Die buildup, also called die drool, die bleed, or plate-out, can plague any extrusion process. It caus a variety of problems, from visible surface imperfections on extrudates to process disruption and outright product failure. Processors typically expend time and labor to remove die buildup becau they don’t know how to eliminate it any other way.
口模积料，也叫口模流涎或叫口模积垢，它可以危害任何挤出过程。它引起许多问题，从挤出物上可见的表面缺陷到工艺紊乱，乃至产品报废。加工者往往采取延长时间和投入劳动力来去除口模积料，因为他们不懂得采用任何别的方法来消除口模积料。
Simple die shapes allow for cleaning while the line is running. Changing the angle at which the extrudate is drawn away from the die can change the placement of buildup on the die and make it easier to clean. Die buildup can also be intentionally pushed onto the product and removed further down the line. For sheet, mechanical automatic scrapers are available to remove buildup.
对于简单的口模形状，可以在线运行时进行积料清除。改变挤出物的牵引角度，就可以改变挤出物在口模上的堆积位置，这样就容易清除积料了。有些积料可以故意让其附着于产品上，
然后从生产线上将其除掉。对于片材，可以用自动除榍装置除掉积料。
火的部首
But processors often have to schedule costly downtime to remove die buildup. Applying mold relea or silicone to the die exit area after cleaning can reduce the rate of buildup and extend the time between cleanings. Slowing down the process also reduces die buildup, but this hurts output. All the approaches treat the symptom, not the problem. A better solution may be to address what caus buildup.
但是加工者常常得拿出昂贵的停机时间来清除积料。清除积料后在口模出料口使用脱模剂或者硅酮可以减轻积料程度并延长两次清除之间的时间。放慢加工速度也可以减少积料，但这牺牲了产率。所有这些方法都解决的是现象而不是根本问题。因此，需要一个好的方案来解决是什么引起了积料的问题。
Thick, fluffy die buildup may be caud by partial foaming in the melt, resin compatibility issues, or high die stress. (Photo: Extrusion Technical Services)
Die buildup is related to stress at the die exit. Resin flowing along the die inner surface m
oves relatively slowly and then is suddenly accelerated as it exits the die. This sudden acceleration caus stress within the melt. Under stress, low-molecular-weight polymer fractions and other components in the melt can parate and be deposited at the die exit. Solutions are either to reduce die-exit stress or to reduce the tendency for components to parate from the melt. The may involve changes to the process, the material, or the die.
口模积料与口模的出口应力有关。沿口模内表面流动的树脂移动相对慢，随后在流出口模时突然被加速。这种突然加速在熔体中引起应力。在应力作用下，低分子量聚合物部分和熔体中的其它组分就会（与聚合物熔体）分离，并沉积在口模出口上。解决方法要么是减少口模出口应力，要么是减少组分从熔体中分离的倾向。这些解决方法要涉及到工艺、材料或者口模。虎头鲨
内墙抹灰技术交底
CHANGE THE PROCESS 改变工艺
Higher die and melt temperatures are one way to reduce die-exit stress. But gains may be offt by additional degradation, causing an increa in low-MW fractions. Changes in 1990年属马五行属什么
melt and die temperatures should be explored independently. Sometimes lower die temperatures can create a cool layer of resin on the inner surface of the die that creeps slowly to the die exit and then parates from the bulk flow, causing buildup.杜甫的诗300首
怎样学习
较高的口模和熔体温度是减少口模出口应力的一种方法。但是利润可能被额外的降解抵消了，结果还会引起低分子量组分的增加。改变熔体温度和改变口模温度应该分开考虑。有时，较低的口模温度会在口模内表面上生成一个冷却的树脂层，这个树脂层慢慢地移出到口模出口，然后与本体料流分离，从而引起积料。
Start by determining the true melt temperature and t the die body to that temperature. Standard melt thermocouples are often wrong, so check the melt temperatures by hand. It’s difficult to do, but worth the effort when troubleshooting. Also, the die exit surface can be significantly cooler than the die itlf. Try checking the die exit temperature with a surface thermocouple.
从确定真正的熔体温度开始，然后按照这个温度设定口模体的温度。标准的熔体温度常常是错误的，所以要用手工检查熔体温度。这样做很难，但是要解决问题就值得努力。此外，
口模出口表面可能比口模本身要冷很多。要设法用表面热电偶检查口模出口温度。
Air sweeps pointed at the die exit can help reduce and control buildup. The air sweep is a wand contoured to the extrusion profile shape, with holes drilled in it to distribute compresd air. The air sweep can direct any smoke and condensables away from the die. Air sweeps also have the benefit that they can cool die buildup so it doesn’t oxidize and turn dark. Nitrogen is also ud to prevent oxidation, but take care not to blow too hard or cool the die so much that it distorts the extrudate.
对着口模出口进行空气吹扫能帮助减少和控制积料。空气清扫装置是一个具有挤出物外形的套筒，里面钻了很多孔，可以使压缩空气呈现出一定的分布。空气清扫装置可以将任何烟雾物质和可压缩物吹离口模。空气清扫还有冷却积料的好处，以便积料不会氧化和变黑。也可以用氮气防止氧化，但是要记住，不要吹得太过火，否则会将口模过分冷却，这样会导致挤出物变形。
CHANGE THE MATERIAL 改变材料
领带的打法步骤Different materials produce different sorts of die buildup, from thin and runny to thick and fluffy. Thin, runny buildup is often caud by low-MW fractions in the formulation, which volatilize at the die exit and conden on the die face. Thick, fluffy, buildup is often caud by partial foaming within the melt, compatibility issues, or high stress inside the die. Check for excessive moisture in the resin and for resin degradation, possible melt fracture, or inadequate venting.
不同的材料产生不同种类的积料，从稀的流水状的积料到粘稠的绒毛状的积料。稀的流水状的积料常常是配方中低分子组分引起的，它口模出口处挥发，然后在口模表面冷凝。粘稠的绒毛状的积料常常是熔体内部分发泡、相容性问题或口模内部高应力引起的。检查物料的树脂是否过度潮湿或者树脂降解，检查是否存在熔体破裂或者排气不良。
