FMS Designer: An expert system for flexible manufacturing system design

Implementation of flexible manufacturing technology in the batch manufacturing environment has created major problems for designers and engineers who are responsible for specification and design of flexible manufacturing systems (FMS). The FMS design task appears to be an excellent application for expert systems techniques. This paper describes current results of an ongoing research effort to develop an expert system which analyses the output from an FMS simulation model, determines whether operational and financial objectives are met, identifies design deficiencies or opportunities for improvement, and proposes designs which overcome deficiencies or exploit improvement opportunities. An overview of the FMS design expert system is given and a case study is presented to illustrate how the system operates. Areas for future research are also discussed.     

Application of Axiomatic Design principles to control complexity dynamics in a mixed-model assembly system: a case analysis

The purpose of this paper is to test the validity of Axiomatic Design (AD)-based complexity theory as an explanatory construct and as a methodological guidance for the early detection of need for change in flexible manufacturing systems in order to maintain competitiveness even in turbulent environmental conditions. The AD approach postulates that there are general design principles that govern the behaviour of a system. This proposition is empirically investigated for a flexible mixed-model assembly system by the examination of a long-term study conducted in a medium-sized industrial company. The findings of the long-term study suggest the introduction of a company specific cycle of functional periodicity in combination with a set of functional requirements working together as a regular trigger to detect whether the system range is moving away from the once defined manufacturing system's design range. The paper extends the research work made in the field of AD by focusing on mechanisms that help to control the effects of time-dependent complexity in manufacturing (re)design. Examples of methods and lead measures are given that can be used by organisations in early detecting and controlling complexity driven efficiency losses in manufacturing systems.     

论制造系统模式的新进展

分析了制造系统模式变迁的原因；论述了现代制造系统模式的新特征，即客户化动态系统、可变性、自组织、自治与协调、全生命周期高的成本效率以及集成进化；提出了支持现代制造系统模式的若干关键技术，包括时变制造过程建模、自适应生产管理以及现代集成技术等；介绍了可重构制造系统、多智能代理制造系统、子整制造系统以及虚拟生产系统等现代制造系统；并从工业工程的角度，讨论了发展中国现代制造系统模式的若干问题，即改变金字塔式的集中管理组织结构，合理地发挥人的作用以及重视信息技术的应用。     

Development of a dual-robot system for prototype production

A dual-robot machining system has been developed for manufacturing complex objects. The system consists of two six-axis industrial robots with flexible tool changers, a CAD/CAM package for geometric design and toolpath generation, a robot simulation package for collision avoidance, and a vision system for robot calibration. It offers the flexibility to reconfigure the robots of the system to accommodate workpieces of different shapes and sizes. A prototype of the system has been successfully developed and tested, and shows satisfactory performance in machining quality and control over the configurations of the robots. Examples are given of the application of the system to machining objects with spherical and sculptured surfaces. The system has been shown to be flexible, reconfigurable, automatic, and capable of manufacturing complex prototypes in the current industry environment.     

Implications of form postponement to manufacturing: a cross case comparison

While much is written in the literature about the benefits and strategic impact of form postponement (FPp), little is still known about its application. We address ‘how’ FPp is applied in terms of its operational and logistics implications within manufacturing facilities. This paper is a retrospective study of the application of FPp in three diverse manufacturing environments: a manufacturer of specialist high voltage cabling equipment we call Electrico; a manufacturer of industrial electric motors we call Motorco; and a manufacturer of control systems and components mainly for automated telling machines we call Controlco. Our findings show that FPp improved responsiveness of manufacturing in all cases, but that none of the applications of FPp was ideal from a theoretical perspective. The production planning system must be both responsive and flexible to support the application. For highly customised products, the customer order decoupling point (CODP) must be located sufficiently upstream in the manufacturing process to avoid removal of components and time-consuming modifications. We present conclusions from all three studies, including an inventory management decision framework for FPp and a framework for the application of FPp which encompasses a number of practical considerations.     

Applying GMP to Computerization in a Solid-Oral-Dosage-form-Factory

Quality Assurance and Pharmaceutical security as well must be given a particular consideration both for hardware and software when computerized pharmaceutical industrial operations are concerned

Hardware: The preparation of validation should begin with the design of a computerized system and rely upon specifications and upon defined operational limits

It is suitable to prepare documentation as from the development of the system in order to obtain a fruitful communication between all those concerned with design, implementation, maintenance, validation and auditing

A revalidation procedure should be prepared and maintained updated, in the event of a change in one or several operating conditions

Software: As with hardware, validation of software should be envisioned as early as the development phase. Preparation of test procedures and documentation should start at this very stage. Qualification and validation will be designed to find errors in the program and not to prove that no errors exist. They will be carried out at the operational boundaries of the software and will aim at testing the critical decision paths of the program. Verifications must be repeated a sufficient number of times to demonstrate that the results are repeatable

As with other pharmaceutical manufacturing systems, a formal procedure should exist to support changes made to the software. Vendor supplied software should be verified and documented with the same rigour and details that in-house developed software. Manual back-up systems must be provided for and regularly tested in the event of failure of the automated process. Computerized systems and good manufacturing practices applied to manufacturing of solid oral dosage forms: An application of the above-stated principles is given and illustrated     

Visual interactive simulation and artificial intelligence in design of flexible manufacturing systems

The design of flexible manufacturing systems is a complex decision-making process that typically involves the evaluation of a number of different design alternatives. The evaluation is often performed using modelling and simulation techniques. The role of visual interactive modelling and simulation in design of flexible manufacturing systems is discussed. The application of artificial intelligence techniques to implement a set of knowledge sources, used for accomplishment of various design activities, is described. An object-orientated implementation is used to illustrate the underlying concepts.     

An attribute design method: a new approach to flexible welding machine design

We examine the design of flexible welding machines, particularly the process of matching a group of components with an optimum machine design. Analysis of current design methods highlighted the need for a systematic and less time consuming method for the conceptual design of these machines. Also identified was the need to establish a link between components to be manufactured, and the design of welding machines, within appropriate economic constraints. We present the Attribute Design Method, developed to achieve an optimum machine design for a given group of components. The method is applied to the design of a flexible welding unit, but its application may be extended to the design of flexible manufacturing systems.     

Applying GMP to Computerization in a Solid-Oral-Dosage-form-Factory

Abstract

Quality Assurance and Pharmaceutical security as well must be given a particular consideration both for hardware and software when computerized pharmaceutical industrial operations are concerned

Hardware: The preparation of validation should begin with the design of a computerized system and rely upon specifications and upon defined operational limits

It is suitable to prepare documentation as from the development of the system in order to obtain a fruitful communication between all those concerned with design, implementation, maintenance, validation and auditing

A revalidation procedure should be prepared and maintained updated, in the event of a change in one or several operating conditions

Software: As with hardware, validation of software should be envisioned as early as the development phase. Preparation of test procedures and documentation should start at this very stage. Qualification and validation will be designed to find errors in the program and not to prove that no errors exist. They will be carried out at the operational boundaries of the software and will aim at testing the critical decision paths of the program. Verifications must be repeated a sufficient number of times to demonstrate that the results are repeatable

As with other pharmaceutical manufacturing systems, a formal procedure should exist to support changes made to the software. Vendor supplied software should be verified and documented with the same rigour and details that in-house developed software. Manual back-up systems must be provided for and regularly tested in the event of failure of the automated process. Computerized systems and good manufacturing practices applied to manufacturing of solid oral dosage forms: An application of the above-stated principles is given and illustrated     

Logical reconfiguration of reconfigurable manufacturing systems with stream of variations modelling: a stochastic two-stage programming and shortest path model

Designing flexible manufacturing systems in general, and flexible material handling system in particular, is a complex problem, typically approached through several stages. Here the focus is on the conceptual design stage during which valid approximation-based methods are needed. The segmented flow topology (SFT) AGV systems were developed to facilitate control of complex automated material handling systems. This paper introduces a decomposition method, directly derived from timed Petri nets (TPN) theories, to calculate the expected utilization of AGVs (as servers of SFT systems) and to derive simple operational decision rules leading to maximum system productivity at steady state, for a given deterministic routeing of discrete material through the manufacturing system.     

Optimal design of flexible production lines with unreliable machines and infinite buffers

Despite the increasing use of automated manufacturing systems, combining flexible technology, only a few models for designing such systems are available. This paper presents a model for the determination of the profit-maximizing configuration of workstations (both machine types and number) along a flexible production line with unreliable machines and infinite buffers. A mixed integer programming formulation of the problem is introduced and an optimal solution algorithm is developed. For large scale problems a heuristic procedure is presented.     

Framework for designing a flexible cellular assembly system

Modern manufacturing companies have to face competition in a turbulent world market that requires them to improve their operating performances according to increasingly differentiated products with shorter life cycles, low volumes and reduced customer delivery times. The aim of the present paper is to develop a conceptual framework for the simultaneous design and control of a flexible, agile reconfigurable and robust assembly system in conjunction with the analysis and optimization of product, process, system structure, material-handling devices and plant layout. An effective solution for reconfigurability and agility in assembly to order and batch-type systems is a modular semi-automatic approach based on cellular flexible facilities: modularity, automation and human skills are combined to gain the advantages of mass production. Families of parts are produced in flexible cells, i.e. groups of various machines and resources that are physically close together and process one or more families of similar parts. The proposed approach is based on a multistage iterative procedure that integrates different supporting decision techniques and tools such as design for assembly, group technologies and cellular manufacturing. An application to the optimization of a semi-automatic flexible assembly system is illustrated: the system performances of example alternative solutions are presented and compared.     

A multi-level modelling system for the design of flexible machining installations

Modern flexible manufacturing facilities can be highly complex, consisting of the latest developments in machine tool technology, automated material handling systems and sophisticated cell controllers. The design and management of such systems requires a large number of decisions and choices with regard to production mix, assignment of fixtures and cutting tools. A large number of commercial computer modelling packages are now available in the market place. Although these allow valuable assistance in the analysis of a manufacturing facility, they usually take significant amounts of time to build models and require a large amount of training, and can be constraining in their application. This paper establishes a research prototype for a multi-level approach for the realization of a three-phase design and modelling system for flexible machining facilities. It portrays the view of an integrated fully data-driven solution underpinned by a machining cell database, and outlines three major areas of work within the structure, i.e. the 'Cell Configurator', 'Evaluator' and 'Emulator'. The approach is demonstrated and supported throughout the paper by an industrial case study of a modern three-machine flexible machining cell, illustrating the use of the underlying methodology behind the approach and typical inputs/outputs at each phase. The final part of the paper provides a discussion of the approach adopted based on user comments and in relation to commercial simulation tools available.     

TECHNOLOGICAL PROCEDURES OF ELECTRON BEAM WELDING AND REPAIR

The most developed fields of electron beam welding (EBW) industrial application in the world are aerospace industry, nuclear power engineering, turbine manufactures, instrumentation, automobile industry, manufacture of bimetal strip. The expansion of EBW application is associated with the manufacturing of thick-wall steel structures. A short review of EBW techniques is given. The expediency of applying the electron beam facing of edges before welding the relatively contaminated plate materials is explained. The procedure of welded joint repair is presented. The acceptability of rewelding the defective weld areas is shown for the case of high-strength steel.     

The optimal design of flexible manufacturing systems

The optimal design and control of flexible manufacturing systems is essential to minimize operating costs and enhance productivity. We present a hybrid mathematical model of a flexible manufacturing system as a closed network of queues for which the optimal cost effective system configuration is determined by a. partial implicit enumeration algorithm. The optimal configuration of both reliable and unreliable flexible manufacturing systems are considered.     

PRODUCTION SCHEDULING IN A FLEXIBLE MANUFACTURING SYSTEM WITH SETUPS

A model is presented for the planning and scheduling of production batches in a flexible manufacturing system environment in which setup costs and times are nonnegligible and alternate routings are possible. The formulation is an integer program with a multicommodity flow network structure. A heuristic procedure based on price-directive decompostion using column generation is used to obtain solutions. Numerical experimentation is performed to assess die quality of the heuristic versus optimal solutions, and to determine the impact of routing flexibility on total cost, inventory levels, bottlenecks, capacity utilization, throughput time, number of setups and split lots. Important cost-benefit trade-off implications are shown for the design of flexible manufacturing systems.     

A procedure for the application of product modelling

A procedure for the application of product modelling, resulting from a recently concluded PhD project, is presented. The procedure focuses on the various design of products, where the basic product structure is well defined. The procedure is based on four theory elements: reference models for product modelling, work-study analysis, the task concept from systems theory, and the object-oriented paradigm. The procedure has been tested in a Danish company, and it has been shown via a project of moderate size (in this case using 700 engineering hours, including time for experience collection) that it is possible to get started and use product modelling in industrial companies. Furthermore, it has been demonstrated that the application of product models can save considerable engineering resources (1500-3000 hours per year). Another conclusion is that the product modelling activities are an important means for supporting and integrating engineering activities, as the product modelling activities provide engineers from design and methods engineering departments with valuable insight into the knowledge and procedures used for specifying products and as well as into manufacturing methods.     

A framework for the design of cellular manufacturing systems

A two-stage procedure for the design of a cellular manufacturing system is proposed. The first stage forms the part families. The use of clustering techniques with a new proximity measure is advocated for this stage. The proximity measure uses the manufacturing operations and the operations' sequences. The second stage forms the machine cells. An integer programming model is proposed for this stage. The solution of this model will specify the type and the number of machines in each cell and the assignment of the part families to the cells. The relevance of this approach in the design of flexible manufacturing systems is discussed.     

Implementation of an object-oriented tool for the simulation of manufacturing systems and its application to study the effects of flexibility

Although there is a reasonable number of currently available modelling tools for the analysis and evaluation of flexible manufacturing systems, these models, in general, neglect flexibility. They do not consider that in a flexible manufacturing system there is the possibility of different operation sequences. As a consequence, while flexibility in manufacturing is much 'in vogue', the development of models that are able to improve the understanding and consequences of having flexibility is still incipient in the literature. This paper presents work to develop a tool to support the analysis of flexible automation. The tool described is an objectoriented discrete-event simulator, called OOSimFlex, capable of modelling different alternative systems design and analysing a manufacturing system using multiple performance measures under different manufacturing flexibility levels. The paper describes the major theoretical concepts employed for the development of a highly flexible and interactive simulation model environment.     

Optimal algorithms for row layout problems in automated manufacturing systems

In many automated manufacturing environments, particularly flowlines and flexible manufacturing systems (FMSs), machines are arranged along a straight material-handling track with a material-handling device moving jobs from one machine to another. These layouts are referred to as row machine layouts. In this paper we study the row layout problem (RLP) under the design objective of minimizing the total backtracking distance of the material-handling device, which is an NP-complete problem. We propose the use of a dynamic programming algorithm for its solution. A special case of the problem, usually encountered in flexible manufacturing cells and which can be solved with a polynomial procedure, is also discussed. For the equidistance case (i.e., successive candidate locations are in equal distances), we formulate the problem as an integer linear program. The use of standard mathematical programming codes can efficiently solve this formulation.