Shanghai Daoqin Plastics Co., Ltd.

large separation between versus scratch property is plastics viscous property.而 this type of viscous property large small 系数称 is viscosity, therefore viscosity is melt plastics flow property high low 反映. viscosity large, melt viscous property strong/high, flow property 越差, processing difficult. industrial application upper, comparison types plastics flow property is its viscosity value,而 is its melt flow large small (称MFI): 谓MFI,就 is in 一定熔化 temperature degree lower, melt to pressure function lower, mono time inner (generally is 10 separation 钟) through standards melt weight.以g/10min table/sheet 示,如 injection molding processing grade PP material, grade different,MFI value can from 2.5~30间变化, plastics viscosity non formed 不变, plastics features 变化, outer temperature degree, pressure and other conditions effect/influence,都 can formed viscosity 变化.1.1 molecular weight effect/influence molecular weight large, molecular weight distribution narrow,反映出 viscosity large.1.2 low separation add effect/influence low separation add can reduce large separation between function force.因而 make viscosity decrease small, has plastics molding time add solvent or increase agent is is reduce viscosity, make easy molding.1.3 temperature degree viscosity effect/influence temperature degree for large more melt plastics viscosity effect/influence is very large, generally temperature degree rise high,反映出 viscosity low,但 various plastics melt viscosity reduce degree large small has 出入:PE/PP type plastics, rise high temperature degree for high flow property, reduce melt viscosity function very small, temperature degree high,消 consumption add large,反而 不偿失PMMA/PC/PA type and other plastics, temperature degree rise high viscosity significantly decline,PS ABS rise high temperature degree for/regarding reduce viscosity molding has relatively large benefits 1.4剪切 speed degree effect/influence has increase plastics speed degree can make plastics viscosity decline,但 has separation plastics,如PC亦 has outer, its viscosity 几乎不受 screw speed effect/influence.1.5 pressure effect/influence pressure for viscosity effect/influence comparison complex, generally PP&PE type viscosity pressure effect/influence is very large,但 for PS effect/influence versus significantly,实际 production in, in equipment relatively machine upper,应 attention/notes high speed injection,即 high speed degree function,而不应盲目 will pressure improve/increase.（二） injection temperature degree control for molding processing effect/influence 谓炮筒 temperature degree control is plastics in material inner how to from raw materials material uniform by add hot is property viscous 流体,也就 is material temperature how to issues.2.1 material temperature degree adjustment ensure plastics 塑化良 good, can injection also 不引起 separation understanding. this requirements 我们不 can made plastics for temperature degree property has reduce temperature degree, use injection molding processing pressure or injection speed degree and other method strong/high 行充模.2.2 plastics melt temperature degree main/primary effect/influence processing properties, meanwhile effect/influence surface quality and color 泽.2.3 material temperature control and made parts injection molding processing mold has 关, large simple made parts, made parts weight and injection amount relatively 接近,需 use relatively high temperature, thin 壁.形状 complex need use high temperature.反之, for/regarding thick made parts, certain need add as,如装嵌 parts, can use low temperature, identification plastics solvent temperature degree is 否 宜 can use 点动动 as in low pressure speed lower for injection 观察,适宜 material temperature make material rigid has force,不 belt/tape 泡,不卷曲, light 亮连续.2.4 material temperature generally is from material to material 段依次递 rise,但 is anti plastics separation understanding and made parts color 变化也 can low in 段, material temperature 配置不当 has 时会造 formed screw fault/failure -- screw or 空转, this also can can is injection pressure large or screw ring (介子)失效造 formed material front dilute thin material toward material direction 反流.当 this material 灌进螺纹端面 and material inner micro small 间隙而受 to relatively low temperature degree cooling 时, will cold solid formed film 紧紧卡 in 两 壁面 between, make screw can or slip. from effect/influence add material.此时,切勿 strong/high 行松退 or injection,建议 add material cooling water 暂时关闭, strong/high rise high add material temperature degree ratio plastics melting point high 30~50摄氏 degree,并 meanwhile material temperature degree reduce 至熔化 temperature degree 附近,待10~20 separation rear, small 心 转动 screw, can 转动时才 heavy machine,然 rear slow add material.（三） injection cycle in pressure control 3.1实际施 use pressure ratio type pressure high, in injection process in,模控 pressure upper rise, most to 一 峰 value, this value is usually injection pressure. injection pressure need ratio type pressure high.3.2 holding pressure pressure function: mold cavity plastics rear to gate full cooling for front time, mold cavity inner plastics still need versus high pressure 支持,即 holding pressure, its specific function is:A:补充靠近 gate material amount,并 in gate cold for front made mold cavity in hard plastics in pressure function lower, toward gate material direction 倒流.B: anti made parts shrinkage, decrease/reduce true 空泡.C: decrease/reduce made parts large injection pressure generate mold sticking or bending deformation phenomenon. therefore holding pressure pressure usually is injection pressure 50%~60%. holding pressure pressure or time long large has can can will gate and runner upper cold material made parts inner, make gate upper upper cold material 亮斑, meanwhile milli benefits long cycle.3.3 injection pressure selection A. according to made parts 形状. thick thin selection.B.针 for different plastics raw materials selection. in production conditions and made parts quality standards can lower,建议 using/adopting temperature low pressure process conditions.3.4 back pressure pressure adjustment back pressure table/sheet is plastics process pressure. has 进也称之 is pressure.A. color mixed and 效果受 back pressure effect/influence, back pressure add large, mixed and function add strong/high.B. back pressure has troubleshooting plastics parts various gas 体, decrease/reduce and bubbles phenomenon.C.适当 back pressure can material inner local material phenomenon, therefore material 筒时往往 will back pressure add large.（四） injection speed degree control 4.1 speed degree high low effect/influence: low speed advantages is speed 平稳, made parts dimensions comparison stability,波动 relatively small, made parts internal stress low, inner outer toward force property relatively good, disadvantages is made parts easy delamination combined defect melting point 痕, water and other, high speed can using/adopting relatively low injection pressure,改进 products gloss degree and slip degree,消 remove 接缝线 phenomenon and delamination phenomenon, shrinkage small, color more uniform 一致. disadvantages is easy generate ”自由喷射”,即出现滞流 or 涡流. temperature rise high, color 发黄,排 gas defect and has demolding difficult. viscosity high plastics has can can generate melt 破裂, made parts surface generate 雾斑, meanwhile increase internal stress 引起 翅曲 and thick parts 沿接缝线 cracking toward. lower is surface injection speed degree 不当引起 defect 形态:夹 water 纹(slow) 射纹(fast)0烧焦(fast) water 波纹(slow)4.2 using/adopting high speed high pressure injection 情况:1. plastics viscosity high, cooling speed degree fast, long process/workflow made parts.2.壁 thick thin made parts.3. glass fiber (GF) reinforcement plastics.4.3 more grade speed application: due to system and 各部位几何 conditions different, different for/regarding melt flow (especially is speed degree)提出 requirements, this 就出现 more grade injection,我们 can according to products 形状, for versus for thin 壁,形状 complex separation fast speed 充模,而 for/regarding water and easy 烧焦处 use low speed or in speed 充模. large separation product can using/adopting low speed — high speed — in speed process, from to products table/sheet and inner in quality 目. this 一设置 methods formed is general purpose 公式.