Lesson 10 材料物性

材料搜尋技巧 能夠在材料資料庫中搜查所存儲的任何材料性質 查尋包括材料的 Manufacturer Commercial Name Filler data etc..

黏度資料 顯示出壓力、溫度對剪切率兩者間之關係

黏度曲線 黏度曲線決定適當的黏度模式

材料對照比較 使用撿索的方式來比較材料 指定搜尋功能 設定搜查標準來比較材料 透過列表按入搜尋種類 修改標準搜詢樣板是有需要性的 按入Details看詳細資料

流動分析所需之物性屬性 建議成形條件 熱傳 流變值 PVT 比熱 模具溫度 熱傳導係數 熔膠溫度 頂出溫度 黏度 (Cross-WLF內定模式) 轉換溫度 PVT 熔膠密度 2-Domain tait PVT 建議成形條件 模具溫度 熔膠溫度 頂出溫度

其他屬性 建議成形條件 機械性質 一般性質 收縮 纖維 模具暨熔膠最大最小溫度 楊氏系數 最大剪切應力與剪切率 蒲松比 熱膨脹系數 商業名稱 製造公司 材料縮寫 機械性質 楊氏系數 蒲松比 熱膨脹系數 收縮 正確殘留在模穴應力(CRIMS) 纖維 形式 重量百分比

塑膠材料的種類 非結晶性 Amorphous 半結晶性 Semi-crystalline 在成型過程中分子鏈的結構不變 冷卻時分子鏈結構會壓縮， 加熱後變成非結晶性

塑膠的流動模式 凝固層 模壁 熔融塑膠 噴泉流區域 模壁 If you fill the mold too slowly, the mass of the plastic is no longer a major factor, but it freezes more during filling, thereby lowering the viscosity and restricting the flow due to a thicker frozen layer at each mold wall surface. During the filling phase, plastic is pushed into the cavity until the cavity is just filled.As plastic flows into the cavity, the plastic in contact with the mold wall quickly freezes. This creates a frozen layer of plastic between the mold and the molten plastic. At the interface between the static frozen layer and the flowing melt, the polymer molecules are stretched out in the direction of flow. This alignment and stretching is called orientation. 模壁

塑膠的黏度 黏度模式 Newtonian Power Law Cross WLF (內定)     . 4

塑膠的黏度 流動時的抵抗力 黏度會隨著剪切率或是溫度的提高而降低 Material Viscosity Water 10-1 10 Polymer 10,000 Glass 1020 Polymer Viscosity Polymer viscosity is the driving factor for polymer flow simulation. Definition Viscosity is the polymer’s resistance to flow. It is the ratio of the shear stress to the shear rate. It has the units of Pa.s (pascal.seconds) or poise. It is measured using a capillary rheometer. The data is fit to form scientific equations which represent the flow characteristics. Material Comparisons Let me give you an idea of how the polymer flows compared with other materials. Water has a viscosity of 10 poise and molten glass has a viscosity of 1E20 poise. Polymers fall in between these materials. They range from 2 to 3000 poise. 8

熔融指數 在等溫及等剪切率下進行 不同的塑膠材料會採用不同的試驗條件 Low MFR Material Higher Pressure High MFR Material Lower W Flow properties such as melt flow rate (MFR) and viscosity fall into this category. Can someone briefly explain how the MFR is determined? (get feedback from audience and then explain if necessary) The plastic is heated to a certain temperature inside a capillary die with a specific weight placed on top of the molten plastic. However much plastic flows through the die in a ten minute period (weighed in grams) is the melt flow rate. What if I have a low MFR vs. a high MFR; how does this influence pressure? Can you compare two materials such as ABS and PP based on MFR? Why or why not? (MFR test settings are different based on what resin you are testing; for example, the temperature and possibly the weight would be different for ABS than for PP.)

材料對射出壓力及鎖模力的影響 不同的材料需要不同的射出壓力 不同的材料在黏度上的差異極大 PMMA Hi Viscosity PP Low Viscosity Material and Injection Pressure The type of material used can have a tremendous affect on the required injection pressure. Some materials flow quite easily while others are very hard to process. This graph shows the required injection pressure to mold a specific part. The two curves represent two different materials and the required pressure to mold the same geometry. The PP requires less pressure than the PMMA material and has a larger window for appropriate fill times. Inj. Pressure and Clamp Force Fill Time (sec) 14

塑膠的溫度特性 Cp - Specific Heat Capacity k - Thermal Conductivity 吸熱的能力 熱傳的能力 The specific heat (Cp) of a material is the amount of heat required to raise the temperature of a unit mass of material by one degree Centigrade. It is essentially a measure of a material's ability to convert heat input to an actual temperature increase. The thermal conductivity (k) of a material is the rate of heat transfer by conduction per unit length per degrees Celsius. It is essentially a measure of the rate at which a material can dissipate heat. 8

材料對冷卻時間的影響 冷卻時間與熱傳導係數、密度及比熱有關 這些性質總和就是材料的熱擴散係數 Density (p) Specific Heat (Cp) Thermal Conductivity (k) Cooling Time Change The specific heat (Cp) of a material is the amount of heat required to raise the temperature of a unit mass of material by one degree Centigrade. It is essentially a measure of a material's ability to convert heat input to an actual temperature increase. The thermal conductivity (k) of a material is the rate of heat transfer by conduction per unit length per degrees Celsius. It is essentially a measure of the rate at which a material can dissipate heat. 8

PVT 特性 P -壓力 V -比容 T -溫度 描述塑膠如何隨著壓力及溫度的變化而發生體積上的變化在充填及保壓的階段，塑膠隨著壓力的增加而膨脹在冷卻的階段，塑膠隨著溫度的降低而收縮 可利用2-domain Tait PVT 模式之 I KV model constants from MPI 2.0 can be converted to Tait constants

PVT 特性 P -壓力 2-domain Tait PVT model available V -比容 T -溫度 描述塑膠如何隨著壓力及 溫度的變化而發生體積上 的變化在充填及保壓的階 段，塑膠隨著壓力的增加 而膨脹在冷卻的階段，塑 膠隨著溫度的降低而收縮 2-domain Tait PVT model available Pressure Increases Specific Volume Temperature

非結晶性材料 VS.半結晶性材料 當塑膠分子鏈發生整齊 排列，形成類似“結晶” 狀時，稱為結晶化 材料結晶性越高， 表示越容易收縮

非結晶性材料的PVT特性 Increasing Pressure D n Specific Volume Temperature A B P - Pressure V - Specific Volume T - Temperature Increasing Pressure A n D B Specific Volume Shrinkage is a system property. The system is characterized by a set of material data called “pvT” (pressure, specific volume, temperature). The pvT data communicates that as plastic temperature rises, the specific volume (volume per unit of mass, cm3/kg) increases. Also, as a pressure is applied on the plastic, the specific volume decreases because it is compressed. The blue curve represents lower pressure and the red is higher pressure. This set of data is for an amorphous resin. Amorphous resins’ molecular chains keep the same basic “spaghetti-like” structure whether they are solid or molten. In the molten state the molecular chains are spaced further apart so that they are less entangled and the plastic can flow under pressure. Temperature

半結晶性材料的PVT特性 D n Specific Volume Temperature Crystallization Phase A B The pvT curves for a semi-crystalline resin are quite different than for an amorphous resin. Semi-crystalline resins have a different molecular chain structure in the solid state than in the molten state. In the molten state they are much like amorphous materials with the “spaghetti-like” entanglements. However, in the solid state they are packed into very tight crystal shaped areas (thus, the name crystalline). However, they are not completely crystalline in the solid state since there are still regions of amorphous, random structure. Therefore, they are called semi-crystalline resins. Something very radical happens at the transition temperature for a semi-crystalline resin. It suddenly goes from an amorphous structure to a tightly packed crystalline structure. For this reason you can see that the pvT curves have a sudden drop off at the transition temperature. This rapid crystallization as the plastic freezes is the primary reason why semi-crystalline resins shrink more than amorphous resins. The degree of crystallization is also dependent on the cooling rate of the plastic so it is somewhat difficult to capture the full affect of crystallization on part shrinkage. Temperature

溫度性質的影響 Alpha1 Alpha1 (流動方向) 與 alpha2 (垂直流動方向) 均為線性熱膨脹係數 (LTEC) 以線性描述塑膠在溫度改變時 的尺寸變化 Alpha1 與 Alpha2 的數值不同造成產品的翹曲變形 半結晶性材料尤其明顯 alpha2 (mm/C) alpha1 (mm/C)

機械性質的影響 彈性模數 E1 and E2 分別代表流動方向與垂直流動方向的彈性模數值 E值越高，或是E1與E2值相差越小，產品越不容易收縮，也越不容易翹曲變形 非結晶性材料的E1及 E2值有時相差達數倍 添加的材料在E1及E2 值的差異越大，產品也 越容易翹曲變形 E1 E2

添加纖維對於翹曲變形的影響 纖維可增加沖擊強度（Impact Strength） 但是添加纖維可能會造成產品翹曲變形

建立個人資料庫 建立選擇資料庫 儲存資料庫於*.udb檔案格式中 種類(Category) Materials 形式(Type) Thermoplastics material 儲存資料庫於*.udb檔案格式中 The consolidation of the MPI and CM2K material databases has resulted in > 7000 thermoplastic materials You can create a personal database for the following types of materials: coolant material db, mold material db, reactive material db, encapsulation molding compound db, underfill encapsulant db, preform database, wire material db, leadframe material db Viscosity data fitting is no longer available within MPI/Synergy, but can be requested at the Moldflow website. It also provides a validation service in combination with the datafitting service (visit www.moldflow.com for details)

建立個人資料庫 從Moldflow材料資料庫中增加或是編輯 輸入材料資料 MPI (*.rax, *.asc) C-Mold (*.2000.udb) The consolidation of the MPI and CM2K material databases has resulted in > 7000 thermoplastic materials You can create a personal database for the following types of materials: coolant material db, mold material db, reactive material db, encapsulation molding compound db, underfill encapsulant db, preform database, wire material db, leadframe material db Viscosity data fitting is no longer available within MPI/Synergy, but can be requested at the Moldflow website. It also provides a validation service in combination with the datafitting service (visit www.moldflow.com for details)

建立個人資料庫 新材料資料 工具與對話 檢查資料資物性 從Moldflow塑膠網站獲得合適的數據 The consolidation of the MPI and CM2K material databases has resulted in > 7000 thermoplastic materials You can create a personal database for the following types of materials: coolant material db, mold material db, reactive material db, encapsulation molding compound db, underfill encapsulant db, preform database, wire material db, leadframe material db Viscosity data fitting is no longer available within MPI/Synergy, but can be requested at the Moldflow website. It also provides a validation service in combination with the datafitting service (visit www.moldflow.com for details)

QUESTIONS?