Shanghai Daoqin Plastics Co., Ltd.

         injection molding is most important plastics molding methods 之一, how to improve/increase injection molding technology water 平, production high degree plastics products, 创造附 add value high product, mold design is important step/link.

         in injection molding design in, remove 应考虑 generally mold design outer, also need especially 考虑如 lower 事项:

         is to need dimensions products, need 考虑适当 mold dimensions 公差

         need anti generate molding shrinkage 波动

         need anti generate molding deformation

         need anti generate demolding deformation

         need make mold made as most small

         need anti mold degree 波动

        一, mold dimensions and 公差  

         products dimensions degree and mold dimensions degree 关连

        绘出 products 图, mold design, mold made as and molding process. can from products dimensions mold dimensions. mold dimensions made as mold, to mold dimensions. use mold can to molding products, to products dimensions. is 此实际 dimensions how to in need dimensions inner.

        适当 shrinkage rate

        如 upper 述, make in use 同一颜 material resin in, shrinkage rate molding conditions different 而异. in precision molding in, shrinkage rate 变化程 degree need small, expected shrinkage rate and shrinkage semi need can can 无差异. main/primary is using/adopting 整理以往 similar products shrinkage rate shrinkage rate, has use 实验模求实际 shrinkage rate, again positive, design made as production 模 情形.

        但完 full 恰当推定 shrinkage rate is can can, can need in molding rear positive mold. positive 结果, will increase large dimensions, will shrink small dimensions. therefore, for dimensions, will shrinkage rate in small value, for/regarding dimensions will shrinkage rate in large value. gears outer dimensions large can combined, small 时仅齿隙变 large, therefore need will shrinkage rate in small value.

        二, anti generate molding shrinkage 波动

         precision injection molding, must 以确实 can need dimensions made as mold is front 提. however, make mold dimensions 一定, products dimensions 也因实际 shrinkage different 而异.

         therefore in precision injection molding in, shrinkage rate control is separation important. mold design combined and 否支配 shrinkage rate, also resin batch different 而异, 若改变颜 material, shrinkage rate generate 差异. molding machine different, molding conditions setting, again property and molding cycle as has 波动, for shrinkage rate generate and other, shrinkage control is difficult.

         effect/influence shrinkage rate main/primary factors

         mold dimensions can products dimensions add upper shrinkage rate 求, therefore in mold design 时, need shrinkage rate main/primary factors. this effect/influence resin and molding conditions and other project different 而异.

         effect/influence molding shrinkage main/primary factors has:

         resin pressure

         resin temperature degree

         mold temperature degree

         gate 截面积

         injection time

         cooling time

         products thick

         reinforcement material 含盆

        定 toward property

         injection speed degree

        1, resin pressure

         resin pressure for shrinkage rate effect/influence very large, resin pressure large, shrinkage rate small, products dimensions large. make in mold cavity inner, resin pressure products different 而异, therefore generate shrinkage rate 差异. in more 腔模 场 combined, mold cavity inner resin pressure easy generate 差异, 结果各 mold cavity shrinkage rate same.

        2, mold temperature degree

        无论 is non crystallization property resin or is crystallization property resin, mold temperature degree high, shrinkage rate large. precision molding need will mold temperature degree in temperature degree. in mold design 时, must attention/notes cooling design.

        3, gate 截面积

         generally 说, gate 截面积时, shrinkage rate 也变化. shrinkage rate gate dimensions large small, this and resin flow property has 关.

        4, products thick degree

         products thick degree effect/influence rate. for/regarding non crystallization property resin, resin for thick shrinkage rate effect/influence toward different, thick large, shrinkage rate large, 反之, shrinkage rate small. for/regarding crystallization property resin, must 避免壁 thick especially large. in more 腔模 情形, if mold cavity thick has 差异, shrinkage rate will generate 差异.

        5, reinforcement material content

         use fiber reinforcement resin 时, add glass fiber (GF) amount more, shrinkage rate small, flow direction shrinkage rate ratio toward shrinkage rate small, according to resin its relatively large, is anti 止扭曲飞 warpage, must gate 形状飞侥口位置 and gate 数.

        6, toward property

        定 toward property has relatively large 差异, however for has resin in toward property. crystallization property resin toward property especially large, due to thick and molding conditions has 差异.

         in addition, also has generate molding rear shrinkage. effect/influence molding rear shrinkage main/primary factors has:

         internal force and

         crystallization

         temperature degree

         wet degree

         can measures has:

         runner, gate balanced

         shrinkage rate resin pressure 变化. in mono more gate and more 腔模 情形, need 同样进行充模, need gate balanced. resin flow and in runner in flow retardant force has 关, therefore in gate balanced front most good runner balanced.

         mold cavity 排列

         is make molding conditions setting easy, therefore need attention/notes mold cavity 排列. due to melt resin will hot belt/tape mold, in generally mold cavity 排列 情况 lower, mold temperature degree distribution gate is in 心 同心圆状. therefore in selection more mold cavity 排列时, need easy runner balanced, also need gate is in 心 同心回状排列.

        三, anti generate molding deformation  

         molding deformation generate causes is in non-uniform shrinkage lower has internal stress, therefore need anti non-uniform shrinkage. in gears in has 孔 圆形 products 情形, must in in gate. however in resin flow direction and direction shrinkage rate has relatively large 差异时, has generate disadvantages, in need more high degree degree 时, need formed 3点 or 6点 gate.

        但 need separation attention/notes gate balanced. in use gate 时, 3点 gate will make 圆筒状 products inner increase large, in outer table/sheet and 端面不允许 gate 痕迹 情形 less use inner more separation gate, can to good 结果.

        四, anti demolding generate deformation  

         precision products generally relatively small, products thick relatively thin, has also has many thin 筋. tool design must make products deformation, but also can 适当脱棋. for/regarding shrinkage rate relatively small resin, molding pressure high 情形, need attention/notes products easy in mold cavity.. use shrinkage rate small resin molding gears 时, gears separation mold cavity most good design in ejection 一侧 模 sheet/plate upper.

         in use 顶销时, need attention/notes deformation 顶销数 and pressure 位置. belt/tape gears need 芯销, this is has in ejection 时平行 ejection, need ejection sheet/plate upper.

         for/regarding products, can use 冲孔模 sheet/plate ejection, use this type of sheet/plate ejection can anti generate deformation. generally precision products 拔模斜 degree relatively small. is decrease small demolding force, need processing, abrasion direction is direction. need 按拔模 direction easy abrasion separation block type 芯.

        五, anti mold degree 误差  

         ensure sliding parts cycle 定位, need anti mold degree 波动. is sliding parts degree, sliding parts 都应悴火研 abrasion.侧芯 sliding separation combined has 定位退拔部 separation.