Shanghai Daoqin Plastics Co., Ltd.

ＰＣ统称 polycarbonate (PC), due to its excellent mechanical properties anti elastic 胶. ＰＣ tool has machine strong/high degree high, use temperature degree scope/range 广, electrical insulation property good （但 anti electrical property can 不变）, dimensional stability good and other features. in electrical product, table/sheet outer housing/shell, electronics product structural parts upper by use. is polycarbonate (PC) in disadvantages, in injection molding process in easy generate force cracking, for 缺口敏感, 一旦出现缺口, easy expand large, 且呈放射状 development and flow property 差.

ＰＣ／ＡＢＳ alloy is ＰＣ, ＡＢＳ按不 year-on-year made mixed combined material, it improvement ＰＣ easy cracking, flow property disadvantages, meanwhile also tool has excellent heat resistant property, flame retardant property, impact resistant property and dimensional stability, widely used in automotive table/sheet sheet/plate, automotive parts, machine housing/shell and power tools and other high strength and heat resistant products. １ issues analysis in 实际工 as in, use ＰＣ／ＡＢｓ alloy made as certain product outer 罩, outer and metal through 螺钉连接, outer 罩直径 is in ２００ｍｍ. outer through mold injection molding processing , metal through pressure processing. in product use process in, due to outer temperature degree 变化, outer cracking is product fault/failure main/primary 形式, product structure 形式见图１. through for various cracking analysis, 我们 出: outer in injection molding process in generate internal stress is cracking main/primary causes. in solution outer cracking issues process in, 我们摸索 summary 出 几 types remove its internal stress methods, simple 叙述如 lower. （１） improve/increase mold temperature degree. if mold temperature degree low, melt solvent material to mold very fast cooling, is easy injection molding phenomenon, make through adjustment injection molding pressure and holding pressure time can make mold cavity 充满, is due to melt material temperature degree cooling very fast, parts most rear melt combined separation temperature degree already very low, cooling molding rear, parts surface upper is 一体, internal upper has true positive melt combined formed 一体, melt 接痕. force 时, this most thin low step/link very easy cracking. for cracking product outer 罩, 我们沿 裂缝拉开 formed semi, 发现: cracking 处 断茬没 has 撕裂 痕迹, is non light slip, from 而证明 材 material internal 本身就没 has melt combined in 一起. mold temperature degree high, melt solvent material 进入浇注口 rear in mold cavity flow, temperature degree decline very slow, again through adjustment injection pressure and holding pressure time can remove 熔接痕, from 而避免 cracking. usually mold temperature degree is ８０℃～１００Ｃ, for/regarding complex, thin products and requirements relatively high products, mold temperature degree can improve/increase is separation １００℃～１２０Ｃ. （２） increase large 浇注口 dimensions. is plastics mixed combined material is non crystallization type polymer, has obvious melting point, melt viscosity high, flow property good, therefore requirements mold 浇注口 need short coarse, decrease/reduce pressure loss 失, meanwhile need relatively high pressure. 我们 系数 large, is ７６×１０咖ｍ／＇Ｃ, metal aluminum outer is thin parts, is in ２００ｍｍ, high 线胀系数 small, is ２４×ｌＯ－６ｍｍ／℃. for/regarding degree ９５ｒａｍ left right, similar semi housing/shell 体, 原浇们 use product, outer sleeve/set in metal upper, 直径注口 has in １．６ｒａｍ, rear is ｏ３ｒａｍ, is ①２００ｍｍ. in low temperature lower product outer shrinkage large, conditions obvious to improvement. metal aluminum shrinkage small, make outer by 撑开（３） for products hot 处理. 裂. therefore in product in, between need has is remove ＰＣ／ＡＢｓ alloy products in inner 应足够 间隙. ensure outer can 够自由 伸 shrink. force, can for products hot 处理, hot 处理 介质 according to types 材质 线胀系数 and temperature degree 变化范 is gas, and liquid wax and other, hot temperature degree 围, 计算出 semi direction upper is ０．３ｍｍ－０． in １１０℃～１３５℃ between, time products 尺４ｒａｍ left right. 寸, 形状, use requirements and hot 处理介质 different different, can 由几十 separation to small and other. using/adopting ２结语空 gas 介质, in in temperature １２０＂Ｃ left right, ４ small 时. in 实际工 as in, through for above this 几（４） increase fiber. measures use, already will product outer cracking issues tube/pipe ＰＣ材 material dimensional stability good, is solution. meanwhile this methods application to 另一ＰＣ／ＡＢＳ alloy material shrinkage rate also is large metal product in, already to good 效果, tool has aluminum 腔体. is decrease/reduce products temperature degree 变化 收 application. shrink meanwhile improve/increase products strong/high degree, decrease/reduce internal stress formed cracking, can in ＰＣ／ＡＢＳ in add reinforcement 玻璃纤参考文献维. according to requirements different, reinforcement glass fiber (GF) can add ｌＯ％, 【ｌ】马之庚, 陈开 ． engineering plastics manual/handbook ｆＭｌ． machine ２０％ or ３０％. products resistant strong/high degree, flexural strength and industrial 出版社． heat deflection temperature (HDT) has versus improve/increase. selection 【２】 machine design manual/handbook （第一册）【Ｍ】． machine industrial 出２０％ reinforcement glass fiber (GF), resistant strong/high degree and flexural strength 几乎版社． increase 一倍. separation from ５５ＭＰａ, ７５ＭＰａ improve/increase to １００ＭＰａ, １４０ＭＰａ, heat deflection temperature (HDT) from １０４℃ improve/increase to １２０℃, meet/satisfy requirements. add glass fiber meanwhile belt/tape appearance quality decline disadvantages, due to glass fiber add, surface color non-uniform phenomenon, through can 弥补不足. （５） other measures. ＰＣ alloy products cracking causes is products defect formed, another causes also in it and metal parts combined rear, due to hot cold shrink 系数