Đang tải... (xem toàn văn)
Especially in manufacturing today, Computer Numerical Control (CNC) machines, Computer Aided Design (CAD), Computer Aided Manufacturing (CAM) systems are among the most important applications of the information technology in manufacturing, which, in this research, will be called summarily as Computer Aided Technology or CAT for short.
- 1 - Chapter 1 Introduction 1.1 Background We are now in the information era. Information Technology (IT) has been extensively used in almost all areas of the human life. Especially in manufacturing today, Computer Numerical Control (CNC) machines, Computer Aided Design (CAD), Computer Aided Manufacturing (CAM) systems are among the most important applications of the information technology in manufacturing, which, in this research, will be called summarily as Computer Aided Technology or CAT for short. CNC machines, CAD, CAM, have been applied widely not only in the developed countries, such as the United States, Japan, Germany, but also in developing countries like Thailand, India, China, Taiwan and South Korea. For example, in South Korea, from 1986 to 1990, the total value of CNC machines, CAD, CAM used in manufacturing increased from 289 to 420 US$ millions. Such applications grow at the rate of 50% annually in South Korea (Jang Seung Hwan, 1988). The US embargo, which did not allow the transfer of IT into Vietnam, was lifted in early 1994. Consequently, Vietnam is very out of date in terms of IT application. Observation shows that up to 1990, there were only 10,000 personal computers in Vietnam. (Adam Schwarz, 1995) However, in recent years, with the "Open door" policy, IT has been gradually introduced in Vietnam. At the beginning of 1995 the number of computers in Vietnam reached about 50,000, and is growing at the rate of about 40% annually (Adam Schwarz, 1995). Its applications, however, are restricted mostly to office management. In enterprises, IT is used in storing data, accounting, and administrative work. IT is rarely applied in manufacturing. Machine tool is one of the biggest industries in the manufacturing sector in Vietnam. However, the machines and equipment are old and obsolete, which have been in operation for twenty or thirty years. CNC machines, CAD, CAM are almost never used except some research centers such as the Research Institute of Machinery, the Design Institute of Chemical Industry, and the Hanoi University of Technology. Low technology used in the machine tool industry is seen as one of major reasons for low quality of products. Combined with low management skills, this leads to losing customers, and poor or even disastrous financial performance of many state-owned enterprises in recent years. In the emerging market economy of Vietnam, in order to compete effectively with foreign enterprises with high technology, and with the imported machine tools, the applications of CNC machine, CAD, and CAM systems become an immediate survival need for the domestic machine tool companies. The increasingly critical demands of customers in terms of designing, functioning, working life, productivity, ease in use and precision, also require CNC machine, CAD, CAM systems to be introduced. 1.2 Statement of Problem and Significance of the Study - 2 - As IT and CAT are very new for the country. Managers of machine tool companies in Vietnam do not know how CNC machines, CAD, and CAM can benefit them, what conditions are required to introduce these technologies in their companies. As a consequence, they do not know how to develop a plan to introduce CNC machine, CAD, CAM effectively, especially when the production and market conditions are changing almost daily in the country. At the same time, many foreign investors are ready to transfer technological know how to the manufacturing sector in Vietnam, but they do not understand the major difficulties Vietnamese enterprises are facing. Introducing all these technologies at the same time would be extremly difficult, if not at all impossible, for any Vietnamese machine tool firm. Therefore, a major question is what priority order among CNC machine, CAD, CAM should is most appropriate to go ahead for a Vietnam enterprise in machine tool firm, is still in question. 1.3 Objectives The study aims at helping managers in machine tool enterprises in Vietnam gain insight into how these technologies can be introduced in their companies. It may also provide suppliers of CNC machine, CAD, CAM some preliminary ideas about how a Vietnamese enterprise can apply them. Furthermore, it is expected to provide some suggestions to assist the formulation of appropriate policies to encourage the overall objective of the government of Vietnam to "catch " in the more advanced technology. To achieve these goals, this research steps out the following specific objectives: 1. To develop a model for analyzing major factors in introducing of CAT in manufacturing industry in Vietnam 2. To apply the model in one company in machine tool firm in Vietnam to analyze conditions for introducing CAT. 3. To suggest recommendations regarding CAT introduction to the company based on the analysis. 1.4 Scope and Limitations CAT has many applications in manufacturing, the study focuses only on CNC machines, CAD, CAM which means that issues like manufacturing resource planning (MRP II) system, or flexible manufacturing system (FMS) will not fall into the scope of the study, also the research is limited to the machine tool firms in Vietnam. The analysis is carried out based on qualitative information gathered through secondary information sources and direct interview of relevant managers in the company under study. There is not sufficient information about applications of CNC machine, CAD, and CAM of foreign companies to make comparison, so it lacks comparative analysis. - 3 - 1.5 Organization of the Report The research is carried out in 5 steps . 1. Literature Review A review of the literature aims at an overall understanding of information technology, CAT and its applications in manufacturing. The experiences in CAT applications of Asian countries are useful for comparison with Vietnam. 2. Developing a Model In order to assess the conditions of company for introduction of CNC machine, CAD, and CAM, a conceptual framework is developed based on the review of literature and personal knowledge. The framework is presented in the Figure 1.1 3. Data Collection The data are collected through in-depth interviews with the managers and staff of various functional departments of the firm under study, information technology development. Secondary data are the company's internal report articles in public media, and government documents on policy and regulations. 4. Analyzing and Presenting This step carries out the analysis of plant conditions in term of CNC machine, CAD, CAM applications based on the framework developed in step 3. The analysis is presented in the form of comparison between actual conditions and related requirements to show the gaps in introduction of CNC machine, CAD, and CAM 5. Making Recommendations Recommendations for introduction of CNC machines, CAD, CAM to the managers of the plant under study are based on the analysis and conclusions presented in the previous chapters, opinions of manager of computer center of design institute of chemical industry, and manager of CAD department of research institute of machinery, regulations of government of information technology development to year 2000. - 4 - COMPUTER AIDED TECHNOLOGY APPLICATION 1-Knowledge Infrastructure 2- Internal Assets 3-Management 4-Target Products ACTUAL REQUIRED Constraints Advantages Training Research Framework for analyzing of factors for CAT applicationFigure 1-1 - 5 - Chapter 2 Literature Review 2.1 Definition of Information Technology (IT) There are now many definitions about information technology of authors in different fields. Each area of application has its own definition. Here are some of them. -Mc Farlan (1984) stated that IT is "computer remote devices, telecommunications" -Bakkopoulus (1985): IT is a "set of non-human resources as dedicated to the storage, processing and communication of information, and way in which these resources are organized into the system capable of performing a set of tasks". -Poster and Millar (1985): It must be conceived of broadly to encompass the information that business create and use as well as a wide spectrum of increasingly convergent and linked technologies that process the information". -Gerstin (1987) referred IT to "the collective means to assemble and electronically stores, transmit, process, and retrieve word, numbers, images and sound, as well as to electronic means to control machines of all kinds, from every day applicant to vast automated factories". The single definition of IT widely accepted and used is the "use of computers and computer related technology", (Guimaraes, et all, 1988). This definition is most suitable for manufacturing and will be adopted in this research. 2.2 IT in manufacturing: Computer Aided Technology (CAT) Computer aided technology (CAT) implies applications of information technology in manufacturing. At the CAT ' 91 conference in Bangkok, Pier Mercier, consultant of D. Appleton Company Europe, defined that CAT is a new set of technical tactic alternatives that may be used to achieve strategic objectives. CAT is seen as tactics, not strategy. CAT is single tool that can improve productivity, product quality and reliability and cost reduction. Mikell Groover (1987) viewed CAT as directing the technology of manufacturing toward one goal-the fully automated factory of the future. The major reasons for applying in CAT in engineering are product- related for discrete industries, and process- related for process industries. In the discrete industries the aim of using CAT is to reduce the time and cost of designing products and to increase product quality. In the process industries the focus is the design of the process, and the integration of the production equipment. The major areas in which technology can be applied in designing process are design synthesis, design analysis, documentation, simulation, preparation, and planning of the manufacturing process. The selection of the area in which technology will be applied depends on the company and the industry sectors.( John Stark, 1992). - 6 - In engineering, after 30 years of applying computer. It could be thought that great productivity gains would have been achieved in this area, and that there would not be much more progress to be made. Yet the situation is completely the opposite. Very few companies have made significant productivity gains through the use of computers in product development, and there is still a lot more progress to be made. Some companies have benefited greatly from the use of computers in product development. In 1970s uses of computer in product development mainly were Computer Aided Design, Numerical Control Programming, Finite Element Analysis, Computer Aided Process Planning, Simulation, Computer Aided Technical Publications, Robot programming. In 1990s, computers are mostly used in product development, engineering data management, product modeling, engineering data exchange, information models, integration, engineering system procedures, training (John Stark, 1992) Operations in the manufacturing are at the heart of any enterprise. They are affected strongly by production management activities. CAT applications in the production can make real difference in the day to day operations and in the role of the people. Finally the quality of working life can be significantly improved. Jobs are enriched and no longer dominated by old and inflexible technology. Flexible automation can be introduced in production, particularly for replacing manual labor in repetitive operations such as welding, assembly, and painting. Technological integrated factories can take advantages of flexible manufacturing systems that are able to handle a large variety of products economically. Advanced methods, supported by CAT, are becoming increasingly common in the factories. Its applications are all being used the fabrication of parts. Mechanical assembly equipment, usually reserved for very high-volume products with simple assembly process is most frequently are now almost always present in large, modern factories. Handing technology include robots, pick-and-place devices for assembly, machine loading, and palletizing. The application of CAT can: 1.Create a streamlined process in engineering and design, fabrication, and assembly of products 2.Improve use of scare human resources, the product quality increase, and job's satisfaction employees are satisfied with the jobs. 3.Improve cost structure (Pierr Merceir, 1991). 2.3 Components of CAT: CNC machine, CAD, CAM According to Pierr Merceir (1991), the components of CAT include computer aided design (CAD), computer numerical control machine (CNC), flexible manufacturing system (FMS), robotics, and computer aided manufacturing (CAM). According to Mikell Groover (1987) CAM consist of Computer aided process planning (CAPP), Material Requirements Planning (MRP), Direct numerical control (DNC); Manufacturing Resource Planning (MRPII); Shop Floor Data Collection, Computer aided inspection (CAI), Computerized quality control (CAQ). Given time limitation of this study, and the current manufacturing environment and policy in Vietnam, this research will concentrate only on 3 major components: CNC machine, CAD, and CAM which will be described in details below. 2.3.1 Computer Numerical Control Machine (CNC machine) - 7 - CNC was a significant achievement of development of numerical control (NC) technology in batch and job shop manufacturing. It was introduced in the mid to late 1960s and was commercially offered during early 1970s. Computer numerical control machine is a numerical system using a dedicated microcomputer as the machine control unit. CNC systems utilize microcomputer to store machining programs in read-only memories (ROM). Tape reader for initial program entry NC program storage Microcomputer ( software function ) Computer- hardware Interface and servo system ====> <==== Machine tools Figure 2.1 General configuration of a computer numerical control (CNC) system (Source: Mikell Groover, 1987) Figure 2.1 above shows the process of operating CNC machine the machining programmed- which are in the form of tape- are transferred into "Tap-reader". In this stage all program are read. Then they are stored in the " NC program storage". Microcomputer, which is a functioning software, control the stored programs. The relevant commands are transferred to the "machine tools" to process, through the " inter face and servo system". As conventional machines, CNC machine is mainly used to lathe, to bore, and grind, etc. The only difference between CNC machine and conventional machine is that in CNC machine every operation is controlled by computer, rather than worker in conventional machines. Their advantages include their adaptability to different types of machine tools, ease of programming, and information retrieval, and the ability of one computer to simultaneously control one or more machine tools (UNIDO/ESCAP by technonet Asia Singapore, Nov. 1986) The advantages of computer numerical control over conventional NC are: 1.The part program tape and tape reader are used only once to enter the program into memory. The results in improved reliability, since the tape reader is commonly considered the last reliable component of the conventional NC system; 2.Tape editing at machine site. The NC tape can be optimized during tape tryout at the site of the machine tool; 3. Greater flexibility. The most significant advantage over conventional NC is CNC's flexibility. New options can be added to the system easily and at relatively low cost; 4. Metric conversion. CNC can accommodate conversion of tapes prepared in units of inches into the international system; 5. Total manufacturing system. CNC is more compatible with the use of a total manufacturing system. ( Mikell Groover, 1987). 2.3.2 Computer Aided Design (CAD) CAD was introduced in 1960s. At the begin of 1970s it is applied strongly in developed countries. Now it is used widely in different countries in the world, and becomes a very useful tool to gain competitive advantages. - 8 - Mikell Groover (1987) defined CAD as any design activity that involves the effective use of the computer to create, modifies, or document an engineering design. CAD is most commonly associated with the use of an interactive computer graphics system. A computer aided design system can beneficially be used in four phases of the design process. 1. Synthesis (geometric modeling). The geometric modeling is concerned with the use of a CAD system to develop a mathematical description of the geometry of an object. The mathematical description permits the user of the CAD system to display an image of the model on a graphics terminal and to perform certain operations on the middle. These operations include creating new geometric models from basic building blocks available in the system, moving the images around on the screen, zooming in on certain features of the image. These capabilities permit the designer to construct a model of a new product or to modify an existing model. There are various types of geometric models used in computer aided design. One classification distinguishes between two-dimensional models. Two-dimensional models are best utilized for design problems in two dimensions, such as flat objects and layout of buildings. Three-dimensional CAD systems are capable of modeling an object in three dimensions. The operation and transformations on the model are done by the system according to the user instructions in three dimensions. Geometric models in CAD can also be classified as being either wire-frame models or solid models. A wire-frame model uses interconnecting lines to depict an object. Wire-frame model of complicated geometry can become somewhat confusing because all of the lines dipping the shape of the object are usually shown, even the lines representing the other side of the object. Solid models are a more resent development in geometric modeling. More important for engineering purposes, the geometric model is stored in the CAD system as a three- dimensional solid model, thus providing a more accurate representation of the object. 2. Analysis and Optimization (engineering analysis) Some forms of engineering analysis must often be performed as part of the design process. The analysis may take the form of stress-strain calculations, heat transfer analysis, or dynamic simulation. Two examples of the software typically offered on CAD system are mass properties and finite -element analysis. Mass properties analysis involves the computation of such features of a solid object as volume, surface, area, weight, and center of gravity. The finite-element analysis is available on most CAD system to aid in heat transfer, stress-strain and other engineering computations. 3. Evaluation (design review and evaluation). Some of the CAD features that are helpful in evaluating and reviewing a proposed design include * Automatic dimensioning routines, which determine precise distance measures between surfaces on the geometric model identified by the user *Interference checking routines, which identify whether two objects occupy the same place - 9 - *Kinematics Routines, used to test the operation of mechanical linkages. 4. Presentation (automated drafting) CAD system can be used as automated drafting machines to prepare highly accurate engineering drawing quickly. It is estimated that CAD system increases productivity in the drafting function by about fivefold over manual preparation of the drawings. (Mikell Groover, 1987) A Typical CAD System A typical commercially available computer aided design system consists of components : *One or more design workstations *Processor *Secondary storage *Plotter and or other output devices Secondary storage CPU Output Plotters, etc Graphics terminal Input devices Design workstation Figure 2.2 Configuration of a typical CAD system Source: Emory, Zimmer, Mikell Groover, Englewood,NJ, 1984 The design workstation is the interface between CAD system and the user. For the user to accomplish the various phases of the design process, the workstation must be able to receive input instructions from the user and to display output data and graphics to the user. Operator input devices are used for the input functions. The input devices for a CAD system typically include an alphanumeric keyboard, electronic keypad or other device to input special graphic functions and a cursor control device ( e.g., a light pen, " mouse" ,joystick, or electric tablet and " puck"). The graphical design out put is accomplished by means of a graphics display monitor. The processor is the CAD system computer . Connected to the processor is a - 10 - secondary storage for application program and design data. Also connected to the processor are more or one output devises such as X-Y plotters, electrostatic plotters and similar equipment used for automated drafting function (Mikell Groover, 1987) The important reasons for using a computer-aided design system to support the engineering design function: 1. To increase the productivity of the designer. This is accomplished by helping the designer to conceptualize the product and its components. In turn this helps to reduce the time required by the designer to synthesize, analyze, and document the design. 2. To improve the quality of the design. The uses of a CAD system with appropriate hardware and software capabilities permit the designer to do a more complete engineering analysis and to consider a large number and variety of design alternatives. The quality of the resulting design is thereby improved. 3. To improve design documentation. The graphical output of a CAD system result in better documentation of the design than what is practical with manual drafting. The engineering drawings are superior, and there is more standardization among the drawings, fewer drafting errors, and greater legibility. 4. To create manufacturing data base. In the process of creating the documentation for the product design (geometric specification of the product, dimensions of the components, material specification, bill of material, etc.), Much of the required data base to manufacture the product is also created (Mikell Groover, 1987) 2.3.3 Computer Aided Manufacturing (CAM) Mikell Groover (1987) defined CAM as the effective use of computer technology in the planning management and control of the manufacturing function. In his view the applications of CAM consist of two broad categories: 1-Manufacturing planning 2-Manufacturing control The two categories represent two different levels of involvement of the computer in the operation of the plant. The details of its applications are reviewed below: a-In Manufacturing Planning CAM applications for manufacturing planning are those in which the computer is used indirectly to support the production function, but there is no direct connection between the computer and the process. The computer is used "off-line" to provide information for the effective planning and management of production activities. The important applications of CAM are: -Cost estimating -Computer-aided process planning (CAPP) -Computerized machine ability data systems -Computer-assisted NC part programming [...]... with NC, CNC 3- A knowledge of digital technology 4- Experience in working with electronic measuring equipment 5- A desire to enhance knowledge through continuous training 6- Knowledge of basic micro computer fundamentals 3.2.6 Training All of what mentioned above indicate a wide range of needs for training, when a company decides to introduce the information technology in its manufacturing process... sub-systems The model of Chalmet mostly concerns the procedures for implementation of introduction of a new technology This model is not so relevant to the objectives of this study In the CAT "91 conference in Bangkok", Pierr Meceir presented a framework in which all factors impacting the introduction of a new technology are divided into five main groups They are: 1- Knowledge Infrastructure 2- Internal Assets... Background for the Analytical Framework There are different approaches in developing a model to show the requirements in introduction of Computer Aided Technology (CAT) at a firm level Chalmet (1987) developed a model for the introduction of a new production technology in the factory, which consists of five steps as follows: 1- Orientation: Analyzing strengths and weakness of organization and technical-economical... increase The plant more and more actively looks for enlarging its customers base through expanded product line With this, the need for updating the plant technological base and introducing information processing technology emerges as one important survival strategy for the plant 4.1.2 Corporate strategy The management of the plant has set the following long-term goals : • To increase production volume... management indicated that technology is seen as a key success factor of the plant They are proud of the progress that the plant has gained so far However, they also expressed their worries about the recent decline in quality of products due to the obsoleteness of existing machines and equipment The deputy manager for production confided that they are now thinking of which technology the plant should... further developed if CAD system is applied in the plant Now, in Vietnam there are some places using CAD, such as the Research Institute of Machinery, the Mechanical Center of the Hanoi University of Technology The information on CAD is already available in Vietnam However, CAD system is also never used in the plant, so in reality designers do not know how to operate CAD system and how to use CAD to make... Thailand, a neighbor country that has the similar geography, population and national characteristics to Vietnam Thailand has a high economic growth Now, Thailand is more advanced than Vietnam in applying high technology in manufacturing The learning experiences of Thailand is beneficial for Vietnam In Thailand now, no one uses NC machine tools ( no computer involved) more because of its inconvenient Instead... the objectives of the study The main factors of Pierr Meceir model are discussed in detail in the following sections.( See Fig 3.1) 3.2 Knowledge Infrastructure - 15 - The knowledge required for each technology - CNC machines, CAD, and CAM systems are different due to their distinctive functions The knowledge infrastructure is one of the most important factors for the application of new technologies... then writes down the instructions in the G-code language to build the part program To be able to make the part program, the programmer obviously has to master the G-code language and perfect in machining technology The mechanical engineers may be good candidates for programmers (E.Bohez, 1994) In reality, one person can do the jobs of both the programmer and the process planner The division between them... companies Only large organizations for example Thai Oil, Siam Cement Group, Thai International Airline, Petroleum Authority of Thailand have CAD system Educational institutes namely Asian Institute of Technology and Chulalongkorn University, College of engineering have CAD system for research.( UNIDO/ ESCAP Thailand report, 1987) Some factories have small CAD systems such as Auto CAD in use for drafting . Literature Review 2.1 Definition of Information Technology (IT) There are now many definitions about information technology of authors in different . Chapter 1 Introduction 1.1 Background We are now in the information era. Information Technology (IT) has been extensively used in almost all areas