Shanghai Daoqin Plastics Co., Ltd.

design plastics 模时, 确定 injection molding parts mold structure rear can for injection molding parts mold separation detailed design, 即确定各模 sheet/plate and parts dimensions, type and type dimensions and other. this will and has material shrinkage rate and other main/primary design parameters. has specific formed plastics shrinkage rate can type 腔各部 separation dimensions. make injection molding parts mold structure positive 确, use parameters 不当, can can production quality combined 格 塑 parts. plastics shrinkage rate and its effect/influence factors thermoplastic property plastics features is in add hot rear 膨胀, cooling rear shrinkage, add pressure rear 体积也 will shrink small. in injection molding parts formed process in, will melt plastics injection injection molding parts mold type inner, 充填结束 rear material cooling solid 化, from injection molding parts mold in 取出塑 parts 时即出现 shrinkage, shrinkage is molding shrinkage. parts from injection molding parts mold to stability this time inner, dimensions still 会出现 micro small 变化, types is shrinkage, shrinkage is rear shrinkage. types is certain wet property plastics wet 而出现膨胀. nylon 6 10含 water amount is 3%时, dimensions increase amount is 2%; glass fiber reinforcement nylon 66 含 water amount is 40%时 dimensions increase amount is 0.3%. its in main/primary function is molding shrinkage. currently various plastics shrinkage rate （ formed shrinkage ＋ rear shrinkage ） methods, generally recommendation Germany standards in DIN16901 规定. 即以23℃±0.1℃时 injection molding parts mold type dimensions and molding rear 放置24 small 时, in temperature degree is 23℃, versus for wet degree is 50±5% conditions lower amount versus parts dimensions 之差算出. shrinkage rate S由 lower table/sheet 示: S={(D－M)/D}×100% (1) its in: S- shrinkage rate; D- injection molding parts mold dimensions; M-塑 parts dimensions. if already parts dimensions and material shrinkage rate injection molding parts mold type is D=M/(1-S). in injection molding parts mold design in is 简化计算, generally use lower injection molding parts mold dimensions: D=M+MS (2) if 需实施 relatively is 精确 计算, application lower 式: D=M+MS+MS2 (3) in shrinkage rate 时, due to shrinkage rate need more factors effect/influence can use value, use 式(2)计算 type dimensions basic upper meet/satisfy requirements. in manufacturing injection molding parts mold 时, type according to lower processing, type 芯则按 upper processing, necessary can as 适当 修整. difficult 于精确确定 shrinkage rate main/primary causes, is various plastics shrinkage rate is 一 定 value, is scope/range. is different injection molding parts processing production types material shrinkage rate same, make is 一 工 injection molding parts processing production different 批号同 types material shrinkage rate 也不一样. 因而各 injection molding parts processing can is use provide injection molding parts processing production plastics shrinkage rate scope/range. its 次, in formed process in shrinkage rate also to parts 形状, injection molding parts mold structure and formed conditions and other factors effect/influence. lower for this factors effect/influence as introduction. parts for/regarding molding parts thick 说, generally due to thick cooling time relatively long, shrinkage rate relatively large. for generally parts 说, material flow direction L dimensions and 垂直于熔 material direction W dimensions relatively large 时, shrinkage rate 差异也 relatively large. from material flow 距离 看, gate separation pressure loss large, 因而该处 shrinkage rate ratio gate large. add strong/high 筋, 孔, and and other tool has shrinkage resistant force, this shrinkage rate relatively small. injection molding parts mold structure gate for shrinkage rate has effect/influence. use small gate 时, holding pressure 结束之 front gate solid make parts shrinkage rate increase large. injection molding parts in cooling structure is injection molding parts mold design in key/critical. cooling design 不适当, 则因塑 parts temperature degree 不均衡而 generate shrinkage 差, its is make parts dimensions ultra- 差 or deformation. in thin separation, injection molding parts mold temperature degree distribution for shrinkage rate effect/influence more is obvious. molding conditions material temperature degree: material temperature degree （ plastics temperature degree ） relatively high 时, pressure relatively good make shrinkage force decrease small. use small gate 时, gate solid 化早而 make shrinkage rate still relatively large. for/regarding thick parts 说, make material temperature degree relatively high, its shrinkage still relatively large. material: in molding conditions in, amount decrease/reduce material make parts dimensions maintain stability. material 不足则无 method maintain pressure, make shrinkage rate increase large. injection pressure: injection pressure is for shrinkage rate effect/influence relatively large factors, especially is 充填结束 rear holding pressure pressure. in generally lower, pressure relatively large 时, material density large, shrinkage rate relatively small. injection speed degree: injection speed degree for shrinkage rate effect/influence relatively small. for/regarding thin parts or gate non small, and use strong/high material 时, injection speed degree add fast shrinkage rate small. injection molding parts mold temperature degree: usually injection molding parts mold temperature degree relatively high shrinkage rate relatively large. for/regarding thin parts, injection molding parts mold temperature degree high material flow retardant resistant small, shrinkage rate relatively small. molding cycle: molding cycle and shrinkage rate 无直接关系. attention/notes, add fast molding cycle 时, injection molding parts mold temperature degree, material temperature degree and other 必然也发生变化, from effect/influence shrinkage rate 变化. in material experiment/testing 时, according to 由 需 output/production volume molding cycle molding, for parts dimensions 进行检验. use injection molding parts mold plastics shrinkage rate experiment/testing 实例如 lower. injection machine: clamping force 70t, screw 直径Φ35mm, screw speed 80rpm; molding conditions: most high injection pressure 178MPa, material temperature degree 230(225-230-220-210)℃, 240(235-240-230-220)℃, 250(245-250-240-230)℃, 260(225-260-250-240)℃, injection speed degree 57cm3/s, injection time 0.44～0.52s, holding pressure time 6.0s, cooling time 15.0s. injection molding parts mold dimensions and manufacturing injection molding parts mold type and type processing dimensions remove through D=M(1+S)公式计算 basic dimensions outer, also has processing issues. according to 惯例, injection molding parts mold processing is parts 公差 1/3. due to plastics shrinkage rate scope/range and stability property has 差异, 首先必 must combined 理化确定 different plastics formed parts dimensions 公差. shrinkage rate scope/range relatively large or shrinkage rate stability relatively plastics formed parts dimensions 公差应取 large 一. 否则就 can can a large amount of dimensions ultra- 差 waste product. is 此, for plastics parts dimensions 公差专门 made 订 国家 standards or industry standards. China made 订 部 grade standards. large versus injection molding parts mold type dimensions 公差. Germany standards in made 订 塑 parts dimensions DIN16901 standards and versus injection molding parts mold type dimensions DIN16749 standards. standards in world upper tool has relatively large effect/influence, can 供 plastics injection molding parts mold industry 参考. about/regarding parts dimensions and 允许偏差 is combined 理 确定 different shrinkage features material formed parts dimensions 公差, let standards formed shrinkage 差△VS this concept. △VS＝VSR-VST (4) in: △VS－ formed shrinkage 差; VSR－熔 material flow direction formed shrinkage rate; VST－ and material flow direction formed shrinkage rate. according to plastics △VS value, will various plastics shrinkage features separation is 4 组. △VS value most small is high degree 组, type 推, △VS value most large is low degree 组. according to basic dimensions made precision technology, 110, 120, 130, 140, 150 and 160公差组. 并规定, use shrinkage features most stability plastics formed parts dimensions can selection 110, 120 and 130组. use shrinkage features in and other stability plastics formed parts dimensions selection 120, 130 and 140. if use this category of plastics formed parts dimensions selection 110组时, can can a large amount of dimensions ultra- 差塑 parts. use shrinkage features relatively plastics formed parts dimensions selection 130, 140 and 150组. use shrinkage features most plastics formed parts dimensions selection 140, 150 and 160组. in use 此公差 table/sheet 时, also attention/notes below/following 各点. table/sheet in generally used for 不注明公差 dimensions 公差. 直接标注偏差 公差 is used for for parts dimensions 标注公差 公差 belt/tape. its upper, lower can design 人员自行确定. 例如公差 belt/tape is 0.8mm, can selection below/following various upper, lower 偏差构 formed. 0.0, -0.8, ±0.4, -0.2, -0.5 and other. 每一公差组 in has A, B两组公差 value. its in A is injection molding parts mold parts combined formed dimensions, increase injection molding parts mold parts for combined 处不密 combined formed 错差. increase value is 0.2mm. its in B is 直接由 injection molding parts mold parts dimensions. precision technology is 专门设立 一组公差 value, tool has high degree requirements parts use. in use parts 公差之 front, 首先必 must use plastics suitable several 公差组. injection molding parts mold manufacturing Germany standards for parts made versus injection molding parts mold manufacturing standards DIN16749. table/sheet in 共设4 types 公差. 不论何 types material parts, its in 不注明 dimensions dimensions injection molding parts mold manufacturing 公差均 use 序号1 公差. specific value basic dimensions scope/range 确定. 不论何 types material parts in and other degree dimensions injection molding parts mold manufacturing is 序号2 公差. 不论何 types material parts relatively high degree dimensions injection molding parts mold manufacturing is 序号3 公差. precision technology versus injection molding parts mold manufacturing is 序号4 公差. can combined 理 确定 various material parts combined 理公差 and versus injection molding parts mold manufacturing 公差, this not only to injection molding parts mold manufacturing belt/tape 方便, also can decrease/reduce waste product, improve/increase 经济效期益. 自:慧聪网