Shanghai Daoqin Plastics Co., Ltd.

PC property can excellent, transparent degree relatively high, impact tough property good, resistant creep, use temperature degree scope/range wide, PC process features is: melt viscosity for rate property small, for temperature degree property large, obvious melting point, melt viscosity relatively high, high temperature lower resin easy hydrolysis, products easy cracking. for this features, especially need attention/notes difference for 待: need increase melt flow property, is use increase large injection pressure using/adopting improve/increase injection temperature degree method to. requirements injection molding parts mold runner, gate short coarse, decrease/reduce pressure loss 失, meanwhile need relatively high injection pressure. resin in molding processing front 需进行充 separation drying 处理, make its water amount control in 0.02% below/following, in addition, in processing process in for resin also 应采取保 temperature measures, anti heavy new wet. not only need combined products design, also positive 确掌握 molding process, improve/increase injection molding parts mold temperature degree, for products rear and other can decrease/reduce or remove internal stress. product different and positive process parameters. lower 面谈谈 molding process 1, injection temperature degree must comprehensive products 形状, dimensions, injection molding parts mold structure. products property can, requirements and other 各方面 情况 add 以考虑 rear can as 出. generally in molding in selection temperature degree in 270~320℃ between, high material temperature ultra- 340℃时, PC will 会出现 separation understanding, products color deep, surface silver streaks, dark strip/profile, black spots, bubbles and other defect, meanwhile material mechanical properties significantly decline. 2, injection pressure for PC products material mechanical properties, internal stress, molding shrinkage and other has effect/influence for products appearance and demolding property has relatively large effect/influence, low or high injection pressure make products certain defect, generally injection pressure control in 80-120MPa between, for thin 壁, long process/workflow, complex, gate relatively small products, is melt flow retardant force, and 时充满 mold cavity, selection relatively high injection pressure （120 -145MPa）. from obtain 完整而 surface light slip products. 3, holding pressure pressure and holding pressure time holding pressure pressure large small and holding pressure time long short for PC products internal stress has relatively large effect/influence, holding pressure pressure small, shrink function small easy true or surface shrink 凹, holding pressure pressure large, gate easy generate relatively large internal stress, in processing in, high material temperature, low holding pressure method solution. holding pressure time selection products thick thin, gate large small, mold temperature and other 情况而定, generally small thin products very long holding pressure time, versus 反, large thick products holding pressure time relatively long. holding pressure time long short can through gate time experiment/testing 予以确定. 4, injection speed degree for PC products property can separation obvious effect/influence, remove thin 壁, small gate, deep 孔, long process/workflow products outer, generally using/adopting in speed or slow speed processing, most good is more grade injection, generally using/adopting slow - fast - slow more grade injection methods. 5, injection molding parts mold temperature degree generally control in 80-100℃就 can, for complex, relatively thin, requirements relatively high products, can improve/increase to 100-120℃, can ultra- injection molding parts mold heat deflection temperature (HDT). 6, screw speed and back pressure due to PC melt viscosity relatively large, from has 利塑化, has gas, has machine maintenance, anti screw negative large, for screw speed requirements can high, generally control in 30-60r/min is 宜, back pressure control in injection pressure 10-15% between is 宜. 7, PC in injection molding parts process in need control demolding agent use, meanwhile recycled material use can ultra- 三次, use amount is 20% left right. for production PC products machine requirements: requirements products most large injection amount （包括 runner, gate and other ）应不 large 于公称 injection amount 70-80%, screw selection mono 头螺纹 and other 螺距, belt/tape has ring pressure shrink type screw, screw long ratio L/D is 15-20, pressure shrink ratio C/R is 2-3.