注塑成型不良 BS（黑点1.doc

成型不良 BS（黑点）Black Spec何谓黑点（外观）？What is Black spec ? (appearance)黑点是指成型品中出现黑色的点或条纹的现象。 成型品表面上出现的黑色的点便是BS（黑点）。由于某些原因，其成分估计是焦化树脂或碳化树脂。BS is a molding defect where (a) black point(s) or line(s) appears on the surface of a molded product.黑点的生成原因Causes of Black spec Generation树脂分解Decomposition of resin由于塑料是化学物质，因此当在熔点以上继续加热时，塑料便会逐渐分解。温度越高，时间越长，分解就进行得越快。而且机筒内部还有止逆环和螺纹槽等容易滞留树脂的部位。持续滞留在这些部分的树脂发生焦化或碳化后会按某种节奏脱落并混入到成型品中，从而形成黑点。Since a plastics is a chemical substance, it decomposes little by little on heating over the melting point. Decomposition proceeds as temperature is increased and time is prolonged. Inside the cylinder there are places where resin is likely to stagnate such as check ring and screw grooves. When the stagnation continues, the resin is changed to tar or is carbonized. If this part comes off by any chance and is mixed in a molded product, it becomes BS.清洗不足(2-2) Shortage of purging因清洗不充分而使以前使用的树脂残留在成型机内的情况也是黑点的生成原因。如上一项所述，由于存在止逆环和螺纹槽等容易滞留树脂的部位，因此对该部分进行置换时需要使用相应的清洗量和次数，此外还必须采用适合每种材料的清洗方法。如果是PBTPBT等同类树脂的清洗，则比较容易进行，但如果是不同种类的材料的清洗，则由于熔点或分解温度各不相同并且树脂之间也存在相容性（亲和性），因此即使清洗，很多情况下也无法完全排出。When purging is insufficient and the resin used before remains in a molding machine, the remaining resin becomes a cause of BS. As described above, there are parts where resin is likely to stagnate such as check ring and screw grooves, and the replacement of these parts requires a certain level of purging quantity and number of times with a purging way suitable for each material. Though, as in a change from PBT to PBT, purging between the same resins is relatively easy, purging between different materials is often incomplete due to different melting points and decomposition temperatures and to compatibility between resins.异物混入Contamination of foreign matters污染也是产生黑点的成因之一Contamination is also a cause of BS.。如果投放到料斗中的部分粒料内混入分解温度较低的其他树脂，则会因混入树脂发生分解等原因而容易产生黑点。此外还应注意回收塑料。这是因为回收塑料经多次受热（重复回收次数越多，受热时间越长）后变得更容易分解。另外，回收时也有可能被金属污染。When a resin of lower decomposition temperature is mixed in a part of pellets fed in a hopper, BS may be generated by decomposition of the mixed resin. A recycled material is also requires attention. Since a recycled material has already undergone heat histories (As recycling is repeated, the time subjected to heat is longer.) and is susceptible to decomposition. In recycling, also metal may contaminate the material黑点的对策) Countermeasures against black spec首先要充分清洗直至黑点不再出现) To sufficiently purge till no specks are found黑点倾向于滞留在机筒内的止逆环和螺纹槽中。如果曾经出现过黑点，则估计黑点的起因很可能残留在机筒内。因此，出现黑点后，必须在采取对策之前充分清洗（否则黑点永远都不会消失）。BS tends to stagnate around the check ring and in screw grooves in the cylinder. Once BS is generated, the possibility that the origin of BS is remaining in the cylinder is quite high. Accordingly, when BS is found, sufficient purging is absolutely necessary before taking any countermeasure. (Without purging, BS will never be eliminated.)尝试降低树脂温度To lower resin temperature各种树脂都有推荐的使用温度（产品目录或产品包装袋等上面也都含有这方面的信息）。检查成型机的设定温度是否超出范围，如果超出，则请降低温度。另外，成型机上所显示的温度是传感器所处位置的温度，与实际树脂温度多少会有一些差异。如果可能，建议用树脂温度计等测量实际温度。尤其是止逆环等容易产生滞留的部分最容易导致黑点，因此要特别注意其附近的温度。Each resin has its recommended using temperature (The temperature is given in the brochure and on product bags). Check if the set temperature of the molding machine is over the designated range, and, if so, lower the setting. Note that the temperature shown in the machine is the temperature at the place where the sensor is located, and that actual resin temperature is somewhat different from it. If possible, it is recommended to measure actual resin temperature. In particular, since a place where BS is easily formed is that where resin tends to stagnate such as check ring, pay attention to the temperature around that place.VectraABCEiTS级级级级级级：290320：290320：330350：340365：370380：355370各种材料的推荐使用温度Duracon190210Duranex240260Fortron300330缩短滞留时间To shorten residence time即使成型机的设定温度处在各种树脂的推荐温度范围内，但长时间滞留仍会导致树脂劣化，并且容易出现黑点。如果成型机具有延时设定功能，请充分利用这一功能，此外还应使用适合模具大小的成型机。Even if the set temperature of a molding machine is within the recommended temperature range of each resin, a long residence time may degrade the resin and BS is likely to be generated. If the molding machine has a function of delayed time setting, utilize the function. Try to use a molding machine of the size matching to the mold size图4.（例）Duracon M90的耐热变色域有无污染？其他树脂或金属偶尔混入也可能会导致黑点。令人感到意外的是原因多为清洗不足。请在充分清洗并彻底清除上次成型时所用的树脂之后再进行作业。使用回收塑料时，请用肉眼确认粒料中有无异物。Though rarely, another resin or a metal is contaminated to be a cause of BS.An unexpectedly frequent cause is short purging. Ente