Shanghai Daoqin Plastics Co., Ltd.

plastics injection molding processing molding process process main/primary filling, holding pressure, cooling, demolding stage/phase, this stage/phase 直接决定 products molding quality, but also this stage/phase is 一 完整 连续 process.

　　一, filling stage/phase

　　 filling is injection molding ring process in 第一步, time from mold combined injection molding 算起, to mold type filling to large 约95% is 止. upper, filling time short molding efficiency high, is in, molding time or injection molding speed degree need to very more conditions made 约.

　　 high speed filling 时剪切 rate relatively high, plastics due to 剪切变 dilute function in viscosity decline 情形, make overall flow retardant force reduce; local viscous add hot effect/influence make solid thick degree thin. therefore in flow control stage/phase, filling is 往往取决于待 filling large small. in flow control stage/phase, due to high speed filling, melt 剪切变 dilute 效果往往 very large, thin cooling function obvious, is speed rate use upper 风.

　　 low speed filling, hot control low speed filling 时, rate relatively low, local viscosity relatively high, flow retardant force relatively large. due to hot plastics speed rate relatively slow, flow relatively is slow, make hot 传导效应 relatively is obvious, hot amount speed is cold film belt/tape 走. add upper relatively a small amount of viscous add hot phenomenon, solid thick degree relatively thick, also 进一步 increase relatively thin flow retardant force.

　　 due to flow causes, in flow front plastics polymer/macromolecule toward 几乎平行 flow front. therefore plastics in 交汇时, 接触面 polymer/macromolecule versus 平行; add upper 两股熔胶 property 质各异(in film in time different, temperature degree, pressure different), formed 熔胶交汇区域 in micro upper structure strong/high degree 极差. in light lower will parts 摆放适当 角 degree use 肉眼观察, can has obvious combined generate, this is 熔接痕 形 formed mechanism. 熔接痕 not only effect/influence parts appearance, meanwhile due to micro structure dispersion, easy formed force in, from make separation strong/high degree reduce 而发生 fracture.

　　 generally 而言, in high temperature generate 熔接 熔接痕 strong/high degree 极佳, therefore high temperature lower, polymer/macromolecule active property relatively 佳, can versus 穿透缠绕, in addition high temperature degree 区域两股 melt temperature degree relatively is 接近, melt hot property 质几乎 same, increase 熔接区域 strong/high degree, in low temperature 区域, strong/high degree relatively 差.

　　二, holding pressure stage/phase

　　 holding pressure stage/phase function is 持续施 add pressure, pressure melt, increase plastics density, 以补偿 plastics shrinkage is. in holding pressure process in, due to mold cavity in already 经填满 plastics, back pressure relatively high. in holding pressure pressure process in, injection molding machine screw can slow slow toward front micro small 移动, plastics flow speed degree relatively is slow, this flow as holding pressure flow. due to in holding pressure stage/phase, plastics 受模壁 cooling solid add fast, melt viscosity increase very fast, therefore mold type inner retardant force very large. in holding pressure rear 期, material density increase large, plastics 也逐渐 molding, holding pressure stage/phase need 一直持续 to gate solid 化封口 is 止, holding pressure stage/phase mold cavity pressure to most high value.

　　 in holding pressure stage/phase, due to pressure versus high, plastics 呈现部 separation can pressure shrink features. in pressure relatively high 区域, plastics relatively is 密实, density relatively high; in pressure relatively low 区域, plastics relatively is hydrophobic 松, density relatively low, therefore formed density distribution is and time 发生变化. holding pressure process in plastics speed relatively low, flow again 起主导 function; pressure is effect/influence holding pressure process main/primary factors. holding pressure process in plastics already 经充满 mold cavity, 此时逐渐 solid melt as is pressure 介质. mold cavity in pressure plastics 传递至 film surface, has mold trend, therefore need 适当 索模 force 进行索模, force in positive 常情形 lower micro micro will mold 撑开, for/regarding mold gas tool has function; 但若涨模 force large, easy formed molding product flash/burrs, material, 甚至撑开 mold. therefore in selection injection molding machine 时, selection tool has large force injection molding machine, anti 止涨模 phenomenon can has 效进行 holding pressure.

　　三, cooling stage/phase

　　 in injection molding mold in, cooling system design non important. this is is molding plastics products has cooling solid to rigid property, demolding rear can plastics products to outer force generate deformation. due to cooling time molding cycle 约70～80%, therefore design good cooling system can large degree shrink short molding time, improve/increase injection molding production rate, reduce cost. design cooling system make molding time long, increase cost; cold non-uniform more 进一步造 formed plastics products warpage deformation.

　　 according to 实验, melt mold hot amount large separation dispersion 发, separation has 5%经辐射, for 流传递 to large gas in, its in 95% from melt to mold. plastics products in mold in due to cooling water tube/pipe function, hot amount mold cavity in plastics through hot 传导经模架传至 cooling water tube/pipe, again through hot for by cooling liquid belt/tape 走. less by cooling water belt/tape hot amount 则继续 in mold in 传导, 至接触 outer rear dispersion in gas in.

　　 injection molding molding 首期由 clamping time, filling time, holding pressure time, cooling time and demolding time formed. its in cooling time specific gravity most large, large is 70～80%. therefore cooling time will effect/influence plastics products molding cycle long short and output/production volume large small. demolding stage/phase plastics products temperature degree cooling low plastics products heat deflection temperature (HDT), anti plastics products residual stress 导致 松弛 phenomenon or demolding outer force formed warpage and deformation.

　　四, demolding stage/phase

　　 demolding is injection molding ring in most rear step/link. although products already cooling molding, demolding also is for products quality has very important effect/influence, demolding methods 不当, can can 会导致 product in demolding force 不均, ejection 时引起 product deformation and other defect. demolding methods main/primary has types: demolding and material sheet/plate demolding. design mold need according to product structure features selection combined demolding methods, ensure product quality.

　　 for/regarding selection demolding mold, 顶杆 设置应尽 amount uniform, and 位置应选 in demolding retardant force most large and parts strong/high degree and rigid degree most large 方, 以免塑 parts deformation loss bad.

　　而脱 material sheet/plate generally used for deep thin container and 不允许 has 推杆痕迹 transparent products demolding, this type of structure features is demolding large uniform, 运动平稳, obvious 遗留痕迹.