Production engineering-oriented virtual factory: a planning cell-based approach to manufacturing systems design

In the traditional process of designing a manufacturing system, a sequential approach treats each of the design steps individually, without considering the requirements of concurrent design activities. The lack of systematic and concurrent consideration of the interactive impact of design decisions leads to repeated and excessive changes in the design and process. To resolve this problem, this research develops a production engineering-oriented virtual factory — a planning cell-based manufacturing systems design approach. The manufacturing systems design process based on a planning cell is reengineered according to the concept of concurrent engineering. The process modeling of a production engineering-oriented virtual factory is proposed at generic and particular levels. An illustrative example of an engine assembly plant demonstrates the effectiveness of the new approach.     

拟实制造的机械加工过程仿真

叙述了拟实制造技术的含义、构成及发展情况,分析了在拟实制造中占有重要地位的机械加工过程仿真。提出了机械加工过程仿真的系统结构,发展现状与存在的问题,最后讨论了车削加工过程进行仿真及其实现的可能性。     

A model management systems approach to manufacturing systems design

Manufacturing systems design involves the solution of a complex series of interrelated problems. This complexity will increase in the future as manufacturing practices change to meet increased global competition. Research within manufacturing systems design has mainly been focused on finding improved models for solving particular problems, or extending existing modeling techniques. This has resulted in numerous modeling tools being available to support manufacturing systems design. However, little research work has been carried out into consolidating the existing theories and models. As a result, a large body of this work has not been applied in industry.Model management has evolved as a research area which investigates methods for storing, modifying, and manipulating models. This article describes a prototype model management system for manufacturing systems design. The objective here is not to develop another decision support system for manufacturing design, but to illustrate, through the development of a prototype system, a number of key ideas of how concepts from the area of model management systems can be used to support manufacturing systems design. The prototype model management system utilizes the structured modeling framework and uses an extended version of the structured modeling language. An important aspect of the prototype model management system is the incorporation of the model development task, thus allowing the system to be easily updated and adapted. The prototype system was evaluated using a range of queueing network models for manufacturing systems design.     

Development of a prototype customer-oriented virtual factory system

Current Computer integrated manufacturing/Enterprise Resource Planning (CIM/ERP) systems require harmony and communication between humans and facilities. A user’s preferences should also be considered in CIM/ERP systems. Virtual factory (VF), also known as virtual manufacturing (VM), systems can fulfill the requirements of current CIM/ERP systems. A VF system simulates virtual production in a virtual factory environment on the computer system which allows optimization prior to going into production. In this paper, we defined a VF system as a pre-analyzing system for designing, engineering and manufacturing a product in the enterprise system of the real world. The objective of this paper is to design a VF system and to develop a prototype system that the customer can participate in and be satisfied with. We selected a telephone as a sample product for the VF system. The VF system consists of four subsystems: virtual product ordering, design, manufacturing, and CIM/ERP interface. The prototype system aims to develop a virtual product ordering and design system.     

A systems approach to fixture planning and design

Within the last decade, the manufacturing research community has addressed many of the micro issues of automating the fixture design process using computers. Most of this research has concentrated on the geometric and kinematic factors that determine the configuration of a computer-aided fixture design (CAFXD) system. However, before the implementation of any of the researched micro issues can be accomplished, a systematic approach to fixture planning and design must be recognised that considers the macro issues (process planning and fixture design) of the complete design to manufacturing process. In order to improve the effectiveness and implementation of researched micro issues in fixture design, a generic model of the functional activities can provide an understanding of the process and information exchanged between process planning and fixture design. This paper presents such a generic IDEF working model that promotes the functional integration of these two functions — developed from a systems perspective.     

分布式虚拟环境下的产品协同设计与制造

虚拟技术和计算机支持的协同工作（CSCW）技术已经渗透在设计与制造的活动中,并推动制造信息集成和网络协同设计与制造技术的发展。文中分析和讨论了分布式虚拟环境中的协同设计与制造系统的特点及其本要求,以五层结构形式给出了一处系统实现的框架模型。     

A modeling approach for designing a value chain of virtual enterprise

As the advent of digital economy changes business environment dramatically, virtual enterprise (VE), in general the interactions among business partners in a value chain, has become a key factor to survive under the competitive business environment. VE reveals that more complex and dynamic business processes should be considered as assembled service components in order to integrate the collaborative business processes. Therefore, a formal standard schema for describing and managing the business processes is required. In this paper, we propose a consistent modeling approach that combines enterprise modeling and simulation modeling to design a value chain of a VE. This methodology will provide designers with insight into the business processes of a VE and help identify and resolve unpredictable bottlenecks on the execution of virtual business processes. This paper also illustrates an implemented modeling tool which is based on the generalized model suggested by the working group of the international conference on enterprise integration and modeling technology (ICEIMT) and notations by the object management group (OMG)’s unified modeling language (UML) profile for enterprise distributed object computing (EDOC).     

A systematic approach for the sequence controller design in manufacturing systems

This paper presents a systematic approach for the design and implementation of the sequence controller in manufacturing systems. By employing the IDEF0, we construct the simplified Petri net controller (SPNC) through the material flow diagram and the information flow diagram. Then, the ladder logic diagram (LLD) can be transformed from the SPNC through the token passing logic (TPL). The proposed approach, including the IDEF0, SPNC, and TPL tools, leads to the standard IEC1131-3 LLD for PLC implementation. Finally, an application of a stamping process is provided to illustrate the design procedure of the developed approach .     

Parts verification for multi-level-dependent demand manufacturing systems: a recognition and classification structure

This research has developed and implemented a part recognition and classification structure to execute parts verification in a multi-level-dependent demand manufacturing system. The part-recognition algorithm enables the parent and child relationship between parts to be recognised in a finite-capacitated manufacturing system. This algorithm was developed using the SIMAN simulation language and implemented in a multi-level-dependent demand manufacturing simulation model. The part-classification structure enables the modelling of a multi-level-dependent demand manufacturing system between parts to be carried out effectively. The part-classification structure was programmed using Visual Basic Application (VBA) and was integrated into the work-to-list generated from a simulated materials requirements planning (MRP) model. This part-classification structure was then implemented in the multi-level-dependent demand manufacturing simulation model. Two stages of implementation, namely, parameterisation and execution, of the part recognition and classification structure were carried out. A real case study was used and five detailed steps of execution were processed. Simulation experiments and MRP were run to verify and validate the part recognition and classification structure. The results led to the conclusion that implementation of the recognition and classification structure has effectively verified the correct parts and sub-assemblies used for the correct product and order. No parts nor sub-assembly shortages were found, and the quantity required was produced. The scheduled release for some orders was delayed due to overload of the required resources. When the loading is normal, all scheduled release timing is adhered to. The recognition and classification structure has a robust design; hence, it can be easily adapted to new system parameters to study different or more complex cases.     

Production planning of FMS under tool magazine constraints: A dynamic programming approach

Production planning is one of the most important activities for efficient operation of a flexible manufacturing system. This complex acivity is concerned with the decisions related to system set-up, involving solving the problems of selection of a set of part types for simultaneous processing, determining the production ratios, assigning the pallets and fixtures, and assigning operations and tools to machines. In this paper, a dynamic programming algorithm is developed to solve the above problems simultaneously by considering the flexibilities and constraints of the system in order to minimise the unbalanced workload of machines. In this context, various factors such as the tools required for operations, alternative routes available for operations, tool magazine capacity and the limited number of pallets and fixtures are considered. The method is validated with a case study.Notation B a large number - i part type,i=1,...,N - o operation,o=1,...,O _i - k machine,k=1,...,K - j stage,j=1,...,N (N is maximum number of stages required, i.e. equal to the number of part types) - n indicates the number of parts to be introduced into the system (represents the state in DP),n=j,...,nmax. In stagej at least one number of each part type should be introduced into the system. The maximum number of parts can be a user defined maximum,nmax. - P _iok processing time of part typei, operationo on machinek - OA _io set of operation alternatives available for part typei, operation - o an alternative consists of machine number, tool number along with its processing time - pw _ik average workload required by a part typei on machinek - a _i number of parts (ratio) of typei - f _i number of fixtures available to part typei - S(j) {S ₁(j),S ₂(j),...,S _p (j),...}, whereS _p (j) ispth set of selected part types with cardinalityj - |S(j)| ^N C _j - W _k a constant, indicating the average unbalanced workload on a machinek and is a user defined value - L _j,k (S _p (j),n,a _i ) load of machinek at stagej when selection isS _p (j), number of part types isn, and number of parts of type isa _i - L* _j,k (S _p (j),n) load of machinek in stagej at minimum unbalanced workload when selection isS _p (j) and number of parts in system isn - F _j (S _p )(j),n,a _i ) unbalanced workload of all machines at stagej, when selection isS _p (j), number of part types isn, and number of parts of type isa _i - F _j (S _p (j),n) minimum unbalanced workload of all machines, whenS _p (j) is the set of selected part types andn is the number of parts in the system     

Design of integrated manufacturing planning, scheduling and control systems: a new framework for automation

The automation and integration of manufacturing planning, scheduling and control functions have, for a long while, been targeted in computer-integrated manufacturing (CIM) and artificial intelligence (AI) approaches. Current systems, however, are human-based and they can only be characterised as decision support systems (DSS) rather than automated systems. Global competition and the need for improved responsiveness, particularly in low-volume, high-variety manufacturing industries, necessitate further integration and automation in planning, scheduling and control functions. We consider that, to achieve automation, the concepts and techniques from operations research (OR), control theory (CT), and computer science (CS) should be integrated, enriched and unified to provide a platform for automation. This paper presents a fresh perspective for understanding the design issues involved and proposes a new framework for the automation and integration of planning, scheduling and control functions. A fully automated flow shop production system is presented to illustrate the applicability of the new framework.     

An agent-oriented approach to resolve the production planning complexities for a modern steel manufacturing system

The development of strategies for sequencing slabs through the reheat furnace and rolling mill of a modern steel manufacturing system is complicated by multiple and often conflicting objectives. For example, optimal energy efficiency through the reheat furnace may lead to inefficient rolling sequences or a less than desirable product delivery schedule. Thus, not only the model formulation is complicated, but also the combinatorial nature of the problem precludes an optimal solution. To address these complexities, an agent-oriented approach that has originated from distributed artificial intelligence (DAI) is proposed here. It is found that the implementation of agent technology in the steel manufacturing system makes the operations more flexible, economical and energy efficient.     

An integrated methodology for operations analysis of computer integrated manufacturing systems: Application to an FMS for manufacture of medical instruments

This paper contributes a novel methodology for operations analysis of computer integrated manufacturing systems. The methodology employs an integrated set of personal computer-based manufacturing systems modelling software, and is conducted in three stages. The methodology is illustrated in detail for analysis of materials flow and staffing for a flexible manufacturing system (FMS) installed at a medical instruments manufacturing plant. First, a rough-cut capacity and materials flow analysis was performed using a queueing model. Second, a detailed analysis of FMS system characteristics was conducted by creating and analysing a discrete-event simulation model. Finally, a graphical animation package was used to verify previous results and provide visual feedback on FMS system performance. Analysis results were obtained rapidly and conveniently, and were used to advise manufacturing managers regarding FMS operating policy. This analysis methodology can be applied to a wide range of computer integrated manufacturing systems and manufacturing cells.     

A web-based advisory system for process and material selection in concurrent product design for a manufacturing environment

This paper reports the work of selecting suitable manufacturing processes and materials in concurrent design for manufacturing environment. In the paper, a fuzzy knowledge-based decision support method is proposed for multi-criteria decision-making in evaluating and selecting possible manufacturing process/material combinations in terms of the total production cost. Based on the proposed method, a prototype Web-based knowledge-intensive manufacturing consulting service system (WebMCSS) with the client-knowledge server architecture is developed to help designers/users find good processes and materials while still at the conceptual level of design. The system, as one of the important parts of an advanced design for manufacturing tool, is a concept level process and material selection tool that can be used as both a standalone application and a Java applet freely available via the Web. Interlinked with Web pages of tutorials, and reference pages explaining the facets, fabrication processes and material choices, the system performs reasoning and calculations using the process capability and material property data from the remote Web-based database and knowledge base that can be maintained and updated via the Internet. The use of the system is illustrated with an example.     

A computational system for process design of injection moulding: Combining a blackboard-based expert system and a case-based reasoning approach

Process design of injection moulding involves the selection of the injection moulding machine, mould design, production scheduling, cost estimation, and determination of injection moulding parameters. An expert system approach has been used to derive the process solution for injection moulding over the past few years. However, this approach is found to be incapable of determining the injection moulding parameters owing to the fragile nature of the knowledge for setting the moulding parameters. In addition, the existing expert systems for process design lack proper architecture for organising heterogeneous knowledge sources. In this paper, the combination of a blackboard-based expert system and a case-based reasoning approach is introduced to eliminate the deficiency of the existing expert-system approach to process design, from which a computational system for the process design of injection moulding, named CSPD, has been developed. CSPD first derives the process solution including the selection of the injection moulding machine and the mould base, tooling cost, processing cost estimation, and production scheduling based on the blackboard-based expert-system approach. It is then followed by the determination of the injection moulding parameters based on the case-based reasoning approach and the previously derived partial solution.     

An optimal concurrent design and loading strategy for a flexible assembly line system: to control the bottleneck

In this paper, an optimal strategy is presented at the design stage for selection of the required local storages of the workstations and the transporter stations of a finite capacity flexible assembly line system, such that the throughput rate from the system is maximised while controlling the bottleneck problem. For this purpose, a mixed non-Markovian queueing network model is presented to model its performance, a stochastic optimisation model is provided to maximise its throughput rate, and a heuristic algorithm is developed for solving it. Finally, an example is presented and the approximation results are compared against those from a simulation study.     

Using risk analysis and Taguchi’s method to find optimal conditions of design parameters: a case study

Variation in product performance can be seen as a design failure. The fundamental principle of robust design proposed by Taguchi is to improve the quality of a product by minimizing the effect of causes of variation, without totally eliminating the causes. A method of robust design is briefly explained and its application is demonstrated with the help of a case study from Roots Industries Ltd., Coimbatore. This paper describes how the inherent modeling of product and process requirements in key characteristics (KCs) can be used to express and capture the product design intent. KCs are those features which significantly affect product function and performance, or occur when there is variation. A prototype software program (VRM Tool) was developed to house all the critical design data for process optimization and its eventual reuse. We establish a systematic process of identifying, assessing and mitigating risk in the early stage of design for a Windtone class of automobile electric horn, using robust design concept. The results suggest that the proposed robust design method is an efficient, disciplined approach that can assist a product delivery team in designing for a better functional performance and improved reliability of the entire system .