CIM implementation for job-shop environments

Abstract

Abstract. The small to medium-sized job-shop manufacturing industry can benefit most from the implementation of computer integrated manufacturing (CIM) technology, to meet the increasing demand for high-quality and economically priced products. The injection mould making industry is a typical representative for this group, where a manufacturer would generally produce moulds which consist of parts that are standard to every mould type or very similar. Thus, manufacturing techniques, such as group technology (GT), and production planning and control (information) management systems could make significant contributions in improving the efficiency of design and production operations.

The objective of the project, presented in this paper, was the development of a GT-based classification and coding (C/C) system for injection mould parts especially for the design and process planning phases, and the development of a production planning and shop-floor control (SFC) information management system.

An extensive investigation was carried out on existing GT-based C/C systems. This investigation, followed by a thorough examination of many injection mould parts for determining geometric similarities, led to the development of part families (classes) required for GT implementation. An OPITZ-type GT system was developed, thereafter, for the C/C of the manufactured parts of the target company.

The production planning and control software that has been developed for the target company utilizes a relational data base management system. It consists of 13 application programs, which provide a tool of organizing information for efficient production planning and SFC. The programs are designed to cover all manufacturing operations of a job from the proposal to the final testing stage. Shop orders and dispatch lists are created using this software for effective and prioritized SFC. Shop status and job status reports are generated based on feedback information received through time card entries.     

A note on the within-cell layout problem based on operation sequences

The existing studies in the literature usually ignore the within-cell layout problem while forming part families and manufacturing cells. A new approach is proposed to solve the part-family and machine-cell formation problem and to determine the spatial arrangement of machines in each cell simultaneously. Furthermore, a dissimilarity measure between parts based on operation sequences is presented since the operation sequences not only specify the type of machine tools needed but also impact the flow of material. As a result, we can both minimize the material handling cost and streamline the material flow in each cell.     

Assessing End‐Of‐Supply Risk of Spare Parts Using the Proportional Hazard Model

Operators of long field‐life systems like airplanes are faced with hazards in the supply of spare parts. If the original manufacturers or suppliers of parts end their supply, this may have large impacts on operating costs of firms needing these parts. Existing end‐of‐supply evaluation methods are focused mostly on the downstream supply chain, which is of interest mainly to spare part manufacturers. Firms that purchase spare parts have limited information on parts sales, and indicators of end‐of‐supply risk can also be found in the upstream supply chain. This article proposes a methodology for firms purchasing spare parts to manage end‐of‐supply risk by utilizing proportional hazard models in terms of supply chain conditions of the parts. The considered risk indicators fall into four main categories, of which two are related to supply (price and lead time) and two others are related to demand (cycle time and throughput). The methodology is demonstrated using data on about 2,000 spare parts collected from a maintenance repair organization in the aviation industry. Cross‐validation results and out‐of‐sample risk assessments show good performance of the method to identify spare parts with high end‐of‐supply risk. Further validation is provided by survey results obtained from the maintenance repair organization, which show strong agreement between the firm's and the model's identification of high‐risk spare parts.     

An assessment of GRAI Grids and their use in the Strathclyde Integration Method

The purpose of this paper is to present a critical assessment of GRAI Grids as a tool for improved manufacturing integration. GRAI Grids, a key component of the GRAI approach, form an integral part of the Strathclyde Integration Method SIM for manufacturing integration. The contribution of the paper is thus to provide a 'third party' view of the effectiveness of GRAI Grids as a modelling tool. The paper presents a brief overview of the GRAI approach, concentrating particularly on the Grids, and an overview of SIM, showing how GRAI Grids are used. The main section of the paper presents an assessment and critique of GRAI Grids. Several benefits and limitations of the Grid as used in SIM and some suggestions for extensions are presented. The paper concludes that the use of the GRAI Grid, within a methodology, provides a unique insight into the behaviour and design of manufacturing information systems and that those who criticize the technique perhaps do so from a lack of awareness of its concepts, principles and advantages.     

Information-Processing Alternatives for Coping with Manufacturing Environment Complexity

Investment in information systems and technology is often justified as a necessary strategy for coping with the increased complexity and information needs of today/s manufacturing environments. However, the world class manufacturing paradigm suggests that increased complexity is not always necessary to meet the needs of markets and customers. Galbraith/s (1973, 1977) seminal information-processing model is applied to a manufacturing environment, supported by the world class manufacturing paradigm, to test the role of various information-processing alternatives for coping with increased environmental complexity. Moderated regression and multiple discriminant analysis are used to test hypotheses in a sample of 164 manufacturing plants. Environmental complexity was found to be related to manufacturing performance for each of the five dependent variables. This relationship was moderated by at least one information-processing alternative for each dependent variable, including self-contained tasks, lateral relations, and environmental management strategies for reducing manufacturing, supplier, and goal diversity. Investments in information systems and reduction of labor and customer diversity did not moderate this relationship. Practices that were found to be particularly effective in moderating this relationship included the use of multifunctional employees, communication of manufacturing strategy, coordination of decision making, product design simplicity, reduction of parts counts, supervisory interaction facilitation, recruiting and selection for flexible employees, JIT practices, blanket purchase orders, and strong customer relationships.     

Planning a cost-effective cellular manufacturing process—a case study

The drive key is one of the most important high-precision components of aircraft braking systems. In this paper, a cost-effective drive key manufacturing process is developed. This proposed manufacturing process makes use of near net shape manufacturing, CNC machining, and cellular manufacturing methods. To make the proposed process a reality, proper engineering changes of the parts along with group technology are applied to the product design, in conjunction with the pro posed manufacturing methods. In addition, a general spread sheet program is developed for each style of fixture module to assist in part program coding. Moreover, statistical process control (SPC) is implemented to verify product quality and accept the product at the point of manufacture. It is observed that the implementation of the proposed drive key cellular manufacturing process results in a tremendous improvement in quality, throughput and productivity as well as a drastic reduction in manufacturing operations, workholding fixtures, cutting tools, and inspection media.     

Linking hybrid systems to ACD models: a case study in the fibre-glass industry

This paper is aimed at formalising and testing a model for hybrid systems where the interactions between the continuous process parts and the manufacturing sub-systems are given by minor stoppages. The proposed approach consists in representing the effects of the continuous process dynamics on discrete manufacturing sub-systems by means of autoregressive conditional duration (ACD) models originally conceived to treat high-frequency and irregularly spaced financial transaction data. The model has been applied to a real-life furnace and spooling-bushing department system of a fibre-glass production plant. Results conclude that the ACD-based model proved useful for representing the occurrence of fibre-glass breakage on the spooling-bushing machines and, in more general terms, that the proposed methodology could be really suitable for the logical modelling of the hybrid production systems where the relationships between the continuous and the discrete parts are given by the occurrence of minor stoppages.     

COMPUTER-INTEGRATED MANUFACTURING: A TAXONOMY OF INTEGRATION AND RESEARCH ISSUES

The past decade has seen an upsurgence in the number of manufacturing companies that are attempting to transform into computer-integrated enterprises. However, much of the computer-based integration efforts in these manufacturing organizations have been limited in scope and localized within certain areas of the organization (particularly, technology-intensive areas such as the shop floor). Such compartmentalized and myopic approaches to the development of computer-integrated manufacturing (CIM) systems undermine the ability of these systems to reach their fullest potential. CIM is much larger in scope and can impact an organization along various dimensions and at various levels. The fact that no completely integrated manufacturing enterprise has been developed to date can be attributed, in part, to a lack of understanding of the scope and implications of CIM. The purpose of this paper is, therefore, twofold. First, the paper presents a meta-schema (called TRIAD) for multidimensional and multilevel integration of a manufacturing system. Second, on the basis of the proposed meta-schema, the paper develops a taxonomical framework for defining key integration issues in CIM system design and discusses critical research needs that exist in this area. It is hoped that this paper will serve as a road map for research efforts that will enable the emergence of comprehensive CIM systems.     

Strategic Manufacturing Planning Systems and Their Linkage to Planning System Success

Academics and practitioners alike are focusing more attention on manufacturing strategy after having recognized the important role it plays in shaping the success of industrial firms. Even though research in this area has increased in the last decade, the focus of much of that work has been on the content rather than the process of the manufacturing strategy. Consequently, this study attempts to understand the important elements of the strategic manufacturing planning process and its effectiveness. Borrowing from the extant literature in the fields of strategic management and information systems, we propose a research model that relates strategic manufacturing planning system design to planning system success. Using structured questionnaires, empirical data is collected from over 200 manufacturing executives to test the model hypotheses. Planning process in manufacturing was found to be a bottom‐up approach from a corporate or business perspective, which differs from the top‐down planning process prevalent in strategic information systems planning process. Findings also indicate that greater planning system success in manufacturing is associated with a planning system that combines some “rational” elements (formality, comprehensiveness, control focus, longer horizon) with others that lend adaptability (wider participation and more intense interaction). But the strategic manufacturing planning system is more than just a collection of independent planning characteristics. Instead, it can be viewed as a gestalt planning system whereby planning characteristics move together in affecting overall planning system success.     

The new production theory for health care through clinical reengineering: a study of clinical guidelines--Part I

Drucker writes that the emerging theory of manufacturing includes four principles and practices: statistical quality control, manufacturing accounting, modular organization, and systems approach. SQC is a rigorous, scientific method of identifying variation in the quality and productivity of a given production process, with an emphasis on improvement. The new manufacturing economics intends to integrate the production strategy with the business strategy in order to account for the biggest portions of costs that the old methods did not assess: time and automation. Production operations that are both standardized and flexible will allow the organization to keep up with changes in design, technology, and the market. The return on innovation in this environment is predicated on a modular arrangement of flexible steps in the process. Finally, the systems approach sees the entire process as being integrated in converting goods or services into economic satisfaction. There is now a major restructuring of the U.S. health care industry, and the incorporation of these four theories into health care reform would appear to be essential. This two-part article will address two problems: Will Drucker's theories relate to health care (Part I)? Will the "new manufacturing" in health care (practice guidelines) demonstrate cost, quality, and access changes that reform demands (Part II)?     

Modelling and controlling product manufacturing systems using bond-graphs and state equations: Continuous systems and discrete systems which can be represented by continuous models

This paper presents an approach to the modelling and control phases involved in a cooperative process of design and management of the manufacturing systems. Modelling the evolution of the production flow, in the different sections of the system, is based upon the use of the bondgraph methodology in order to reach the state formalism which constitutes one of the modern representations of automation. The class of the systems studied ranges from continuous systems to discrete systems, which can be represented by a continuous approach according to the level of approximation required. The first part of this paper is dedicated to the development of generic models associated with the various basic entities of the manufacturing systems. Then, the bondgraph model of any system is obtained by assembling generic models in relation to the implementation of the means of the studied system, thus guaranteeing a representation which is quite close to the engineering sketches. Finally, switching to the state equation is performed systematically with the easiness provided by this formalism while taking into account the causality principle. An application, involving most of the elementary models developed, concludes the paper.     

An Optimal Model for Cell Formation Decisions

This study develops an approach to cell formation decisions for cellular manufacturing layouts in group technology settings. An optimal 0–1 integer programming model is used to provide an analysis for determining which machines and parts should be assigned to cells in cellular manufacturing layouts. This approach minimizes the cost of manufacturing exceptional parts outside the cellular system, subject to machine capacity constraints. Part–machine matrices are partitioned into disconnected cells and use far fewer 0–1 variables than earlier approaches. Formulation of the model is described with a numerical example and computer solutions to realistic problems are obtained. The characteristics of computer run times, model performance, and applications of the model are discussed.     

Managing AMI in a Just-In-Time Environment in the UK and Japan

In recent years many commentators have addressed the ‘crisis’ in manufacturing industry (Gerwin, 1982; Drucker, 1988, 1990; Hayes and Jaikumar, 1988). Some have offered cross-national comparisons on Japanese and Western management methods and techniques (Kharbanda and Stallworthy, 1991; Oliver and Wilkinson, 1987; Pascale and Athos, 1981) whilst others have concentrated on improving performance in specific fields such as management accounting (Kaplan, 1984; Cooper, 1991) or manufacturing management (Schonberger, 1982; Halt, 1983). Empirical research into managing AMT in Japan and the UK (Currie 1991a) considers some of the broader managerial issues in manufacturing. Cultural differences are common in the areas of investment appraisal, post-auditing of AMT and preventive maintenance policy. For example, in Japan JIT is perceived ‘holistically’ incorporating production management, total quality assurance (TQA) and total preventive maintenance (TPM). This is contrary to the UK in that many large manufacturing companies fail to include TPM in their manufacturing strategies (Currie and Seddon, 1991). There are few management information systems (MIS) which provide an understanding of machine performance using both non-financial and financial information. Focusing on maintenance as a central theme, the paper discusses the development of the Failure And Scheduled Maintenance Analysis (FASMA) system, which offers a practical solution to the problem of collecting and manipulating manufacturing data on the shopfloor (Seddon, 1991a). Essentially, FASMA attempts to interface both the manufacturing and management accounting functions by translating machine performance data into valuable information from which preventive maintenance policy may be improved. Using FASMA to measure machine performance at a major UK automotive manufacturer, machine down-time has averaged 61% each month over a 3-year period. By manipulating this data, performance measurement information may be utilized by management accountants. FASMA thus develops a link between manufacturing and management accounting by providing data on machine performance which can be used for cost analysis within a manufacturing environment. The paper concludes by arguing that manufacturing strategies can only be developed using appropriate management information systems (MIS) designed to enhance functional integration. This will enable a better understanding of how the ‘manufacturing jigsaw’ fits together.     

The Value of Using Scheduling Information in Planning Material Requirements*

Current research and practice in the field of production and inventory planning is dominated by hierarchical, material requirements planning-based methods. The objective of this research is to determine the merits of a major redirection for the design of manufacturing planning systems—a direction that more directly exploits the capabilities of modern computer technology. We test the relative performance of two fundamentally different classes of manufacturing planning systems: (1) those that make no use of sequencing and scheduling information in the planning of material deliveries (for example, traditional MRP-based systems), and (2) those that use sequencing and scheduling information to plan delivery of materials. We first derive an analytical expression for the expected benefit (in terms of flow time reduction) of using scheduling information for a single machine system. We then describe and test a simple heuristic for predicting the improvement that could be realized in more complicated multimachine systems, under certain conditions. Results from controlled simulation experiments, over a wide range of operating environments, suggest that although the value of scheduling information is influenced by the operating environment, it could be substantial.     

Fuzzy Overall Equipment Effectiveness (FOEE): capturing performance fluctuations through LR Fuzzy numbers

The paper focuses on the Overall Equipment Effectiveness (OEE), a performance indicator that is extensively used in the industry. The aim is to extend the capabilities of the OEE, so as to capture the day-to-day fluctuations to which manufacturing performances are subjected. To this aim, manufacturing losses are decomposed into elementary causes and modelled as LR fuzzy numbers. Next, in order to compute the Fuzzy Overall Equipment Effectiveness (FOEE), single losses are aggregated using the ‘fuzzy transformation model’. This approach limits the fuzzy overestimation phenomenon and assures both results’ accuracy and robustness. An industrial application, part of a lean project carried on by an important Italian manufacturing firm, is finally presented. Results are encouraging, since the FOEE made it possible to trace back the share of the overall fluctuations that is ascribable to each cause of loss. In this way, it provided the basis for setting improvement priorities and directed the lean team toward the selection of appropriate corrective actions.     

Shop floor characteristics influencing the use of advanced planning and scheduling systems

The purpose of this article is to investigate how the manufacturing process, the shop type and the data quality, i.e. the shop floor characteristics, influence the use of advanced planning and scheduling (APS) systems in production activity and control (PAC). The methodology implemented is a multiple case study at three case companies. Each company has different shop floor characteristics, but all use a scheduling module in an APS system, which supports production scheduling. A theoretical framework is developed suggesting how APS system are used in the PAC activities, and which major aspect to consider. The case analysis shows that the scheduling module in APS system, foremost supports sequencing and dispatching. In particular, the shop type is influenced by the decision of how often the APS runs and what freedom is given to the shop floor. The manufacturing process influences how the dispatch list is created. Contrary to the literature presuming that APS systems are most suitable in job shop processes, it is found that the manufacturing process is not a crucial factor when deciding whether APS systems are an appropriate investment. It is found that the level of data quality needed in the APS system depends to a large extent on how the dispatch list is used. For example, is the dispatch list used as a guideline, not a regulation, the need for accurate data in the module is reduced. This article extends the previous literature concerning APS systems by analysing how APS systems influence PAC as a whole and increase the understanding of the challenges of using APS systems in PAC.     

System Perspectives of Experts and Farmers Regarding the Role of Livelihood Assets in Risk Perception: Results from the Structured Mental Model Approach

Pesticide application is increasing and despite extensive educational programs farmers continue to take high health and environmental risks when applying pesticides.
The structured mental model approach (SMMA) is a new method for risk perception analysis. It embeds farmers' risk perception into their livelihood system in the elaboration of a mental model (MM). Results from its first application are presented here. The study region is Vereda la Hoya (Colombia), an area characterized by subsistence farming, high use of pesticides, and a high incidence of health problems. Our hypothesis was that subsistence farmers were constrained by economic, environmental, and sociocultural factors, which consequently should influence their mental models.
Thirteen experts and 10 farmers were interviewed and their MMs of the extended pesticide system elicited. The interviews were open-ended with the questions structured in three parts: (i) definition and ranking of types of capital with respect to their importance for the sustainability of farmers' livelihood; (ii) understanding the system and its dynamics; and (iii) importance of the agents in the farmers' agent network. Following this structure, each part of the interview was analyzed qualitatively and statistically. Our analyses showed that the mental models of farmers and experts differed significantly from each other.
By applying the SMMA, we were also able to identify reasons for the divergence of experts' and farmers' MMs. Of major importance are the following factors: (i) culture and tradition; (ii) trust in the source of information; and (iii) feedback on knowledge.     

过程系统管理与技术的综合集成

在激烈的市场竞争中,过程企业不仅要重视技术、更要加强管理,实现全局优化运行。提高过程企业的市场竞争能力必须全面综合集成人、组织、战略管理、经营管理、过程管理及信息自动化技术等因素。本文以石化企业为背景,对过程企业面临的问题及发展趋势进行了分析,并且对过程企业管理模式、过程企业的体系结构以及过程集成与优化技术进行了探讨。     

Twelve questions to ask about your outcomes monitoring system--Part II

Commercial and customized outcomes monitoring systems designed to assess the results of care, whether clinical outcomes or resource use, are not all of equal value or equally appropriate for every use. In creating each system, its developers had to make critical decisions about such matters as definitions of outcomes for study, selection of patients, selection of data elements, methods and timing of data collection, and method of analysis and reporting. Each system represents a unique set of choices that were made. This series of two articles presents answers to 12 questions that will help users understand the basic workings of an outcomes monitoring system--to be able to distinguish good systems from the mediocre and the bad, and to make wise use of a system already in operation. In addition to the six questions presented in the April 1994 issue of Physician Executive, the following six questions are of critical importance in determining a system's value to you and your organization.