Shanghai Daoqin Plastics Co., Ltd.

in plastics melt, process in, material 不断移 toward material micro front 端（计 amount inner ）, 且越 越 more, 逐渐形 formed pressure screw toward rear 退. is retardant screw rear fast, ensure material uniform pressure 实, need to screw provide 一 反 direction pressure, this direction retardant screw rear pressure is back pressure. back pressure 亦称塑化 pressure, it control is through adjustment injection 油缸之回油节流阀 achieve, 预塑化 screw injection molding parts machine injection rear 闻都设 has back pressure 阀, adjustment screw rear injection 油缸泄油 speed degree, make maintain pressure （如 lower 图 示）; full electrical machine screw rear speed degree （ retardant force ） is, 由AC伺服阀 control. 适当调校 back pressure benefits: 1, can will inner material pressure 实, increase density, improve/increase amount, products weight and dimensions stability property. 2, can will material inner gas 体“ extrusion ”, decrease/reduce products surface gas 花, internal bubbles, high gloss uniform property. 3, decrease speed slow screw rear speed degree, make inner material separation 塑化, increase color powder, masterbatch and material mixed combined uniform degree, products mixed color phenomenon. 4, improves back pressure, can improvement products surface sink marks and product 周边 走胶情况. 5, can improves material wet degree, make material quality improve/increase, improvement material 充模时 flow property, products surface cold 胶纹. high back pressure, easy lower issues: 1, front 端 熔 material pressure high, material temperature high, viscosity decline, material in screw in and material and screw 间隙 漏流 amount increase large, reduce efficiency （ mono time inner material amount ）. 2, for/regarding heat stabilized property plastics （如PVC, POM and other ） or color agent, material temperature degree rise high in material in hot time growth formed hot separation understanding, or color agent color degree increase large, products surface color / gloss 变差. 3, back pressure high, screw rear slow, 预塑回 material time long, increase cycle time, production efficiency decline. 4, back pressure high, material pressure high, rear nozzle easy 发生熔胶流涎 phenomenon, lower 次射胶时, water runner inner cold material 会堵塞 water or products in cold material 斑. 5, in process in, 常会因 back pressure large, nozzle 出现漏胶 phenomenon, raw materials 并导致射嘴附近 发 hot bad. 6, machine and screw machine abrasion loss increase large. back pressure low 时, easy lower issues: 1, back pressure low 时, screw rear fast, 流入迷炮筒 front 端 熔 material density small （ relatively dispersion ）, 夹入空 gas more. 2, 会导致塑化 quality 差, amount unstable, product weight, products dimensions large. 3, products surface 会出现 sink marks, gas 花, cold material 纹, gloss and other defect phenomenon. 4, product internal easy bubbles, product and easy 走不满胶. back pressure 调校: injection molding parts back pressure 调校应视 raw materials property can, drying 情况, product structure and quality 状况而定, back pressure generally in 3-15kg/cm3. product surface has less gas 花, mixed color, sink marks and product dimensions, weight large 时, can increase back pressure. 当射嘴出现漏胶, 流涎, material hot separation understanding, product color and material slow can 考虑适当 decrease low back pressure. back pressure is injection molding parts molding process in control material quality and product quality important parameters 之一, combined back pressure for/regarding improve/increase product quality has important function, can overlook!