Shanghai Daoqin Plastics Co., Ltd.

 PP通称 polypropylene (PP), its excellent resistant property can by is “百折胶”. tool has high strength, high insulation property, low water absorption, high formed temperature degree, low density, crystallization degree high and other features.

modified filling material usually has glass fiber, material filler, thermoplastic property and other. different applications PP its flow property relatively large, generally use PP flow speed rate 介于ABS and PC between.

PP injection molding processing process

Ⅰ☞   plastics 处理

pure PP is semi transparent or white pellets, can formed various color . PP generally use masterbatch material 进行染 color. 户 outer use products, generally use UV stabilizer and carbon filling. recycled material use ratio/proportion need ultra- 15%, 否则会引起 strong/high degree decline and separation understanding color. PP injection molding processing front generally especially drying 处理.    

Ⅱ☞   injection molding machine selection

for injection molding machine selection has requirements. due to PP tool has high crystallization property, using/adopting injection pressure relatively high and can more control injection molding machine. clamping force generally 按3800t/㎡ 确定, injection amount 20%-85%即 can.    

Ⅲ☞   mold and gate design

mold temperature degree 50-90℃（ for/regarding dimensions requirements relatively high use high mold temperature ）. type temperature degree ratio type temperature degree low 5℃ above, runner 直径4-7mm, gate long degree 1-1.5mm, can small 至0.7mm. gate long degree short good, is 0.7mm, deep degree is thick semi, wide degree is thick 两倍, mold cavity inner long degree increase.

mold must has good gas property, gas deep 0.025mm-0.038mm, thick 1.5mm, need shrinkage 痕, need use large 而圆 注口 and runner, add strong/high thick degree need small （如 is thick 50-60%）. homopolymer PP manufacturing product, thick degree can ultra- 3mm, 否则会 has bubbles （ thick products can use copolymer PP）.   

Ⅳ☞  熔胶 temperature degree

PP melting point is 160-175℃, separation understanding temperature degree is 350℃, 但 in injection processing temperature degree setting can ultra- 275℃. melt temperature degree most good in 240℃.   

Ⅴ☞   injection speed degree

is decrease/reduce internal stress and deformation, selection high speed injection, has and other grade PP and mold suitable. has surface 出现由 gate expand dispersion dark versus strip/profile 纹, need use low speed injection and relatively high mold temperature.   

Ⅵ☞  熔胶 back pressure    

can use 5bar熔胶 back pressure, color powder material back pressure can 适当调 high.   

Ⅶ☞   injection and holding pressure

using/adopting relatively high injection pressure （1500-1800bar） and holding pressure pressure （约 is injection pressure 80%）. large in full 行程 95%时转 holding pressure, use relatively long holding pressure time.   

Ⅷ☞   products rear 处理

is anti rear crystallization generate shrinkage deformation, products generally hot water 浸泡处理.

injection molding process parameters

▶ 喂 material 区: 30～50℃（50℃）

 ▶ 区1: 160～250℃（200℃）

 ▶ 区2: 200～300℃（220℃）

 ▶ 区3: 220～300℃（240℃）

 ▶ 区4: 220～300℃（240℃）

 ▶ 区5: 220～300℃（240℃）

 ▶  nozzle: 220～300℃（240℃）

括号 inner temperature degree as is basic setting value, utilizing rate is 35％ and 65％, parts long and thick ratio is 50: 1 to 100: 1

 ▶ 熔 material temperature degree: 220～280℃

 ▶  material temperature degree: generally material temperature degree control in 210~280℃, nozzle temperature degree ratio material temperature degree low 10~30℃. in need injection pressure and injection speed degree relatively small 时, can selection relatively low material temperature degree. molding thin 壁, complex parts 时, material temperature degree high 者; parts relatively thick 时, material temperature degree low 者.

 ▶  mold temperature degree: production in mold temperature adjustment to 20~60℃. PP crystallization can force relatively strong/high, improve/increase mold temperature has increase crystallization degree, has large separation 子松弛, decrease/reduce separation orientation function, from reduce parts internal stress, decrease/reduce material, bubbles and other defect.

 ▶  injection pressure: generally control in 70~100MPa. specific value mold trial 决定, parts material, material and generate and bubbles is 准. in injection molding 时, improve/increase injection pressure has increase large material flow property. 柱塞式 injection molding machine injection pressure ratio screw need high.

 ▶  holding pressure pressure: 约 is injection pressure 30％～60％

 ▶  back pressure: 5～20MPa（50～200bar）

 ▶  injection speed degree: for thin packaging container need high injection speed degree （ belt/tape can device ）; in and other injection speed degree comparison suitable for its it type plastics products.

 ▶  screw speed: high screw speed （线 speed degree is 1.3m/s） is 允许, need meet/satisfy cooling time front formed process can.

 ▶ 计 amount 行程: 0.5～4D（ most small value ～ most large value ）; 4D amount can is material provide long time, this is very important.

 ▶ 残 material amount: 2～8mm, 取决于计 amount and screw speed.

 ▶ 预烘 dry: 不 need dry; if conditions good, in 80℃ temperature degree lower dry 1h即 can.

 ▶  recycling rate: can 100％ recycling.

 ▶  shrinkage rate: 1.2～2.5％; shrinkage degree relatively high; 24h rear again shrinkage （ molding rear shrinkage ）.

 ▶  gate system: 点式 gate or more gate, add hot hot runner, temperature hot runner, inner sleeve/set; gate in products most thick 点, easy large sink marks.