Shanghai Daoqin Plastics Co., Ltd.

 PBT molding processing properties  
    1)PBT wet property relatively small, in high temperature lower water separation comparison 敏感, molding processing make PBT separation degradation, color deep, surface generate 斑痕, usually 应进行 drying 处理.  
    2)PBT熔 material has good flow property, therefore easy molding thin 壁, complex products, need attention/notes mold 溢 material, and nozzle phenomenon.  
    3)PBT has obvious melting point, temperature degree rise melting point above 时, flow property 会猛然 increase, need attention/notes.  
    4)PBT molding processing scope/range relatively narrow, cooling crystallization very fast, add flow property good, especially fast speed injection.  
    5)PBT has relatively large shrinkage rate and its shrinkage scope/range, in different direction shrinkage rate relatively other plastics more obvious.  
    6)PBT for 缺口, reaction very 敏感, in this easy 出现应 force in, make can force large is decline, in force or impact easy 发生破裂, therefore in design parts attention/notes this 一点, has 转角处, especially is internal 转角应尽 amount using/adopting 圆弧 渡.  
    7) pure PBT elongation can 达200%, therefore belt/tape has relatively small products can from mold upper strong/high made demolding. use glass fiber (GF) or filler filling rear, its elongation large is decline, in products in has 凹陷就不 can strong/high made demolding.  
    8)PBT mold runner in can can lower short coarse is 佳, runner most good. generally modified and modified PBT均 can use runner, glass fiber reinforced PBT application hot runner molding can has good 效果.  
    9)点 gate and gate function large, can reduce PBT熔 material table/sheet viscosity, has molding, is using/adopting gate, gate 直径应以偏 large is good.  
    10) gate most good positive for type or type 芯, this can 避免喷射, make material in mold cavity in flow 时回补 most small. 否则, products easy generate surface defects, make property can poor 化.  
    PBT main/primary injection molding conditions  
    1) material temperature degree. material temperature degree selection for PBT molding separation important, temperature degree low, defect, formed products material, 凹陷, shrinkage and gloss and other phenomenon. temperature degree high, formed nozzle 流涎严 heavy, 溢边, color deep, degradation. usually, material temperature degree control in 240~280℃, glass fiber reinforced PBT control in 230~260℃. nozzle temperature degree control in low material front temperature degree 5~10℃.  
    2) mold temperature degree. mold temperature and products dimensional stability, warpage deformation, molding cycle and crystallization degree has 直接关系. PBT easy crystallization, make in normal temperature lower crystallization very fast, mold temperature degree need high, usually is 40~60℃,而 glass fiber reinforced PBT mold temperature high, usually is 60~80℃.  
    3) injection pressure. PBT melt viscosity low, flow property good, can using/adopting in and other degree injection pressure, generally is 60~90MPa, glass fiber reinforced PBT is 80~100MPa, usually injection pressure parts thick degree increase add large, need ultra- 100MPa,否则会 make demolding difficult.