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摘要

本次设计的是食品搅拌机，这种搅拌机是我们生活中使用的搅拌机的其中一种，搅拌机在生活中的应用相当的广泛，搅拌水果，奶油，得出的味道爽口，还可以搅拌蛋糕液，馅料、打蛋及和制面团，特别在酒家、饭店、面包屋以及食品厂家等作搅拌食料，揉和面团之用，是生产优质糕点的理想设备，使我们的生活更加方便。搅拌非常均匀，生产率高，质量好，成本低。整机结构紧凑,其主要组成结构包括：搅拌装置，搅拌传动系统。它是通过电动机带动皮带轮，用联轴器连接，经过减速器后通过四杆机构搅拌。本设计主要设计内容是食品搅拌机的机架设计、传动设计、搅拌动作的设计、电机选用，四杆机构设计，机架外型尺寸的确定，各零部件结构的选材、校核，完成总装图和零件图。

关键词：食品搅拌机；联轴器；四杆机构设计；传动设计；

Abstract

The design of the food mixer, this mixer is a mixer used in our lives in one of mixer applications in life quite extensive, stirring fruit, cream, come to the taste of refreshing, you can stir the cake liquid filling, beat eggs and and made the dough, especially in restaurants, hotels, housing and food manufacturers such as bread for stirring foodstuffs, dough kneading and use, is ideal for production of high quality bakery equipment, make our lives more convenient. Mixing is very uniform, high productivity, good quality and low cost. Compact structure, the structure of its main components are: stirrer, stirring drive. It is driven by the motor pulley, with the coupling connection, after a gear after the mixing through the four-bar linkage. The design of the main design elements are food mixer rack design, transmission design, mixing action design, motor selection, the four-bar linkage design, frame shapes and sizes determine the structure of each component selection, verification, complete the assembly map and part drawing.

Keywords:food mixer；coupling； four-bar linkage design；transmission design；

引言1

1食品搅拌机的工作原理和原理图3

2食品搅拌机的用途3

3食品搅拌机的设计要求和原始数据4

4设计方案的分析4

5连杆机构的设计4

5.1曲柄存在的条件5

5.2运动轨迹的计算6

6电动机选择7

6.1电动机选用的基本原则7

7带传动的设计9

7.1带传动组成、类型9

7.1.1传动带的组成及工作原理9

7.1.2V带的类型9

7.2带传动的设计计算和参数选择10

7.2.1确定计算功率Pc10

7.2.2确定V带的型号11

7.2.3确定带轮直径11

7.2.4确定带长及中心距a012

7.2.5验算包角13

7.2.6确定V带的根数z14

7.2.7确定初拉力F015

7.2.8计算带轮轴所受的压力Q15

7.3V带的截面尺寸15

7.4带轮的设计16

8减速器的选用18

9轴系零、部件的设计19

9.1轴的设计19

9.2轴的校核21

9.3轴承的选用23

9.3.1轴承的型号23

9.3.2滚动轴承的配合形式23

9.3.3滚动轴承的轴向定位23

9.4联轴器的选用23

9.4.1选用的联轴器型号23

9.4.2联轴器的配合形式24

10搅拌容器的设计24

11机架的设计24

11.1底架的设计24

11.1.1底架的材料选择24

11.1.2底架的大体尺寸25

11.2支架的设计25

11.3减速器底架的设计25

12零件的加工工艺规程26

12.1工艺路线26

结论28

谢辞30

参考文献31

附录31

引言

饮食水平是一个国家文明程度和人民生活质量高低的重要标志。食品的质量和供应状况，直接关系着全民族的体质，影响到国家的政治安定和社会进步。世界上经济发达的国家都十分重视发展食品工业。中国食品工业负有满足人民日益增长的物质文化生活需要和为国家经济建设提供积累的双重任务，是国民经济的重要组成部分。发展食品工业可以加速农业结构及其产品品质的优化调整，提高农产品经济价值，促进农业生产的良性循环。同时，对于带动和促进饲料工业、包装机械工业、机械工业、电子工业和精细化学工业等相关行业协调发展，适应餐饮业，旅游业等第三产业崛起的需要，繁荣城乡市场，扩大外贸出口以及扩大劳动就业等都具有十分重要的作用。 80年代以来，中央和地方都十分重视食品工业的发展，制定了一系列支持食品工业发展的政策。同时，国务院制定了“90年代中国食物结构发展与改革纲要”中国食品工业协会制定了“九五中国食品工业科技发展纲要”。河南省食品工业经过20多年的快速发展，各项指标已走在中国的前列，尤其是作为一个农业大省，在调整经济结构、推进农业产业化进程中，大力发展食品工业更是具有重要的意义。因此，在刚刚结束的省人代会上把以畜产品加工、粮油加工、果蔬加工为主体的食品工业做为第一大支柱产业来培育。目前，中国食品工业已初步形成门类比较齐全、技术不断进步、产品日益丰富、运销网络通畅的生产经营体系，成为国民经济中处于重要战略地位的一大产业。年产值5400多亿元。在中国各工业门类中，产值第一。

由上可知，食品机械在国民经济中的地位是如此之高。搅拌机在生活中的应用相当的广泛，搅拌水果，奶油，得出的味道爽口，还可以搅拌蛋糕液，馅料、打蛋及和制面团，特别在酒家、饭店、面包屋以及食品厂家等作搅拌食料，揉和面团之用，是生产优质糕点的理想设备。因此设计一个合理的搅拌机是非常的必要。

在目前市场上，搅拌机的种类很多，食品搅拌机也有各种各样的。因此，对一个搅拌机进行设计和研究是很有必要的，同时也有一定实践价值。从学习层面及设计手法上看：使用了UG或PRO/E等软件来完成机构的三维造型，并用软件对其机构进行模拟运动仿真，分析其可行性。这是一种有别于以前靠用做出相应的实物来验证其可行性的新设计方法。使用运动仿真的优点：节省了实验成本、缩短了设计时间、能轻易通过软件改变一些参数实现更多的验证方案、有利于创新设计的实现等等。

这是一个比较综合性的设计课题，自己的经验也不足，要想做好该课题，必须要熟悉的掌握机械原理、机械优化设计、工程力学、机械设计、数控加工、机械制造基础、产品造型等方面的一些理论知识。因此，这也是对我大学四年所学专业知识的一个综合应用。通过做此课题，我将能了解这本科四年来我对专业知识掌握的程度，同时也是一个系统的复习。这将给我以后走向社会起到一个很好的开头作用。

搅拌机包含的机构及需要实现的动作:

搅拌机构：实现模仿手的动作对食品作用。可以将搅拌机构设计为4杆机构，实现搅拌头的曲线运动。

容器机构：使容器得以不断有序的循环转动。可以将容器机构看作是一个圆周运动，容器盆下加一块装有电机的支撑板，由带传动带动容器盆旋转运动。

中间机构：实现搅拌机构与容器盘机构连接，保证他们相互间的联合运动。

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内容简介：: 桂林电子科技大学毕业设计报告（论文）用纸编号：毕业设计(论文)外文翻译（原文）院（系）：应用科技学院专业：机械设计及其自动化学生姓名：李雪梅学号： 0701120404 指导教师单位：应用科技学院姓名：李锐锋职称：讲师 2011年 6 月 12 日18New Manufacturing TechnologiesINTRODUCTIONDriven by international competition and aided by application of computer technology, manufacturing firms have been pursuing two principal approaches during the 1980s:* automation, and* integration.Automation is the substitution of machine for human function; integration is the reduction or elimination of buffers between physical or organizational entities. The strategy behind manufacturing firms application of new automation technologies is multidimensional:* to liberate human resources for knowledge work,* to eliminate hazardous or unpleasant jobs,* to improve product uniformity, and* to reduce costs and variability.The execution of that strategy has lead firms automate away simple, repetitive, or unpleasant functions in their offices, factories, and laboratories.Integration, when used as an approach to improve quality, cost, and responsiveness to customers, requires that firms find ways to reduce physical, temporal, and organizational barriers among various functions. Such buffer reduction has been implemented by the elimination of waste,the substitution of information for inventory, the insertion of computer technology, or some combination of these.In most process industries - oil refining and papermaking, for example - automation and integration have been critical trends for decades. However, in discrete goods manufacture - electronics and automobiles, for example - significant movement in these directions is a recent phenomenon in the United States.This chapter defines, examines, and illustrates the application of technologies that support the trends toward more automation and integration in discrete goods manufacturing. We begin with a discussion of the technological hardware and software that has been evolving. We then look at six management challenges that must be addressed to support these trends. And, finally, we look at the issue of economic evaluation the new technologies.AUTOMATION IN MANUFACTURINGAs characterized, for example, by Toshiba, in their OME Works facility, automation in manufacturing can be divided into three categories:*factory automation,*engineering automation, and*planning and control automation.Automation in these three areas can occur independently, but coordination among the three, as is being pursued by this Toshiba facility, drives opportunities for computer integrated manufacturing, discussed below.Factory AutomationAlthough software also plays a critical role, factory automation is typically described by the technological hardware used in manufacturing: robots, numerically controlled (NC) machine tools, and automated material handling systems. Increasingly, these technologies are used in larger, integrated systems, known as manufacturing cells or flexible manufacturing systems (FMS).The term robot refers to a piece of automated equipment, typically programmable, that can be used for moving material to be worked on (pick and place) or assembling components into a larger device. Robots are also used to substitute for direct human labor in the use of tools or equipment, as is done, for example, by a painting robot, or a welding robot, which both positions the welder and welds joints and seams. Robots can vary significantly in complexity, from simple single-axis programmable controllers to sophisticated multi-axis machines with microprocessor control and real-time, closed-loop feedback and adjustment.A numerically-controlled (NC) machine tool is a machine tool that can be run by a computer program that directs the machine in its operations. A stand-alone NC machine needs to have the workpieces, tools, and NC programs loaded and unloaded by an operator. However, once an NC machine is running a program on a workpiece, it requires significantly less operator involvement than a manually operated machine.A CNC (computer numerically-controlled) machine tool typically has a small computer dedicated to it, so that programs can be developed and stored locally. In addition, some CNC tools have automated parts loading and tool changing. CNC tools typically have real-time, on-line program development capabilities, so that operators can implement engineering changes rapidly.A DNC (distributed numerically-controlled) system consists of numerous CNC tools linked together by a larger computer system that downloads NC programs to the distributed machine tools. Such a system is necessary for the ultimate integration of parts machining with production planning and scheduling.Automated inspection of work can also be realized with, for example, vision systems or pressure-sensitive sensors. Inspection work tends to be tedious and prone to errors, especially in very high volume manufacturing settings, so it is a good candidate for automation. However, automated inspection (especially with diagnosis capability) tends to be very difficult and expensive. This situation, where automated inspection systems are expensive to develop, but human inspection is error-prone, demonstrates the value of automated manufacturing systems with very high reliability: In such systems, inspection and test strategies can be developed to exploit the high-reliability features, with the potential to reduce significantly the total cost of manufacture and test.Automated material handling systems move workpieces among work centers, storage locations, and shipping points. These systems may include autonomous guided vehicles, conveyor systems, or systems of rails. By connecting separate points in the production system, automated material handling systems serve an integration function, reducing the time delays between different points in the production process. These systems force process layout designers to depict clearly the path of each workpiece and often make it economical to transport workpieces in small batches, providing the potential for reduced wait times and idleness.A flexible manufacturing system (FMS) is a system that connects automated workstations with a material handling system to provide a multi-stage automated manufacturing capability for a wider range of parts than is typically made on a highly-automated, non-flexible, transfer line. These systems provide flexibility because both the operations performed at each work station and the routing of parts among work stations can be varied with software controls.The promise of FMS technology is to provide the capability for flexibility approaching that available in a job shop with equipment utilizations approaching what can be achieved with a transfer line. In fact, a FMS is a technology intermediate to these two extremes, but good management can help in pushing both frontiers simultaneously.Automated factories can differ significantly with respect to their strategic purpose and impact. Two examples, Matsushita and General Electric, may be instructive.In Osaka, Japan, Matsushita Electric Industrial Company has a plant that produces video cassette recorders (VCRs). The heart of the operation features a highly automated robotic assembly line with 100-plus work stations. Except for a number of trouble-shooting operators and process improvement engineers, this line can run, with very little human intervention, for close to 24 hours per day, turning out any combination of 200 VCR models. As of August 1988, the facility was underutilized; Matsushita was poised to increase production, by running the facility more hours per month, as demand materialized.In this situation, the marginal cost of producing more output is very low. Matsushita has effectively created a barrier to entry in the VCR industry, making it very difficult for entrants to compete on price.The second example is General Electrics Aircraft Engine Group Plant III, in Lynn, Massachusetts. This fully automated plant machines a small set of parts used by the Aircraft Engine Groups assembly plant. In contrast to Matsushitas plant, which provides strategic advantage in the VCR product market, the strategic advantage provided by GEs plant seems to address its labor market. Plant IIIs investment is now sunk. Eventually, it will run around the clock at very high utilization rates with a very small crew.As volume is ramped up, GE has the ability to use Plant IIIs capacity and cost structure as leverage with its unionized labor force which is currently making many of the parts that could eventually be transferred to Plant III. Thus, factory automation can address a variety of types of strategic needs, from product market considerations to labor market concerns.Engineering AutomationFrom analyzing initial concepts to finalizing process plans, engineering functions that precede and support manufacturing are becoming increasingly automated. In many respects, engineering automation is very similar to factory automation; both phenomena can dramatically improve labor productivity and both increase the proportion of knowledge work for the remaining employees. However, for many companies, the economic payback structure and the justification procedures for the two technologies can be quite different.This difference between engineering automation and factory automation stems from a difference in the scale economies of the two types of technologies. In many settings, the minimum efficient scale for engineering automation is quite low. Investment in an engineering workstation can often be justified whether or not it is networked and integrated into the larger system. The firstorder improvement of the engineers productivity is sufficient.For justification of factory automation, the reverse is more frequently the case. The term island of automation has come to connote a small investment in factory automation that, by itself, provides a poor return on investment. Many firms believe that factory automation investments must be well integrated and widespread in the operation before the strategic benefits of quality, lead time, and flexibility manifest themselves.Computer-aided design is sometimes used as an umbrella term for computer-aided drafting, computer-aided engineering analysis, and computer-aided process planning. These technologies can be used to automate significant amounts of the drudgery out of engineering design work, so that engineers can concentrate more of their time and energy on being creative and evaluating a wider range of possibledesign ideas. For the near future machines will not typically design products. The design function remains almost completely within the human domain.Computer-aided engineering allows the user to apply necessary engineering analysis, such as finite element analysis, to propose designs while they are in the drawing board stage. This capability can reduce dramatically the need for time-consuming prototype work up and test during the product development period.Computer-aided process planning helps to automate the manufacturing engineers work of developing process plans for a product, once the product has been designed. Planning and Control Automation Planning and control automation is most closely associated with material requirements planning (MRP). Classical MRP develops production plans and schedules by using product bills of materials and production lead times to explode customer orders and demand forecasts netted against current and projected inventory levels. MRP II systems (second-generation MRP) are manufacturing resource planning systems that build on the basic MRP logic, but also include modules for shop floor control, resource requirements planning, inventory analysis, forecasting, purchasing, order processing, cost accounting, and capacity planning in various levels of detail.The economic considerations for investment in planning and control automation are more similar to that for investment in factory automation than that for engineering automation. The returns from an investment in an MRP II system can only be estimated by analyzing the entire manufacturing operation, as is also the case for factory automation. The integration function of the technology provides a significant portion of the benefits.INTEGRATION IN MANUFACTURINGFour important movements in the manufacturing arena are pushing the implementation of greater integration in manufacturing:* Just-in-Time manufacturing (JIT),* Design for Manufacturability (DFM),* Quality Function Deployment (QFD), * Computer-integrated Manufacturing (CIM).Of these, CIM is the only one directly related to new computer technology. JIT, QFD, and DFM, which are organization management approaches, are not inherently computer-oriented and do not rely on any new technological developments. We will look at them briefly here because they are important to the changes that many manufacturing organizations are undertaking and because their integration objectives are very consonant with those of CIM.Just-in-Time Manufacturing (JIT)JIT embodies the idea of pursuing streamlined or continuous-flow production for the manufacture of discrete goods. Central to the philosophy is the idea of reducing manufacturing setup times, variability, inventory buffers, and lead times in the entire production system, from vendors through to customers, in order to achieve high product quality (conformity), fast and reliable delivery performance, and low costs.The reduction of time and inventory buffers between work stations in a factory, and between a vendor and its customers, creates a more integrated production system. People at each work center develop a better awareness of the needs and problems of their predecessors and successors. This awareness, coupled with a cooperative work culture, can help significantly with quality improvement and variability reduction.Investment in technology, that is, machines and computers, is not required for the implementation of JIT. Rather, JIT is a management technology that relies primarily on persistence in pursuing continuous incremental improvement in manufacturing operations. JIT accomplishes some of the same integration objectives achieved by CIM, without significant capital investment. Just as it is difficult to quantify the costs and benefits of investments in (hard) factory automation, it is also difficult to quantify costs and benefits of a soft technology such as JIT. A few recent models have attempted to do such a quantification, but that body of work has not been widely applied.Design for Manufacturability (DFM)This approach is sometimes called concurrent design or simultaneous engineering. DFM is a set of concepts related to pursuing closer communication and cooperation among design engineers, process engineers, and manufacturing personnel. In many engineering organizations, traditional product development practice was to have product designers finish their work before process designers could even start theirs. Products developed in such a fashion would inevitably require significant engineering changes as the manufacturing engineers struggled to find a way to produce the product in volume at low cost with high uniformity.Ouality Function Deployment (OFD)Closely related to Design for Manufacturability is the concept of Quality Function Deployment (QFD) which requires increased communication among product designers, marketing personnel, and the ultimate product users. In many organizations, once an initial product concept was developed, long periods would pass without significant interaction between marketing personnel and the engineering designers. As a result, as the designers confronted a myriad of technical decisions and tradeoffs, they would make choices with little marketing or customer input. Such practices often led to long delays in product introduction because redesign work was necessary once the marketing people finally got to see the prototypes. QFD formalizes interaction between marketing and engineering groups throughout the product development cycle, assuring that design decisions are made with full knowledge of all technical and market tradeoff considerations.Taken together, Design for Manufacturability and Quality Function Deployment promote integration among engineering, marketing, and manufacturing to reduce the total product development cycle and to improve the quality of the product design, as perceived by both the manufacturing organization and the customers who will buy the product.Like Just-in-Time, Design for Manufacturability and Quality Function Deployment are not primarily technological in nature. However, technologies such as Computer-aided Design can often be utilized as tools for fostering engineering/manufacturing/marketing integration. In a sense, such usage can be considered as the application of computer integrated manufacturing to implement these policy choices.Computer-interated Manufacturing (CIM)Computer-integrated manufacturing refers to the use of computer technology to link together all functions related to the manufacture of a product. CIM is therefore both an information system and a manufacturing control system. Because its intent is so all-encompassing, even describing CIM in a meaningful way can be difficult.We describe briefly one relatively simple conceptual model that covers the principal information needs and flows in a manufacturing firm. The model consists of two types of system components:* departments that supply and/or use information, and* processes that transform, combine, or manipulate information in some manner.The nine departments in the model are:1. production2. purchasing3. sales/marketing4. industrial and manufacturing engineering5. product design engineering6. materials management and production planning7. controller/finance/accounting8. plant and corporate management9. quality assurance.The nine processes that transform, combine, or manipulate information in some manner are:1. cost analysis2. inventory analysis3. product line analysis4. quality analysis5. workforce analysis6. master scheduling7. material requirements planning (MRP)8. plant and equipment investment9. process design and layout.To complete the specification of the model for a specific manufacturing system, one must catalog the information flows among the departments and information processes listed above. Such an information flow map can serve as a conceptual blueprint for CIM design, and can aid in visualizing the scope and function of a CIM information system.Design and implementation of a computer system to link together all of these information suppliers, processors, and users is typically a long, difficult, and expensive task. Such a system must serve the needs of a diverse group of users, and must typically bridge a variety of differentsoftware and hardware subsystems.The economic benefits from such a system come from faster and more reliable communication among employees within the organization and the resulting improvements in product quality and lead times.Since many of the benefits a CIM system are either intangible or very difficult to quantify, the decision to pursue a CIM program must be based on a long term, strategic commitment to improve manufacturing capabilities. Traditional return-on-investment evaluation procedures that characterize the decision-making processes of many U.S. manufacturing concerns will not justify the tremendous amount of capital and time required to aggressively pursue CIM. Despite the high cost and uncertainty associated with CIM implementation, most large U.S. manufacturing companies are investing some resources to explore the feasibility of using computerized information systems to integrate the various functions of their organizations.TECHNOLOGY ADOPTION CONSEQUENCES: FLEXIBILITY AND CAPITAL INTENSIVENESSAs explained above, investments in factory automation and CIM move a firm in the direction of more automation and integration. To fully evaluate such investment opportunities, and to weigh the potential pay-offs against the costs, one must consider two consequences of these technologies:1) the flexibility of the manufacturing operation, and2) the capital intensiveness of the operation.In this section, we look briefly at these two effects before discussing six challenges created by the new manufacturing technologies.Manufacturing flexibility - flexibility to change product mix, to change production rate, and to introduce new products - is achieved by shortening lead times within the manufacturing system and by automating setups and changeovers for different products. The importance of manufacturing flexibility for firm competitiveness has become apparent over the past decade as the rate of economic and technological change has accelerated and as many consumer and industrial markets have become increasingly internationalized.As a consequence of this increased competition, product life cycles shorten as each firm tries to keep up with the new offerings of a larger group of industrial rivals.To survive, companies must respond quickly and flexibly to competitive threats. Therefore, firms must pay particular attention to evaluating the flexibility component of the new manufacturing technologies.Increased capital intensiveness follows directly from automation on a large scale that replaces humans with machines. A transformation to a capital intensive cost structure has two important effects.First, the manufacturing cost structure changes, from one with low fixed investment and high unit variable costs, to one with high fixed investment and low variable costs. This change will affect significantly a firms ability to weather competitive challenges, because low variable costs allow a firm to sustain short-term profitability even in the face of severe price wars.Second, the changes in both employment levels and work responsibilities brought about by automation require significant organizational adjustment. Challenges brought about by this type of change are discussed below.SIX CHALLENGES CREATED BY THE NEW MANUFACTURINGTECHNOLOGIES1.Design and Development of CIM SystemsBecause of their ambitious integration objectives, CIM systems will be large, complex information systems. Ideally, the design process should start with the enunciation of the CIM mission, followed by a statement of specific goals and tasks. Such a top-down design approach insures that the hardware and software components are engineered into a cohesive system.In addition, since the foundation of CIM consists of an integrated central database plus distributed databases, database design is critical. Also, since many people in the organization will be responsible for entering data into the system, they must understand how their functions interact with the entire system. Input from users must be considered at the design stage, and systems for checking database accuracy and integrity must be included.Hardware and software standardization must also be considered at the system design stage. At many companies, computing and database capabilities have come from a wide variety of vendors whose products are not particularly compatible. Either retooling, or developing systems to link these computers together, requires significant resources.Obviously, designing a system that will be recognized as a success, both inside and outside the organization, is a formidable challenge. Few, if any, companies have fully accomplished this task to date.2. Human Resource Management SystemAs mentioned above, significant adjustment is required for an organization to coalesce behind the implementation of new factory automation and CIM technology. If the new technology is not installed in a greenfield site, then layoffs are often one consequence of the change. Reductions in force are inevitably associated with morale problems for the remaining employees who may view the layoffs as a sign of corporate retreat rather than revitalization.Furthermore, human resource problems are not typically limited to simply laying off a set number of people and then just moving forward with the remaining group. CIM and automation technologies place significantly greater skill demands on the organization. Retraining and continuous education must be the rule for firms that hope to be competitive with these technologies; the firm must undergo a cultural transformation.Requirements for retraining and continuous education are at least as strong for managers and engineers who work with these new technologies as for the factory workers on the plant floor. Designing automated factories, managing automated factories, and designing products for automated factories all require supplemental knowledge and skills compared with those required for a traditional, labor intensive plant. Senior managers, who must evaluate CIM technologies, as well as the people who work with them, also can benefit significantly from education about the technologies.3. Product Development SystemFactory automation and CIM can make product designers jobs more difficult. Human-driven production systems are infinitely more adaptable than automated manufacturing systems. When designers are setting requirements for a manually built product, they can afford some sloppiness in the specifications, knowing that the human assemblers can either accomodate unexpected machining or assembly problems as they occur, or at least can recognize problems and communicate them back to the designers for redesign.In an automated setting, designers cannot rely on the manufacturing system to easily discover and recover from design errors. There are severe limits to the levels of intelligence and adaptability that can be designed into automated manufacturing systems, so product designers must have either intimate knowledge of the manufacturing system or intimate communication with those who do. Developing such a design capability in the organization is a difficult, but necessary step for achieving world-class implementation of the manufacturing system.4. Managing Dynamic Process ImprovementIn most well-run, labor-intensive manufacturing systems, continuous improvement results from a highly motivated workforce that constantly strives to discover better methods for performing its work. In a highly automated factory, there are few workers to observe, test, experiment with, think about, and learn about the system and how to make it better. As a consequence, some observers claim that factory automation will mean the end of the learning curve as an important factor in manufacturing competitiveness. Such an assertion runs counter to a very long history of progress in industrial productivity, resulting from a collection of radical technological innovations, each followed by an extensive series of incremental improvements that help perfect the new technology. Most students of the subject estimate that the accumlation of such incremental improvements accounts for as much total productivity growth as do the radical innovations. In essence, any radical innovation may be thought of as a first pass innovation which requires much more innovation before it reaches its maximum potential.To presume that factory automation and CIM will reverse this historic pattern is premature at best, and potentially very misleading to managers and implementers of these technologies. Because these technologies are so new aid so complex, one cannot expect to capture all of the relevant knowledge at the system design stage. If a firm assumes that once it is in place, the technology will not be subject to very much improvement, it will evaluate, design, and manage the system much differently than if it assumes that much benefit can be achieved by learning more about how best to use and improve the system once it is in place.(potential innovators) in it, firms who invest in this technology would be wise to assure that those people who are present are trained to discover, capture, and apply as much new knowledge as possible. In fact, discovering and exploiting opportunities for continuous improvement might be the primary reasons for firms to avoid completely unattended factories.5. Technology ProcurementBefore evaluating a specific technological option, that option must be reasonably well defined. A firm needs to choose equipment and software vendors, and to decide how much of the design, production, installation, and integration of the technology will be performed with in-house staff. Many observers argue for doing as much technology development in house as possible, to minimize information leaks about the firms process technology, and to assure a proper fit between the firms new technology and its existing strategy, people, and capital assets.For external technology acquisition, technological options must be generated before they can be evaluated. In developing these options, a firm must consider its current assets, environment, and market position, as well as those of its competitors. Equipment vendors must be brought into the decision process. Vendor and technology evaluation criteria must be developed and utilized within the organization.6. System Control and Performance EvaluationOnce a technology investment choice has been implemented, managers typically want to track the efficacy of that investment. The shortcomings of the traditional methods for measuring manufacturing performance are widely recognized. Many of these methods can be manipulated to make current results look good at the expense of potential future results. When managers spend only a small fraction of their careers in one facility or position, they often have an incentive to engage in such manipulations. In addition, in many settings, the appropriate performance yardstick for a facility requires information on one or more competitors facilities, on which timely, accurate data may be unavailable.Increasingly, firms are using multidimensional measures of manufacturing performance. Rather than depending on just a profitability summary statistic, measures of quality, lead times, cost of quality, delivery performance, and total factor productivity are being utilized to evaluate performance. Despite this trend, firms could benefit from more research on how, for example, to set standards for productivity and learning rates in a highly automated, integrated environment.ECONOMIC EVALUATION FOR NEW TECHNOLOGY ADOPTIONThe technology adoption costs that are the most visible and easiest to estimate in advance are the up-front capital outlays for purchased hardware, software, and services. Most models consider only these costs. Also important, however, are (1) costs of laying off people whose skills will not be used in the new system, (2) costs of plant disruption caused by the introduction of new technology into an operating facility, and (3) costs of developing the human resources required to design, build, manage, maintain, and operate the new system.The benefits that flow from investment in factory automation and CIM are both tactical and strategic. These benefits relate to changes in a firms cost structure, increased process repeatability and product conformance, lower inventories, increased flexibility, and shorter flow and communication lines.With respect to cost structure, investment in CIM and factory automation tends to represent a large up-front cost that leads to a reduction in variable costs per unit of output. This characteristic results primarily from replacement of labor by machines. Low variable costs can provide significant competitive advantage when interfirm rivalry is high. In addition, reduced variable costs sometimes lead firms to cut prices, potentially increasing market share and revenues.The advantages arising from the increased repeatability and product conformance afforded by CIM and factory automation can also have significant competitive impact. Decreased process variability、 reduces scrap and rework costs, a source of variable cost savings that can be as important as the reduction of direct labor costs by automation. In addition, improved product conformance can provide significant sales gains in product markets.Secondary effects of improved process control include improved morale (and consequent reduced absenteeism and turnover) of employees happy to work in a system that runs well.Inventory reduction following automation and integration investments can originate from several sources. First, factory automation can reduce setup times for some types of operations, reducing the need for cycle stocks. Second, decreased process variability can decrease uncertainty in the entire manufacturing system, reducing the need for safety stocks. Third, factory integration can shorten manufacturing cycle times, reducing the in-process inventories flowing through the system.Manufacturing flexibility is another key strategic advantage offered by CIM and factory automation. Rapid tool and equipment changeovers enable firms to quickly change product mix in response to varying market demands. In addition, NC programming and computerized process planning shorten the time to market and time to volume for new products introduced into the factory. Fully-automated manufacturing systems provide volume flexibility as well. The highly-automated Matsushita VCR factory mentioned earlier can change its output rate with relatively low and adjustment costs by increasing or decreasing the number of hours it runs each month. Because the factorys direct labor force is quite small, output declines will not lead to dramatic underemployment, and increases do not require major hiring and training efforts.Finally, reduced lead times between work stations will lower the flow times of work between stations, thus decreasing the need for WIP in the system. As inventories and lead times are reduced, firms may increase their profit margins by charging more for rapid delivery or may increase market share by offering better service and holding prices constant.SUMMARY AND CONCLUSIONSIncreased global competition and environmental volatility require that firms adapt quickly or face the possibility of extinction. Investment in automation and integration, including hardware such as automated machines and flexible manufacturing systems, software such as CIM systems, and managerial approaches such as just-in-time and design for manufacturability, can help firms to achieve and maintain competitiveness.Of course, the assets always in shortest supply are managerial vision and leadership. Manufacturing strategy creation must precede technology investment decisions, because good technology rarely saves poor management. Therefore, firms must complement their learning about technology options with information and insights about their business challenges and opportunities.Charles H. Fine teaches operations management and manufacturing strategy at MITs Sloan School of Management. He holds Ph.d and Masters degrees from Stanford University, and a Bachelors degree from Duke University. He has authored a number of articles on manufacturing issues, including pieces on the economics of quality improvement and on models for investment in flexible manufacturing systems. His industrial consulting, executive teaching, and research project experience includes work at Digital Equipment Corporation, Eastman Kodak, General Electric, IBM, and Motorola.A Knowledge Base System for the Design and Manufacture of Injection-Molded Plastic ProductsAbstractThis paper presents the development and implementation of a knowledge base system (KBS) for an important polymer molding. This KBS, named Enlighten, is built on top of web-based technology because of its ubiquity, ease of use, convenient content dissemination, its hypertext, navigation, and search capabilities, as well as the support of interactivity (via Java, JavaScript, and CGI) and multimedia (text, graphics, video, and audio). By design, the contents and tools in Enlighten can be viewed and shared by parties that are involved in the process, using any major Web browser, either locally via CDROM or through the Internet, (intranet or extranet).I. INTRODUCTIONThe knowledge-based system is an ideal technology for preserving knowledge within the organization and for building the corporate memory of the firm l. It also plays an important role in integrating knowledge across different departments, disciplines, and organizations. Information technology removes geographic and time barriers, making information readily assessable at ones desktop or notebook computer through networks. We developed and implemented Enlighten for a complex injection molding procees a perfect candidate for a KBS. The tasks involved in the design and manufacture of injection-molded plastic parts consist of product styling, part engineering, material selection, mold engineering, mold fabrication (tooling), injection molding, and computer-aided engineering (CAE). These multidisciplinary tasks require knowledge of and decision-making abilities in the design of parts and molds, material properties, processing, computer simulation, and troubleshooting of molding problems. The sheer volume of information and skills required, as engineers of different departments conduct the project concurrently, goes beyond the storage capacity of the human brain. It also requires a means to store and share product information. The Enlighten task was initiated to establish a scaleable framework that encapsulates, organizes, and disseminates crucial design, processing, and CAE analysis information to plastics engineers and managers. Using web-based technology, we have created a knowledge base that supplies a powerful information storage and retrieval system via a well-designed user interface built upon a solid data structure. The system components and implementation process will be discussed in the following sections. SYSTEM COMPONENTSA. Source Files and DatabaseThe major building block of Enlighten is the information module (see B. Information Modules and Images). We chose FrameMaker, one of the most popular and powerful desktop publishing tools available, as the source file format. Although we considered converting the FrameMaker files to the Portable Document Format (PDF) to be viewed by Adobe Acrobat Reader, (which is free for downloading), we decided to go with the HyperText Markup Language (HTML) format, a prevailing standard on the World Wide Web (WWW). One or the reasons for this decision was the improved quality of our graphicsrich pages when displayed by the browser. We use a third-party conversion tool (Web Works Publisher) to translate the FrameMaker files into HTML format, as depicted in Figure 1. Publisher allows us to define formatting styles to ensure a consistent look-and- feel in the resulting HTML documents.Since Enlighten must sustain continuous future growth, a commercial relational database application has been employed to manage the vast number of source and HTML files (see Figure 1). Each source file is logged in as a record in the database. The record stores information about a files (information modules) title, author, directory path, and unique eight-digit alphanumeric. The record also keeps track of the date the source was created, whether its HTML counterpart has been generated, and which main heading in the knowledge base the information module should be plugged into. The database filename field is keyed to specific entries in a keyword table so we can dynamically generate indexes that are automatically hyperlinked.B. Information Modules and ImagesThe information module, which manifests as a single HTML page in the knowledge base, is the fundamental constituent unit of Enlighten. Each information module provides information on a specific subject, and can contain hyperlinks to other related information modules and public web sites (see Figure 1). As their name implies, information modules are modular, reusable chunks of information. Enlightens user interface is the vehicle for organizing these modules into logical categories, and presenting them to the user. Yet the modules are completely independent of the user interface structure. We can add modules, shuffle them around, access one module from any number of menus, or remove modules altogether. The modules are stored in one location, but will appear wherever theyre called. The graphical and digital images included in Enlighten are produced with Macromedias FreeHand and Adobe PhotoShop. They are saved in either the Graphic Image Format (GIF) or Joint Photographic Expert Group (JPEG) format. Graphics are animated by layering several GIF files in sequence, creating the illusion of motion.C. Main Topic HeadingsThe user interface

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