İmalat stratejileri ve imalat teknolojisi seçiminde uzman sistem yaklaşımı

Abstract

İmalat stratejisi, yarına sahip olmak için bu gön ne yapılması gerektiğine dair, firmaların yaşamsal kararlarım kapsayan bir karar modelidir. İmalat stratejisi, rekabet üstünlüğü sağlamak için imalat sistemiyle ilgili temel kararlan ve rekabet önceliklerini ifade eder. Literatüre, imalat süreçlerinin yeniden yapılanmasının bir gereği olarak girmiştir. Bu çalışma, işletmelerin hem en üst düzey stratejik kararlarım, hem de daha alt seviyedeki imalat operasyonları ile ilgili kararlan bütünlük içerisinde ele alarak, endüstri mühendisliği disiplinine katkıda bulunmayı amaçlamaktadır. Bu çalışma altı bölümden oluşur. İlk bölüm imalat stratejisinin tanıtımına ayrılmıştır. Bu bölümde imalat stratejileriyle ilgili temel kavramlar ve ilgili özellikler ayrıntılı biçimde ele alınmaktadır. İkinci bölümde imalat teknolojileri ve süreç seçimine temel teşkil eden üretim teknolojisi bilgileri verilmektedir. Temel üretim sistemleri, teknolojideki gelişmeler ve teknoloji stratejisi incelenmekte, imalat sistemi seçimi için alternatif sistem tasarımlan geliştirilmektedir. Üçüncü bölümde imalat teknolojilerini değerlendirme teknikleri tanıtılmaktadır. Ayrıca, literatürde kullanılan tekniklerin ileri teknolojileri değerlendirmede yeterli olup olmadıktan ve uygulamalardaki uygunluk yönleri araştırılmaktadır. Dördüncü bölümde karar destek sistemleri ve uzman sistemler tanıtılmaktadır. Uzman sistemle karar destek sistemlerini bütünleştirme çabalan incelenmektedir. Ayrıca uzman sistem geliştirme araçları anlatılmaktadır. Beşinci bölümde teknoloji seçimi için imalat stratejisi geliştirme aracı olarak bir karar destek modeli sunulmaktadır. Bu yaklaşım, teknoloji seçimiyle ilgili imalat stratejisi geliştirerek, firma yöneticilerine yol gösterme görevini üstlenir. Altıncı bölüm bir önceki bölümde sunulan karar modelinin çözümü için, karar modeli ve uzman sistemleri bütünleştiren bir uygulamadır. Uzman sistem uygulamasıyla, hem karar destek sistemleri fikrinin, hem de uzman sistem yaklaşımının yeteneklerini arttırma olanağım sağlar.

Manufacturing strategy is a field of growing concern in most industries. It is a long term plan for developing consistent operations policies and providing focused facilities to achieve limited but absolutely key corporate strategic objectives. It is the management principles dictating how a product is manufactured, how resources are deployed in production, and how the infrastructure necessary to support manufacturing should be organized. It creates and adds value by helping a firm establish and sustain a defensible competitive advantage which is the unique position an organization develops against its competitors. Manufacturing strategy is viewed as the effective use of manufacturing capability for the achievement of business and corporate goals. The aim of manufacturing strategy is to use the production system as a strong source of competitiveness. This study has two main goals: First goal is to show what manufacturing strategies are, how they are formulated, and how the key decision elements are linked. In other words, this study attempts to provide a conceptual framework that links manufacturing systems to manufacturing strategy and market requirements and analyze the fitness between manufacturing systems and competitive strategies. Second to examine usefulness of expert systems for the manufacturing strategy determination, especially to manufacturing technology selection, and integrate the key decisions using the expert systems framework in an integrated decision support. In other words, using the expert system approach attempts to provide a conceptual framework mat links manufacturing systems to manufacturing strategy and market requirements and analyze the fitness between manufacturing system configuration and competitive strategies. This study is composed of six chapters. Chapter 1 presents an overview of manufacturing strategy and introduces fundamental concepts. The concept of manufacturing based competitiveness and the problem of manufacturing strategy are defined. Chapter 2 deals with manufacturing technologies and system choice. Main topics of this chapter are advanced manufacturing technologies, technology strategy, the classification of manufacturing systems and manufacturing system design. Chapter 3 discusses the existing evaluation and selection techniques for especially advanced manufacturing technologies. Main topics of this chapter are justification approaches; economic, analytic, strategic justification and information approaches. In chapter 4, the purpose is to explain the nature of expert systems and decision support systems. It explains the linkage between expert systems and decision support systems. Chapter 5 presents a decision support framework for formulating manufacturing strategy, especially selecting manufacturing technology. This chapter provides a detailed analysis and methodology for supporting the formulation of manufacturing strategy. Chapter 6 describes a solution procedure for the proposed model in Chapter 5. The main contribution of this chapter is to solve the manufacturing strategy problem by expert system approach. In the section of conclusion and recommendation, the proposed decision model and expert system approach compared with the analytical models and the conceptual frameworks in term of their advantages or disadvantages. In the following, the main points of every chapter are presented briefly. CHAPTER 1 The content of manufacturing strategy refers to the plans made to achieve and sustain competitiveness through optimally aligning a firm's capacity, technology, human resource and other aspects. The term "manufacturing strategy" refers to competitive priorities and key decisions taken in managing a manufacturing system in order to gain comparative advantage. Manufacturing strategy reflects the goal and strategies of business, and enables the manufacturing function to contribute to the long-term competitiveness and performance of business. In the last decade is that some countries have gained the competitive upper hand, and this advantage has been achieved through manufacturing. One of the keys to this achievement through manufacturing has been the integration of these functional perspectives at the level of corporate strategy debate. There are two important roles that manufacturing can offer as part of the strategic strengths of a company. The first is to provide manufacturing process, which will give the business a distinct advantage in the marketplace. The second is to provide coordinated manufacturing support for the essential ways in which products win orders in the marketplace at a level better than its competitors In the past manufacturing strategy has been a neglected area. In fact, manufacturing has frequently been regarded as the poor relation of other higher profile functions of finance and marketing. In 1990s, it is becoming increasingly apparent that rather than being a passive vehicle for the implementation of strategies determined elsewhere, manufacturing should itself be a key strategic asset and an equal partner in formulating the organization's strategy. In fact, manufacturing is now becoming recognized as the platform by which overall business strategy can be realized and new competitive thrusts launched. Manufacturing strategy is also a process. The process of formulating and implementing manufacturing strategy requires the recognition of both internal and external factors of competition. As inputs, it requires knowledge of the economic driving forces of the chosen industry. Factors of production include technology, facilities, human resources and infrastructure. XI CHAPTER 2 In the competitive environment, manufacturing firms that hope to survive and prosper in the future, must acquire capabilities to lower production costs for smaller batch size and greater product-mix complexity, while producing consistently better quality products. These firms also develop the capabilities to introduce new products quickly, and cope with short delivery cycles. Acquisition and implementation of new technology are considered indispensable to achieve the above capabilities for competitive success and future survival. In order to appreciate the issues involved in the evaluation and adoption of advanced automation based on new manufacturing technology. New manufacturing processes comprise a broad menu of technologies, including engineering techniques such as group technology and computer aided design and engineering; manufacturing techniques such as robotics, computer aided manufacturing, transfer lines, flexible manufacturing systems, automated storage and retrieval, and cellular manufacturing; and management techniques such as MRPII, Just-In-Time, total quality management, and autonomous work groups. The major advantages of using manufacturing systems based on new technology include reduction in inventory, throughput time, manual labor and space requirement on the factory floor. As a result, considerable savings in cost and improvements in customer services can be achieved. In addition, these systems allow improved utilization of material due to scrap reduction, and improvement in quality and reliability are also achieved. The flexibility inherent in the computer based manufacturing systems allows an increase in product variety without high cost penalty, and makes it possible to introduce new product design, market demand and product mix is enhanced considerably. The manufacturing function takes inputs and converts them into products. To complete this, a business usually has a range of choices to make between different manners of manufacturing. They usually choose one or several ways. This decision must be to ensure that the choice of process is the one best able to support the company the competitively in the market. To understand what is involved in this decision mere are several important perspectives to be taken into consideration. Each choice of process will bring with it certain implications for a business in terms of response to its markets, manufacturing capabilities and characteristics, level of investment required, unit costs involved, and the type of appropriate control and style of management. To help understand these, it is necessary to review the process choices available. There are five classic types of manufacturing process: project, job shop, batch, line, and continuous process. However, in many situations, hybrids have been developed. Some of the more important hybrid developments are computer numerical control machines, machining centers, flexible manufacturing systems, mix mode assembly, dedicated use of general purpose process, group technology and transfer lines. xn CHAPTER 3 A major problem in the choice of manufacturing technology is the prerequisite justification process. This chapter identifies and demonstrates the range of techniques that have been used by firms to justify investments and describes the conditions under which it is most appropriate to employ them. Corresponding to the different categories of new manufacturing technologies, separate approaches to the justification issue seem to exist. For stand alone systems where the purpose is the straightforward replacement of old equipment, even if some economic benefits not usually considered are obtained, the standard economic justification approaches can be used with an allowance for economic benefits or costs. When synergy, flexibility, risk, and non-economic benefits are expected, as with the linked systems, more analytical procedures are needed. With systems approaching full integration, clear competitive advantages and major increments toward the firm's business objectives are usually being obtained. Here, the strategic approaches are needed to take these benefits into consideration. Each of these justification categories which spans a number of approaches are described and discussed their pros and cons. The approaches are categorized as follows: There are a number of formulations and approaches that firms use for the economic justification of equipment. Examples include break-even analysis, net present value, return on investment, accounting rate of return and pay-back. The analytic techniques described in this chapter are largely quantitative but more complex than the economic approaches. Also they tend to capture more information and frequently consider uncertainty and multiple measures and effects. Three major approaches are value analysis, portfolio analysis and risk analysis. The strategic approaches tend to be less technical than the two previous categories. Four main approaches are commonly used at this level; technical importance, business objectives, competitive advantage, research and development. CHAPTER 4 The purpose of decision analysis is to provide the decision maker with information for use in the support of decision making process, where such information has been derived through a logical, scientific, and systematic process. One conception of a decision support system is that of a computerized system for accessing and processing data, developing managerial displays, and providing recommended courses of action as developed through the use of modern analytical methods. A decision support system generally consists of the following xiii components: A database containing data about a problem domain; a data processor system; an analytical method (algorithms ); and a user interface to handle communication with the user. Everything above is assumed to be contained within the decision support system, in particular within the computers and computer networks employed by the decision support systems. An expert system is an intelligent computer program that uses knowledge and inference procedures to solve problems that are difficult enough to require significant human expertise for their solution. Their application is usually performed in a specific knowledge of limited scope. An expert system generally consists of the following components: A knowledge base containing knowledge about a problem domain; a working memory for keeping track of inputs and outputs; an inference engine for manipulating the stored knowledge to produce solutions to problems; a knowledge acquisition module to assist with the development of the knowledge base; and a user interface to handle communication with the user in natural language. Decision support system designer has begun to use heuristics and expert systems where within the decision support system architecture. When expert systems are employed in such a manner, they are termed "embedded" expert systems. The combined system provide a logical extension, as well as an enhancement, to either the decision support system concept or the expert systems. That is, it allows for the choice between analytical tools and expert heuristics, depending on the specific characteristics of the problem at hand. In fact, it permits the use of both approaches to the same problem CHAPTERS The integration process is a structured approach that starts with a suitable competitive strategy and eventually leads to a new manufacturing technology that should be implemented. A manufacturing firm must adopt a suitable competitive strategy and identify market requirements that must be fulfilled to compete effectively. In order to satisfy market requirements, the manufacturing system should possess appropriate system capabilities. Next, appropriate manufacturing technology types that provide the desired system capabilities must be identified. The process involves several sequential decisions that is a 10-step approach to manufacturing technology choice. The process begins with the choice of a suitable competitive strategy by a firm. The chosen competitive strategy is then linked with the market requirements, system attributes and appropriate manufacturing technology choices. This presented model belongs to the category of analytical models. This framework emphasizes the relationship between different decision categories. The framework also identifies important research areas and provides guidelines to develop a better procedure for evaluating acquisition of new manufacturing technology. This approach is a step-by-step procedure (i.e., an algorithm) and the key steps of algorithm are as follows: xiv Step 0: Defining the corporate mission or objectives. Step 1 : Determining competitive strategy that can be pursued by manufacturing firms. Step 2: Determining market requirements. Step 3: Determining the degree of importance of market requirements corresponding to a chosen competitive strategy. Step 4: Determining the necessary manufacturing system capabilities to meet the desired market needs. Step 5: Determining the importance ratings of system requirement corresponding to any given market requirements. Step 6: Determining the importance ratings of appropriate system attributes to match the needs of the competitive strategy. Step 7: Identifying manufacturing technology choices. Step 8: Determining the importance ratings between system attributes and manufacturing technology types. Step 9: Determining the relative suitability of a technology type corresponding to the chosen competitive strategy. Step 10:Selection of the most suitable manufacturing system configuration matching the competitive strategy of the firm. The iterative process would ultimately result in the selection of the most desirable manufacturing system that is consistent with the strategic needs of the firm. The proposed model is integrated by an expert system approach that includes strategic factors of both tangible and intangible nature. CHAPTER 6 The problem of appropriate manufacturing technology selection can be solved by using the expert system approach. The expert system for manufacturing technology selection is a rule based system. All the information existing on competitive strategies, market requirement, systems attributes can be placed into the knowledge base. The system will ask the user several questions regarding the suitability pair of the competitive strategy with marketing requirements, market requirements with system capabilities and system capabilities with manufacturing technology types. It uses the knowledge base and the rules to determine the best match between the users needs and the available manufacturing technology options. The system will retrieve the manufacturing technology and its descriptions from the knowledge base and display it on the screen. In expert system development top-down design and modular programming approaches are used. Top-down design starts with a major idea or problem. The problem is divided into a series of smaller problems. Each level of refinement breaks the current problem into smaller submits until, ultimately, solutions can be found. Modular programming attempts to develop independent program or knowledge base units ( modules ) that perform a single function or a group of closely related functions. xv The main issues in the building of an expert system are knowledge acquisition, knowledge representation and inference strategy. These issues are briefly discussed in the following: The first step in the process of creating a knowledge base is to evaluate the issues involved with coordinating the three dimensions. It is customary to consult an expert and to review literature in order to accomplish this task. The second step in creating a knowledge base is translating the hierarchy of information from the decision tree into a language that the expert system's inference engine understands. This accomplished through the development of rules and parameters. Parameters are listing of all categories of decisions that are made when choosing a technology option When the user operates the expert system, he will be given a series of questions from the parameter list and will be provided with a selection of choices. To arrive at a goal, the values of 125 main parameters and several minor parameters must be determined. Five of 125 parameters represents fitness of competitive strategy and market requirements, 40 parameters represents fitness of the market requirements and the system capabilities, 8 parameters represents fitness of the competitive strategy and the system capabilities, 64 parameters represents fitness of the system capabilities and the manufacturing technology configurations, and finally 8 parameters represents the competitive strategy and manufacturing technology configurations. The developed expert system for manufacturing technology selection uses a backward chaining strategy. They begin with a goal, or conclusion, and attempt to establish support for the conclusion. The expert system for choosing a suitable technology decision making knowledge base consists of 217 rules corresponding to the number of possible pathways along the decision tree. In this study FIND clause initiates a backward chaining sequence. After encountering a FIND clause, the inference engine attempts to locate rules that draw a conclusion about the current goal. If such a rule is found, the inference engine checks to see if the conditions of the rule have been met. If a conclusion is reached, the backward chaining sequence stops.