Design of cellular manufacturing systems with assembly considerations

This research proposes incorporating assembly aspects associated with a product into the design of Cellular manufacturing System (CMS). The literature on CMS design implicitly assumes that finished part is the end product by itself. In practice, often, manufacturers produce parts which are assembled into a finished product. The methodology employs a part–subassembly matrix derived from the product structure in addition to the part–machine matrix. A mathematical programming model is developed which determines an assignment of parts, machines and subassemblies to manufacturing cells. The proposed model employs a new similarity coefficient between part, machine and subassembly. The model resulted in a nonlinear program with 0-1 variables. A case study has been analyzed based on a published part–machine matrix and a randomly generated product structure. The analysis reveals that it may be required to forego some of the efficiencies of Group Technology (GT) in order to achieve integration of assembly operations with production of parts. From a practical stand point of view it is preferred to have a system design which has a mix of GT and integration efficiencies, compared to a design which outperforms on GT criteria and completely lacks integration of assembly operations with production of parts.     

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.     

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.     

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.     

Robots in flexible manufacturing systems

The use of computer controlled manufacturing systems incorporating robots and flexible control is of paramount interest today. A number of economists have noted that strength in high technology industries such as aircraft, missiles, communications, electronic and computers, in contrast to older industries, gives the economy of any country strong long-term growth prospects.During the past two decades, the concept of a flexible, programmable automation device, which has come to be known as an “industrial robot”, has become a reality. A variety of these automation modules have been developed, offering a wide range of capabilities and application possibilities. Robots currently help weld, cast, form, assemble, machine, transfer, inspect, load and unload parts into and out of a number of differing machines and processes.The first part of this paper analyzes the significance of FMS in industries today. The second part of the paper attempts to evaluate some of the areas of savings as a result of using robots.     

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.     

An innovative integration of fuzzy-logic and systems dynamics in sustainable supplier selection: A case on manufacturing industry

Globally, supply chains compete in a complex and rapidly changing environment. Hence, sustainable supplier selection has become a decisive variable in the firm’s financial success. This requires reliable tools and techniques to select the best sustainable supplier and enhance understanding about how supplier behavior evolves with time. System dynamics (SD) is an approach to investigate the dynamic behavior in which the system status alterations correspond to the system variable changes. Fuzzy logic usually solves the challenges of imprecise data and ambiguous human judgment. Thus, this work presents a novel modeling approach of integrating information on supplier behavior in fuzzy environment with system dynamics simulation modeling technique which results in a more reliable and responsible decision support system. Supplier behavior with respect to relevant sustainability criteria in the past, current and future time horizons were sourced through expert interviews and simulated in Vensim to select the best possible sustainable supplier. Simulation results show that an increase in the rate of investment in sustainability by the different suppliers causes an exponential increase in total sustainability performance of the suppliers. Also, the growth rate of the total performance of suppliers outruns their rate of investment in sustainability after about 12 months. A dynamic multi-criteria decision making model was presented to compare results from the systems dynamics model.     

Challenges in business systems integration

Four main frameworks for intercompany relationships (SCOR, CPFR, ISA95 and OAG) are discussed and compared. The link between the frameworks and different supply chain integration applications such as ERP, CRM and VMI are pictured. Finally the state-of-the-art, future state and challenges of the supply chain integration applications are discussed. It is concluded that the main challenge with respect to frameworks supporting business systems integration is to extend them with implementation functionality to better support business system application development. An example of this is customer requirement fulfillment processes such as product development and order fulfillment. Not only do they cross the borders of the company's departments (sales, logistics, purchasing, etc) but also various companies in the supply chain. In spite of this development, business integration across systems and borders are still not matured and to a large extend based on human interaction.     

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.