Shanghai Daoqin Plastics Co., Ltd.

         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.

        1. 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:

         resin pressure

         resin temperature degree

         mold temperature degree

         gate 截面积

         injection time

         cooling time

         products thick

         reinforcement material

        定 toward property

         injection speed degree

         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.

         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.

         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.

         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.

         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.

        定 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, its main/primary factors has:

         internal force and

         crystallization

         temperature degree

         wet degree

        2. can measures

         runner, gate balanced

        如 upper 述, 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

        3. anti 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.