【正文】 Place an adequate venting system throughout the enti。FIGURE 2. (1) Normal filling with no ripples. (2) Generation of ripples with cold mold wall and low meltfront velocity. Remedies Actions that increase the meltfront velocity or mold/melt temperature will help to eliminate the ripples. 增加熔體前端速度或模具/熔體溫度可以幫助消除水波紋。FIGURE 4. Adjust ramspeed profile to avoid jetting.Ripples 水波紋What are ripples? Ripples are the wavelets or small fingerprintlike waves near the edge or at the end of the flow. 水波紋是邊緣附近或流動(dòng)末端出現(xiàn)的波紋或類(lèi)似于指紋樣的波紋FIGURE 1. Ripples Cause of ripples 原因According to a recent visual analysis using a glassinserted mold, the ripple defect is due to the flow front portion of the melt cooling on a cavity wall, and the repeated phenomena of the subsequent melt getting over and cooling, as shown in the below. Flowfront velocity and mold temperature have a stronger influence on the formation of ripples pared to the shape of the gates and the melt temperature. 根據(jù)可視化玻璃插件顯示，水波紋是由于流動(dòng)前端在模具壁冷卻，后來(lái)的熔體越過(guò)并冷卻。Adjust the barrel temperature to increase or decrease the melt temperature The explanation for this is not well understood, but might be related to the dieswell effect and the change of the melt properties (such as viscosity and surface tension). For example, for most polymers, die swell increases as temperature decreases, while some materials, such as rigid PVC, exhibit increasing die swell as temperature ，它是與粒子膨脹效應(yīng)和熔體性能（比如粘度和表面張力）改變有關(guān)。ll often find that the trouble lies with the gate Direct the melt against a metal Use an overlap gate or a submarine gate as shown in Figure 2 ，如圖2所示FIGURE 2. Using an overlap gate to avoid jettingSlow down the melt with a gradually divergent flow A tab or fan gate provides a smooth transition from the gate to the cavity. This reduces the melt shear stress and shear ，減少了熔體的剪切應(yīng)力和剪切速率。FIGURE 1. Jetting vs. normal filling pattern. Effects of jetting 噴射的影響Jetting leads to part weakness, surface blemishes, and a multiplicity of internal defects. Contrast this with a normal filling pattern, in which melt advances in a progressive pattern from the gate to the extremities of the cavity, as illustrated above. 噴射導(dǎo)致制品強(qiáng)度較弱，表面有污痕，以及各種各樣的內(nèi)部缺陷。比如噴嘴、流道、澆口、進(jìn)入開(kāi)放性的厚壁區(qū)域，并與型腔壁分離。 moving the gate away from the thin section reduces hesitation. 這樣是使得滯流發(fā)生較遲且持續(xù)時(shí)間也較短。Alter the part design改變零件設(shè)計(jì)Reduce part thickness Alter the mold design改變模具形狀Position the gate away from the thinsectioned areas, or regions of sudden thickness 。ll need to rethink both your part and mold design. You can also try finetuning your processing conditions. 當(dāng)發(fā)現(xiàn)零件存在滯流問(wèn)題時(shí)，可以考慮零件或模具的設(shè)計(jì)是否正確。當(dāng)凝固的熔體前端被沖入零件表面時(shí)，就產(chǎn)生了滯流痕的表面缺陷。結(jié)果，熔體將在薄壁部分停留直到零件的其余部分被填滿(mǎn)，然后停留的熔體再次開(kāi)始填充。滯流可以通過(guò)改變壁厚或移動(dòng)澆口位置去除。將在水波紋進(jìn)行討論Remedies Alter the mold design改變模具的設(shè)計(jì)Change the size of the cold well in the runner system to trap the cold material during the filling The proper length of the cold well is usually equal to that of the runner Increase the runner system and gate size for the specific mold and Flow marks are sometimes caused by a restrictive runner system and gate size that freezeoff prematurely so that the material cannot be pensated during the packing 。 Low injection pressure 注射壓力低 Low mold temperature 模具溫度低但要注意，避免熔體溫度過(guò)低而增大注射壓力產(chǎn)生飛邊Reduce the injection and packing pressure to reduce the clamp force Reduce the feed setting (stroke length) to reduce metering (overfill).減少進(jìn)料量設(shè)置Increase the injection time or slow down the injection Flow marks 流痕What is a flow mark? A flow mark or halo is a surface defect in which circular ripples or wavelets appear near the gate. 流痕或圈是出現(xiàn)在澆口附近的環(huán)繞成水波狀的一種表面缺陷FIGURE 1. Flow marks Causes of flow marks Flow marks are caused by cold material near the gate or lack of pensated material during the packing stage. The problem can usually be attributed to: 流痕是澆口附近有冷料或保壓階段補(bǔ)料不足產(chǎn)生的，通常與以下因素有關(guān)： 不合理的排氣槽An improperly designed venting system, a very poor venting system, or a venting system that is too deep, will cause flash. 排氣孔的設(shè)計(jì)不合理，排氣系統(tǒng)較差或排氣系統(tǒng)槽設(shè)計(jì)太深都會(huì)引起飛邊Remedies Adjust the mold setup調(diào)整模具的安裝Set up the mold to seal properly. A mismatch or undesirable gap between the cavity and core sides of the mold will result in flash. 使模具安裝適當(dāng)封閉。由于變形的模具結(jié)構(gòu)，分型面的缺陷，不合理的機(jī)臺(tái)和模具的安裝，飛邊或多余材料將在分型面產(chǎn)生Molding conditions 模具條件 鎖模力低If the clamp force of the injection machine is too weak to hold the mold plates together during the molding process, flash will occur. 成型過(guò)程中注射機(jī)鎖模力太弱以至于不能將模板合并在一起，就會(huì)產(chǎn)生飛邊Gap within the mold Flash 飛邊What is flash? Flash is a defect where excessive material is found at locations where the mold separates, notably the parting surface, movable core, vents, or venting ejector pins. 飛邊是鏟射與模具分離處產(chǎn)生的過(guò)量材料，特別是在分型面，移動(dòng)型心、排氣孔甚至是排氣頂針。 remendations and are still experiencing problems, try making the following 、背壓、螺桿轉(zhuǎn)速。Adding ten percent of regrind is a good start, if regrind is ，在一開(kāi)始就加入10%的再生料Store different materials separately and keep covers on the containers or bags to avoid blending different Adjust the molding conditions調(diào)整成型條件Material suppliers usually provide the information about barrel temperature, back pressure, and screw rotation speed for specific materials. If you39。 背壓和螺桿轉(zhuǎn)速低If the screw rotation speed and the back pressure setting are set too low, there might not be enough frictional heating to melt the material pletely in the barrel before the ，沒(méi)有足夠的剪切熱使注射前熔體在料筒中完全熔化。 Material contamination Too much regrind FIGURE 1. Unmelted materials in the melt stream causes fish eyes Causes of fish eyes Fish eyes are caused by: Low barrel temperature 料筒溫度低Purge the injection unit pletely if there is any material Reduce the barrel temperature and nozzle If the barrel and nozzle temperature are too high, the material in the barrel will be overheated, leading to thermal degradation and the color ，材料將過(guò)熱導(dǎo)致熱降解和顏色改變。 Burn marks Remedies Handle the material carefullyMaintain