Part 2 Unit 09 Computer-Integrated Manufacturing System

1、Computer-integrated manufacturing or (CIM) is the term used to describe the most modern approach to manufacturing. 計(jì)算機(jī)集成制造是解釋現(xiàn)代加工方法的一計(jì)算機(jī)集成制造是解釋現(xiàn)代加工方法的一個(gè)專用名詞。個(gè)專用名詞。Although CIM encompasses many of the other advanced manufacturing technologies such as computer numerical control (CNC), computer-aided d

2、esign/computer-aided manufacturing (CAD/CAM), robotics, and just-in-time delivery (JIT), it is more than a new technology or a new concept. 盡管盡管CIM包含現(xiàn)有的很多先進(jìn)制造技術(shù)，諸如計(jì)包含現(xiàn)有的很多先進(jìn)制造技術(shù)，諸如計(jì)算機(jī)數(shù)控、計(jì)算機(jī)輔助設(shè)計(jì)或計(jì)算機(jī)輔助制造、算機(jī)數(shù)控、計(jì)算機(jī)輔助設(shè)計(jì)或計(jì)算機(jī)輔助制造、機(jī)器人學(xué)和及時(shí)供貨（適時(shí)生產(chǎn)）等，但它不機(jī)器人學(xué)和及時(shí)供貨（適時(shí)生產(chǎn)）等，但它不是一種更高層次的新技術(shù)或新概念。是一種更高層次的新技術(shù)或新概念。 Comp

3、uter-integrated manufacturing is actually an entirely new approach to manufacturing and a new way of doing business. 實(shí)際上計(jì)算機(jī)集成制造是一套完整的新型制造實(shí)際上計(jì)算機(jī)集成制造是一套完整的新型制造方法和商業(yè)運(yùn)行方法。方法和商業(yè)運(yùn)行方法。To understand CIM, it is necessary to begin with a comparison of modern and traditional manufacturing. Modern manufacturing

4、 encompasses all of the activities and processes necessary to convert raw materials into finished products, deliver them to the market, and support them in the field. These activities include the following. 1) identifying a need for a product 2) designing a product to meet the needs 3) obtaining the

5、 raw materials needed to produce the product 4) applying appropriate processes to transform the raw materials into finished products 5) transporting product to the market 6) maintaining the product to ensure a proper performance in the field This broad, modern view of manufacturing can be compared w

6、ith the more limited traditional view that focuses almost entirely on the conversion processes. The old approach separates such critical preconversion elements as market analysis research, development, and design for manufacturing, as well as such after-conversion elements as product delivery and pr

7、oduct maintenance. In other words, in the old approach to manufacturing, only those processes that take place on the shop floor are considered manufacturing. This traditional approach of separating the overall concept into numerous stand-alone specialized elements was not fundamentally changed with

8、the advent of automation. While the separate elements themselves became automated (i.e, computer-aided drafting and design (CADD) in design and CNC in machining), they remained separate. Automation alone did not result in the integration of these islands of automation. With CIM not only are the vari

9、ous elements automated, but the islands of automation are all linked together or integrated. Integration means that a system can provide complete and instantaneous sharing of information. In modern manufacturing, integration is accomplished by computers. With this background, CIM can now be defined

10、as the total integration of all manufacturing elements through the use of computers. Fig.9.1 is an illustration of a CIM system, which shows how the various machines and processes used in the conversion process are integrated. However, such an illustration cannot show that research, development, des

11、ign, marketing, sales, shipping, receiving, management, and production personnel all have instant access to all information generated in this system. This is what makes it a CIM system. The term “computer-integrated manufacturing” was developed in 1974 by Joseph Harrington as the title of a book he

12、wrote about tying islands of automation together through the use of computers. It has taken many years for CIM to develop as a concept, but integrated manufacturing is not really new. In fact, integration is where manufacturing actually began. Manufacturing has evolved through four distinct stages (

13、Fig.9.2.): 1) manual manufacturing 2) mechanization/specialization 3) automation 4) integration 1. Manual Manufacturing Manual manufacturing using simple hand tools was actually integrated manufacturing. All information needed to design, produce, and deliver a product was readily available because i

14、t resided in the mind of the one person who performed all of the necessary tasks. The tool of integration in the earliest years of manufacturing was the human mind of the craftsman who designed, produced and delivered the product. An example of integrated manual manufacturing is the village blacksmi

15、th producing a special tool for a local farmer. The blacksmith would have in his mind all of the information needed to design, produce, and deliver the farmers tool. In this example, all elements of manufacturing are integrated. 2. Mechanization/Specialization With the advent of the industrial revol

16、ution, manufacturing processes became both specialized and mechanized. Instead of one person designing, producing, and delivering a product, workers and/or machines performed specialized tasks within each of these broad areas. Communication among these separate entities was achieved using drawings,

17、specifications, job orders, process plans, and a variety of other communication aids. To ensure that the finished product matched the planned product the concept of quality control was introduced. T h e p o s i t i v e s i d e o f t h e mechanization/specialization stage was that it permitted mass p

18、roduction interchangeability of parts, entire levels of accuracy, and uniformity. The disadvantage is that the lack of integration led to a great deal of waste. 3. Automation Automation improved the performance and enhanced the capabilities of both people and machines within specialized manufacturin

19、g components. For example, CADD enhanced the capability of designers and drafters; CNC enhanced the capabilities of machinists; and computer-assisted process planning (CAPP) enhanced the capabilities of industrial planners. But the improvements brought on by automation were isolated within individua

20、l components or islands. Because of this, automation did not always live up to its potential. To understand the limitations of automation with regard to overall productivity improvement, consider the following analogy. Suppose that various subsystems of an automobile (i.e., engine, steering, brakes)

21、 were automated to make the drivers job easier. Automatic acceleration, deceleration, steering and braking would certainly be more efficient than the manual versions. However consider what would happen if these various automated subsystems were not tied together in a way that allowed them to communi

22、cate and share accurate, up-to-date information instantly and continually. One system might be attempting to accelerate the automobile while another system was attempting to apply the brakes. The same limitations apply in an automated manufacturing setting. These limitations are what led to the curr

23、ent stage in the development of manufacturing: integration. 4. Integration With the advent of the computer age, manufacturing has developed full circle. It began as a totally integrated concept and, with CIM, has once again become one. However, there are major differences in the manufacturing integr

24、ation of today and that of the manual era of the past. First, the instrument of integration in the manual era was the human mind. The instrument of integration in modern manufacturing is the computer. Second, processes in the modern manufacturing setting are still specialized and automated. Another

25、way to view the historical development of CIM is by examining the ways in which some of the individual components of CIM have developed over the years. Such components as design, planning and production have evolved both as processes and in the tools and equipment used to accomplish the processes. D

26、esign has evolved from a manual process using such tools as slide rules, triangles, pencils, scales, and erasers into an automated process known as computer-aided design (CAD). Process planning has evolved from a manual process using planning tables, diagrams, and charts into an automated process kn

27、own as computer-aided process planning (CAPP). Production has evolved from a manual process involving manually controlled machines into an automated process known as computer-aided manufacturing (CAM). These individual components of manufacturing evolved over the years into separate islands of autom

28、ation. However, communication among these islands was still handled manually. This limited the level of improvement in productivity that could be accomplished in the overall manufacturing process. When these islands and other automated components of manufacturing are linked together through computer

29、 networks, these limitations can be overcome. Computer-integrated manufacturing has enormous potential for improving productivity in manufacturing, but it is not without problems. As with any new philosophy that requires major changes to the status quo, CIM is not without problems. The problems asso

30、ciated with CIM fall into three major categories.1. technical problems 2. cultural problems 3. business-related problems These types of problems have hindered the development of CIM over the years and will have to be overcome for CIM to achieve widespread implementation. 1. Technical Problems of CIM

31、 As each island of automation began to evolve, specialized hardware and software for that island were developed by a variety of producers. This led to the same type of problem that has been experienced in the automotive industry. One problem in maintaining and repairing automobiles has always been t

32、he incompatibility of spare parts among various makes and models. Incompatibility summarizes in a word the principal technical problem inhibiting the development of CIM. Consider the following example. Supplier A produces hardware and software for automating the design process. Supplier B produces h

33、ardware and software for automating such manufacturing processes as machining, assembly, packaging, and materials handling. Supplier C produces hardware and software for automating processes associated with market research. This means a manufacturing firm may have three automated components, but on

34、systems produced by three different suppliers. Consequently, the three systems are not compatible. They are not able to communicate among themselves. Therefore, there can be no integration of the design, production, and market research, processes. An effort known as manufacturing automation protocol

35、 (MAP) is beginning to solve the incompatibility of hardware and software produced by different suppliers. As MAP continues to evolve, the incompatibility problem will eventually be solved and full integration will be possible among all elements of a manufacturing plant. 2. Cultural problems of CIM

36、Computer-integrated manufacturing is not just new manufacturing technology; it is a whole new approach to manufacturing, a new way of doing business. As a result, it involves significant changes, for people who were educated and are experienced in the old ways. As a result, many people reject the ne

37、w approach represented by CIM for a variety of reasons. Some simply fear the change that it will bring in their working lives. Others feel it will altogether eliminate their positions, leaving them functionally obsolete. In any case, the cultural problems associated with CIM will be more difficult t

38、o solve than the technical problems. 3. Business-Related Problems of CIM Closely tied to the cultural problems are the business problems associated with CIM. Prominent among these is the accounting problem. Traditional accounting practices do not work with CIM. There is no way to justify CIM based on traditional accounting practices. Traditional accounting practices base cost-effectiveness studies on direct