for the future development of integrated systems explored. Particular attention is paid to the emergence (and potential role) of ‘product models’ which seek to encapsulate the full range of data elements required to define completely an engineering artefact.