PET注塑成型的工艺条件
1） PET的吸湿性比PBT略大，粒料在高温下对水比较敏感，当含水量超标时，在成型加工时会发生水解，使质量大幅下降，因此，在成型加工前，必须对原料进行干燥。
2） PET的结晶度比PBT小，且随相对分子量增高而降低，故成型周期较长，不能像PBT那样快速成型。]
3） PET的成型收缩率较大，一般为1.8%左右，玻纤增强PET为0.2~1.0%，高模温所得塑件的收缩率大，低模温塑件的收缩率小。
4） PET制品中往往残留一定的内应力，因此一般成型后常需后处理。
5） 在PET成型时加入的回料应是充分烘干和没有产生降解的，加入量应不超过20%。
6） PET在熔融状态下的流变体为非牛顿流型，温度对熔体粘度影响不大，可以调节压力来增大剪切英里或剪切速率。
7） PET有明显的熔点，加工温度范围窄，为270~290℃，当超过300℃时会发生热降解。
8） PET成型时的保压时间不能过长，否则会使内应力增加，一般为20~50s。
9） 由于PET熔体的固化较快，故应采用高速注射，以使熔体尽快充满模腔。
10） PET与PBT一样，对尖角、缺口非常敏感，这些地方易出现应力集中，使承载能力大为下降，在受力或受冲击时易发生破裂，故对这些地方应尽量采用圆弧过度。
11） PET模具流道应尽可能减少熔体压力降，避免采用较高熔体温度，流道以短而粗较好，表面积和横截面积之比应小，多用圆形流道。
12） 在避免熔料喷射的前提下，PET浇口应开设在塑件最厚处，可避免流动阻力大和冷却快的缺点，保证其充满型腔。
13） PET浇口的开设方位最好能正对型腔壁和粗大的型芯，这样可以改变流向、降低流速，使熔料能均匀填充型腔，避免表面缺陷。
14） PET在熔融时为假塑性流体，且流动性好，可选用点浇口或潜伏浇口，但浇口以偏大为好，过小，会增大压力降。
（2） PET的主要注塑成型条件
1） 料筒温度。PET的成型温度范围窄，温度的高低会直接影响制品的性能。若温度过低，则塑化性不好，使塑件出现凹陷、缺料等缺陷；反之，温度过高，会造成溢边，喷嘴流延，色泽变深，机械强度下降，甚至引起降解。通常，料筒温度控制在240~280℃，玻纤增强PET的料筒温度为250~290℃，不得超过300℃，喷嘴温度一般比料筒温度低10~20℃。
2） 模距温度。模温直接影响熔料的冷却速度和结晶度，结晶度不同，则塑件性能不同。通常，模具温度控制在100~140℃，当成型薄壁塑件时，可取小值；成型厚壁时，可取大值。
3） 注射压力。PET熔体的流动性好，易于成型，通常采用中等压力，压力为80~140MPa，玻纤增强PET的注射压力为60~150MPa。注射压力的确定，应考虑PET的粘度、填料的种类和数量，浇口的位置及大小，塑件的形状和尺寸、模温，注塑机类型等。
英文翻译：
PET injection molding process conditions
1) PET hygroscopicity slightly larger than the PBT, Materials in the water under high temperature sensitive, when the water content exceeding, in molding and processing will occur hydrolysis, so that the quality of substantial decline, therefore, during processing, the need for raw materials for drying. 2) the degree of crystallinity of PET than PBT small, and with relatively higher and lower molecular weight, the molding cycle is longer, PBT did not like rapid prototyping. ] 3) PET molding shrinkage rate larger, usually around 1.8%. Glass Fiber Reinforced PET 0.2 ~ 1.0%, from the high-temperature plastic parts shrinkage rate, the low-temperature plastic parts smaller contraction rate. 4) PET products usually within a certain residual stress, it is generally required after molding often after treatment. 5) In PET molding to the material should be back to full drying and not producing biodegradable, the amount should not exceed 20%. 6) PET in the molten state of a non-Newtonian fluid flow, temperature of the melt viscosity of the impact is not great, It can adjust the pressure to increase shear miles or shear rate. 7) PET has obvious melting point, the narrow scope of the processing temperature of 270 ~ 290 ° C, When more than 300 ° C thermal degradation will occur. 8) PET molding the pressing time not too long, otherwise would stress is increasing, and for 20-50s. 9) As the melt faster curing, the high-speed injection should be used to melt as soon as possible so that full-scale cavity. 10) PET and PBT, the right corner, and the gap is very sensitive to these places prone stress concentration, carrying capacity so that the significant decline in the force or impact of the breakdown-prone, Hence, these areas should be to maximize the use of excessive arc. 11) PET mold flow should, as far as possible to reduce the melt pressure drop, in order to avoid using high melt temperature, Road to flow and short rough better, and the surface area of cross sectional area ratio should be small and more circular flow. 12) in order to avoid jet melt under the premise that PET should open gate in the thick plastic parts, avoid resistance movement and cooling fast shortcomings, and ensure its full cavity. 13) PET runner position in the creation is the best-thick wall and the core, this can change the flow lower velocity, melt evenly filled cavity to avoid surface defects. 14) PET in the melting of pseudoplastic fluid, liquid, and may choose to point gate or potential gate, But to have the gate for good, too small, would increase pressure drop. (2) PET injection molding of the main conditions of a) melt temperature. PET molding temperature range is narrow, and the temperature would have a direct impact on product performance. If the temperature is too low, then the plastics is bad, the place plastic parts, shut defects; Instead, the high temperature will cause overflow edge, extension nozzle flow, deep color change, decreased mechanical strength, even causing degradation. Usually, melt temperature control at 240 ~ 280 ° C, Glass Fiber Reinforced PET melt temperature of 250 ° C-290, not more than 300 ° C, nozzle temperature generally lower than the melt temperature of 20 ° C ~ 10. 2) mode from the temperature. Mold temperature melting materials directly affect the cooling rate and the degree of crystallinity, degree of crystallinity were different, different properties of plastic parts. Usually, mold temperature control at 100 ~ 140 ° C, when the molding thin-walled plastic parts, the desirability of small value; Thick molding, desirable big value. 3) injection pressure. PET melt flow, and easy to shape, usually adopts the middle of pressure for the 80-140MPa. Glass Fiber Reinforced PET injection pressure for the 60-150MPa. Injection pressure setting, PET should consider the viscosity, filler type and quantity gate of the location and size, Plastic Parts of the shape and size, die temperature, injection molding machine type.
网上找到的，不知可不可以
内容全部来源于网络收集，如有侵权，请联系网站删除：QQ：24596024