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: 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.

        针 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 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 mold temperature degree, for products rear and other can decrease/reduce or remove internal stress. product different and positive process parameters.

         lower 面我们聊聊 molding process:

        1. raw materials drying

        PC type plastics, make to non low water 份也会 generate hydrolysis 而断键, molecular weight reduce and material property strong/high degree reduce phenomenon. therefore in molding processing front, 应严格 control polycarbonate (PC) water in 0.02% below/following, 以避免 molding product machine strong/high degree reduce or surface generate bubbles, and other 之异常 appearance.

        PC for water its 敏感, therefore injection molding front must separation drying, make its water amount reduce to 0.02% below/following, PC generally drying conditions: 100~120℃, time less 4 small above;

        2. injection temperature degree

         injection temperature degree must comprehensive products 形状, dimensions, 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. PC for temperature degree very 敏感, melt viscosity temperature degree rise high obvious decline, material temperature degree 250~320℃.(most good need ultra- 350℃), improve/increase temperature degree material temperature degree for PC塑化 has benefits. necessary internal stress 退火, temperature degree 125~135℃, time 2 small 时, cooling to normal temperature.

        3. 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.

         flow property 差, use high pressure injection, 但需顾 and parts large internal stress (can can cracking), injection speed degree: thick in speed, thin high speed.

        4. 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.

        5. 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.

        6. mold temperature degree

         mold temperature control: 85~120℃, generally control in 80-100℃就 can, for complex, relatively thin, requirements relatively high products, can improve/increase to 100-120℃, can ultra- mold heat deflection temperature (HDT). mold temperature high decrease/reduce mold temperature and PC material temperature 差异, can reduce made parts internal stress.

        7. 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.

        8. additives use

        PC in injection molding process in need control demolding agent use, meanwhile recycled material use can ultra- 三次, use amount is 20% left right.

        9.PC injection molding, for mold requirements relatively high:

        1) design can can coarse short, bending less runner, use 圆形截面 separation runner and runner abrasion light and other is make reduce material flow retardant force.

        2) injection gate can using/adopting 任何形式 gate, water 位直径不 small 于1.5mm.

        10. 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%;

        锁模 pressure: formed product 投影面积每平方公 separation 乘0.47至0.78吨(or 每平方寸乘3至5吨);

         machine large small: formed product weight is injection molding machine amount 40至60% is most 佳, machine polystyrene (PS) table/sheet its amount (盎斯)时, decrease/reduce 10%, is use GUANG DA之容 amount. 1盎斯=28.3公克.

         screw: screw long degree most less has 15 直径 long, its L/D is 20: 1 most 佳. pressure shrink ratio is 1.5: 1至30: 1. screw front 端之止流阀应 using/adopting sliding ring 式, its resin can flow most less has 3.2MM.

        11.PC injection molding rear 处理: use PE material machine