Moldflow铜牌考试大纲.ppt

美的空调moldflow基础培训教程 The properties listed here are the ones used in our program material’s database to concentrate the attention on concepts needed to interpret better the results. Highlight the importance of this values: ejection temperature, maximum shear stress and shear rate. Note: 1) The transition temperature can be read from the pvT curves of the material. 2) MFR is a industry standard but it doesn’t apply well to injection molding because the testing is performed at low shear rates which do not relate to injection molding shear rates values. 8 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. 14 Thermal diffusivity concept taken from: /kr/encyclopedia/Thermal_diffusivity/ 14 Elastic modulus concept /courses/engri111/modulus.htm Shear modulus /library/glossary/s/bldef-s4824.htm Poisson’s ratio /crcd/farkas/lectures/mechprop/tsld010.htm So, thermoplastics are materials capable to be molded when heated while thermosets are set into their final shape when heated. From /s_plasticsresource/sec.asp?TRACKID=VID=46CID=124DID=226 “Molecular Arrangement of Polymers Think of how spaghetti noodles look on a plate. This is similar to how polymers can be arranged if they lack a specific for or are amorphous. Controlling and quenching the polymerization process can result in amorphous organization. An amorphous arrangement of molecules has no long-range order or form in which the po