Shanghai Daoqin Plastics Co., Ltd.

what is 欠注（Short Shot)?

欠注 also short 射, short shot, made parts 不满, 俗称欠注, material 流末端出现部 separation 不完整 phenomenon or more in separation filling 不满, especially is thin or flow 路径 末端区域. its performance is melt in has type cold 凝, material type rear has 充填完 full, product material. right 图 示.

generate short main/primary causes is flow retardant force large, formed melt method flow. effect/influence melt flow long degree factors 包括: made parts thick, mold temperature degree, injection molding pressure, melt temperature degree and material formed separation. this factors if 处理不 good 都会造 formed short 注.

欠注（Short Shot)- defect analysis

  
due to generate gas surface products thick 引起肋筋欠注 viscosity large speed slow made parts 角落欠注  

1 equipment type 不当

in use equipment 时, injection molding machine most large injection amount must large parts and water heavy, injection heavy can ultra- 出 injection molding machine amount 85%. opw

2 供 material 不足

currently commonly used control add material method is 定体积 add material method, its material amount and raw materials 果粒经 is 否均一, add material 口底部 has 无“架桥” phenomenon. add material temperature degree high, 也会引起落 material 不畅. for 此, hydrophobic and cooling add material 口.

3 material flow property 差

raw materials flow property 差时, mold structure parameters is effect/influence main/primary causes. therefore improvement mold system defect, combined 理设置浇道位置, expand large gate, runner and material dimensions, and using/adopting relatively large nozzle and other. meanwhile can in raw materials formulation in increase amount additives improvement resin flow property can. in addition, also 应检查 raw materials in recycled material is ultra- amount, decrease/reduce its use amount.

4 lubricant ultra- amount

if raw materials formulation in lubricant amount more, material screw ring and material abrasion loss relatively large 时, material in material in 回流严 heavy 会引起供 material 不足, 导致欠注. for 此, decrease/reduce lubricant use amount and adjustment material and material screw and ring 间隙, equipment.

5 cold material retardant material 道

当熔 material inner 杂质堵塞 nozzle or cold material retardant 塞
gate and runner 时, will nozzle lower or expand large mold cold material and runner 截面.
6 浇注 system design combined 理

一模 more 腔时, 往往因 gate and balanced design combined 理导致塑 parts appearance defect. design system 时, need attention/notes gate balanced, type inner parts weight need and gate large small formed positive ratio, make type can meanwhile 充满, gate need selection in thick 壁处, can using/adopting separation runner balanced design solution/scheme. gate or runner small, thin, long, material pressure in flow process in loss large, flow retardant, easy generate filling defect. for expand large runner and gate 面积, necessary can using/adopting more material methods.

7 mold gas defect

当 mold inner gas defect 而残留 a large amount of gas to material pressure, generate large injection pressure high pressure 时, retardant material type formed 欠注. for 此, 应检查 has 无设置 cold material or its is positive 确, for/regarding type relatively deep mold, in 欠注 部位 increase gas or gas 孔; in clamping upper, can deep degree is 0.02~0.04mm, wide degree is 5~10mm gas 槽, gas 孔应设置 in type most 终充模处. use water separation and easy material content ultra- 标 raw materials 时也会 generate a large amount of gas 体, mold gas defect. 此时, for raw materials drying and remove easy material.

in addition, in mold system process as 方面, can through improve/increase mold temperature degree, reduce injection speed degree, decrease small system flow force, and decrease small clamping force, add large mold and other measures improvement gas defect.

8 mold temperature degree low

熔 material low temperature mold cavity rear, cooling fast method type 腔 各 角落. therefore, machine front must will mold preheating process requirements temperature degree, rigid machine 时, 应适当节 made mold inner cooling water through amount. mold temperature degree rise upper, 应检查 mold cooling system design is combined 理,

9 熔 material temperature degree low

usually, in combined molding scope/range inner, material temperature and long degree 接近于 positive ratio/proportion 关系, low temperature material flow property can decline, make long degree decrease short. material temperature low process requirements temperature degree 时, 应检查 material add material device is good method improve/increase material temperature degree. rigid machine 时, material temperature degree ratio material add hot device table/sheet temperature degree need low 一, attention/notes will material add hot to table/sheet temperature degree rear also temperature time can machine. if is anti material separation understanding 不 不采取 low temperature injection 时, can 适当延 long injection ring time, 克服欠注. for/regarding screw injection molding machine, can improve/increase material front 部区段 temperature degree.

10 nozzle temperature degree low

in injection process in, nozzle is and mold versus 接触, due to mold temperature degree generally low nozzle temperature degree, temperature relatively large, frequency 繁接触 rear make nozzle temperature degree decline, 导致熔 material in nozzle cold 冻.

if mold structure in has cold material 穴, cold material type rear 立即凝 solid, make in rear hot material method type 腔. therefore, in mold opening make nozzle and mold separation 离, decrease/reduce mold temperature for nozzle temperature degree effect/influence, make nozzle temperature degree maintain in process requirements scope/range inner.

if nozzle temperature degree very low rise upper, 应检查 nozzle add hot device is loss bad, method improve/increase nozzle temperature degree, 否则, material pressure loss large 也会引起欠注.

11 injection pressure or holding pressure 不足

injection pressure and long degree 接近于 positive ratio/proportion 关系, injection pressure small, long degree short, type filling 不满. for 此, can through decrease slow injection front speed degree, 适当延 long injection time and other method improve/increase injection pressure. in injection pressure method 进一步 improve/increase lower, can through improve/increase material temperature, reduce material viscosity, improve/increase melt flow property can remedy. value attention/notes is material temperature high make material hot separation understanding, effect/influence parts use property can.

in addition, if holding pressure time short, 也会导致 filling 不足. therefore, will holding pressure time control in scope/range inner, need attention/notes, holding pressure time long 也会引起 its it fault/failure, molding according to parts specific 情况酌情 adjustment.

12 injection speed degree slow

injection speed degree and speed degree related. if injection speed degree slow, material 充模缓 slow, low speed flow melt very easy cooling, make its flow property can 进一步 decline generate 欠注.

for 此, 应适当 improve/increase injection speed degree. attention/notes, if injection speed degree fast, very easy its it molding fault/failure.

13 塑 parts structure design combined 理

当塑 parts thick degree and long degree formed ratio/proportion, 形体十 separation complex molding very large 时, material very easy in parts thin 壁部位 入口处 flow retardant, make type very difficult 充满. therefore, in design parts structure 时, attention/notes parts thick degree and material 充模时 极限 flow long degree has 关.

in injection molding in, parts thick degree using/adopting most more is 1~3mm, large type parts is 3~6mm, generally recommendation most small thick degree is; polyethylene (PE) 0.5mm,醋 acid fiber and acid acid fiber plastics 0.7mm, fiber plastics 0.9mm, polymethyl methacrylate (PMMA) 0.7mm, polyamide (PA) 0.7mm, polystyrene (PS) 0.75mm, polyvinyl chloride (PVC) 2.3mm. usually, parts thick degree ultra- 8mm or small 于0.5mm都 for injection molding 不利, design 时应避免 using/adopting this thick degree.

in addition, in molding complex structure parts 时, in process upper need using/adopting necessary measures, combined 理确定 gate 位置, adjustment runner 布局, improve/increase injection speed degree or using/adopting fast speed injection. improve/increase mold temperature degree or selection flow property can relatively good resin and other.

欠注 defect troubleshooting method

 
欠注 defect troubleshooting 检查点 Short Shot Checkpoints

（1） process conditions control 不当. 应适当 adjustment.
（2） injection molding machine injection can force small parts weight. use relatively large specifications injection molding machine.
（3） runner and gate 截面太 small. 应适当 add large.
（4） mold cavity inner material flow 距离太 long or has thin separation. 应设置 cold material 穴.
（5） mold gas defect, mold cavity inner 残留空 gas 导致欠注. improvement mold gas system.
（6） raw materials flow property can 太差. use flow property can relatively good resin.
（7） material temperature degree low, injection pressure or material injection time short 也会引起欠注. versus improve/increase has process parameters control amount.