后蓋塑料成型工藝與模具設計【一模一腔】

后蓋塑料成型工藝與模具設計【一模一腔】,一模一腔,后蓋塑料成型工藝與模具設計【一模一腔】,塑料,成型,工藝,模具設計 設計中期檢查表學生姓名學 號指導教師 選題情況課題名稱后蓋塑料成型工藝與模具設計難易程度偏難適中偏易工作量較大合理較小符合規(guī)范化的要求任務書有無開題報告有無外文翻譯質量優(yōu)良中差學習態(tài)度、出勤情況好一般差工作進度快按計劃進行慢中期工作匯報及解答問題情況優(yōu)良中差中期成績評定：所在專業(yè)意見： 負責人： 年 月 日 機 械 加 工 工 藝 過 程 卡 模具號零件號零 件 名 稱00-04型芯固定板XYZ-003牌 號硬 度T10A50-55HRC工序號工 序 名 稱設 備夾 具刀 具量 具工 時名 稱型 號名 稱規(guī) 格名 稱規(guī) 格名 稱規(guī) 格01下料02鍛造達尺寸260mm210 mm50mm蒸汽錘直尺03粗銑六面達尺寸252mm202mm42mm銑床虎鉗30面銑刀 10銑刀游標卡尺04磨上下表面及一直角面平面磨床磁力夾具、精密平口鉗砂輪游標卡尺，刀口尺05鉗工劃線去毛刺做螺紋孔立式鉆床虎鉗鉆頭、鉸刀、絲錐高度尺、游標卡尺06熱處理（淬火、回火）保證硬度50-55HRC熱處理爐硬度儀，游標卡尺07磨削上下面及一直角面平面磨床磁力夾具、精密平口鉗砂輪游標卡尺，刀口尺08線切割各個型孔留余量0.02mm線切割慢走絲機床復式支撐0.2mm黃銅絲千分表，游標卡尺09鉗工研磨各型孔達尺寸要求游標卡尺10檢驗游標卡尺 編制 校對 審核 批準 設計說明書畢業(yè)設計題目：后蓋塑料成型工藝與模具設計系 部 專 業(yè) 班 級 學生姓名 學 號 指導教師 2014年 4 月25 日設計評語學生姓名： 班級: 學號：題 目： 后蓋塑料成型工藝與模具設計 綜合成績： 指導者評語： 指導者(簽字)： 年 月 日畢業(yè)設計（論文）評語評閱者評語： 評閱者(簽字)： 年 月 日答辯委員會（小組）評語： 答辯委員會（小組）負責人(簽字)： 年 月 日后蓋塑料成型工藝與模具設計摘要：該設計較系統(tǒng)的介紹了簡單注塑模具的設計過程。同時對塑件的成形工藝及模具成型結構對塑件質量的影響進行了分析。在設計過程中，首先對塑件進行工藝分析，了解塑件的材料、形狀、尺寸及精度要求，參考工藝的可行性，選擇滿足要求的工藝方案。然后我按照設計要求對組成注塑模具的成型零部件、澆注系統(tǒng)、導向機構、脫模結構、側向分型與抽芯機構、加熱與冷卻系統(tǒng)、排氣系統(tǒng)和其它零部件進行設計。在模具設計過程中較多的考慮了模具結構的調整性、易更換性及模具成本。從控制制件尺寸精度出發(fā)，對計算機按鍵注塑模的各主要尺寸進行了理論計算，以確定各工作零件的尺寸。模具零件設計完畢后，對重要的工作結構和零件進行了校核。校核結束后對模具安裝并調試。從模具設計到零部件的加工工藝以及裝配工藝等進行詳細的闡述，并應用CAD進行各零件的設計。關鍵詞：工藝分析；塑件成型；澆注系統(tǒng)；模具結構；校核 Back cover plastic forming technology and die designAbstract ：The molding process of plastic parts, the effect analysis to plastic parts quality caused by molding structure, as well as the casting system design, partial and general design of mold moulding introduced respectively. The critical points of mold for plastic design are introduced, and the adjustable character of molding structure、exchange character as well as the molding costs are all considered farther. Starting from controlling dimensional accuracy, the theoretical calculation to the main dimensions of injection molding are carried out so as to determine the size of different parts, the molding design and the process of parts as well as assembling process and etc of injection molding are stated in details.Key words: process analysis; plastic parts moulding; casting system; molding structure. 機 械 加 工 工 藝 過 程 卡 模具號零件號零 件 名 稱00-05滑塊XYZ-004牌 號硬 度T10A50-55HRC工序號工 序 名 稱設 備夾 具刀 具量 具工 時名 稱型 號名 稱規(guī) 格名 稱規(guī) 格名 稱規(guī) 格01下料02鍛造達尺寸136 mm99mm20mm蒸汽錘直尺03粗銑六面達尺寸132mm95mm17.5mm銑床虎鉗30面銑刀, 10銑刀游標卡尺04磨上下表面及一直角面平面磨床磁力夾具、精密平口鉗砂輪游標卡尺，刀口尺05鉗工劃線去毛刺做螺紋孔立式鉆床虎鉗鉆頭、鉸刀、絲錐高度尺、游標卡尺06熱處理（淬火、回火）保證硬度50-55HRC熱處理爐硬度儀，游標卡尺07磨削上下面及一直角面平面磨床磁力夾具、精密平口鉗砂輪游標卡尺，刀口尺08線切割各個型孔留余量0.02mm線切割慢走絲機床復式支撐0.2mm黃銅絲千分表，游標卡尺09鉗工研磨各型孔達尺寸要求游標卡尺10檢驗游標卡尺 編制 校對 審核 批準 目錄1緒 論21.1國內外模具的現(xiàn)狀和發(fā)展趨勢21.1.1國內模具的現(xiàn)狀2 1.1.2國外模具的發(fā)展趨勢41.2 塑料注射模具設計與制造方面41.2 塑料注射模具設計的設計思路42后蓋注射成型模具設計72.1 塑件成型工藝性分析72.1.1 塑件的分析72.1.2、POM的性能分析82.1.3塑件的生產批量分析82.1.4注射工藝參數(shù)82.2擬定模具的結構形式92.2.1 分型面的確定92.2.2 型腔數(shù)量及排列方式的確定92.3 注射機型號的確定92.3.1 注射量的計算92.3.2 澆注系統(tǒng)凝料體積的初步計算92.3.3 選擇注射機102.3.4 注射機相關參數(shù)的校核102.4 澆注系統(tǒng)的設計112.4.1主流道的設計112.4.2 冷料穴的設計142.5 成型零件的結構設計及計算142.5.1 成型零件的結構設計142.5.2 成型零件鋼材的選用152.5.3 成型零件工作尺寸的計算15 2.6 模架的確定172.6.1 模板尺寸的確定17 2.6.2 架各尺寸的校核182.6.3 排氣槽的設計182.7 脫模推出機構的設計182.7.1 脫模方式的確定182.7.2 脫模力的計算192.8 側抽的設計192.8.1側抽方式的選擇192.8.2 相關計算192.8.3 斜導柱設計202.9 冷卻系統(tǒng)的設計212.9.1 冷卻介質212.9.2 冷卻系統(tǒng)的簡單計算213總結23致 謝24參考文獻25 1緒 論1.1國內外模具的現(xiàn)狀和發(fā)展趨勢1.1.1國內模具的現(xiàn)狀近年來隨著我國模具工業(yè)的迅猛發(fā)展，模具零件的標準化、專業(yè)化和商品化工作，已具有較高的水平，取得了長足的進步。自1983年全國模具標準化技術委員會成立以來，組織專家對模具標準進行制定、修訂和審查，共發(fā)布了90多項標準，其中沖模標準22項、塑料模標準20余項。這些標準的發(fā)布、實施，推動了模具行業(yè)的技術進步和發(fā)展，產生了很大的社會效益和經濟效益。模標準件的研究、開發(fā)和生產正在全面深入展開，無論是產品類型、品種、規(guī)格，還是產品的技術性能和質量水平都有明顯的提高。目前我國模具的標準化程度和應用水平還比較低，樂觀地估計不足30%，與國外工業(yè)發(fā)達國家(70-80%)相比，尚有較大的差距?，F(xiàn)在生產銷售廠家雖然逐年增加，但大多數(shù)是規(guī)模小、設備陳舊、工藝落后、成本高、效益低。只有普通中小型標準沖模模架和塑料模模架、導柱、導套、推桿、模具彈簧、氣動元件等產品，商品化程度較高，可基本滿足國內市場的需求，并有部分出口。而那些技術含量高、結構先進、性能優(yōu)異、質量上乘、更換便捷的具有個性化的產品，如球鎖式快換凸模及固定板、固體潤滑導板和導套、斜楔機構及其零部件，高檔塑料模具標準件和氮氣主彈簧等在國內的生產廠家甚少，且由于資金缺乏，技改項目難以實施，生產效率低，交貨周期長，供需矛盾日益突出。因此，每年尚需從國外進口相當數(shù)量的模具標準件，其費用約占年模具進口額的3-8%。國產模具標準件在技術標準、科技開發(fā)、產品質量等方面，還存在不少問題。諸如，產品標準混亂，功能元件少且技術含量低，適用性差;技改力度小、設備陳舊、工藝落后、專業(yè)化水平低、產品質量不穩(wěn)定;專業(yè)人才缺乏，管理跟不上、生產效率低、交貨周期長;生產銷售網(wǎng)點分布不均，經營品種規(guī)格少，供應不足;某些單位為了爭奪市場，不講質量，以次充好，偽劣商品充斥市場。還有不計成本、盲目降價、擾亂市場的現(xiàn)象，是需要認真研究，丞待解決的?？傮w來分析，中國模具標準件行業(yè)發(fā)展前景非常樂觀，標準件行業(yè)成為如今陽光產業(yè)，正一步步快速發(fā)展。趨勢:第一：隨著車輛等發(fā)展，壓鑄模各方面隨之提高，并且要求也就高了很多。第二：模具技術含量不斷提高第三：模具的精度越來越高。第四：模具的趨大型化。第五：模具標準件的應用將日漸廣泛。 第六：多功能復合模具進一步發(fā)展。1.1.2國外模具的發(fā)展趨勢國外，特別是歐美和日韓等發(fā)達地區(qū)的模具工業(yè)起步較早，擁有比較先進的生產管理技術及經驗，值得我們國內模具行業(yè)學習和借鑒，在歐美，許多模具企業(yè)將高技術應用于模具設計和制造，主要體現(xiàn)在；(1) CAD/CAE/CAM/ERP的廣泛應用，發(fā)揮了信息技術帶動和提升模具工業(yè)的優(yōu)越性（2）高速切削五軸高速加工技術基本普及，大大縮減制模周期，提高企業(yè)的市場競爭力（3）快速成型技術和快速制模技術得到普及應用（4）從事模具行業(yè)的人員精簡，一專多能，一人多職，精益生產（5）模具產品專業(yè)化，市場定位準確（6）采用先進的管理信息系統(tǒng)，實現(xiàn)集成管理（7）工藝管理先進，標準化程度高 據(jù)調查研究，日本模具加工的未來發(fā)展方向主要表現(xiàn)為無人手修模，無放電加工，加工時間短，五軸加工等方面。1.2 塑料注射模具設計與制造方面1.2 塑料注射模具設計的設計思路（1）收集、分析、消化原始資料 收集整理有關制件設計、成型工藝、成型設備、機械加工及特殊加工數(shù)據(jù)，以備設計模具時使用。消化塑料制件圖，了解制件的用途，分析塑料制件的工藝性，尺寸精度等技術要求。例如塑料制件在外表形狀、顏色透明度、使用性能方面的要求是什么，塑件的幾何結構、斜度、嵌件等情況是否合理，熔接痕、縮孔等成型缺陷的允許程度，有無涂裝、電鍍、膠接、鉆孔等后加工。選擇塑料制件尺寸精度最高的尺寸進行分析，看看估計成型公差是否低于塑料制件的公差，能否成型出合乎要求的塑料制件來。此外，還要了解塑料的塑化及成型工藝參數(shù)。（2）消化工藝數(shù)據(jù)，分析工藝任務書所提出的成型方法、設備型號、材料規(guī)格、模具結構類型等要求是否恰當，能否落實。成型材料應當滿足塑料制件的強度要求，具有好的流動性、均勻性和各向同性、熱穩(wěn)定性。根據(jù)塑料制件的用途，成型材料應滿足染色、鍍金屬的條件、裝飾性能、必要的彈性和塑性、透明性或者相反的反射性能、膠接性或者焊接性等要求。確定成型方法采用直壓法、鑄壓法還是注射法。（3）選擇成型設備根據(jù)成型設備的種類來進行模具，因此必須熟知各種成型設備的性能、規(guī)格、特點。例如對于注射機來說，在規(guī)格方面應當了解以下內容：注射容量、鎖模壓力、注射壓力、模具安裝尺寸、頂出裝置及尺寸、噴嘴孔直徑及噴嘴球面半徑、澆口套定位圈尺寸、模具最大厚度和最小厚度、模板行程等，具體見相關參數(shù)。要初步估計模具外形尺寸，判斷模具能否在所選的注射機上安裝和使用。具體結構方案（4）確定模具類型 如壓制模（敞開式、半閉合式、閉合式）、鑄壓模、注射模等。選擇理想的模具結構在于確定必需的成型設備，理想的型腔數(shù)，在絕對可靠的條件下能使模具本身的工作滿足該塑料制件的工藝技術和生產經濟的要求。對塑料制件的工藝技術要求是要保證塑料制件的幾何形狀，表面光潔度和尺寸精度。生產經濟要求是要使塑料制件的成本低，生產效率高，模具能連續(xù)地工作，使用壽命長，節(jié)省勞動力影響模具結構及模具個別系統(tǒng)的因素很多，很復雜：型腔布置。根據(jù)塑件的幾何結構特點、尺寸精度要求、批量大小、模具制造難易、模具成本等確定型腔數(shù)量及其排列方式。對于注射模來說，塑料制件精度為3級和3a級，重量為5克，采用硬化澆注系統(tǒng)，型腔數(shù)取4-6個；塑料制件為一般精度（4-5級），成型材料為局部結晶材料，型腔數(shù)可取16-20個；塑料制件重量為12-16克，型腔數(shù)取8-12個；而重量為50-100克的塑料制件，型腔數(shù)取4-8個。對于無定型的塑料制件建議型腔數(shù)為24-48個，16-32個和6-10個。當再繼續(xù)增加塑料制件重量時，就很少采用多腔模具。7-9級精度的塑料制件，最多型腔數(shù)較之指出的4-5級精度的塑料增多至50%。（5）確定分型面。分型面的位置要有利于模具加工，排氣、脫模及成型操作，塑料制件的表面質量等。確定澆注系統(tǒng)（主澆道、分澆道及澆口的形狀、位置、大?。┖团艢庀到y(tǒng)（排氣的方法、排氣槽位置、大?。?。選擇頂出方式（頂桿、頂管、推板、組合式頂出），決定側凹處理方法、抽芯方式。決定冷卻、加熱方式及加熱冷卻溝槽的形狀、位置、加熱組件的安裝部位。根據(jù)模具材料、強度計算或者經驗數(shù)據(jù)，確定模具零件厚度及外形尺寸，外形結構及所有連接、定位、導向件位置。確定主要成型零件，結構件的結構形式?？紤]模具各部分的強度，計算成型零件工作尺寸。在設計的過程中，將有一定的困難，但有指導老師的悉心指導和自己的努力，相信會完滿的完成畢業(yè)設計任務。由于學生水平有限，而且缺乏經驗，設計中難免有不妥之處，肯請各位老師指正。7 2后蓋注射成型模具設計2.1、塑件成型工藝性分析2.1.1、塑件的分析 （1）該產品是后蓋，此產品的形狀較規(guī)則，精度要求不高，它們的尺寸是相配合的，所以只須設計一套注塑模具。該產品大批量生產，故設計時要有較高的效率，澆注系統(tǒng)能夠自動脫模。塑件的尺寸雖然不算太大，但由于內部的結構復雜，故采用一模一腔，澆口采用主澆口。（2）、精度等級：查表4-21統(tǒng)一按MT7。 圖1 制件圖5 2.1.2、POM的性能分析聚甲醛POM為熱塑性結晶聚合物，被譽為“超鋼”或“賽鋼”。均聚甲醛的熔融溫度為180左右。POM堅韌有彈性，在低溫下仍有很好的抗蠕變性，幾何穩(wěn)定性和抗沖擊性。POM可分為：均聚物和共聚物。均聚物材料具有很好的延展強度，抗疲勞強度，但不易于加工。共聚物材料有很好的熱穩(wěn)定性，化學穩(wěn)定性并且易于加工，吸水性小。POM的高結晶程度導致它有相當高的收縮率，可高達到2%3.5%，對于各種不同的增強型材料有不同的收縮率。POM聚甲醛的性能：表面光滑，有光澤，表面硬度大，吸水率低，剛性好，韌性好，彎曲強度，耐疲勞性強度高，良好的滑動性，耐磨性非常優(yōu)異，電性能優(yōu)良，尺寸穩(wěn)定性好，產品的尺寸精度高，可在-40到100C溫度范圍內長期使用，良好的耐油，耐過氧化物性能。不耐酸，不耐強堿和不耐月光紫外線的輻射。POM塑料比重： 1.41-1.43克/立方厘米 成型收縮率：0.8-3.0% 2.1.3塑件的生產批量分析塑件的生產類型對注射模具結構、注射模具材料使用均有重要的影響。在中批量生產中，由于注射模具壽命問題比較突出，所以可以考慮使用自動化程度較高、結構復雜、精度壽命高的模具；如果是小批量生產，則應盡量采用結構簡單、制造容易的注射模具，以降低注射模具的成本。因為該塑件的產量大批量生產。因此，在模具設計中要提高塑件的生產率，傾向于采用多型腔、高壽命、自動化脫模模具，以便降低生產成本。2.1.4注射工藝參數(shù)、注射機：查表選螺桿式，螺桿轉數(shù)為45r/min，高螺桿轉速是允許的，只要滿足冷卻時間結束前完成塑化過程就可以。、料筒溫度（）170 、查表3-44模具溫度（）：6080、查表3-11注射壓力（MPa）：70120，注射時間為：15s保壓壓力（MPa）5060，保壓時間2050s.93 、注射時間：1.6s 冷卻時間：12.5s 輔助時間：8s2.2擬定模具的結構形式2.2.1 分型面的確定分型面，及模具閉合式動定模相配合的接觸平面。通過對塑件的分析，知道后蓋的成型要用到側抽的結構，所以分型面定在側抽的分割線上，另外由于是局部運用側抽結構，所以分型面還有側抽模的上下面。2.2.2 型腔數(shù)量及排列方式的確定為了制模具與注塑機的生產能力相匹配，同時考慮到生產效率，并保證塑件精度，模具設計時應確定型腔數(shù)目。型腔數(shù)目的確定一般可以根據(jù)經濟性、注射機的額定鎖模力、注射機的最大注射量、制品的精度等。該塑件精度要求不高，生產批量較大，且運用到哈夫模結構，從模具尺寸及塑融填充考慮，初定一模一腔，主澆口，模具結構一般，容易保證塑件質量。2.3 注射機型號的確定2.3.1 注射量的計算 通過UG三維建模設計分析得 塑件體積： V塑=69.9871cm3塑件質量：m塑 =69.98710.91g=63.688g2.3.2 澆注系統(tǒng)凝料體積的初步計算澆注系統(tǒng)的凝料在設計之前是不能確定準確的數(shù)值的，但可以根據(jù)經驗按照塑料體積的0.21倍來估算。由于本設計采用一模兩腔，側澆口，塑件體積較小，澆注系統(tǒng)的凝料按塑件體積的1倍來計算，故一次注入模具型腔塑料熔體的總體積（即澆注系統(tǒng)凝料和2個塑件體積之和）為：V總=2.5V塑）=69.98712.5cm3=174.968 cm 37 2.3.3 選擇注射機根據(jù)第二步計算得出一次注入模具型腔的塑料總體積V總=174.968 cm 3V總/0.8=174.968/0.8cm3=218.710cm3根據(jù)以上的計算，初步選定公稱注射量為250cm3的注射機，注射型號為XS-ZY-250式注射機。其主要參數(shù)見表（2）理論注射容量/cm3250移模行程/mm500螺桿直徑/mm50最大模具厚度/mm350注射壓力/MPa147最小模具厚度/mm200鎖模力/KN1800開模行程1802.3.4 注射機相關參數(shù)的校核、注射壓力校核查表3-12可知，POM所需注射壓力為80130MPa。這里取Po=100MPa，該注射機的公稱注射壓力P公=147MPa。注射壓力安全系數(shù)k1=1.251.4,這里取k1=1.3，則：k = 1.3 100=130 MPa147 MPa所以注射機壓力合格。、鎖模力的校核a、塑件在分型面上的投影面積A塑，則A塑=100*80=8000.000 mmb、澆注系統(tǒng)在分型面上的投影面積 A澆，即流道凝料（它包括澆口）在分型面上的投影面積和A澆數(shù)值可以按照多腔模的統(tǒng)計分析來確定。初步估算A澆=0.5A塑。c、塑件和澆注系統(tǒng)在分型面上的總投影面積A總，則A總= A塑+A澆=3A塑=24000 mm=24cmd、模具型腔內的脹型力F脹，則F脹=A總P模=2445=945KN式中P模是模具型腔內塑料熔體平均壓力值（MPa），一般為注射壓力的0.30.65倍。查表3-11得POM塑料模具型腔內的壓力P模為90MPa。由上表2知該注射機的公稱鎖模力F鎖=1800KN，鎖模力安全系數(shù)為k2=1.11.2，這里取k2=1.2，則k2F脹=1.2F脹=1.2945=1134F鎖所以，注射機鎖模力合格。2.4 澆注系統(tǒng)的設計2.4.1主流道的設計主流道的設計 澆口又稱進料口或內流道，它是分流道與塑件之間的狹窄部分，也是澆注系統(tǒng)中最短小的部分。它能使分流道輸送來的熔融塑料的流速產生加速度，形成理想的流態(tài)，順序、迅速地充滿型腔，同時還起著封閉型腔防止熔料倒流的作用，并在成型后便于使?jié)部谂c塑件分離。澆口是指連接分流道和型腔的進料通道，它是澆注系統(tǒng)中截面尺寸最小且長度最短的部分。澆口的作用表現(xiàn)為：塑料熔體通過澆口時剪切速率增高，粘度降低，有利于充型；同時熔體的內摩擦加劇，使料流的溫度升高、粘度降低，從而提高了塑料的流動性，有利于充型；另外在注射過程中，塑料充型后在澆口處及時凝固，防止熔體的倒流；成型后也便于塑件與整個澆注系統(tǒng)的分離。澆口的尺寸過小會使壓力損失增大，冷凝加快，補縮困難；澆口的尺寸過大，澆口周圍產生過剩的殘余應力，導致產品變形或破裂，且澆口的去除困難等。澆口的形狀、尺寸和進料位置對塑件的質量影響很大。澆口的設計與塑料的品種、塑件形狀、塑件壁厚、模具結構及注射成型工藝參數(shù)等有關。對澆口總的設計要求是：要使塑料熔體以較快的速度進入并充滿型腔，同時在型腔充滿后適時冷卻封閉。一般要求澆口截面小、長度短。實際使用時，澆口的尺寸常常需要通過試模，按成型情況酌情修正。澆口位置選擇的正確與否，對塑件質量影響很大，選擇不當時會使塑件產生變形、熔接痕、凹陷、裂紋等缺陷。一般來說，澆口位置選擇要遵循以下原則：澆口位置的設置應使塑料熔體填充型腔的流程最短、料流變向最少。校核流動比。若流動比小于允許值，則塑件大致上能夠成型；若流動比超過允許值，會出現(xiàn)充型不足，這時應調整澆口位置或增加澆口數(shù)量，增大流道直徑或厚度。澆口位置的設計應有利于排氣和補縮。 澆口位置的設置應減少或避免產生熔接痕、提高熔接痕的強度。 澆口位置的選擇要避免塑件變形。 澆口位置的設置應避免引起熔體破裂。 澆口位置的設置應防止型芯變形。 澆口位置的設置應考慮塑件的外觀。 澆口與塑件連接處應做成R0.5的圓角或0.545的倒角，并防止在分離澆注系統(tǒng)時把塑件剪裂。澆口與分流道的連接處一般做成3045的斜角，并以R1R2的圓角與分流道底面相交，以便熔體流動并減小壓力損失。側澆口適用于各種形狀及一模多腔的塑件，它是最常用的一種形式。其優(yōu)點是：去澆口方便，殘留痕跡??；熔體流速高；翹曲變形比直接澆口?。灰顺尚捅”?、復雜形狀塑件。缺點是：注射壓力損失大；保壓補縮作用比直接澆口小；對殼形塑件排氣不方便，易產生熔接痕。、主流道長度：小型模具L主應盡量小于60mm，本次設計中初取50mm。、主流道小端直徑：d=注射機噴嘴尺寸+(0.51)mm=(4+1)mm=5mm 、主流道大端直徑：d=d+2L主tan=6mm、主流道出口端應有圓角，圓角半徑R取2mm。、主流道表壁的粗糙度取1m. 圖2澆口簡圖主流道澆口套的形式 主流道小端入口處與注射機噴嘴反復接觸，易磨損。對材料的要求較嚴格，為了防止?jié)部谔妆粩D出，用螺釘固定。同時也便于選用優(yōu)質鋼材進行單獨加工和熱處理。設計常采用碳素工具鋼（T8A或T10A），熱處理淬火表面硬度為5055HRC，如圖2所示。 圖3澆口套2.4.2 冷料穴的設計本設計采用Z型拉料桿將凝料拉出Z型拉料桿頂部距分流道底面h1取6mm；Z型拉料桿中間拐角處距分流道底面12mm；其余按標準取。2.5 成型零件的結構設計及計算2.5.1 成型零件的結構設計凹模的結構設計 凹模是成型制品的外表面的成型零件。凹模的基本結構有整體式，組合式和整體嵌入式等?；顒尤π螤詈唵危圆捎谜w式凹模，如零件圖所示。凸模是成型零件內表面的成型零件，通?？梢苑譃檎w式和組合式兩種類型，通過對塑件的結構分析可知，該塑件有一個型芯，型芯反嵌入模板背面，節(jié)約優(yōu)質鋼材，同時嵌入式結構有足夠強度與剛度，使用可靠且置換方便?；瑝K的結構設計滑塊是由一塊可移動的滑板組成來成型制件外輪廓。哈夫塊由壓塊的導滑槽導向，斜導柱推動，彈簧銷定位。2.5.2 成型零件鋼材的選用根據(jù)對成型零件的綜合分析，該塑件的成型零件要有足夠的剛度、強度、耐磨度及良好的抗疲勞性能，同時考慮它的機械加工性能和拋光性能。又因為該塑件為大批量生產，所以構成型腔的嵌入式凹模鋼材選用T10A。對于成型零件型芯來說，由于脫模時與塑件的磨損嚴重，因此鋼材選用高合金工具鋼Cr12MoV。對于哈夫塊由于要不斷摩擦，受壓，故選用45鋼調質處理。2.5.3 成型零件工作尺寸的計算 采用模具專業(yè)畢業(yè)手冊表13-1中的平均尺寸法計算成型零件尺寸，塑件尺寸公差按照塑件零件圖中給定的公差計算。（1）、凹模尺寸的計算H=(H+HS-1/2-z /2) +z0 =99.75 +0.67 H=100 =2.10H=(H+HS-1/2-z /2) +z0=19.8 +0.90 H=20 =0.88(2)滑塊尺寸計算Dm1= （1+Scp）Ls- +z0 由于塑件尺寸精度為MT7，查手冊可得=2.10 Dm1= （1+Scp）Ls- +z0= （1+0.8）100-2.10 +0.560=99.225 +0.560Dm1=100Dm2= （1+Scp）Ls- +z0 =（1+0.8）80-2.10 +0.560=89.065 +0.560Dm2=80 =2.10Lm2= （1+Scp）Ls+ +z0 =（1+0.8）5+0.48 +0.160=5.4+0.160Lm2=5 H1=(H+HS-1/2-z /2) +z0 = 9.832+ HI=10 =0.58 H2=(H+HS-1/2-z /2) +z0 =1.629 + H2=2 =0.58(3)型芯高度尺寸Hm1=h+hs+1/2+z /2 0-z =25.95 0-1.00 hm1=25.5=0.90 hm2=h+hs+1/2+z /2 0-z =5.44 0-0.12 hm2=5.3 =0.68 Hm3=h+hs+1/2+z/2 0-z =10.57 0-0.16 Hm3= 10.5 =0.68(4)型芯外形尺寸 dm1=d+ds+=8.4990-0.145 dm=23.5 =0.88dm2=d+ds+=8.59 0-0.20 dm2=16.4 =0.24dm3=d+ds+=5.41 0-0.18 dm3=20 =0.44式中塑件的平均收縮率，查表得POM的收縮率為0.8%.Ls為塑件公稱尺寸，mm為塑件公差值，mm z 為制造公差，mm2.6、模架的確定2.6.1 模板尺寸的確定 （1）、A板尺寸。A板是定模板，考慮到定模板的強度，以及為下面壓板的安裝讓位，還要考慮到定模型腔下部哈夫塊的強度，厚度。A板取50mm厚（2）、壓板厚度，壓板的厚度由滑塊的厚度決定，等于16.5mm（3）、B板尺寸。B板式型芯固定板，同時也成型制件外輪廓，由質件決定，分析制件得B板厚度為40mm 。（4）、支撐板的厚度支撐板，1取20mm支撐板2取30mmC取50綜上所述模架的外形尺寸：寬高長=200mm240mm250mm，如圖6 所示。 圖32.6.2 架各尺寸的校核根據(jù)所選注射機來校核模具設計的尺寸。模具平面尺寸，模具平面尺寸250mm200mm250mm235mm校核合格。2.6.3 排氣槽的設計該塑件由于中間由斜導柱模具成型，內部由反嵌型芯成型，且流程較長，所以無形中有很多排氣通道。故須再專門設計排氣槽。2.7 脫模推出機構的設計2.7.1 脫模方式的確定分析本塑件，開模后由于塑件對型芯的包緊力使得塑件留在動模，可采用推桿推出。為不影響塑件尺寸和使用，一般使推桿與塑件接觸部位凹進塑件0.1mm左右。2.7.2 脫模力的計算型芯脫模力F，參考塑料注射模結構與設計 式9-1得F=AP/(cos-sin)所以（1）、推出面積A=4913mm A1=(55+55+53) 3=195 mmA2=126.8=3074.68 mmA3=(164-1) 1.814.5=2897.1 mm（2） 推出力 F=AP/(cos-sin)=9624.8N（3） 推出應力=1.2F/A=1.29624.8/230.79= 50.21Mpa69Mpa（抗壓強度）合格 A4=3.53.56=230.79 mmA-塑件包裹型芯的面積，mmP-塑件對型芯單位面積上的包緊力；模內冷卻的塑件，p取2.4107Mpa -塑件對鋼的摩擦系數(shù)，為0.1-0.3取0.1-脫模斜度2.8 側抽的設計2.8.1側抽方式的選擇后蓋采用側抽成型，由斜導柱推動，結構簡單、安全、可靠。 2.8.2 相關計算（1）、抽芯距的計算 S抽=sc+3=15 sc=12（2）、抽芯力的計算 抽芯力的計算跟脫模力的計算方法一樣。型芯脫模力F1，參考塑料注射模結構與設計 式9-1得F=AP(cos-sin)所以F1=AP(cos-sin)= 4452.8310-6107 /（0.1cos1-sin1)=2895.66N A=A1+A2+A3+A4+A5+A6+A7=4452.83 mmA1=31 2=194.68A2=(15-14)4=1356.48A3=23 5=361.1A4=A2=1356.48A5=31 5=486.7A6=40 2.5=314A7=35 3.5=384.65A-塑件包裹型芯的面積，mmP-塑件對型芯單位面積上的包緊力；模內冷卻的塑件，p取0.8107Mpa -1.2107Mpa-塑件對鋼的摩擦系數(shù)，為0.1-0.3-脫模斜度2.8.3 斜導柱設計（1）、參考文獻附錄F，選取斜導柱為12mm 由于抽拔方向與開模方向垂直，斜導柱所需有效長度45mm，總長計算得98mm。（2）、斜導柱彎曲力計算抽拔方向與開模方向垂直，斜導柱彎曲力N=F/cos(1-2ftan-f)=2895/cos20(1-20.5tan20-0.5)=1253 N1500N 校核合格（3）、哈夫塊、壓塊、楔緊塊及定位裝置的設計. 哈夫塊由壓塊導向運動，楔緊塊壓緊。見裝配圖。2.9 冷卻系統(tǒng)的設計冷卻系統(tǒng)的計算很麻煩，在此只進行簡單的計算。設計時忽略模具因空氣對流、輻射以及注射機接觸所散發(fā)的熱量，按單位時間內塑料熔體凝料時所放出的熱量應等于冷卻水所帶走的熱量。2.9.1 冷卻介質POM材料的成型溫度及模具溫度分別為300和60 80。出選模具溫度為60，用常溫水對模具進行冷卻。2.9.2 冷卻系統(tǒng)的簡單計算（1）、單位時間內注入模具中的塑料熔體的總質量W、塑料制品的體積V=V+V=21.500cm、塑料制品的質量m=V=21.5001.41g=19.483g、塑件壁厚平均為5，可以查表4-341得t冷=12.5s。取注射時間t注=2s，脫模時間t脫=8s，則注射周期：t=t注+t冷+t脫=（2+12.5+8）s=22.5s。由此得每小時注射次數(shù)：N=（3600/22.5）次=160次、單位時間內注入模具中的塑料熔體的總質量：W=Nm=16010kg/h=3.177kg/h（2）、確定單位質量的塑件在凝固時所放出的熱量Qs 查表4-351直接可知POM的單位熱流量Qs的值為590kj/kg。（3）、計算冷卻水的體積流量qv設冷卻水道入水口的水溫為2=22，出水口的水溫為1=25，取水的密度=1000kg/m3,水的比熱容c=4.187kj/kg。則根據(jù)公式可得：Qv=wQs/60c(Q1-Q2)=3.177590/(6010004.1873)=0.00018m/min(4)、確定冷卻水路的直徑d當=0.00018mmin時，查參考文獻1 表4-30可知，為了使冷卻水處于湍流狀態(tài)，取模具冷卻水孔直徑d=8mm。（5）、冷卻水在管內的流速V=4qv/(60d)=40.00018/(603.148)=0.6m/s（6）、求冷卻管壁與水交界面的膜傳熱系數(shù)h平均水溫t=23.5查參考文獻1 表4-31可知f=0.67 則有：H=4.178f(v)0.8/d0.2=0.78103KJ(m h)（7）、計算冷卻水通道的導熱總面積AA=WQs/(h)=0.0042m（8）計算模具所需冷卻水管的總長度LL=A/(d)=56mm由于本塑件較小所以得到的冷卻水管總長度L也太小，不足模架寬度，但考慮到塑料旋鈕頭部為實體，還有生產效率，故只在兩個旋鈕頭部開設兩條循環(huán)冷卻水路。23 3總結后蓋設計結束了，在設計中，我學到了很多.畢業(yè)設計是對所學課程的一次綜合練習，主要是設計理念的培養(yǎng)，自己能力不足，在做的過程中總是前后不能總體把握，也意識到了自身的不足，雖然設計中會遇到諸多難題，但是只要我們有一顆堅定的心，相信自己一定能完成，就會柳暗花明。另外，我也切身體會到了理論與實際相結合的重要性，只有理論，實際中我們將無從下手；只有實踐，我們無法探索的更深。在此次畢業(yè)設計中鍛煉了自己獨立解決問題的能力，相信有了這次的嘗試，以后的工作就容易多了。同時也要感謝老師們、同學們的教導和幫助。25 致 謝 通過本次畢業(yè)設計，我對塑料模的設計思路、方案分析，擬定等各個環(huán)節(jié)有了較為清晰、深入的了解，拿到一個塑料制件，首先要對制件進行工藝分析，在滿足制件使用要求的前提下，為提高制件質量、精度還可以對制件的某件的某些部位進行改進，注射模的設計步驟主要還包括：模具型腔個數(shù)的確定、分型面的選擇、型腔配置、澆道、澆口系統(tǒng)的確定、側凹處理的方式、推件裝置的確定、拉料桿型式的確定流道凝料脫落形式的確定、溫度控制方式的確定、型腔、型芯固定方式的確定、型芯抽拔方式的確定、校核、繪制主要需件工作簡圖等，在設計時要對各個方案進行權衡量，盡早彩用標準件以縮短設計周期，降低設計成本，在塑料模選材的方面，我認識到塑料模所用材料與冷沖模，玻璃模等其它模具所用的材料有所不同，其選標主要按用途而定如在這副模具中，模具用于成大量生產，所以應具有足夠的耐磨性，并應具有良好的定模板。在設計的過程中，曾碰到了許多不夠成熟和理解的技術方面，制造方面，但經過指導老師的悉心教導和各參考書的參閱均得到了較為圓滿的答案。由于本次畢業(yè)設計是在未曾真正接觸運用，操縱過模具的情況下僅憑書本認識和指導下完成，難免有些地方存在不足之處，還有待遇于今后在工作崗位上不斷的揣磨，積累經驗提高設計的本領。 感謝母校河南機電高等?？茖W校的辛勤培育之恩！感謝材料工程系給我提供的良好學習及實踐環(huán)境，使我學到了許多新的知識，掌握了一定的操作技能。 最后，我非常慶幸在三年的的學習、生活中認識了很多可敬的老師和可親的同學，并感激師友的教誨和幫助！參考文獻1 翟德梅主編，模具制造技術M.北京；化學工業(yè)出版社，2011.22 伍先明主編.塑料模具設計指導M .北京：國防工業(yè)出版社，2011.23 熊小平，張增紅主編.塑料注射成型M.北京：化學工業(yè)出版社，2005.34 王孝培主編.塑料成型工藝及模具簡明手冊M .北京：機械工業(yè)出版社，2006.6.5 許洪斌主編.塑料注射成型工藝及模具M .北京：化學工業(yè)出版社，2006.11.6 王文廣主編.塑料注射模具設計技巧與實例M .北京：化學工業(yè)出版社，2003.12.8 馮炳堯主編.模具設計與制造簡明手冊M.上海：上海科學技術出版社，2001.5.9 楊占堯 王高平主編.塑料注射模結構與設計M.北京：高等教育出版社，2011.7.10 魏春雷 朱三武 章南主編.模具專業(yè)畢業(yè)手冊M.天津：天津大學出版社，2010.1編號： 畢業(yè)設計外文翻譯 （原文）題 目： Injection Molding Guide 學院： 機電工程學院 專 業(yè)： 機械設計制造及其自動化 學生姓名： 梁松強 學 號： 1000110123 指導教師單位： 桂林電子科技大學 姓 名： 彭曉楠 職 稱： 副教授 2014年5月26日桂林電子科技大學畢業(yè)設計（論文）說明書用紙 第26頁 共25頁Injection Molding GuideINTRODUCTIONObjectiveThis document provides guidelines for part design, mold design and processing of styrenic block copolymer (SBC) TPEs. The GLS product families that include styrenic TPEs are Kraton compounds, Dynaflex TPE compounds and Versaflex TPE alloys.SBC RheologyOne major characteristic of SBCs is that they are shearing dependent. A material is shear dependent when its viscosity is higher at low shear rates (such as extrusion) and lower at high shear rates (as in injection molding). Therefore, SBC compounds will flow more easily into thin areas of the mold at high shear rates. The shear thinning behavior of SBCs should be considered when designing injection molds and also when setting mold conditions during processing.Figure 1.The effect of shear rate on the viscosity of GLSstyrenic TPE compounds (measured at 390F (200C).To obtain information regarding the viscosity of an individual grade, refer to the Product Technical Data Sheet, available at www.glscorporation.com or contact your GLS representative.PART DESIGNGeneral Part Design ConceptsWhen designing a TPE part, there are a few general rules to follow: The part wall thickness should be as uniform as possible. Transitions from thick to thin areas should be gradual to prevent flow problems, back fills, and gas traps. Thick sections should be cored out to minimize shrinkage and reduce part weight (and cycle time). Radius / fillet all sharp corners to promote flow and minimize no-fill areas. Deep unventable blind pockets or ribs should be avoided. Avoid thin walls that cannot be blown off the cores by air-assist ejection. Long draws with minimum draft may affect ease of ejection.Flow Length and Wall ThicknessThe maximum achievable flow length is dependent on the specific material selected, the thickness of the part, and processing conditions. Generally, GLS compounds will flow much further in thinner walls than other types of TPEs. The flow to thickness ratio should be 200 maximum; however this is dependent on the material and the part design. High flow GLS TPE compounds (such as Versalloy) have been used successfully to fill flow ratios up to 400.The measurement of spiral flow offers a comparative analysis of a materials ability to fill a part. The spiral flow test is performed by injecting a material into a spiral mold (similar to a ribbon formed into a spiral). The distance the material flows is measured in inches. In this case, the spiral flow test was conducted using two different injection speeds (3 in/sec and 5 in/sec). The typical spiral flow lengths for the various GLS product families are summarized in Table 1. With specific compounds, flow lengths of up to 40 inches (at 5 in/sec injection speed) are possible.Table 1. Typical Spiral Flow Lengths for GLS Compounds*SeriesFlow length, in3 in/sec5 in/secDynaflex D13-1518-20Dynaflex G12-2218-30Versaflex 9-1613-26*Spiral flow tests performed using 0.0625 in thickness and 0.375 in width channel at 400F.For spiral flow information about a specific grade or additional details about the spiral flow test procedure, please refer to the GLS Corporation TPE Tips Sheet #7, available at www.glscorporation.com or by contacting your GLS representative.UndercutsThe flexibility and elastic nature of TPEs allows for the incorporation of undercuts into the part design. Because of their excellent recovery characteristics, GLS compounds are capable of being stretched and deformed, allowing them to be pulled from deep undercuts (Figure 2). If both internal and external undercuts are present on the same part, slides or core splits may be necessary. Parts with internal undercuts (e.g. bulb shaped parts) may be air ejected from the core by use of a poppet valve in the core. Minor permanent elongation (3% - 8%) due to deformation may occur during ejection.Figure 2. An example of TPE parts with large undercuts.Gate and Knit Line LocationsThe product engineer should indicate the areas of the part that are cosmetic and those that are functional and include this information on the drawing. This will help the mold designer to determine the allowable gate and knit line locations.AnisotropyThermoplastic materials that have different properties in the flow direction versus the cross-flow direction (90 perpendicular to the flow direction) are characterized as “anisotropic” materials. Properties that may be affected are shrinkage and tensile properties. Anisotropy is caused when the polymer chains orient in the direction of flow, which leads to higher physical properties in the flow direction. Wall thickness, injection speed, melt temperature and mold temperature are a few variables that affect anisotropy. Depending on the processing conditions and mold design, most GLS styrenic TPE compounds exhibit a degree of anisotropy.ShrinkageDue to their anisotropic nature, GLS styrenic TPE compounds shrink more in the flow direction than in the cross-flow direction. Generally, SEBS compounds have higher shrinkage and are more anisotropic than SBS compounds. Typical shrinkage values for SEBS-based compounds are 1.3% - 2.5%, whereas those for SBS based compounds are 0.3% - 0.5 %. Softer SEBS compounds (below 30 Shore A) will shrink more than harder 6 materials. Some grades, such as Dynaflex G7700, G7800, and G7900 Series contain filler, which reduces their shrinkage.The shrinkage values reported by GLS are determined using a 0.125” thick plaque. It should be noted that shrinkage is not an exact number, but a range value. This range can be affected by the part wall thickness, melt temperature, mold temperature, injection speed, hold/pack pressures and also the time between molding and measuring. As a result, prototyping is strongly recommended for parts with close tolerances to better quantify the realistic shrinkage of a specific grade of material in a specific application.For shrinkage values for specific grades, please refer to the product Technical Data Sheet, available at www.glscorporation.com or by contacting your GLS representative.MOLD DESIGNTypes of MoldsGLS SBC compounds can be molded in two- and three-plate molds. Both conventional and hot runner tool designs have been used with GLS compounds. Self-insulating hot runner tool designs are not recommended due to the potential for material degradation in the stagnation zones. Two-shot molds and insert molds can also be used. If a family mold is required, the cavity volumes should be similar, otherwise over packing and flashing of the smaller cavity may occur.Steel SelectionGLS styrenic TPEs are generally non-abrasive and non-corrosive. The selection of tool steel will depend on the quantity and quality of parts to be produced. For high volume production, the initial expense of quality tooling is a sound investment.A wide variety of tool steels are available for injection mold construction. Table 2 lists the properties of common tool steels and the typical mold components for which they are used. Soft metals, such as aluminum and beryllium copper, can be used for prototype parts or short production runs up to 10,000 parts.Table 2. Typical Tool Steel for Injection Mold ConstructionSteel TypeSteel PropertiesMold ComponentP-20Pre-hardened, machines well, high carbon, general-purpose steel. Disadvantage: May rust if improperly stored.Mold bases, ejector plates, and some cavities (if nickel or chrome plated to prevent rust).H-13Good general purpose tool steel. Can be polished or heat-treated. Better corrosion resistance.Cavity plates and core plates.S-7Good high hardness, improved toughness, general-purpose tool steel. Machines well, shock resistant, polishes well. Disadvantage: Higher cost.Cavity plates, core plates and laminates, as well as thin wall sections.A-2Good high toughness tool steel. Heat-treats and polishes well.Ejector pins, ejector sleeves, and ejector blades.D-2Very hard, high wear characteristics, high vanadium content, somewhat brittle. Disadvantage: Difficult to machine.Gate blocks, gibe plates to prevent galling, gate blocks to prevent wear.420 SSTough corrosion resistant material.Heat-treats and polishes well.Disadvantage: High cost.Cavity blocks, ejector pins, sleeves, etc.Some part designs may benefit from the use of higher thermal conductivity materials such as beryllium copper. This material is less durable than steel and may hob or wear faster than steel if used at the parting-line. Beryllium copper can be used for inserts, slides or cores to increase heat transfer rates and reduce cycle times. In cases where there is a long draw core, a fountain-type bubbler may be beneficial.Mold Surface Treatment, Finishing and TexturingMost GLS materials replicate the mold surface fairly well. To produce a glossy surface, a polished mold is required and an unfilled grade should be used. A highly polished tool and a transparent material are required to produce a part with good clarity. If a matte finish similar to that of a thermoset rubber is required, a rougher mold texture should be used (or a GLS product such as GLS Versalloy TPV alloys, which naturally produce a matte surface). In general, an EDM surface will produce a good texture and may improve release from the tool during part ejection. Matte surfaces can also help to hide any flow marks or other surface defects. Vapor honing, sand or bead blasting and chemical etching are also used to produce textured surfaces with varying degrees of gloss and appearance. To aid in release, the cavity or core may be coated with a release coating such as PTFE impregnated nickel after it has been given a sandblast or EDM finish.Sprue and Sprue Puller DesignThe sprue should have sufficient draft, from 1 to 3 to minimize drag and sprue sticking. Longer sprues may require more taper (3 - 5), as shown in Figure 3. Typically, the sprue diameter should be slightly larger than the nozzle diameter. An EDM finish is acceptable for most styrenic TPE materials. Permanent surface lubricant treatments have also been used successfully.Sprue puller designs vary with the hardness of the material. The different sprue designs possible and their relative dimensions are shown in Figures 4 through 7. In addition, Table 3 shows the typical hardness range for which a particular sprue design is applicable.Table 3. Typical Sprue Designs for Various Hardness ValuesTypical TPE Hardness RangeMost Common Sprue Puller TypesFigure50 Shore ATapered, Pin, Z-Type3, 4 and 640-70 Shore AUndercut55-40 Shore APine Tree7Hot sprue bushings and extended nozzles may also be used with GLS compounds. In many molds, the sprue is the thickest wall section in the mold and will control the minimum cooling time. The use of a hot sprue, which may be viewed as an extension of the machine nozzle, can sometimes reduce cycle time. Extended machine nozzles may also be used to reduce sprue length and size. When hot sprues are used, the machine nozzle tip should be a free-flow nozzle rather than a reverse tip.Figure 3. Tapered Sprue Puller Figure 4. Z-Pin Sprue PullerFigure 5. Undercut Sprue PullerFigure 6. Sucker Pin Sprue Puller Figure 7. Pine Tree Sprue PullerConventional Runner Configuration and DesignA balanced runner configuration is critical to achieve uniform part quality from cavity to cavity. In a balanced runner system, the melt flows into each cavity at equal times and pressure. The runner balance can be designed by using computer mold-flow analysis programs and verified by performing short-shot studies.An unbalanced runner may result in inconsistent part weights and dimensional variability. The cavity closest to the sprue may be over packed and flashing may occur. As a result of over packing, parts may also develop high molded-in stresses, which lead to warpage. Examples of balanced runner systems are shown in Figures 8 and 9.Figure 8. Example of Balanced Spider Runner Figure 9. Example of Balanced Cross-RunnerFigure 10 shows different runner cross-sections and their associated efficiency. Full round runners have the least resistance to flow and surface area, allowing the material to stay molten longer. The second most efficient runner cross-section is the modified trapezoid. This runner geometry most closely simulates a full round runner but only requires machining in only one plate. Figure 11 shows typical ball cutter dimensions and the corresponding modified trapezoid runner sizes. Figure 12 illustrates typical runner dimensions.Figure 10. Typical Runner Cross-SectionsFigure 11. Modified Trapezoid Runner SizesFigure 12. Runner Design and DimensionsCold slug wells should be used at each runner transition (turn). Cold slug wells serve to remove the leading edge of the melt. The slug well associated with the sprue should be large enough to trap the cold material formed in the machine nozzle during the mold-open cycle. Typical slug well dimensions are approximately 1.5 to 2.0 times the diameter or width of the feed runner.Runner KeepersRunner keepers or sucker pins provide undercuts to keep the runner on the desired plate but should not restrict material flow through the runner. Figures 8 and 9 show typical locations for runner keepers and sucker pins. Figure 13 illustrates an example design of a runner keeper.Figure 13. Runner Keeper designGate Design and LocationMost conventional gating types are suitable for processing GLS styrenic TPE compounds.The type of gate and the location, relative to the part, may affect the following: Part packing Gate removal or vestige Part cosmetic appearance Part dimensions (including warpage)The type of gate selected is dependent on both part and tool design. The gate location is equally important. To prevent the chances of jetting, locate the gate entrance in an area where the flow will impinge on a cavity wall. For automatically degating tools, the highly elastic nature of softer TPEs makes submarine gate designs or three plate tools with selfdegating drops more difficult. Higher hardness and filled grades usually have lower ultimate elongation and therefore are more easily degated. To assure the gates will break at a specific location, they should have a short land length to create a high stress concentration.Tab/Edge GatesTab or edge gates (Figure 14) most commonly utilize a conventional sprue and cold runner system. They are located along the tool parting line. A small undercut can be placed where the gate meets the part to minimize gate vestige caused by degating. Advantages of edge gates are ease of fabrication, modification and maintenance. The 14 gate depth (D) should be 15% - 30% of the wall thickness at the gate entrance. Common practice is to start “steel safe”. A good starting point for the gate width should be 1.0 - 1.5 times the gate depth. The gate land should be equal to or slightly longer than gate depth. The gate size may also depend on the part volume. The gate area may be inserted to facilitate gate maintenance or modification.Figure 14. Tab or edge gate Figure 15. Submarine GateSubmarine or tunnel gates are self-degating. During part ejection, the tool steel separates the part and the runner. Figure 15 shows a typical design of a submarine gate. Cashew type submarine gates should not be used for medium to soft hardness compounds due to their high coefficient of friction and high elongation.Fan GatesA fan gate is a streamlined variation of a tab gate (Figure 16). The fan gate distributes material into the cavity more evenly; thus it is normally used in parts that require a high degree of flatness and absence of flow lines. It also minimizes the possibility of gate pucker or part warpage.Figure 16. Fan gateSprue or Direct GateThe sprue or direct gate is often used on prototype parts because it is inexpensive. This type of gating is not recommended for GLS styrenic compounds because of their high elongation. In addition, the sprue will need to be trimmed thus appearance quality of the part is usually poor. If sprue gating is selected, care should be taken to keep both the sprue length and diameter as short and small as possible.Diaphragm GateThe diaphragm gate is used to maintain the concentricity of round parts. It allows even flow into the cavity and minimizes the potential for knit lines. Due to anisotropic shrinkage, flat round parts using center or diaphragm gating may not lay flat. A ring gate may also be used on the outside of a circular part.Table 4 compares the advantages and disadvantages of the various gate types discussed in this section.Table 4. Advantages and Disadvantages of Various Gate TypesGate TypeAdvantageDisadvantageEdge/Tab/Fan Gate Appropriate for flat parts Easy to modify Post-mold gate/runner removal is difficult Poor gate vestigeSubmarine Gate Automatic gate removal Minimal gate vestige More difficult to machineDiaphragm Gate Concentricity Appropriate for round parts No knit lines Scrap Post-molding gate removalPin gate (3-plate) Automatic gate removal Minimal gate vestige Localized cooling Requires floater plate More scrap Higher tool costValve gate (Hot runner systems) Minimal gate vestige Positive shut-off Minimizes post pack Higher tool cost Higher maintenance Only for hot runner systemsGate LocationStyrenic TPE compounds are anisotropic, thus they have different physical properties in the flow direction versus the cross-flow direction. Depending on the products intended usage, these property differences could be critical to the performance of the final part. As a result, the anisotropic nature of the styrenic TPE needs to be taken into consideration when determining the gate location on the part.The material flow may be estimated by eye or by using flow analysis programs. For higher shrinkage grades, the part may shrink near the gate, which causes “gate pucker” if there is a high molded-in stress at the gate. Parts shaped like a handle grip may warp toward the gate side of the part. Locating the gate at the top of the part minimizes this problem. Using two gates on opposite sides of the part can also address the issue, but it will result in two knit lines. If filling problems exist in thin walled parts, adding flow channels or minor changes in wall thickness can alter the flow. In some cases, it may be necessary to add a second gate to properly fill the parts.The gate should be placed so that the flow path is as short as possible. Locating the gate at the heaviest cross section of the part can improve packing and minimize voids or sinks. If possible, the gate should be positioned so as to avoid obstructions (flowing around cores or pins) in the flow path.The flow path of the material should minimize the possibility of formation of knit lines and flow marks. Upo