进水阀盖注射模设计-注塑模具【三维PROE】[32张CAD图纸和说明书等资料]
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任务书填写要求1毕业设计（论文）任务书由指导教师根据各课题的具体情况填写，经学生所在专业的负责人审查、系部领导签字后生效。此任务书应在第七学期结束前填好并发给学生；2任务书内容必须用黑墨水笔工整书写或按教务处统一设计的电子文档标准格式（可从教务处网页上下载）打印，不得随便涂改或潦草书写，禁止打印在其它纸上后剪贴；3任务书内填写的内容，必须和学生毕业设计（论文）完成的情况相一致，若有变更，应当经过所在专业及系部主管领导审批后方可重新填写；4任务书内有关“系部”、“专业”等名称的填写，应写中文全称，不能写数字代码。学生的“学号”要写全号；5任务书内“主要参考文献”的填写，应按照国标GB 77142005文后参考文献著录规则的要求书写，不能有随意性；6有关年月日等日期的填写，应当按照国标GB/T 74082005数据元和交换格式、信息交换、日期和时间表示法规定的要求，一律用阿拉伯数字书写。如“2009年3月15日”或“2009-03-15”。毕 业 设 计（论 文）任 务 书1本毕业设计（论文）课题应达到的目的： 塑料件在各行业及日常生活广泛使用，塑料模具的设计制造的社会需求也日益增长，而且要求越来越高。通过对进水阀盖注射模设计，培养学生检索资料，综合应用所学知识，并根据工程实际的要求解决工程实际问题的方法与能力，训练学生模具设计制造的基本技能和模具CAD设计能力，提高独立工作的能力，适应社会需求。2本毕业设计（论文）课题任务的内容和要求（包括原始数据、技术要求、工作要求等）：本设计要求学生根据所给进水阀盖实物，测绘零件图纸，并设计成型注射模具，并学习Pro/Engineer、UG或Solidworks等大型CAD软件在模具设计中的应用，具体要求如下：1） 查阅资料（不少于15篇），翻译一定量的外文资料（不少于3000汉字），撰写开题报告及文献综述（不少于2000字）；2） 测绘塑件图纸，完成其CAD三维造型设计；3） 完成塑件注射模具方案设计和相关设计计算，要求一模两腔；4） 完成该注射模具装配设计；5） 模具成型零件CAD三维造型设计；6） 完成全部零件及装配图纸设计；7） 撰写设计说明书。毕 业 设 计（论 文）任 务 书3对本毕业设计（论文）课题成果的要求包括毕业设计论文、图表、实物样品等： 课题成果内容包括：1) 塑件图纸及CAD三维数据模型；2) 全套注射模具图纸，成型零件三维造型；3) 毕业设计论文。4主要参考文献：1 成都科技大学，北京化工学院，天津轻工业学院合编.塑料成型模具M.北京：中国轻工业出版社，19822 胡石玉.模具制造技术M.南京：东南大学出版社，19973 骆志斌.模具工手册M.南京：江苏科学技术出版社，20004 机械设计手册联合编写组.机械设计手册（第3版上、中、下）M.北京：化学工业出版社，19875 王庆五，仇亚琴，张昱等编著.SolidWorks 2006中文版模具设计专家指导教程M.北京：机械工业出版社，20066 模具实用技术丛书编委会.塑料模具设计制造与应用实例M.北京：机械工业出版社，20027 张明善主编.塑料成型工艺及设备M.北京：中国轻工业出版社，19988 轻工业部广州轻工业学校编.塑料成型工艺学M.北京：中国轻工业出版社，19909 唐志玉主编塑料模具设计师指南M.北京：国防工业出版社，199910 模具设计与制造技术教育丛书编委会编模具常用机构设计M.北京：机械工业出版社，200311 林清安.Pro/ENGINEER零件设计（基础篇上、下）M.北京：北京大学出版社，2000毕 业 设 计（论 文）任 务 书5本毕业设计（论文）课题工作进度计划：起 迄 日 期工 作 内 容2009年3月 9日 3月15日熟悉课题，查阅有关资料，完成资料翻译3月16日 3月29日完成文献综述，撰写开题报告，学习注射模设计方法，熟悉Solidworks或ProE三维CAD软件3月30 日 4月8 日测绘塑件零件图纸，熟悉Solidworks或ProE三维CAD软件，完成塑件三维数据模型设计4月9日 4月15日进行注射模结构方案设计4月16日 4月29日基本掌握CAD软件操作，完成塑件注射模方案设计和基本计算4月30日 5月10日塑件注射模结构设计，利用Solidworks或ProE等CAD软件进行零件造型设计5月11日 5月17日完成塑件注射模零件造型、装配体设计和修改完善5月18日 5月31日完成塑件注射模工程图和装配图设计6月1 日 6月7日完善图纸，撰写设计说明书6月8日 6月13日打印设计说明书和图纸，整理相关资料6月14日 准备答辩所在专业审查意见：负责人： 年 月 日系部意见：系部主任： 年 月 日毕业设计(论文)外文资料翻译系部： 机械工程系 专 业： 机械工程及自动化 姓 名： 学 号： 外文出处：Journal of Materials ProcessingTechnology 171 (2006) 259267 附 件： 1.外文资料翻译译文；2.外文原文。指导教师评语：译文语句通顺，专业词汇较准确，基本符合规范和毕业设计相关要求。 签名： 年 月 日附件1：外文资料翻译译文注塑模具的设计及其热分析S.H. Tang , Y.M. Kong, S.M. Sapuan, R. Samin, S. Sulaiman摘要：本文介绍注塑模具设计生产翘曲测试样本以及为了获得残余热应力的影响在模具中执行热分析。这项技术、理论、方法在注射模具设计中必须被考虑运用。在商业计算机上使用13.0版本的计算机辅助设计软件UG进行模具的设计。使用商用有限元分析软件LUSAS分析家分析发现并揭示由于试样的冷却不均匀使塑件存在残余热应力的分析报告。该软件提供模型的温度等高线分布图并通过注塑周期时间响应曲线绘制温度变化曲线。结果表明与其它区域相比收缩更可能会发生在冷却渠道附近。模具这种不平衡的冷却效果有助于不同区域翘曲的产生。关键词：注塑模具 设计 热分析1 引言塑料工业被列为一个数十亿美元的产业，是世界上增长最快的行业之一。在日常生活中几乎所有的用品都离不开塑料，而大多数这些塑料都可以用注塑的方法生 1 。 众所周知注塑成型加工是以较低的成本生产各种形状复杂的几何体产品 2 。注塑成型加工是一个循环过程。在注塑过程中有四个重要的阶段。这四个阶段是加料阶段、保压阶段、冷却阶段和顶出顶出。塑料注塑成型加工首先是往注射机料斗中添加树脂和适当的添加剂，并加热塑料注射机的料斗到喷嘴部分 3 。在注射温度下模具型腔充满热聚合物熔体，在模具型腔填满后的保压阶段，更高压力下更多的聚合物熔体装入型腔，以补偿前期聚合物凝固引起的收缩。接下来是模具的冷却阶段，塑件在排出前被冷却到足够的强度。最后一步是顶出阶段，模具开模同时顶出塑件， 然后模具再次合上并开始下一个周期。事实证明设计和制造理想性能的高分子注塑成型零件是一个昂贵的工程，包括反复修改加工，在模具设计任务中，设计模具明确附加几何结构，核心方面通常包括相当复杂的凸凹面5。为了设计模具必须考虑许多重要的设计因素。这些因素分别是模具的尺寸、型腔数、型腔的布局、浇注系统、浇口系统、收缩和顶出机构 6 。在模具的热分析中，其主要目的是分析影响残余热应力或压力对产品尺寸的影响。热诱导应力主要发生在注塑成型的冷却阶段，主要是因为其热传导性低以及熔融树脂与模具之间的温差。在冷却期间产品的冷却腔周围温度存在不均衡 7 。在冷却时，冷却管道附近的冷却效果比远离冷却管道区域的冷却效果好。不同的温度导致不同的收缩，不同的收缩导致热应力而显着的热应力可能会导致翘曲问题。因此，在冷却阶段对注射工件进行残余热应力模拟分析是非常重要的 8 。通过了解热应力的分布特点，可以预测残余热应力引起的变形。本文介绍了注塑模具设计生产翘曲试样以及为了获得残余热应力影响而在模具中执行热分析。2. 方法2.1 设计翘曲测试样本本节说明了用于注塑模具的翘曲测试样品的设计。很显然翘曲的主要问题存在于产品的薄壳特征。因此，产品开发的主要目的是设计一个塑件，以确定注塑工件薄壳翘曲问题的有效因素。翘曲测试样本是薄壳塑料。样本的总体尺寸长120mm，宽50mm,厚1mm. 用丙烯腈-丁二烯-苯乙烯共聚物（ABS）作为材料，在注射温度为210，压力为60MPa,持续3s时间生产翘曲测试样本。图1显示了翘曲测试样本的制作图1 翘曲测试样本制作2.2 翘曲测试样本注塑模具的设计本节介绍了设计生产翘曲测试标本时，在模具的设计方面和其他方面的考虑因素。用于生产翘曲测试样本注塑模具的材料是AISI1050碳钢。在模具设计时考虑了四个构思，其中包括：i. 三板式模具（构思1 ）有一个型腔两个分型面。由于成本高，所以不适用。ii. 两板式模具（构思2 ）有一个型腔一个分型面但无浇注系统。由于单位时间内注射生产量低，不适用。iii. 双板模具（构思3 ）有一个分型面和两个型腔，带浇注和顶出系统。由于塑件的是薄壳的，顶杆可能破坏工件，所以不适用。iv. 双板模具（构思4 ）有一个分型面和两个型腔带浇注系统，只用拉料杆为顶出机构，避免顶出时破坏塑件。翘曲测试样本模具设计的第四个构思被应用。在模具设计中，还有许多因素需要考虑。首先，根据注塑机使用的压板尺寸设计模具。注塑机行程是有限的，通过两个拉杆间的距离确定注射机的最大行程。注射机两个拉杆间的距离为254mm，因此，最大模板宽度不应超过254mm这个距离。此外在模具和两连杆中留出4mm的间隙便于模具的拆装。这最终使模具最大宽度250mm。250X250的标准模架最终被使用。其他有关模板的尺寸则列于表1成分规格（ mm ）宽高度厚度顶端夹紧板定模座板动模座板支承板推杆固定板推板夹紧板底250 250 25200 250 40200 250 4037 250 70120 250 15 120 250 20250 250 25模具已设计了夹紧压力，锁模力应高于内部腔力（反作用力）以避免飞边的发生。以提供的标准模架尺寸为根据，凹模的宽度和高度的分别是200和250毫米，使得模板上的这些尺寸有足够的空间设计两个水平的型腔，而凸模只需留有固定浇口套的空间以便注入溶融塑料。因此，在产品的表面只设计了一个分型面。在开模的时候，塑件和流道在分型面上被分开。模具设计了直接浇口或侧浇口。浇口位于流道和塑件之间。为了便于注入塑料浇口底部设计了一个20的锥角斜度和0.5mm的壁厚。为了熔融塑料的流入，还设计了4mm宽，0.5mm厚的浇口。在模具设计时，选定了抛物面类型的流道。在这种情况下，它的优点是仅需简单的加工模具凸模部分。然与圆形截面类型相比，这种类型的流道有不利之处，如更多的热量损耗和废料。这可能会导致熔融塑料更容易固化。所以在设计时应缩短流道长度并增大流道直径至少有6mm。材料或熔融塑料在同一温度同一压力下同时被送到个模腔对于流道设计来说是很重要的一点。基于这点，模腔的布局一般都是对称的。另一个设计方面是考虑到了气孔设计。凹模和凸模配合面之间有非常好的修整，以防止飞边的发生。然而当模具闭合时，可能会导致空气闭于型腔内，导致塑件注射不足或不完整。设计足够多的通风孔以确保型腔内的空气可以被释放，避免不完整的塑件发生。为了让冷却更均匀，冷却系统沿着模具型腔水平设置。在紊流的情况下，冷却渠道提供了足够的冷却水冷却模具。图2显示了在凸模上气孔和冷却管道的布局。图2 凸模上气孔和冷却管道的布局在此模具设计中，顶出系统只由推杆固定板、拉料杆，浇口套组成。拉料杆设置与凸模的中心位置，在模具打开时不仅承担拉着塑件到适当的位置，而且在顶出阶段，作为推杆从模具中推出塑件。因为生产的产品仅有1毫米非常薄的，所以没有额外推杆被使用或设置。在顶出阶段额外的推杆可能会造成塑件产生孔或破坏塑件。最后，为补偿材料的收缩足够的尺寸偏差被考虑。 图3显示三维实体造型，以及利用UG开发的模具的线框模型图3 三维实体造型以及利用UG开发的模具的线框模型3结果和讨论3.1塑件的制作生产及调整从模具设计和制作的角度看，在试运行阶段制作的翘曲测试样本存在缺陷。该缺陷是注射不足，飞边和翘曲。飞边后来通过在型腔角上铣削额外的气孔让空气排除的方法解决。同时，通过减小注塑机压力减少了飞边的产生。通过控制注射时间、注射温度、熔融温度等不同参数，控制翘曲变形。经过这些修改，模具在低成本的情况下生产出了高质量的翘曲测试样本，这些试样还需要修整。图4显示修整后的模具，这是加工额外的排气孔可以消去注射不足。图4 加工额外的排气孔可以消去注射不足3.2.模具和产品详细分析在塑料注射成型过程中，熔融ABS在210 C温度下通过凹模上的浇口衬套直接注射到模具型腔，经过冷却，塑件就成型了。塑件的生产周期需要花35秒，包括20秒冷却时间。用于生产翘曲测试样本材料的是ABS在注射温度、时间、压力分别为210，3秒和60MPa。用于生产翘曲测试样本注塑模具的材料是AISI1050碳钢。运用有限元软件分析材料性能在决定温度上非常重要。表2列出了ABS以及AISI 1050碳钢的性能。模具分析主要是凹模和凸模，因为他们是形成塑件的地方。因此，使用13.5版本的商用有限元分析软件LUSAS分析家研究不同时段温度的分布。使用二维热分析研究残余热应力在不同区域对模具的影响。由于对称性，只要通过凸模的垂直断面或在注射阶段当凸凹模合在一起时的侧面图建立模型执行热分析。图5所示的是模板的热分析模型。图5 模具热分析建立模型包括分配各部分的性能以及模型的循环周期。这样可以用有限元分析软件用造型模拟模具模型进行分析，还可以绘制时间响应曲线显示再某段时间内特定区域的温差变化。对试样分析，使用13.5版本的LUSAS分析家进行双向拉伸应力分析。一般只需在试样的一端施加拉力另一端则固定住，然后慢慢增加拉力一直到达塑性极限。图6所示的是分析的负载模型。图6 负载模型分析的产品。3.3. 模具及试样分析的结果及讨论模具分析过程对不同时间段的热量分布作了观测。图7所示是在一个完整的注塑周期中不同时间段的二维等高线热量分布图。图7 不同时段温度分布图对模具进行二维分析后，可绘制出时间响应曲线以分析残余热应力对制件的影响。图8所示是绘制时间响应曲线所选的节点。图8 绘制时间响应曲线所选的节点图9到图17显示了在图8中被标注的不同节点的温度分布曲线 图9节点284温度分布图10 节点213温度分图11 节点302温度分布图12 节点290温度分布图13 节点278温度分布图14 节点1838温度分布图15 节点1904温度分布图16 节点1853温度分布图17 节点1866温度分布从图917中很显然被选择用来绘制曲线的每一个节点的温度都是递增的,也从室温到高于室温，然后再次温度下保持一段时间。这些温度上升是由于塑料溶液注入到了塑件的型腔内造成的。经过一段时间后，温度进一步上升直至达到最高温度，然后保持在最高温度下。由于保压阶段涉及高压导致温度上升。温度保持不变直到冷却阶段开始，从而导致模具温度减小到一个低值，然后保持该低值。绘制的曲线是不平滑的，因为注入熔融塑料的速率和冷却速率是相应的。绘制的曲线图仅仅显示了在周期内温度能达到的最大值。冷却阶段是决定残余热应力的最关键阶段。这是因为冷却阶段，材料冷却从上面到下面玻璃化转变温度。物质的不均匀收缩可能产生热应力从而引起翘曲。如图9-17中所示冷却阶段后的温度，很明显在冷却管道附近的塑件由于温度减小的更多，塑件获得了更好的冷却而远离冷却管道区域的塑件冷却效果差。冷却效果好、冷却速度快意味着在该区域发生更多的收缩。最远的区域节点284，虽然远离冷却管道，但由于向空气中散热冷却更快。因此，冷却通道设在产品型腔的中心，造成冷却管道附近和其他区域间产生温差。由于发生收缩使得在塑件的中心区域产生压应力以及由于发生不均衡的收缩导致翘曲。然而，在冷却后不同节点的温差很小，翘曲变形也不是很明显。对设计师来说设计一副残余热应力效果小和高效的冷却系统是非常重要的。对于产品分析,从被实行开始到分析塑料产品,在产品上不同载荷因素的状态下的应力分配情况可以通过观察生成的二维曲进行线分析。图1821显示了不同荷载增量下的等效应力图。图18 荷载增量1下的等效应力图图19 荷载增量14下的等效应力图图20 荷载增量16下的等效应力图图21 荷载增量23下的等效应力图 在关键的127节点，选定产品的最大拉应力进行分析。应力应变曲线和应力负载增量曲线。如图22和23图22 应力应变曲线图23 应力与负载增量曲线参考负载应力曲线如图23,它很清楚表明产品在增加拉力载荷，直到它达到了23的负载因数,这意谓产品能抵抗的1150 N的拉力。由图23可知,对产品的固定端以施加最大应力3.27 107 Pa时损坏可能发生在其附近区域。该产品应力分析资料十分有限，因为生产产品的目的是为了翘曲测试，所以没必要进行拉伸负载分析。但是在未来，应当确定产品情况，以便在其他各种负载情况下执行进一步的分析。4结论经过翘曲测试试样的分析确定影响翘曲的参数来设计的模具已经使产品质量达到最高。生产测试试样所需的成本很低而且只需经过很少的表面处理。通过注塑模的热分析得出残余热应力对试样的影响，对加载拉应力的分析也可以预测到翘曲测试试样所能承受的最大拉力。鸣谢作者要感谢马来西亚博特拉大学工学部发行出版了本文。Journal of Materials Processing Technology 171 (2006) 259267Design and thermal analysis of plastic injection mouldS.H. Tang, Y.M. Kong, S.M. Sapuan, R. Samin, S. SulaimanDepartment of Mechanical and Manufacturing Engineering, Universiti Putra Malaysia, 43400 Serdang, Selangor, MalaysiaReceived 3 September 2004; accepted 21 June 2005AbstractThis paper presents the design of a plastic injection mould for producing warpage testing specimen and performing thermal analysis forthe mould to access on the effect of thermal residual stress in the mould. The technique, theory, methods as well as consideration neededin designing of plastic injection mould are presented. Design of mould was carried out using commercial computer aided design softwareUnigraphics, Version 13.0. The model for thermal residual stress analysis due to uneven cooling of the specimen was developed and solvedusing a commercial finite element analysis software called LUSAS Analyst, Version 13.5. The software provides contour plot of temperaturedistribution for the model and also temperature variation through the plastic injection molding cycle by plotting time response curves. Theresults show that shrinkage is likely to occur in the region near the cooling channels as compared to other regions. This uneven cooling effectat different regions of mould contributed to warpage. 2005 Elsevier B.V. All rights reserved.Keywords: Plastic Injection mould; Design; Thermal analysis1. IntroductionPlastic industry is one of the worlds fastest growingindustries, ranked as one of the few billion-dollar industries.Almost every product that is used in daily life involves theusage of plastic and most of these products can be producedby plastic injection molding method 1. Plastic injectionmolding process is well known as the manufacturing processtocreateproductswithvariousshapesandcomplexgeometryat low cost 2.The plastic injection molding process is a cyclic process.There are four significant stages in the process. These stagesare filling, packing, cooling and ejection. The plastic injec-tion molding process begins with feeding the resin and theappropriateadditivesfromthehoppertotheheating/injectionsystemoftheinjectionplasticinjectionmoldingmachine3.This is the “filling stage” in which the mould cavity is filledwithhotpolymermeltatinjectiontemperature.Afterthecav-ityisfilled,inthe“packingstage”,additionalpolymermeltispacked into the cavity at a higher pressure to compensate theexpectedshrinkageasthepolymersolidifies.ThisisfollowedCorresponding author.E-mail address: .my (S.H. Tang).by “cooling stage” where the mould is cooled until the part issufficiently rigid to be ejected. The last step is the “ejectionstage” in which the mould is opened and the part is ejected,after which the mould is closed again to begin the next cycle4.The design and manufacture of injection molded poly-meric parts with desired properties is a costly process domi-nated by empiricism, including the repeated modification ofactual tooling. Among the task of mould design, designingthe mould specific supplementary geometry, usually on thecore side, is quite complicated by the inclusion of projectionand depression 5.In order to design a mould, many important designingfactors must be taken into consideration. These factors aremouldsize,numberofcavity,cavitylayouts,runnersystems,gating systems, shrinkage and ejection system 6.In thermal analysis of the mould, the main objective isto analyze the effect of thermal residual stress or molded-instresses on product dimension. Thermally induced stressesdevelop principally during the cooling stage of an injectionmolded part, mainly as a consequence of its low thermalconductivity and the difference in temperature between themolten resin and the mould. An uneven temperature fieldexists around product cavity during cooling 7.0924-0136/$ see front matter 2005 Elsevier B.V. All rights reserved.doi:10.1016/j.jmatprotec.2005.06.075260S.H. Tang et al. / Journal of Materials Processing Technology 171 (2006) 259267During cooling, location near the cooling channel experi-ences more cooling than location far away from the coolingchannel. This different temperature causes the material toexperience differential shrinkage causing thermal stresses.Significantthermalstresscancausewarpageproblem.There-fore,itisimportanttosimulatethethermalresidualstressfieldof the injection-molded part during the cooling stage 8. Byunderstanding the characteristics of thermal stress distribu-tion, deformation caused by the thermal residual stress canbe predicted.In this paper the design of a plastic injection mould forproducingwarpagetestingspecimenandforperformingther-mal analysis for the mould to access on the effect of thermalresidual stress in the mould is presented.2. Methodology2.1. Design of warpage testing specimenThis section illustrates the design of the warpage testingspecimen to be used in plastic injection mould. It is clearthat warpage is the main problem that exists in product withthin shell feature. Therefore, the main purpose of the prod-uct development is to design a plastic part for determiningthe effective factors in the warpage problem of an injection-moulded part with a thin shell.The warpage testing specimen is developed from thinshell plastics. The overall dimensions of the specimen were120mminlength,50mminwidthand1mminthickness.Thematerial used for producing the warpage testing specimenwas acrylonitrile butadiene stylene (ABS) and the injectiontemperature, time and pressure were 210C, 3s and 60MPa,respectively. Fig. 1 shows the warpage testing specimen pro-duced.2.2. Design of plastic injection mould for warpagetesting specimenThissectiondescribesthedesignaspectsandotherconsid-erationsinvolvedindesigningthemouldtoproducewarpagetestingspecimen.ThematerialusedforproducingtheplasticFig. 1. Warpage testing specimen produced.injectionmouldforwarpagetestingspecimenwasAISI1050carbon steel.Four design concepts had been considered in designing ofthe mould including:i. Three-plate mould (Concept 1) having two parting linewith single cavity. Not applicable due to high cost.ii. Two-platemould(Concept2)havingonepartinglinewithsingle cavity without gating system. Not applicable dueto low production quantity per injection.iii. Two-plate mould (Concept 3) having one parting linewithdoublecavitieswithgatingandejectionsystem.Notapplicable as ejector pins might damage the product asthe product is too thin.iv. Two-platemould(Concept4)havingonepartinglinewithdoublecavitieswithgatingsystem,onlyusedspruepulleract as ejector to avoid product damage during ejection.In designing of the mould for the warpage testing spec-imen, the fourth design concept had been applied. Variousdesign considerations had been applied in the design.Firstly,themouldwasdesignedbasedontheplatendimen-sion of the plastic injection machine used (BOY 22D). Thereis a limitation of the machine, which is the maximum area ofmachine platen is given by the distance between two tie bars.The distance between tie bars of the machine is 254mm.Therefore, the maximum width of the mould plate shouldnot exceed this distance. Furthermore, 4mm space had beenreserved between the two tie bars and the mould for mouldsetting-up and handling purposes. This gives the final max-imum width of the mould as 250mm. The standard mouldbasewith250mm250mmisemployed.ThemouldbaseisfittedtothemachineusingMatexclampattheupperrightandlower left corner of the mould base or mould platen. Dimen-sions of other related mould plates are shown in Table 1.The mould had been designed with clamping pressurehaving clamping force higher than the internal cavity force(reaction force) to avoid flashing from happening.Based on the dimensions provided by standard mould set,thewidthandtheheightofthecoreplateare200and250mm,respectively.Thesedimensionsenableddesignoftwocavitieson core plate to be placed horizontally as there is enoughspace while the cavity plate is left empty and it is only fixedwithspruebushingforthepurposeoffeedingmoltenplastics.Therefore,itisonlyonestandardpartinglinewasdesignedatTable 1Mould plates dimensions.ComponentsSize (mm)widthheightthicknessTop clamping plate25025025Cavity plate20025040Core plate20025040Side plate/support plate3725070Ejector-retainer plate12025015Ejector plate12025020Bottom clamping plate25025025S.H. Tang et al. / Journal of Materials Processing Technology 171 (2006) 259267261the surface of the product. The product and the runner werereleased in a plane through the parting line during mouldopening.Standardorsidegatewasdesignedforthismould.Thegateis located between the runner and the product. The bottomland of the gate was designed to have 20slanting and hasonly 0.5mm thickness for easy de-gating purpose. The gatewas also designed to have 4mm width and 0.5mm thicknessfor the entrance of molten plastic.In the mould design, the parabolic cross section type ofrunnerwasselectedasithastheadvantageofsimplermachin-ing in one mould half only, which is the core plate in thiscase. However, this type of runner has disadvantages such asmoreheatlossandscrapcomparedwithcircularcrosssectiontype. This might cause the molten plastic to solidify faster.This problem was reduced by designing in such a way thatthe runner is short and has larger diameter, which is 6mm indiameter.Itisimportantthattherunnerdesigneddistributesmaterialor molten plastic into cavities at the same time under thesame pressure and with the same temperature. Due to this,the cavity layout had been designed in symmetrical form.Another design aspect that is taken into consideration wasair vent design. The mating surface between the core plateand the cavity plate has very fine finishing in order to preventflashingfromtakingplace.However,thiscancauseairtotrapin the cavity when the mould is closed and cause short shotor incomplete part. Sufficient air vent was designed to ensurethat air trap can be released to avoid incomplete part fromoccurring.The cooling system was drilled along the length of thecavities and was located horizontally to the mould to alloweven cooling. These cooling channels were drilled on bothcavity and core plates. The cooling channels provided suffi-cientcoolingofthemouldinthecaseofturbulentflow.Fig.2shows cavity layout with air vents and cooling channels oncore plate.In this mould design, the ejection system only consists ofthe ejector retainer plate, sprue puller and also the ejectorFig. 2. Cavity layout with air vents and cooling channels.plate. The sprue puller located at the center of core plate notonly functions as the puller to hold the product in positionwhen the mould is opened but it also acts as ejector to pushthe product out of the mould during ejection stage. No addi-tional ejector is used or located at product cavities becausethe product produced is very thin, i.e. 1mm. Additional ejec-tor in the product cavity area might create hole and damageto the product during ejection.Finally, enough tolerance of dimensions is given consid-eration to compensate for shrinkage of materials.Fig. 3 shows 3D solid modeling as well as the wireframemodeling of the mould developed using Unigraphics.3. Results and discussion3.1. Results of product production and modificationFrom the mould designed and fabricated, the warpagetesting specimens produced have some defects during trialrun. The defects are short shot, flashing and warpage. Theshortshotissubsequentlyeliminatedbymillingofadditionalair vents at corners of the cavities to allow air trapped toFig. 3. 3D solid modeling and wireframe modeling of the mould.262S.H. Tang et al. / Journal of Materials Processing Technology 171 (2006) 259267Fig. 4. Extra air vents to avoid short shot.escape. Meanwhile, flashing was reduced by reducing thepacking pressure of the machine. Warpage can be controlledby controlling various parameters such as the injection time,injection temperature and melting temperature.After these modifications, the mould produced high qual-ity warpage testing specimen with low cost and requiredlittle finishing by de-gating. Fig. 4 shows modifications ofthe mould, which is machining of extra air vents that caneliminate short shot.3.2. Detail analysis of mould and productAfterthemouldandproductsweredeveloped,theanalysisofmouldandtheproductwascarriedout.Intheplasticinjec-tionmouldingprocess,moltenABSat210Cisinjectedintothe mould through the sprue bushing on the cavity plate anddirected into the product cavity. After cooling takes place,the product is formed. One cycle of the product takes about35s including 20s of cooling time.The material used for producing warpage testing speci-men was ABS and the injection temperature, time and pres-sure were 210C, 3s and 60MPa respectively. The materialselected for the mould was AISI 1050 carbon steel.Properties of these materials were important in determin-ing temperature distribution in the mould carried out usingfinite element analysis. Table 2 shows the properties for ABSand AISI 1050 carbon steel.The critical part of analysis for mould is on the cavity andcore plate because these are the place where the product isformed. Therefore, thermal analysis to study the temperatureFig. 5. Model for thermal analysis.distribution and temperature at through different times areperformedusingcommercialfiniteelementanalysissoftwarecalled LUSAS Analyst, Version 13.5. A two-dimensional(2D) thermal analysis is carried out for to study the effectof thermal residual stress on the mould at different regions.Due to symmetry, the thermal analysis was performed bymodeling only the top half of the vertical cross section orside view of both the cavity and core plate that were clampedtogether during injection. Fig. 5 shows the model of thermalanalysis analyzed with irregular meshing.Modelingforthemodelalsoinvolvesassigningpropertiesandprocessorcycletimetothemodel.Thisallowedthefiniteelement solver to analyze the mould modeled and plot timeresponse graphs to show temperature variation over a certainduration and at different regions.For the product analysis, a two dimensional tensile stressanalysis was carried using LUSAS Analyst, Version 13.5.Basically the product was loaded in tension on one end whilethe other end is clamped. Load increments were applied untilthe model reaches plasticity. Fig. 6 shows loaded model ofthe analysis.3.3. Result and discussion for mould and productanalysisFor mould analysis, the thermal distribution at differenttime intervals was observed. Fig. 7 shows the 2D analysisTable 2Material properties for mould and productCarbon Steel (AISI 1050), mouldABS Polymer, productDensity, 7860kg/m3Density, 1050kg/m3Youngs modulus, E208GPaYoungs modulus, E2.519GPaPoissons ratio, 0.297Poissons ratio, 0.4Yield strength, SY365.4MPaYield strength, SY65MPaTensile strength, SUTS636MPaThermal expansion, 65106K1Thermal expansion, 11.65106K1Conductivity, k0.135W/(mK)Conductivity, k49.4W/(mK)Specific heat, c1250J/(kgK)Specific heat, c477J/(kgK)S.H. Tang et al. / Journal of Materials Processing Technology 171 (2006) 259267263Fig. 6. Loaded model for analysis of product.contour plots of thermal or heat distribution at different timeintervals in one complete cycle of plastic injection molding.For the 2D analysis of the mould, time response graphsare plotted to analyze the effect of thermal residual stress onthe products. Fig. 8 shows nodes selected for plotting timeresponse graphs.Figs. 917 show temperature distribution curves for dif-ferent nodes as indicated in Fig. 8.From the temperature distribution graphs plotted inFigs. 917, it is clear that every node selected for the graphplotted experiencing increased in temperature, i.e. from theambient temperature to a certain temperature higher thanthe ambient temperature and then remained constant at thistemperatureforacertainperiodoftime.Thisincreaseintem-perature was caused by the injection of molten plastic intothe cavity of the product.After a certain period of time, the temperature is thenfurther increased to achieve the highest temperature andremained constant at that temperature. Increase in temper-ature was due to packing stages that involved high pressure,Fig. 7. Contour plots of heat distribution at different time intervals.264S.H. Tang et al. / Journal of Materials Processing Technology 171 (2006) 259267Fig. 8. Selected nodals near product region for time response graph plots.Fig. 9. Temperature distribution graph for Node 284.Fig. 10. Temperature distribution graph for Node 213.Fig. 11. Temperature distribution graph for Node 302.Fig. 12. Temperature distribution graph for Node 290.which caused the temperature to increase. This temperatureremains constant until the cooling stage starts, which causesreduction in mould temperature to a lower value and remainsat this value. The graphs plotted were not smooth due to theabsence of function of inputting filling rate of the moltenplastic as well as the cooling rate of the coolant. The graphsplotted only show maximum value of temperature that canbe achieved in the cycle.The most critical stage in the thermal residual stress anal-ysis is during the cooling stage. This is because the coolingFig. 13. Temperature distribution graph for Node 278.S.H. Tang et al. / Journal of Materials Processing Technology 171 (2006) 259267265Fig. 14. Temperature distribution graph for Node 1838.Fig. 15. Temperature distribution graph for Node 1904.stage causes the material to cool from above to below theglasstransitiontemperature.Thematerialexperiencesdiffer-ential shrinkage that causes thermal stress that might resultin warpage.From the temperature after the cooling stage as shown inFigs. 917, it is clear that the area (node) located near thecooling channel experienced more cooling effect due to fur-Fig. 16. Temperature distribution graph for Node 1853.Fig. 17. Temperature distribution graph for Node 1866.ther decreasing in temperature and the region away from thecooling channel experienced less cooling effect. More cool-ing effect with quite fast cooling rate means more shrinkageisoccurringattheregion.However,thefarthestregion,Node284experiencemorecoolingalthoughfarawayfromcoolingchannel due to heat loss to environment.Asaresult,thecoolingchannellocatedatthecenteroftheproduct cavity caused the temperature difference around themiddle of the part higher than other locations. Compressivestress was developed at the middle area of the part due tomoreshrinkageandcausedwarpageduetounevenshrinkagethat happened. However, the temperature differences aftercooling for different nodes are small and the warpage effectisnotverysignificant.Itisimportantforadesignertodesignamouldthathaslessthermalresidualstresseffectwithefficientcooling system.Fortheproductanalysis,fromthestepsbeingcarriedouttoanalyze the plastic injection product, the stress distributionon product at different load factor is observed in the twodimensional analysis. Figs. 1821 show the contour plots ofequivalent stress at different load increments.A critical point, Node 127, where the product experiencesmaximum tensile stress was selected for analysis. The stressversus strain curve and the load case versus stress curves atthis point were plotted in Figs. 22 and 23.Fromtheloadcaseversusstresscurvesatthispointplottedin Fig. 23,
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