Shanghai Daoqin Plastics Co., Ltd.

crystallization type plastics crystallization degree and crystallization effect/influence to products material 理, mechanical properties. molding cooling speed degree slow, has crystallization 进行, can improve/increase crystallization degree. therefore, need to mechanical properties excellent and surface gloss good products for/regarding mold temperature control is is important. is let cooling speed degree slow, 以便充 separation crystallization, must improve/increase injection molding parts mold temperature degree, can 避免 会 make molding cycle long. crystallization type plastics in its melting point 附近时 ratio 容（cm3/g）变化 relatively large. has material in cooling has 一定程 degree shrinkage, generally crystallization type plastics tool has ratio non crystallization type plastics molding shrinkage large features. therefore, its products easy generate deformation, its thick products easy generate 凹痕, large made parts has can can warpage, in relatively thick separation formed 凹痕. 总之, not only 应考虑 to injection molding parts mold temperature degree high low, but also need attention/notes to products separation must uniform cooling solid （ or uniform crystallization ）, this non important. table/sheet is various plastics molding material generally molding conditions. table/sheet commonly used plastics material injection molding parts molding conditions （a） crystallization type plastics plastics molding conditions high density polyethylene (PE) polypropylene (PP) polyamide (PA) polyoxymethylene (POM) nylon 6 nylon 66 homopolymer copolymer material temperature degree /℃210～280200～270210～260140～300180～200180～210 resin temperature degree /℃210～290210～280220～300250～310190～210190～220 injection molding parts mold temperature degree /℃30～9030～10060～8060～8080～12080～120 injection pressure /MPa50～15040～10070～16060～15080～11060～150（b） non crystallization type plastics plastics molding conditions polystyrene (PS) （ general purpose grade ）ABS resin polymethyl methacrylate (PMMA) polycarbonate (PC) modified PPO（Noryl） hard polyvinyl chloride (PVC) material temperature degree /℃180～240200～280180～220260～310240～280165～185 resin temperature degree /℃190～200200～240200～230280～320250～300175～195 injection molding parts mold temperature degree /℃30～8040～8040～9085～12065～10040～60 injection pressure /MPa40～13080～15070～15080～15085～140100～150[注1] 均 is filling glass fiber and other non reinforcement plastics data; [注2] resin temperature degree * is in material inner resin temperature degree, generally ratio material temperature degree high, table/sheet from nozzle toward in injection melt resin temperature degree. （1） polyethylene (PE) polyethylene (PE) generally in molding flow property good. can is its heat stabilized property 担心. however, it separation orientation property strong/high, therefore products easy generate deformation. high density polyethylene (PE) tool has crystallization temperature degree. generally 说, requirements relatively high injection pressure and injection speed degree. especially is for/regarding thick products, injection speed degree versus important, it can improvement products surface gloss, anti products warpage and reduce molding shrinkage. （2） polypropylene (PP) polypropylene (PP) has very more and polyethylene (PE) versus 似, 如图6 示, its flow property positive ratio material temperature degree, in 280℃ left right 时, resin aging, requirements temperature degree control in 270℃ below/following is 宜. its separation orientation property relatively strong/high, in relatively low temperature degree molding 时, due to its separation orientation, easy generate warpage, and other deformation, must attention/notes control temperature degree. various nylon melting point molding temperature degree product types melting point /℃ molding temperature degree /℃ nylon 6 215220～300 nylon 66 255260～320 nylon 6 10213220～300 nylon 12 177185～300（3） polyamide (PA) （ nylon ） polyamide (PA) viscosity temperature degree 变化极 is 敏感. it and its it thermoplastic property plastics different, nylon melting point comparison obvious （ table/sheet 7 示）. polyamide (PA) in its melting point upper molding, therefore its molding temperature degree must ratio generally material need high. about/regarding nylon crystallization degree and injection molding parts mold temperature degree between 关系如图8 示. due to nylon wet property relatively large, must 预先充 separation drying. however, in 90℃ above drying 便会变 color, must add attention/notes. （4） polyoxymethylene (POM) polyoxymethylene (POM) （POM） has homopolymer and copolymer, is flow property good resin. type resin easy hot separation understanding, must attention/notes control molding temperature degree. POM copolymer ratio POM homopolymer heat stabilized property good （图9）, it can in high temperature degree conditions lower molding processing, 但此材 material in material inner time long, 否则, 会发生 hot separation understanding make products color 泽发黄. （5）PBT resin PBT resin （ polybutylene terephthalate (PBT) ） and PET（ polyethylene terephthalate (PET) ）均 belongs to saturated and polyester （ thermoplastic polyester ）. PBT resin features is melt viscosity low, molding property good. it crystallization speed, solid fast. PBT and PET resin generally more using/adopting glass fiber reinforcement improve/increase property can. in 此, introduction non reinforcement resin molding key points. its add hot material generally is 230～270℃（ flame retardant grade is 250℃）. injection molding parts mold temperature degree is 40～90℃, tube/pipe in relatively low mold temperature can molding, is to surface gloss products, using/adopting relatively high mold temperature. injection pressure scope/range is 50～130 MPa. resin solid speed, therefore injection speed degree fast, make products appearance good and has improve/increase property can. in addition, due to wet resin melt 时, 会发生遇 water separation understanding rear 果, make products 变脆, therefore in processing front must resin drying.