塑胶模具设计_徐昌煜.ppt

1、塑膠產品設計 Plastic Part Design 徐昌煜 Charles Hsu,就傳統射出成形而言，實用的最小壁厚在0.75到1.00mm 之間。 如果要採用更薄的壁厚，卻又缺乏實際的經驗，可以借助CAE作科學的決定。 For conventional injection molding , a practical minimum wall thickness is in the range of 0.75 to 1.00 mm. When thinner walls are required but actual experience is absent, the minimum po

2、ssible thickness can be scientifically determined by CAE.,壁厚Wall Thickness,壁厚不均是注塑成形中最大的麻煩製造者。 這對薄壁零件尤然。 這些麻煩包括了遲滯現象、短射、凹陷、發赤、噴流、翹曲及長冷卻時間等；目前都可用CAE以直接或間接的方式預測。 Non-uniform wall thickness is the biggest trouble maker in plastic injection molding. This is especially true to thin-wall part. The trouble

3、s, including hesitation, short shot, sink mark, blush, jetting, warpage and long cooling time etc., can be predicted, directly or indirectly, by using CAE.,壁厚不均Non-uniform Wall Thickness,設計高收縮率材料成型品時，設計者應將壁厚變化限制在10%。 就低收縮率材料而言， 許容壁厚變化可到25%。 While designing injection molded parts in high mold shrinka

4、ge factor materials, the designer should try to limit wall thickness variation to 10%. The allowable wall thickness variation for the low mold shrinkage factor materials can be up to 25%.,壁厚不均Non-uniform Wall Thickness,壁厚設計 Wall Thickness Design,掏空設計(1) Coring Out Design (1),掏空設計(2) Coring Out Desig

5、n (2),外側凸轂 Outside Boss,空洞或/和凹陷的形成 Void or/and Sink Mark Forming,肋厚和內圓角半徑的影響 The Effect of Rib Thickness showing a dramatic cooling time reduction of 94% (15/16) .,平板和肋板的比較Comparison between Plain (b) Self-opening Hinge Design,Most Common Living Hinge Design: (a) before, and (b) after Bending 180,Re

6、commended Living Hinge Design with the Neutral Axis in the Center: (a) before, and (b) at Bending Angle of 180,Cross Section through the Entire Hinge Showing Its Principal Dimensions,Cross Section of a Portion of a Living Hinge Design and Its Neutral Axis Position,Hinge Design Detail: (a) as Molded;

7、 (b) as Assembled,“Right Way”Assembly Hinge Detail,Cable Ignition Bracket Axonometric View,Cable Ignition Bracket Side View,Cable Ignition Bracket Top View,Hinge Detail:(a) Initial Design;(b) Improved Design,Hinge Behavior after Assembly,POLYPROPYLENE HINGE DESIGN,NOTES: 1. Y DIM. PER PART DESIGN 2.

8、 X DIM. = 2Y + 0.25,POLYPROPYLENE HINGE DESIGN,孔 Holes,以射出成型而言，圓孔形狀理想，原因是塑料冷卻時， 它收縮到心型銷，若銷為圓形，應力會均勻的分布在圓銷面上。 Round holes are the ideal shape for the injection molding process. The reason for this is that as plastic material cools it shrinks onto the core pin that forms a hole and, with round holes,

9、the stress is uniformly distributed around it.,孔 Holes,這一尼龍風扇因安裝孔的直線孔緣末端的鎖入應力而損毀。 This nylon fan failed due to molded-in stress at the end of the straight section on the mounting hole.,孔 Holes,孔 Holes,最初，此一玻纖補強的尼龍計時鏈輪中央的方型驅動軸孔，有四個銳角。 使用幾個月後，這些鏈輪，從方孔的銳角，到其附近的鏈輪齒根，產生裂隙而報廢。 後來，在方孔的四個角落，加了向外延伸的小孔之後，鏈輪便不

10、再開裂。 The glass-fiber-reinforced nylon timing sprockets were introduced with sharp corners on the square drive shaft hole. These sprockets failed after several months in the field due to cracks radiating from a corner on the square hole to the root of a nearby gear tooth. These field failures were el

11、iminated by adding the outwardly extending radiuses.,孔 Holes,內圓角和向外延伸的內圓角(B, C, D)可以減低鎖入的應力並且使得產品變強。 Inside and outwardly extending radiuses (B, C, D) reduce molded-in stress and result in a stronger part.,孔 Holes,孔A和B能以簡單直接開模的方式成形，孔C則須要一較複雜的側向運動心型，方能成形。 Holes A and B can be molded with a simple, st

12、raight opening mold. Hole C requires a more complex side-acting mold.,從易於成型的觀點來看，相鄰二孔緣的距離， 或是孔緣和產品邊緣的距離， 至少要有壁厚的兩倍， 而絕對不可小於壁厚。 From an ease of molding perspective, the distance from one hole to the next , or to the edge of a part, must be at a minimum two times the parts wall thickness, and never le

13、ss than the parts wall thickness,孔 Holes,孔 Holes,圖中的孔太靠近產品的邊緣，塑料的收縮使得該孔和其周圍的薄壁都因之扭曲。 The hole shown here is too close to the edge of the part. Shrinkage of the plastic material has distorted this hole and the thin wall around it.,孔 Holes(Figure I),孔 Holes,圖I的盲孔A的長徑比應以2:1或3:1為限。 形成圖I穿孔B的心型銷的自由端是頂在母模面

14、上。 這樣的心型銷獲得支持，而長徑比可增加到6:1 。 The length-to-diameter ratio of the blind hole in Figure I(A) is limited to only 2:1 or 3:1. The through hole B in Figure I allows the free end of the core pin to be seated against the cavity. This supports the core and allows its length-to-diameter to be 6:1.,孔 Holes,如圖I

15、的C所示，將型心延伸至母模側的配合孔，可以提供額外的支撐，兩頭支撐的型心銷的長徑比可達12:1。 如圖I的D所示，以二支型心銷成型深孔，可以消除型心銷和母模面的磨耗。 這種方法產生的孔也可有12:1的長徑比。 Telescoping the core into a mating hole in the cavity, C in Figure I, provides additional support. A core pin anchored at both ends can have a length-to-diameter ratio of 12:1. Molding a deep hol

16、e with two core pins, D in Figure I, eliminates wear between the core pin and the cavity. Holes produced in this manner can also have a 12:1 length-to-diameter ratio.,塑膠工業協會(SPI)指定12種拋光，從鑽石高度拋光，到噴砂粗度拋光。 依照SPI模具拋光指南，來指定表面光滑度，已經被國際接受。 The Society of the Plastics Industry (SPI) specified 12 finishes, r

17、anging from a high diamond polish to a rough, blasted surface. The SPI Mold Finish Guide has become the internationally accepted for specifying surface finishes.,表面光滑度Surface Finish,如果型心形成的內面沒有拋光，頂出力和循環時間都會相應增加。 If the core that forms the inside surfaces is not smoothly polished, the ejection forces

18、 and the cycle time will increase accordingly.,表面光滑度Surface Finish,只在成型品頂出方向拋光，可以消除側凹。 這種拋光方法被稱作“抽拋” 。 設計工程師應於零件須要最小或0脫模角時，指定抽拋。 Polishing the mold only in the direction that the molded part moves during ejection eliminates these undercuts. This polishing technique is called “draw polishing.” Design

19、 engineers would be well advised to specify draw polishing on parts requiring minimal or no draft angles.,表面光滑度Surface Finish,無論模面如何光滑，低密度聚乙烯都無法產生和聚苯乙烯接近的光亮外表。 補強料加得多的塑料不能有效的產生光亮的外表。 一般說來，熱模較之冷模，較能產生光滑的外表。 保壓不足的產品無法忠實的複現模面的光滑。 Regardless of the finish on the mold, low-density polyethylene can never

20、produce the shiny appearance of a polystyrene part. Heavily filled or reinforced polymer cannot reliably produce shiny surfaces. Generally speaking, a hot mold will produce better surfaces than a cold mold. A poorly packed out part will not faithfully replicate the mold polish on all of the part sur

21、faces.,表面光滑度Surface Finish,最軟的聚乙烯和聚氯乙烯、 polyurethanes 和某些熱塑性elastomers 有沾黏高度拋光金屬面的傾向。 這類黏的材料，一般較易從粗糙面或輕度噴砂面脫模。 The softest polyethylenes and polyvinyl chlorides, polyurethanes, and some thermoplastic elastomers have a tendency to adhere to highly polished metal surfaces. Sticky materials of this typ

22、e will normally release better from molding surfaces with matte or lightly blasted surface finish.,表面光滑度Surface Finish,強壯而又有些彈性的塑膠，像聚丙烯、ABS和耐衝擊聚苯乙烯，較之剛而脆的材料， 如一般用途用聚丙烯和壓克力，更能接受粗略拋光的模面。 對這些硬而脆的材料，抽拋是非常有益的 。 Strong but somewhat flexible plastics, such as polypropylene, ABS, and impact styrene, are mor

23、e tolerant of roughly polished molding surfaces than rigid, brittle materials, such as general-purpose styrene and acrylics. Draw polishing is very beneficial with these hard, brittle materials.,表面光滑度Surface Finish,不能指望產品設計師、模具製造者以及拋光公司知道所有不同塑料的癖性。然而，我們可以倚賴塑料供應商和有經驗的成型者， 他們知道那一種模面光滑度適合那一種特定的塑料。 Prod

24、uct designers, moldmakers, and polishing companies cannot be expected to know the idiosyncrasies of all of the different plastic materials. Plastic material suppliers and experienced molders can, however, be relied upon to know what mold finish is optimal for a given material.,表面光滑度Surface Finish,有些

25、工業界的內行者 ， 估計拋光代表了模具平均成本的10% 。 這個平均值當然會有明顯的差異，這要看模具的尺寸和形狀、金屬的硬度、 要求拋光的程度、 以及拋光前模面的光滑程度。 Some industry insiders have estimated that, on the average, polishing can represent 10% of a mold overall cost. This average will obviously vary, depending on the size and shape of the mold, the hardness of the me

26、tal, the level of polish required, and how well the mold was finished prior to polishing.,表面光滑度Surface Finish,對不透明件而言，大多數消費者無法分辨SPI指南中最高三級光滑度的分別 ， SPI的最高二級光滑度應為可以看穿的透明件保留。 換言之，為何要花錢在消費者無法感激的表面光滑度上？ Most consumers will not notice the differences between the SPI Guide three highest finishes on an opaq

27、ue part. The two best SPI finishes should be reserved for transparent, see-through parts. In other words, why spend money on a surface finish that the consumer cannot appreciate ?,表面光滑度Surface Finish,產品圖上必須標明表面光滑度，高度建議參照SPI模具光滑度指南。 The surface finish must be clearly indicated on the part drawing. It

28、 is strongly recommended that surface finish be specified according to SPI Mold Finish Guide.,表面光滑度Surface Finish,一般說來，成本或交貨期，會隨著決定採用電火花加工法、噴砂法和照相化學腐蝕法的順序而增加。 所有方法都能供給不同程度的表面花紋。 較細的花紋像編織物或風乾木材的紋理，只能靠照相化學腐蝕提供。 Generally speaking, the cost and delivery time increases with the decision to go from EDMin

29、g to blasting to PCEing. All three techniques can provide varying degrees of matte finishes. The more detailed finishes, such as fabric or weathered wood, are available only with PCEing. Note: PCE is Photo Chemical Etching,表面花紋Pattern,根據經驗法則，對母模側模壁(冷卻時，塑料從其離開)而言，每0.025mm咬花深度， 單邊至少要有1.5 脫模角。 有些咬花供應商要

30、求在公模側模壁(冷卻時，塑料向其包裹) ，提供2倍的脫模角。 安全的作法是避免在内面採用咬花。 The rule of thumb, applied to the side wall of cavities that the material shrinks away from as it cools, is a minimum of 1.5 of draft per side for each 0.025mm (0.001 inch) of texture depth. Some texture suppliers ask for twice as much draft on inside

31、surfaces, that the material shrinks onto as it cools. A safer approach is to avoid using texture on inside surfaces.,咬花Texture,設計者必須指出咬花從那裏開始，到那裏結束。 一個好的咬花標註，應該指出花紋號碼 、咬花深度、 咬花位置，如果要更得當的話，還要加上花紋的方向。 當一產品是由數件零件組合而成，一定要指出咬花花紋的方向。 The designer must indicate where the texture stops and starts. A good te

32、xturing note should indicate the pattern number, depth of texture, its location, and - if appropriate - the direction of the pattern. In those instances where several parts fit together in one product, the direction of the texture pattern absolutely must be specified.,咬花Texture,設計者完成產品設計之前，能做的最重要的單一

33、事項，就是會同專業的咬花供應商作專案檢討。 The single most important thing that a designer can do to optimize the use of texturing is to review the project with a knowledgeable texture supplier before finalizing the part design.,咬花Texture,半結晶塑料的收縮率較高，這些塑料因在平行和垂直於熔膠流動方向有著不同的收縮率，而多了一層問題。 這問題又因成型條件改變致使結晶度變化而更形複雜。 如果塑料冷卻得慢，

34、結晶度和收縮率都會增加。 The semi-crystalline plastics has higher mold shrinkage factors. These materials have the additional problem of different shrinkage factors parallel to and perpendicular to the direction of melt flow. This problem is further compounded by variations in the degree of crystallinity caused

35、 by changes in molding conditions. If the material is cooled slowly, there will be an increase in crystallinity and mold shrinkage.,收縮Shrinkage,非結晶塑料收縮率低，較易維持尺寸的複現性。 發表的收縮率， 是以3.175mm (0.125吋)的壁厚為準。 It is easier to maintain dimensional reproducibility with low mold shrinkage factor amorphous materia

36、ls. The published mold shrinkage data is based on a molded part with a 3.175mm (0.125inch) wall thickness.,收縮Shrinkage,設計射出成型零件，當塑料收縮率高時，應試圖限制壁厚變化在10%之內 。 當塑料收縮率低時， 許容壁厚變化在25%以內。 While designing injection molded parts in high mold shrinkage factor materials, the designer should try to limit wall thi

37、ckness variations to 10%. The allowable wall thickness variation for the low mold shrinkage factor materials can be up to 25%.,收縮Shrinkage,塑膠模具設計 Plastic Mould Design 徐昌煜 Charles Hsu,模具設計的優先順序 Priorities of Mould Design,澆注系統設計 (Filling System Design) 排氣系統設計 (Venting System Design) 冷卻系統設計 (Cooling Sy

38、stem Design) 脫模系統設計 (Ejecting System Design),澆注系統設計 Filling System Design,徐 昌 煜 Charles Hsu,澆注系統設計的優先順序 Priorities of Filling System Design,產品設計 (Part Design) 型腔設計 (Cavity Design) 澆口設計 (Gate Design) 流道設計 (Runner Design) 豎澆道設計 (Sprue Design) 噴嘴設計 (Nozzle Design),典型的澆注系統 Typical Filling System,每增加一個澆口

39、，至少增加一條熔接線，同時增加一個澆口痕跡、增加流道的體積以及增加較多的積風。 Every time one gate is added, one weld line, at least, one gate mark, more runner volume and more air traps will be added. 在型腔能夠完滿充填的前提下，澆口數目是愈少愈好。 As long as the cavity is able to be filled appropriately, gates are the less the better. 為了減少澆口數目，每一澆口應就塑流力所能及的流

40、長/壁厚比之內，找出可以涵蓋最大零件面積的進澆位置。 In order to reduce the number of gates, each gate shall be located at where the melt is able to cover maximum part area based on the largest melt flow length/thickness ratio .,澆口數目 The Number of Gates,熔膠波前推進 Melt-Front Advancement,充填模式,積風和熔接線 Filling Patterns, Air-Traps an

41、d Weld Lines Location,熔接線 Weld Lines,更改澆口位置以重新定位熔接線 Weld Lines Can Be Relocated By Changing Gate Location,典型對頭熔接線伸張強度保留值 Typical Butt Weld Tensile Strength Retention Values,熔接線冷料井 Weld Slug Well,熔接線 Weld Lines,熔接線 Weld Lines,當波前相遇後，繼續一塊兒流動，如此產生的熔接線是動態的。 這樣的線條也稱作熔合線。 熔接線形成後，熔膠不再流動，如此產生的熔接線是靜態的或是對頭的。

42、靜態的熔接線位於型腔的末端， 一般比靠近澆口的動態的熔接線脆弱而且明顯。 When the flow fronts meet and continue to flow together, the resulting weldline is referred to as dynamic. This type of weldline is also called a meldline. Weldlines that are formed with no additional melt flow are referred to as static or butt weldlines. Static

43、weldlines located at the extremities of a cavity are normally weaker and more obvious than dynamic weldlines formed close to a gate.,左邊澆口在這些窗葉的中央，產生了靜態的熔接線。 The gate located on the left side creates static weldlines in the middle of these louvers.,熔接線 Weld Lines,熔接線 Weld Lines,這一部分充填的產品，顯示了兩條靜態的熔接線，

44、在外面二孔外產生； 澆口位於產品上邊中央。 This partially filled part shows two static weldlines by the outside holes. The gate is located at the center of the part, near the top.,積風 Air Traps,排氣 Vent,流動平衡 Flow Balance,熔膠波前於同一時間抵達型腔各末端。 Melt front reaches the ends of cavity at the same time.,洗衣機圈板,洗衣機圈板,冷氣通風飾罩-原始設計 Air-

45、conditioner Grille, Original,18 gates pressure: 76 MPa,冷氣通風飾罩-更正設計 Air-conditioner Grille, Revised,8 gates pressure: 75 MPa,分析結果比較 Comparison of Analysis Results,十二澆口設計 12 Gate Design,四澆口設計 4 Gate Design,電子零件置物箱四澆口 和十二澆口設計比較表,論語季氏第十六 不患寡而患不均， 不患貧而患不安。 - 孔子 -,如何快速平衡多型腔模之塑流 How to Balance Flows In A M

46、ulti-cavity Mould,一排支流道之不平衡充填 Unbalanced Flow In A Branch,一排支流道平衡後之充填 Balanced Flow In A Branch,128型腔模之不平衡充填 Unbalanced Flow In A 128 Cavity Mould,128型腔模平衡後之充填 Balanced Flow In A 128 Cavity Mould,The runner system shows that warmer, low-viscosity material (yellow and red) follows the inside wall whe

47、n the melt splits at an intersection.,Melt ” Flipper ”,剪切速率 Shear Rate,剪 切 應 力 shear stress 黏 度 viscosity 剪 切 速 率 shear rate,剪切應力 Shear Stress,澆口種類 Gate Types,導致平直製件的澆口設計 Gate Design for Flat Part,澆口設計(減少滯流效應) Gate Design to Avoid Hesitation,0.94秒時，遲滯現象在1.2mm厚凸片處發生,幫浦零件(Part, Pump) 塑料(Polymer): POM,

48、公稱厚度3.2mm,沒有遲滯現象,幫浦零件(Part, Pump) 塑料(Polymer): POM,澆口設計(避免凹陷和空洞) Gate Design to Avoid Sink Mark filling pattern, weld lines and air traps are changed.,多澆口設計 Multi-gate Design,閥式澆口 Valve Gate,矩形邊緣澆口設計 Rectangular Edge Gate Design,扇形澆口設計 Fan Gate Design,重疊式澆口設計 Overlap Gate Design,凸耳澆口設計 Tab Gate Desi

49、gn,針點澆口設計 Pin Gate Design,潛伏式澆口設計 Subgate Design,水力直徑 Hydraulic Diameter,Where is the hydraulic diameter 水力直徑 A is the cross-sectional area of the flow 流路斷面積 P is the wetted perimeter 濕周長,在不同剖面形狀，相同斷面積下之變化 Various runner profiles, based on the same cross-sectional area,水力直徑 Hydraulic Diameter,流道尺寸設計

50、 (1) Runner Sizing (1),D: 流道直徑 ( mm ) runner diameter in mm W: 下游塑膠重量 ( g ) downstream plastic weight L: 流道長度 ( mm ) runner length in mm,流道尺寸設計(2) Runner Sizing (2),流道尺寸設計(3) Runner Sizing (3),流道尺寸設計(4) Runner Sizing (4),H/2 (L),比較圓形流道截面積(AR)與改良型梯形流道截面積(AT)。假設圓形流道的直徑與改良型梯形流道的高度相等。 Comparing the cros

51、s-sectional area of full-round runner(AR) and the one of modified trapezoidal (AT),when the diameter of the round runner and the height of the trapezoidal runner are the same.,換言之，改良型梯形流道所使用的材料比圓形流道的材料多了20.38%。 In other words，modified trapezoidal runner uses 20.38% more material than full-round runn

52、er does.,冷料井設計 Cold Slug Well Design,冷料井設計 Cold Slug Well Design,冷料井設計 Cold Slug Well Design,澆道襯套尺寸 Sprue Bushing Sizing,噴嘴球頭和澆道襯套承窩半徑 Radius of Nozzle Head material constitutes 6% and the mould only 4% of the cost of each part. Small thin-wall parts typically benefit from improved cooling more than thick parts.,冷卻設計Cooling Design,典型的冷卻系統 Typical Cooling System,模溫調節機 Temperature controlling unit,軟管 Hoses,冷卻迴路 2 Cooling Circuit 2,冷卻迴路 1 Cooling Circuit 1,泵 Pump,收集歧管 Collection manifold,供給歧管 Supply manifold,模具冷卻系統 Mould Cooling Syst