Shanghai Daoqin Plastics Co., Ltd.

         polyolefin usually ethylene, propylene or high grade polymer, shrink is PO. its in polyethylene (PE) and polypropylene (PP) most important.

         about/regarding polyolefin tube/pipe process control

         extrusion molding process control parameters molding temperature degree, pressure, screw speed, extrusion speed degree, speed degree, add material speed degree and cooling type and other.

        1． Raw Materials 预处理

         polyolefin is non water property material, usually water separation content very low, can meet/satisfy extrusion need, polyolefin water property material, 如炭黑时, for wet degree 敏感. another, in use material and filling material 时, water amount increase large. water separation 不但导致 pipe/tube inner outer surface coarse 糙, but also can can melt in bubbles. usually for raw materials 进行预处理. generally using/adopting drying 处理, can add versus tool has remove wet function additives. defoamer and other. PE dry temperature degree generally in 60-90 degree. in temperature degree lower, output/production volume can improve/increase 10%--25%.

        2． temperature degree control

         extrusion molding temperature degree is make molding material material and plastics melt flow necessary conditions. for/regarding polyolefin temperature degree scope/range relatively wide. usually in melting point above, 280 degree below/following 均 can processing.

        口模 and temperature degree for tube/pipe surface light degree has effect/influence, in scope/range inner, and mold temperature degree high, tube/pipe surface light degree high. usually 讲, 口模 export temperature degree ultra- 220 degree , machine 头入口 melt temperature degree is 200 degree, machine 头入口 and export melt temperature 差不应 ultra- 20 degree.

         polyethylene (PE) pipe/tube extrusion melt temperature degree upper generally is 230 degree, generally control in 200 degree left right is 佳. polypropylene (PP) pipe/tube extrusion melt temperature degree upper generally is 240 degree.

        3． pressure control

         extrusion process in most important pressure parameters is melt pressure, machine pressure. melt pressure usually control in 10-30MPa between.

        4． true type

         true type main/primary control true degree and cooling speed degree parameters. usually in meet/satisfy pipe/tube appearance quality front lower, true degree can can low, this pipe/tube internal stress small, product in process in deformation small.

        5． cooling

         polyethylene (PE) pipe/tube extrusion molding in cooling water temperature requirements generally relatively low, usually in 20 degree below/following, in production PPR pipe/tube 时, 第一段 temperature degree can high, rear relatively low, from formed temperature degree degree.

        6． screw speed and extrusion speed degree

         screw speed is control extrusion speed rate, output/production volume and products quality heavy parameters. mono screw extrusion machine speed increase, output/production volume improve/increase. speed rate increase, melt table/sheet viscosity decline. has material material 均化.

        7．牵引 speed degree

        牵引 speed degree effect/influence product thick, dimensions 公差, property can and appearance, speed degree ratio must stability, 且牵引 speed degree and pipe/tube extrusion speed degree versus 匹配. 牵引 speed degree and extrusion speed degree ratio value 反映出 products can can orientation degree, ratio value is tensile ratio, its value must and other or large 于1.

        8． pipe/tube in quality control and rear 处理

         polyolefin crystallization polymer, rigid lower pipe/tube property can and pipe/tube products use dimensions and property can has 差距.

         main/primary causes has: 一, polyolefin melt cooling process in need crystallization function, and temperature degree and time has 关. 第二, rigid lower pipe/tube temperature degree usually high normal temperature. 第三, rigid lower pipe/tube internal stress relatively large. is to property can and dimensions stability property, generally polyethylene (PE) pipe/tube lower 线放置24 small 时, polypropylene (PP) pipe/tube 需放置48 small rear, can versus standards property can testing.

         polyolefin pipe/tube extrusion Common issues

        一, surface 黯淡无 light

         generate causes

        1, raw materials water separation

        2, melt temperature degree combined 适

        3, extrusion machine extrusion melt material material non-uniform

        4, sleeve/set short

        5, molding short

         solution methods

        1, raw materials 预处理

        2, adjustment temperature degree

        3, increase back pressure, use relatively fine 滤网, design screw structure

        4, add long sleeve/set

        5, add long molding 段

        二, surface has 斑点

         generate causes

        1, raw materials in has water separation

        2, water in tube/pipe upper has bubbles

         solution methods

        1, drying raw materials

        2, remove bubbles. adjustment process temperature degree.

        三, outer surface light transparent block 状

         generate causes

        1, machine temperature degree high

        2, cooling water small or 不足, or non-uniform

         solution methods

        1, reduce machine temperature degree

        2, cooling water large or 清理定径 sleeve/set

        四, pipe/tube light slip outer surface 规则 斑纹

         generate causes

         pipe/tube toward viscous 附定径 sleeve/set

         solution methods

         add large cooling water amount water or drop speed

        五, pipe/tube outer surface relatively deep 波纹

         generate causes

        定径 sleeve/set 口模没 for 准

         solution methods

         for in, maintain 定径箱 and in 同一轴线

        六, inner surface coarse 糙

         generate causes

        1, raw materials wet

        2, mold temperature degree low

        3, and 芯模间隙 large

        4, 口模定 type short

         solution methods

        1, dry, or 预处理

        2, increase temperature degree or temperature time

        3, 换芯模

        4, relatively long 口模

        七, tube/pipe inner 壁波纹状

         generate causes

        1, extrusion machine output/production volume 变化, lower material 不稳

        2, 牵引打 slip

        3, pipe/tube cooling 不均

         solution methods

        1, reduce screw material temperature degree

        2, adjustment gas pressure

        3, adjustment water 路

        八, tube/pipe inner has 凹坑

         generate causes

        1, raw materials water separation large

        2, filling material dispersion property 差未塑化, 杂质

         solution methods

        1, raw materials preheating drying

        2, material, adjustment temperature degree, raw materials

        九, tube/pipe inner has 焦粒

         generate causes

        1, machine and inner dry 净

        2, local temperature degree high

        3, 口模积 material heavy

         solution methods

        1, 清模

        2, hot electrical is positive 常

        3, 清模, reduce temperature degree

        十, outer or thick 随时变化

         generate causes

        1, extrusion speed degree 变化

        2, speed degree 发生变化 or slip

        3, lower material 不稳

        4, melt unstable property

        5, cooling 不均

         solution methods

        1, 检查牵引 machine

        2, improve/increase pressure

        3, raw materials or pelletizing

        4, improve/increase material temperature, reduce speed degree, increase 模口间隙

        5, water 路

        十一, pipe/tube thick 不均

         generate causes

        1, 口模没 for in

        2, mold temperature degree 不均

        3, machine and sleeve/set 口模没 for 准

        4, sleeve/set and 口模距离太远

         solution methods

        1, adjustment 口模同心

        2, adjustment temperature degree

        3, machine and sleeve/set maintain in 同一轴线 upper

        4, 拉近定径 sleeve/set and 口模 距离

        十二, 熔接缝 defect

         generate causes

        1, molding short

        2, melt temperature degree low

        3, in plastics dispersion

        4, machine machine structure combined 理

         solution methods

        1, relatively long molding 段

        2, improve/increase material temperature

        3, 清理模头

        4, more or renovation

        十三, pipe/tube loss bad 穿孔

         generate causes

        1, water 泡

        2, bubbles

        3, 杂质

        4, material or filling material dispersion defect

         solution methods

        1, drying raw materials

        2, remove wet or reduce temperature degree

        3, raw materials or use 滤网

        4, adjustment temperature degree or more raw materials

        十四, pipe/tube loss bad （脆 property bad ）

         generate causes

        1, material temperature low

        2, temperature degree high, raw materials separation understanding

         solution methods

        1, improve/increase material temperature

        2, mold, reduce temperature degree

        十五, pipe/tube cracking

         generate causes

        1, machine temperature degree low, extrusion speed degree fast

        2, cooling water large

         solution methods

        1, rise temperature, drop speed

        2, decrease small cooling water amount

        >>>>

        十六, pipe/tube degree good, bending

         generate causes

        1, 口模, in 心位置不 positive

        2, machine temperature degree 四周不均

        3, cooling water 离口模太近

        4, cooling water force large

        5, cooling water 喷淋太 small

        6, water high

        7, machine pressure large

         solution methods

        1, adjustment 同心

        2, adjustment temperature degree

        3, adjustment cooling water 位置

        4, adjustment 喷头角 degree

        5, water 路

        6, water

        7, adjustment gas pressure