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Robotics and Computer-Integrated ManufactCityenterprises.development of injection moulds can be realized by developing an Internet-based mould design system as one of the modules of acollaborative product development system. This paper presents a prototype Internet-based intelligent design system for injection moulds.Due to its ability to produce complex-shape plastic partswith good dimensional accuracy and very short cycle times,and Internet technology, CAD/CAE/CAM integrationtechnology, concurrent engineering, artificial intelligence,most cases, quality of mould is responsible for theeconomics of the entire process. Injection mould designmeters. Unfortunately, it is presently impossible to coverthe growing demand for such experienced designers.Therefore, intelligent CAD tools that can assist in theARTICLE IN PRESSvarious tasks of the mould design process are veryimportant to the productivity of the mould-makingindustry.0736-5845/$-see front matter r 2006 Elsevier Ltd. All rights reserved.doi:10.1016/j.rcim.2006.05.003C3Corresponding author. Fax: +85227888423.E-mail address: .hk (C.K. Mok).injection moulding has become the most important processfor manufacturing plastic parts in the plastic industrytoday. However, the current plastics industry is under greatpressure, due to the globalization of the market, the shortlife cycle of product development, increasing productdiversity, high demand of product quality. To meet suchrequirements, it is very important for this trade to adoptvarious advanced technologies which include informationinvolves extensive empirical knowledge (heuristic knowl-edge) about the structure and functions of the componentsof the mould. Nowadays, mould design faces withincreasing deadline pressures and the design itself ispredominantly based upon experience of the moulddesigner. Mould designers are required to possess thoroughand broad experience, because detailed decisions requirethe knowledge of the interaction among various para-solution together with artificial intelligence techniques is employed to develop such a networked interactive CAD system. In this system,the computational module, the knowledge base module and the graphic module for generating mould features are integrated within aninteractive CAD-based framework. The knowledge base of the system would be accessed by mould designers through interactiveprograms so that their own intelligence and experience could also be incorporated with the total mould design. The approach adoptedboth speeds up the design process and facilitates design standardization which in turn increases the speed of mould manufacture.A practical case study is presented to illustrate the operations of the Internet-based mould design system.r 2006 Elsevier Ltd. All rights reserved.Keywords: Internet; Knowledge-based expert systems; Injection mould design; Collaboration1. IntroductionPlastic, which is one of the most versatile in the modernage, is widely used in many products throughout the world.and so on, to effectively aid the development of injection-moulded product.In injection moulding, the design of a mould is of criticalimportance for product quality and efficient processing. InThe architecture of the system consists of an interactive KB mould design system embedded in an Internet environment. A Java-enabledAn Internet-based intelligent designC.K. Moka,C3, K.S. ChinaDepartment of Manufacturing Engineering and Engineering Management,bSchool of Mechanical Engineering, ShandongReceived 18 October 2005; received in revisedAbstractThe rapid growth of Internet and information technologies in recentproduct developments among different geographically distributeduring 24 (2008) 115system for injection mouldsa, Hongbo Lana,bUniversity of Hong Kong, Tat Chee Avenue, Kowloon, Hong KongUniversity, Jinan 250061, Chinaform 24 April 2006; accepted 5 May 2006years provides a solution to support and facilitate collaborativeAn effective and feasible tool to aid the /locate/rcimARTICLE IN PRESSThe growing trend in global manufacturing is to a largeextent supported by Internet, information technologies andglobal marketing. Nowadays, it is common to see thatdesign, manufacturing and final assembly of a product aremade in companies located in different parts of the world.The various parties concerned would need to share theirexpertise and experiences during the product developmentprocess. The current progress of Internet and informationtechnologies can provide a solution to support andfacilitate collaborative product developments among dif-ferent geographically distributed enterprises. Developingan Internet-based intelligent mould design system asone of the module of a collaborative product develop-ment system can provide an effective and feasible tool toaid the collaborative development of injection moulds inthe small- and medium-sized enterprises to satisfy thestringent requirements of nowadays competitive globalmarket.This paper presents an Internet-based intelligent moulddesign system using Internet technology and knowledge-based approach. The system can shorten the design cycle ofinjection mould and can effectively aid the design anddevelopment works of injection moulds in the small- andmedium-sized enterprises to meet the increasing pressure ofthe current competitive world market. The rest of the paperis organized as follows. Section 2 gives a brief introductionof injection mould design. Section 3 introduces earlierresearch works on mould design and related fields. Thearchitecture of the Internet-based mould design system ispresented in section 4. The knowledge-based part of themould design system is described in section 5. Section 6discusses the development of the system. A practical designcase is demonstrated in section 7. Conclusion is made insection 8.2. Injection mould designThe basic features of an injection mould consist of cavitynumber and layout, feed system, cooling system, ejectionsystem and mould construction. Fig. 1 shows the generalprocedure of mould design 1. It can be seen that howinterrelated the conditions are and which boundary andsecondary conditions have to be met by the main functions.A mould design project normally starts with economicconsiderations, namely the question of how many parts canand should be produced in one mould in one shot in orderto meet the delivery date and other requirements. This isfollowed by consideration of the arrangements of thecavities in the mould frame, which might directly includethoughts on the ease of ejection and subsequently, theconnection between mouldings and runners and partquality (number, position and shape of gates). The feedsystem accommodates the molten plastic material comingfrom the injection nozzle of the moulding machine anddistributes it into each cavity. To remove the heat from theC.K. Mok et al. / Robotics and Computer-In2moulding, it is necessary to provide the mould with acooling system. After the moulding has solidified andcooled down, it has to be removed from the mould by theejection system. Mould is normally constructed by stackingseveral metal plates to form a rigid body. It has to housevarious mould components in correct positions for theproper functioning of the mould. Mould constructionnormally involves the selection of mould bases andstandard mould parts. For complicated plastic parts, someother mechanisms such as slides, unscrewing device, etc.,might also be involved in the whole mould structure.3. Related researchA number of research activities have been carried out onmould design and its related field over the years usingcomputer-aided techniques. These research activities rangefrom studying specific areas of mould design to investigat-ing mould design as a whole integrated system. They canbroadly be classified into three areas: the functional andinitial mould designs; the algorithms to automate mouldgeneration; and system development of mould design.Hui and Tan 2 presented a heuristic search approachbased on sweep operations to develop automated moulddesign systems for determining parting direction, partingline, side core, etc. Huang et al. 3 used solid modellingtechniques to build mould plates and library of standardmould components. Chen and Liu 4 have developed acost model, which depicts the relationships between costfactors and product development activities as well as theirrelationships with product geometry, for cost-effectivenessdesign for injection moulding. Fu et al. 5 proposed anefficient methodology which systematically presents theundercut feature definition, classification, undercut featureparameters, and the recognition criteria of all types ofundercut features for undercut feature recognition in aninjection mould design system. Chen et al. 6 presented amethod for determination of parting direction based ondexel model and fuzzy decision-making. Li JC 7 presenteda neural network approach for modelling and optimizationof injection mould gate parameters. Li CL 8 used afeature-based approach to design the cooling system ofinjection moulds. Chung and Lee 9 proposed a frame-work of collaborative design environment for injectionmoulding in which geographically distributed, multi-disciplinary designers can collaborate with one another.Ma et al. 10 described the development of a standardcomponent library for plastic injection mould design usingan object-oriented approach. Low and Lee 11 introduceda methodology of providing the initial design in 3D solidmodel instead of 2D drawings using the standardizationmethod. Ashaab et al. 12 described a supporting plasticengineering development system to facilitate the sharing ofinjection moulding information and knowledge betweeninterested parties via the Internet for the collaborativedesign of injection mould. Li et al. 13 used graph-basedtechnique and developed a heuristic search algorithm totegrated Manufacturing 24 (2008) 115automate the layout design of plastic injection mouldcooling system.ARTICLE IN PRESSC.K. Mok et al. / Robotics and Computer-InResearchers have started to adopt a knowledge-basedapproach to solve the injection moulding and mould designproblems in recent years. DTMOULD-1 14 is a KBS forof injection moulds cost estimation. EIMPPLAN-1 15incorporated mouldability considerations into part designsand addressed the conceptual design development ofinjection-moulded parts. CADFEED 16 was developedfor injection mould design. They are, however, limited tospecific design areas or simple parts, and are not matureand practical enough to cover general mould design.Fig. 1. The general proceduretegrated Manufacturing 24 (2008) 115 3Bozdana and Eyercioglu 17 developed an expert systemfor the determination of injection moulding parameters ofthermoplastic materials. Chan et al. 18 presented the basicstructure of a CAD knowledge-based assisted injectionmould design system which covers both the mould designprocess and mould knowledge management.From the above review it can be seen that most of theprevious work consider only certain aspects of the totaldesign and some of them are too theoretical to be appliedfor practical mould design which involves a substantialof mould design 1.practical knowledge component about functions andstructure of a mould, human heuristic knowledge andempirical type of knowledge. The KB system has demon-strated great potential to assist the designer to interact witha CAD system for conceptualized design as well as the finalengineering design of a mould by using engineering rules ofthumb with extensive analytical means. In addition, there isstill relatively few research works on Internet-basedintelligent system for injection mould design.4. Architecture of the Internet-based mould design system4.1. OverviewAt the present time, most CAD systems provide only thegeometric modelling functions which facilitate the draftingoperations of mould design, and do not provide moulddesigners with necessary knowledge to develop good moulddesigns. Conventional computer-aided engineeringpackages are usually good at data processing for informa-tion-intensive problems or at number manipulation forformulation-intensive problems. The former comprehendsthe computer-aided drafting and graphics, and datareduction and transformation; while the latter involvesformulation-intensive knowledge. Therefore, conventionalcomputer-aided design technology is unsuitable for proces-sing heuristic and empirical type of knowledge which iscritical in the mould design problems. In general, the majoradvantage of the KB system for mould design overconventional computer-aided design systems is the explicitrepresentation and manipulation of a body of knowledge,representing the human expertise.An Internet-based mould design system using Internettechnology and knowledge-based approach can provide aneffective and feasible tool to aid the collaborative develop-ment of injection moulds in the small- and medium-sizedenterprises to satisfy the stringent requirements of nowadayscompetitive global market. Moreover, there is a consistentneed to check and update the information to ensure that thedata is accurate and updated as mould manufacturers andstandard components suppliers continually improve andupgrade their equipments and processes. By taking fulladvantage of the fast evolving computer network andinformation technologies, an Internet-based mould designsystem could have the ability to continually update andupgradethe large amount of information related to injectionmould design in a prompt and convenient manner.ARTICLE IN PRESSFeed design System C.K. Mok et al. / Robotics and Computer-Integrated Manufacturing 24 (2008) 1154numerical (or mathematical) modelling and analysis.However, in design problem, especially in mould designwhich involves a substantial practical knowledge compo-nent about functions and structure of a mould, humanheuristic knowledge and empirical type of knowledge areneeded in addition to the information-intensive andInternet User Layer Network Layer Business Logic Layer Data and most of the knobs, buckets and cups arebasically circular in shape. The Opitz system 19 which isthe popular classification system for mechanical parts, hasalso been referred to in developing part of the codingsystem.The code is divided into three sections and has a total of12 digits. The first section which describes the plastic partcontains the first four digits. The second section whichdescribes the relation between the part and the mouldincludes the fifth digit. The third section which describesthe mould contains the last seven digits.5.1.1. The first section: part descriptionThis section includes the first four digits. They representthe part class, part external shape, undercut features andmaterial class, respectively.. Part class. The first digit distinguishes the part asa circular part or a non-circular part. There are sevennumeric positions for this digit as shown below.(1) Circular part with H/Dp0.5.(2) Circular part with 0.5oH/Do3.(3) Circular part with H/DX3.(4) Variational circular part.(5) Non-circular part with H/Dep0.5.featuresgraphic(6)(7)are stored in terms of rmation has been inputted, the geometthe detailed dimensions of the geometry ofroutine. In the knowledge base of mould featurebase of mould feature geometry through thetegrated Manufacturing 24 (2008) 115Non-circular part with 0.5oH/De o3.Non-circular part with H/DeX3.only.only.and internal undercut.according to its material constant nfor the fourth digit.1234one digitt .describes the relation between the directions of the partsevent digit.ARTICLE IN PRESS115 7appropriate mould for this type of products is inevitably(4) Straight axis, varying cross-section stepped to one end.(5) Straight axis, varying cross-section along the entireheight.(6) Curved axis.. Undercut feature. Mould designers are frequentlyencountered with demoulding problems resulting fromundercuts existing on the plastic parts. An undercut can bedefined as any interference occurring between the mouldand the moulded part when the part is knocked out fromthe mould in the withdrawal direction. The design of anmore complicated than for those without any undercuts. In(3)generalextertion.Straight axis, uniform, other than rectangular cross-section.(2) Straight axis, uniform cross-section, with one devia-corner.(1) Straight axis, uniform cross-section, no deviation inClass 67(5) Irregular contoured flat part.(4) Flat part, regularly arched or dished.gular.(3) Rectangular with circular deviation.(1)(2)Rectangular with no deviation in corner.Rectangular with one deviation right angle or trian-5Class(3) More than one non-parallel rotating axes.(2) More than one parallel rotating axes.(1) Curved rotating axis.ClassHaving various diameters along the entire height.4(2)(3)height.Cone, diameter stepped to one end.(1) Smooth, having a uniform diameter along the entireClass 13as follclass the part belongs and the classification rules areows:.whichPart external shape. The second digit depends onHere H is the height of the part measured from theparting line. D is the diameter of a circular part. De is theequivalent diameter of a non-circular part with length Land width W (De O(4LW/p). Parts belong to Class 1and Class 3 are like flat discs and long cylindersrespectively. Parts belonging to Class 5 and Class 7 arelike flats and long prisms, respectively.C.K. Mok et al. / Robotics and Computer-Inundercuts can be classified into three types,nal undercut, internal undercut and internal thread.. Runner system. There are four positions for theninth digit.(3)(1)(2)Unscrewing.(2) Collapsible core.(1) Angled form pin.three positions for the eighth digit.(2) Sliding splits.(3) Angled-lift splits.. Internal undercut release mechanism. There are(1) Side core.Cold runner.Insulated runner.three positions for the hthe sixth digit.Position 1 2 3 4 5 6 7 8 9No. of cavi