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1、塑膠產品設計 Plastic Part Design,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 possible thickness
2、 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 troubles, including he
3、sitation, 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 shrinkage factor mate
4、rials, 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 Design (2),外側凸轂 Ou
5、tside 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 & Fillet Radius,突出件和公稱厚壁相交處的內圓角半徑太大，會致使凹陷、空洞、殘餘應力和長的冷卻時間。 該內圓角半徑太小，會致使應力集中。 一個好的折中方案是採用公稱壁厚的25% ，作為內圓角半徑。 A large fillet radius causes sink mark, void, residual stress and long cooling time. A small fillet ra
6、dius causes stress concentration. A good compromise is to use a radius, which is 25% of the nominal wall (NW), at the junction of the NW and a projection.,內圓角半徑 Fillet Radius,肋的底部厚度 Bottom Thickness of Rib,肋的設計 (一 ) Rib Design ( 1 ),肋的設計 (二 ) Rib Design ( 2 ),角板設計 (三 ) Gusset Design ( 3 ),與側壁相連之凸轂(熱
7、塑性塑膠) Boss at Wall ( Thermoplastics ),遠離側壁之凸轂(熱塑性塑膠) Boss Away From Wall( Thermoplastics ),Wall Thickness, Rib,Conventional 0.080 to 0.125 in (2.0 to 3.2 mm),Thinwall: 0.050 to 0.080 in 0.050 in (1.2 to 2.0 mm) (1.2 mm),Wall Thickness, Bosses,Conventional 0.080 to 0.125 in (2.0 to 3.2 mm),Thinwall:
8、0.050 to 0.080 in 0.050 in (1.2 to 2.0 mm) (1.2 mm),Wall Thickness, Gussets,Conventional 0.080 to 0.125 in (2.0 to 3.2 mm),Thinwall: 0.050 to 0.080 in 0.050 in (1.2 to 2.0 mm) (1.2 mm),突出件在和公稱厚壁相交處的建議厚度：以高縮水率的結晶性塑膠而言，可採用公稱壁厚的50% 。 以低縮水率的非結晶性塑膠而言，可採用公稱壁厚的75% 。 The recommended thickness at the junctio
9、n of a projection and the nominal wall (NW) is 50% of the NW thickness for high-mold-shrinkage, crystalline materials. The lower-mold-shrinkage-factor, amorphous plastics can have thicknesses of up to 75% of the parts NW thickness .,突出件壁厚 Thickness of the Projection,有些情形，在美觀的考慮下，是不容許些微凹陷的。 設計者應當考慮將建
10、議厚度減少10%。 In those cases where aesthetic considerations preclude even a slight sink mark, a designer should consider reducing the recommended rib thickness by an additional 10 percent .,突出件壁厚 Thickness of the Projection,從成型容易的觀點來看，突出件的高度以產品公稱壁厚的2.5到3倍為宜。 From an ease of molding perspective, the heig
11、ht of projections should be limited to 2.5 to 3 times the part nominal wall thickness.,突出件高度 Height of the Projection,強固的、脆的、剝蝕性的、黏的塑件要有大的脫模角和光滑的拋光。 軟的、延展性的、和光滑的塑件則可有小的脫模角。 Large draft angles and a smooth polish are required for parts molded in strong, brittle, abrasive, and sticky materials. Smalle
12、r draft angles can be used on soft, ductile, and slippery materials.,突出件脫模角 Draft Angle of the Projection,以成本和可製造性的觀點，理想的脫模角是消費者可以接受的前題下，最大的角度。 就多數情況而言，每邊1應已足夠，但2 或 5 可以更好。 模穴應順著開模方向打光。 The ideal draft angle, from a cost and manufacturability perspective, is the largest angle that will not distract
13、from the consumers acceptance of the product. In most cases, 1 per side will be adequate, but 2 or 5 per side would be better. The cavities that form projections should be draw-polished.,突出件脫模角 Draft Angle of the Projection,距離應大於產品公稱壁厚的2倍。 使得模具鋼材具備足夠的強度以抵抗彎曲，並且提供足夠的吸熱器，以免產生凹陷和成型應力。 This distance sho
14、uld be at least 2 times the parts nominal wall thickness, so the mold steel provide enough strength to resist bending and enough heat sink to avoid sink mark and molded in stress.,突出件和側壁/突出件的距離 The Distance between Projection and Side Wall/Projection,Where 1/r : 樑的曲率 curvature of the beam M : 彎曲力矩 b
15、ending moment E : 彈性模數 modulus of elasticity I : 斷面積對中立軸的慣性矩 moment of inertia of the cross- sectional area with respect to the neutral axis EI : 撓曲剛性 flexural rigidity,撓曲剛性 Flexural Rigidity,Where : 最大偏移 maximum deflection W : 負荷 load L : 樑長 length of beam E : 彈性模數 modulus of elasticity I : 斷面積對中立軸
16、的慣性矩 moment of inertia of the cross- sectional area with respect to the neutral axis EI : 撓曲剛性 flexural rigidity : 最大應力 maximum stress : 中立軸到到其斷面離其最遠的點的距離 distance from the extreme point of a cross section to the neutral axis of this cross section,Youngs Modulus, E,The ratio between stress and strain is constant, obeying Hookes Law, within the elasticity range of any material. This ratio is c
