塑胶设计原理

1、射出成型塑膠產品與模具設計 Injection Molding Plastic Part showing a dramatic cooling time reduction of 94% (15/16) .,平板和肋板的比較Comparison between Plain 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

2、 Overlap Gate Design,凸耳澆口設計 Tab Gate Design,L = 0.5 0.75 mm d = 澆口直徑( mm ) gate diameter in mm t = 零件壁厚( mm ) wall thick. in mm A = 型腔表面積 ( mm ) surface area of cavity in mm n= 材料常數 material constant 0.6 for PE, PS 0.7 for POM, PC, PP 0.8 for CA, PMMA, PA 0.9 for PVC,針點澆口設計 Pin Gate Design,d,L,t,潛伏式

3、澆口設計 Subgate Design,W= w= 澆口寬度 mm gate width in mm A= 型腔表面積 mm2 surface area of cavity in mm2 n= 材料常數 material constant 0.6 for PE, PS 0.7 for POM, PC, PP 0.8 for CA, PMMA, PA 0.9 for PVC 澆口厚度 gate thick. in mm = nt t= 零件壁厚 wall thick. in mm ,水力直徑 Hydraulic Diameter,Where is the hydraulic diameter 水

4、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,水力直徑 Hydraulic Diameter,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,流道尺寸設計 (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

5、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),流道尺寸設計(A1) Runner Sizing (A1),G : 重量 weight S : 零件厚度 thickness D : 參考直徑 reference diameter,流道尺寸設計(A2) Runner Sizing (A2),G : 重量 weight S : 零件厚度 thickness D : 參考直徑 reference diameter,流道尺

6、寸設計(B) Runner Sizing (B),D : 參考直徑 reference diameter L : 長度 length fL :長度係數 Length coefficient D : 流道直徑 runner diameter,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,熱澆道設計 Hot Runner Design,徐昌煜 Charles Hsu,熱澆道的問題似乎發生在三處: 1. 澆口直徑 2. 澆口長度 3. 噴嘴孔徑 Problems with hot

7、 runner seems to be in three places: 1. Gate diameter 2. Gate land 3. Nozzle orifice diameter,熱澆道的問題所在 Where Causes Problems with of Runner,任何發生在澆口處的發赤或噴流，表示澆口太小。 變褐則表示材料過熱而劣解。,Any blush or jetting at the gate means the gate is too small, and brown discolorations mean the material is being degraded

8、by too much heat.,受限的塑流通道 Restricted Flow Path,BROWN STREAK WITH FLOW LINES A brown streak on the part molded from easy- flow polycarbonate with the flow lines.,為了保持澆口暢通而格外加熱塑料，加上塑料在射出時通過長澆口時承受的剪切力，有可能造成褐線。,It was probably a combination of shear through the long land of the gate during injection and

9、 the extra heat needed to keep the gates open that are causing the brown streak.,褐線 Brown Streak,只以噴嘴口徑去配合熱澆道口徑是不對的。 首先要將澆道口徑加大，以配合下游塑流通道口徑，然後再加大噴嘴口徑以配合澆道口徑。,It isnt just sizing the nozzle orifice to match the hole in the hot sprue bushing . First you might have to increase the hole size of the spru

10、e bushing to match the flow channel diameter, then drill the nozzle out to match the sprue diameter.,受限的塑流通道 Restricted Flow Path,理想的澆道襯套設計 Optimized Sprue Bushing Design,當塑流通道受限於小或長的澆口，成型技術員常將設定溫度調高，以確保型腔充填、保壓無虞。,When the flow path is restricted by a small gate diameter or a long land length, you w

11、ill usually see higher heat settings being used by the molding technicians to get the parts to fill and pack out. 這樣的作法產生的問題有製品的翹曲，澆口的外觀缺陷和長的成型時間。 The problem with this approach is that it usually causes warpage of the parts, cosmetic defects around the gate area, and long molding cycles.,受限的塑流通道 Re

12、stricted Flow Path,如果歧管溫度設定得比料管前區為高，澆口尺寸或許有問題。 如果必須將噴嘴溫度設定得特別高，噴嘴口徑或許沒配合上熱澆道口徑。,If you find you have to run the manifold heats higher than the front zone of the barrel, you probably have gate sizing problems. If you have to run the heats up on the nozzle, the nozzle orifice probably hasnt been drill

13、ed out to match the hot sprue bushing diameter.,受限的塑流通道 Restricted Flow Path,如果塑流通道的尺寸正確，料管的前區、噴嘴和加熱歧管的溫度可以設定得一樣； ABS：232 C、易流PC：274 C。,If the flow path is sized correctly, you will be able to set the heat settings on the front zone of the barrel, the nozzle, and the heated manifold, such as 232C ac

14、ross the board for ABS or 274C for easy-flow PC.,受限的塑流通道 Restricted Flow Path,易流的PE和PP : 壁厚的50% 50% of wall thickness for easy-flow PE and PP ABS, SAN和壓克力: 壁厚的75% 75% of wall thickness for ABS, SAN, and acrylics PC/acetal/PVC/加玻纖材料和PPO : 壁厚的90% 90% of wall thickness for PC/acetal/PVC/glass-filled ma

15、terials and PPOs,熱澆道模具的澆口直徑 Gate Diameter for Hot Runner Molds,澆口長度應小於0.125mm。 Land should be no longer than 0.125mm. 諮詢熱澆道製造廠，以獲得正確的澆口長度。 Consult with your hot runner manufacturer for correct land length.,熱澆道模具的澆口長度 Gate Land Length for Hot Runner Molds,排氣系統設計 Venting System Design,徐昌煜 Charles Hsu,

16、為何排氣仍然還是一個問題？ Why venting is still a problem ? 因為降低射速，讓積風有較多的時間逃氣，是一件太容易的事。但是 Because it is too easy to slow down the injection speed and give the trapped air more time to escape. But .,排氣 Vent,射速一降，熔膠溫度很快降低，射壓必須提高，殘餘應力隨之提高，翹曲的可能性增加。 如果想藉提高料溫，以降低射壓，料溫必須升得很高，這樣又會引起塑料裂解。 When injection speed is lower,

17、 melt temperature goes down very fast, injection pressure has to be increased, residual stress is increased and the possibility getting warppage becomes higher. If one would like to increase barrel temperature to reduce the required injection pressure, the barrel temperature has to be increased to a

18、 quite high level and polymer degradation would be induced.,排氣 Vent,高料溫和高射壓都說明充填系統有了流動的問題,Both high barrel temperature and high injection pressure are indications of flow problem in the filling system.,排氣 Vent,我們常發現: 射速提高時，塑料表現得更為出色。 It is quite common that material performs better when it is inject

19、ed faster. 最適化螺桿速度充分運用摩擦熱，將塑流保持在最佳狀態。許多充填和翹曲的問題也就迎刃而解。 An optimized ram speed profile fully uses the friction heat to keep the best flow characteristics, which corrects many of the fill and warpage problems.,排氣 Vent,有了適當的排氣，射速可以提高，充填和保壓可達良好狀態，不須過度增加料管和噴嘴的溫度。,With proper venting, the injection speed

20、could be increased to achieve good fill and pack conditions, without having to raise the barrel and nozzle heats, improperly.,排氣 Vent,深度(depth) : 1. 0.075 mm易流塑料(easy-flow mat.) 2. 0.125 mm難流塑料(stiffer-flow mat.) 3. 深度深到流道末端見毛邊為準 (deep enough to feel flash at runner end) 寬度(width) : 和流道同寬(as wide as

21、 runner dia.) 排氣唇部(vent lip): 1.5mm A1拋光(finish) 排氣通道通大氣(vent channel to atmosphere): 1mm深(deep),流道排氣 Runner Vents,深度(depth): 參照廠商建議 (refer to manufacturers recommendation) 寬度(width): 全圓周長(whole perimeter) or 5mm 長度(length): 1.5mm A1拋光(finish) 排氣通道通大氣(vent channel to atmosphere): 1mm深(deep),分模面排氣 Pa

22、rting Line Vents,分模面排氣 Parting Line Vents,深度(depth): 參照廠商建議 (refer to manufacturers recommendation) 寬度(width): 全圓周長(whole perimeter) 長度(length): 1.5mm 排氣溝(vent groove): 1mm深(deep),頂出銷或心型銷排氣 Ejector and Core Pin Vents,冷卻系統設計 Cooling System Design,徐昌煜 Charles Hsu,模具冷卻設計的目的 Purposes of Mold Cooling Des

23、ign,1. 均衡冷卻(改良產品品質) Even Cooling (Improve Part Quality) 2.有效冷卻(提高生產力) Efficient Cooling (Increase Productivity),薄殼產品不像傳統壁厚者一般可以承受較大的因熱傳不均而產生的殘餘應力。 為了將收縮彎翹控制在可以接受的程度，均衡的冷卻設計變得非常重要。 Thin-wall part can not afford as much thermal induced residual stress as the conventional one does. An even cooling desi

24、gn becomes very important to control the shrinkage and warpage at an acceptable level.,冷卻設計Cooling Design,射出成型週期時間 Injection Molding Cycle Time,充填時間 Fill Time,開模時間 Open Time,後充填時間 Post-fill Time,對冰箱蔬果盤之類的大零件而言，材料往往佔成本50%以上。 對小而薄的零件而言， 成形機費用可佔成本的90% ，材料6% ，而模具只佔4%。 小而薄的產品較之厚者更能從冷卻的改善而獲得效益。 For larger

25、 molded parts, material typically represents more than 50% of the part cost for a refrigerator crisper tray. In the case of a thin-wall small part, the press cost could be 90% of the cost of the part; material constitutes 6% and the mold only 4% of the cost of each part. Small thin-wall parts typica

26、lly benefit from improved cooling more than thick parts.,冷卻設計Cooling Design,典型的冷卻系統 Typical Cooling System,模具冷卻管路 Mold Schematic,冷卻孔道 Cooling Channels,噴泉管 Bubbler,障板管 Baffle,熱管 Heat Pipe,熱管的應用 The Application Of Heat Pipe,理論上最短冷卻時間 Min. Possible Cooling Time,冷卻時間和厚度分佈 Cooling Time and Thickness Profile,冷卻孔道直徑、深度和節距建議值 Recommended Diameter, Depth & Pitch,D : 直徑為10至14mm Diameter of Cooling Channel, 10 to 14 mm d : 深度為D至3D Depth, D, to 3D P : 節距為3D至5D Pitch, 3D to 5D,原始設計 Original Design,修正設計 Revised Design,原始設計 Original Design,修正設計 Revised Design,原始設計 Original Design,修正設計 (一) Re