塑胶成型不良问题及对策处理.中英文新doc.doc

Air traps 困气What is an air trap? An air trap is air that is caught inside the mold cavity. It becomes trapped by converging polymer melt fronts or because it failed to escape from the mold vents, or mold inserts, which also act as vents. Air-trap locations are usually in areas that fill last. Lack of vents or undersized vents in these last-to-fill areas are a common cause of air traps and the resulting defects. Another common cause is race-tracking (the tendency of polymer melt to flow preferentially in thicker sections), caused by a large thickness ratio. 困气是气体存在于模具型腔内无法排出，困气会形成气孔是其聚集在熔体前端或未从模具排气孔以及镶件排出。困气通常发生在最终填充位置。在填充末端缺少排气孔或排气孔太小都会引起空位造成制品缺陷。另一个较为普遍的原因是跑马场效应（聚合物熔体有优先向肉厚方向流动的趋势），是由于壁厚突变引起的。FIGURE 1. Air trap locations indicated by the computer-predicted melt-front advancements. (To replay the animation, click Replay) Problems caused by air traps Entrapped air will result in voids and bubbles inside the molded part, a short shot (incomplete fill), or surface defects such as blemishes or burn marks. To eliminate air traps, you can modify the filling pattern by reducing the injection speed, enlarging venting, or placing proper venting in the cavity. 困气将引起成型制品内部空位和气泡，短射（浇不足），或表面缺陷如污痕或烧焦。可以利用改善成型条件来解决困气问题，如减少注射速度，扩大排气孔，或者适当位置开设排气孔。In the figure below, an air trap results from race-tracking in a part with a large thickness ratio. In this case, the entrapped air can be vented by changing the thickness ratio or by placing a vent (e.g., via an ejector pin) at the air trap location.以下的例子中，困气是由于壁厚突变产生的跑马场效应引起的。困气可以由减小壁厚变化率或者适当位置开设排气孔消除。Remedies 补救措施Alter the part design改变零件的设计Reduce the thickness ratio.减少壁厚变化This will minimize the race-tracking effect of polymer melt.可以减少聚合物熔体的跑马场效应。Alter the mold design改变模具的设计Pay close attention to the proper placement of your vents.密切关注开设排气孔位置Place vents in the areas that fill last.在熔体流动末端开设排气槽Vents are typically positioned at discontinuities of mold material, such as at parting surfaces, between the insert and mold wall, at ejector pins, and at mold slides.排气孔通常开设在模具中断处，比如分型面、镶件与模具间隙、顶针、滑块等。Re-design the gate and delivery system.重新设计浇口和浇注系统Changing the delivery system can alter the filling pattern in such a way that the last-to-fill areas are located at the proper venting locations.改变浇筑系统可以改变充填形式使得流动末端布置好排气。Make sure the vent size is large enough so that the air present in the cavity can escape during injection.排气槽尺寸应足够大以使得气体可以在充填过程中排出。Be careful, however, that the vent is not so large that it causes flash at the edge of the molding. The recommended vent size is 0.025 mm (0.001 inch) for crystalline polymers, and 0.038 mm (0.0015 inch) for amorphous polymers.但是，排气槽不能太大防止制品产生飞边。对于结晶型塑料，排气槽应小于0.025mm，不定形塑料应小于0.038mm。Adjust the molding conditions改善填充条件Reduce the injection speed.减少注射速度High injection speeds can lead to jetting, which causes air to become entrapped in the part. Lowering the injection speed will give the air displaced by the melt sufficient time to escape from the vents.速度过高会引起喷射，这会使气体无法逃脱。较低的注射速度可以使气体有充足的时间从排气槽排出。Black specks/black streaks黑斑和黑痕What are black specks and black streaks? Black specks and black streaks are dark spots or dark streaks found on the surface or throughout a molded part. Brown specks or streaks refer to the same type of defect, except the burning or discoloration is not as severe.黑斑和黑痕是出现于制品表面或贯穿在整个零件内部的黑点或黑条纹。它们都是同种形式的缺陷，是不太严重的烧焦或色变。Causes of black specks/black streaks Black specks and black streaks are caused by overheated (degraded, burned) material or by contamination of the resin. 黑斑和黑痕是由于材料过热或树脂被污染而引起的。Material degradation   Overheated materials can degrade and lead to black streaks. Material that stays in the nicked rough surfaces of the barrel wall and screw surfaces for a prolonged period of time after heating will char and degrade, resulting in the defect. 材料过热会降解导致黑痕，材料在加热过程中停留在粗糙的料筒和螺杆表面的时间过长会烧焦并讲解，导致产品缺陷。Material contamination   Contaminants in the air or material, such as dirty regrind, foreign material, different color material, or a lower melt-temperature material, are what most often lead to black specks and black streaks. Airborne dirt can also cause dark spots on the surface of a molded part.在空气中或被其它材料污染，比如被污染的外来料，不同颜色的材料，低熔点材料，都通常引起黑斑和黑痕的原因。空气中的粉尘也是会引起成型制品表面的黑斑。Other defects resulting from the same causes 相同原因引起的其他缺陷· Brittleness 脆化· Burn marks 烧焦· Discoloration 色变Remedies Handle the material carefully小心使用材料Make sure no contaminated materials, such as dirty regrind, are blended into the original material.确保没有被污染的材料，比如脏的再生料加入到原材料当中。Put the cover on the hopper and all bins of material. Airborne dirt can contaminate the original material, leading to black spots.将容器盖上盖子，空气中的灰尘会污染原料导致黑斑。Alter the mold design改变模具设计Clean the ejectors and slides. The streaks could be caused by the grease or lubricants on the slides or ejectors.清洁顶针和滑块，条纹可以由滑块或顶针上的油脂或润滑油引起。Improve the venting system. If the black specks are found at the end of flow paths or blind spots, they are likely caused by a poor venting system. Compressed air trapped in the cavity is sometimes ignited, leading to the defect.改善排气系统，如果在流动末端或盲点发现有黑斑，有可能是由于排气不良引起的。被压缩的型腔内的气体有时会被点燃，造成产品缺陷。Clean or polish any nicked surface on the runner system to keep dirt from lodging in these areas.Clean the mold before molding.清洁或抛光流道内的粗糙表面，使污垢远离这些区域。并在成型前进行清洁。Select a proper machine 选用适合的机台Size a proper injection machine for a specific mold.The typical shot size should be between 20 and 80 percent of machine injection capacity. For temperature-sensitive materials, the range should be narrowed down more. Plastics simulation software can help you select the right size injection machine for a specific mold. This will help avoid resin remaining in the heated barrel for prolonged periods of time.注射量应为注射机最大注射量的20%80%，对于温度敏感型材料，变化范围应该更窄些，塑料仿真软件可以为成型模具选择适合的注射机。有助于避免塑料在加热料筒中停留时间过长。Check for scratched or dented barrel/screw surfaces that trap material.检验刮伤或凹陷的料筒或螺杆表面是否留有材料This could lead to the material becoming overheated or burned.残存的材料将会过热或烧焦Check for local overheating by a run-away heater band or a malfunctioning temperature controller.检验是否因料筒加热器脱离或温度控制器的故障引起局部过热。Adjust the molding conditions调节成型条件Lower the barrel and nozzle temperature.降低料筒或喷嘴温度Material degradation can result from a high melt temperature. 材料讲解会由熔体温度过高引起Purge and clean the injection unit.清洁注射装置The black streaks might be caused by contamination from the barrel wall or the screw surface. When molding with two materials, after switching from one material to the other, the old material might not be purged from the barrel completely. This could generate defects during the molding of the second material.黑痕可能会由于被污染的料筒壁或螺杆表面引起。当注射两种不同材料并从一种材料转换成另一种材料时，旧材料可能没有被完全清洗，在成型第二种材料时就会产生缺陷。Avoid recycling rejected parts with black specks and black streaks.避免回收使用有黑痕或黑斑的不良制品。Recycling such parts could lead to further contamination, unless they'll be used for parts that are in black or for which such defects are acceptable.回收利用该种类型的制品会导致更深一层的污染，除非它们是用于黑色或该缺陷是可以接受的零件。Brittleness What is brittleness? 脆化A brittle molded part has a tendency to break or crack. Brittleness results from material degradation leading to shorter molecular chain length ( thus lower molecular weight). As a result, the physical integrity of the part is substantially less than the specification. 脆性零件有断裂或爆裂的倾向。脆化是由于材料降解导致分析链缩短（可减轻分子量）造成的。结果，零件的物理性能达不到要求。FIGURE 1. Degraded part tends to be brittle and break easily Causes of brittleness Brittleness is caused by material degradation due to 脆化是由于材料讲解引起的：· Improper drying conditions 不合理的干燥条件· Improper temperature setting 不合理的温度设定· Improper runner system and gate design 不合理的流道系统和浇口的设定· Improper screw design 不合理的螺杆设计· Weld line weakness 结合线较弱Other defects resulting from the same causes 相同的原因会导致以下缺陷· Black specks/black streaks 黑斑或黑痕· Burn marks 烧焦· Discoloration 色变Remedies Adjust the material preparationSet proper drying conditions before molding. 成型前设置适合的干燥条件Brittleness can be caused by excessive drying time or drying temperature such as at full heat for several days. Excessive drying either drives off volatiles in the plastic, making it more sensitive to processing, or degrades the material by reducing the molecular weight. Material suppliers can provide optimum drying conditions for the specific materials.脆化可能是由于干燥时间过久或干燥温度过高引起的。过量的干燥不仅会使塑料不稳定，造成对工艺条件较为敏感，而且会使分子量减少造成材料降解。材料供货商会对各种材料提供适合的干燥条件。Reduce regrind material. The brittleness could be caused by too much reground material added into the original virgin material.脆化也有可能是因为太多再生料加入到原料当中。Change to a high-strength material since low-strength materials tend to become more brittle if processed improperly.在工艺条件不适当的条件下，如果 强度材料容易脆化，则改用高强度材料Alter the mold designEnlarge the sprue, runner, and/or gate.增大主流道、分流道、浇口。Restrictive sprue, runner, gate, or even part design could cause excessive shear heating that aggravates an already overheated material, causing material degradation.主流道、分流道和浇口甚至制品过小都会产生大量的剪切热，使材料的过热加重，引起材料降解。Select a proper machine/machine componentGet a better screw design for the material you're using to achieve a better mixed melt temperature.改善螺杆设计以使熔体充分混合并达到所需温度Contact material suppliers to get the right screw design information to avoid improper melt mix or overheating that leads to material degradation.联系厂商取得正确的螺杆设计尺寸，避免熔体不适当的混合或过热导致材料降解。Adjust molding conditionsReduce the barrel temperature and nozzle temperature.减少料筒和喷嘴温度If the barrel and nozzle temperature are too high, the material in the barrel will be overheated, leading to thermal degradation and the color change.如果料筒和喷嘴温度过高，料筒内材料将过热，导致降解或颜色变化Reduce the back pressure, screw rotation speed, or injection speed. since shear heating can result in material degradation.减少背压、螺杆转速、或注射速度，因为剪切热会导致材料降解Within the limit not to overheat the material, increase melt temperature, mold temperature or injection pressure if the weld line has a tendency to crack. See Weld lines and meld lines for more information.若材料结合线太弱，在材料过热极限范围内增加熔体温度，模具温度或注射压力Burn marks What is a burn mark? Burn marks are small, dark or black spots that appear near the end of the flow path of a molded part or in the blind area where the air trap forms. 烧焦是小，暗或黑色斑点出现在成型零件的流动末端或形成困气的盲点区域。Causes of burn marks Entrapped air If the injection speed or injection pressure is too high, the air trapped in the runner system and cavity cannot be released to the atmosphere through the venting system properly within a very short filling time. Air traps also occur in improperly vented systems when race-tracking behavior is significant. Consequently, the air will be compressed, resulting in a very high pressure and temperature, and which will cause the polymer to degrade on the surface near the end of the flow path or the blind area. 如果注射速度或注射压力太高，在较短的注射时间下，流道或型腔内的气体无法通过排气系统释放到空气当中。跑马场效应较为严重时，不合理的排气系统的设计奖产生困气。所以空气将被压缩，导致压力和温度增大，这会引起流动末端或盲点区域的制品表面塑料降解。Material degradation Burn marks can also result from the degraded (charred) materials being carried downstream and then appearing on the surface of the molded part or near the venting areas. Material degradation is caused by: 烧焦也有可能是因为已经降解的材料被带到下游并出现在成型零件靠近排气区域，材料降解原因：High melt temperature   Excessive melt temperature can be caused by improper barrel temperature setting, a broken thermocouple, or a malfunctioning temperature controller. 熔体过热是由于不适当的料筒温度的设定、损坏的热电偶或温控器失灵引起的High screw rotation speed   If the screw speed is too high during the plasticization period, it will create too much frictional heat, which could degrade the material. 在熔体塑化阶段，如果螺杆的速度过高，会产生较多的剪切热，这会导致材料降解。Restrictive flow path   When the melt flows through restrictive nozzle, runner, gate, or part sections, it creates a lot of shear (frictional) heat, which could degrade the material. 当熔体流经限制性的喷嘴、流道、浇口或制品截面时，将产生大量的剪切热，导致材料降解。Other defects resulting from the same causes · Black specks/black streaks · Brittleness · Discoloration Alter the mold design改变模具设计Place an adequate venting system throughout the mold to help vent out the entrapped air.开设适当的排气系统。Vents are especially important near the end of the flow path and in the blind area. The recommended venting size is 0.025 mm (0.001 inches) for crystalline polymers, and 0.038 mm (0.0015 inches) for amorphous polymers.流动末端和盲点区域的排气很重要，结晶性材料推荐排气槽尺寸为0.025，不定塑料为0.038。Enlarge the sprue, runner, and/or gate.增大主流道、分流道或浇口Restrictive sprue, runner, gate, or even part design could cause excessive shear heating that aggravates an already overheated material, causing material degradation.Adjust the molding conditions 调节注射条件Reduce the likelihood of burn marks by avoiding excessive melt temperatures during the molding process:避免成型过程中熔体温度过高，减少烧焦的可能性。Reduce the injection pressure.减少射压Reduce the injection speed.减少注射速度Reduce the screw rotation speed.减少螺杆转速Decrease the barrel temperature.减少料筒温度Check the band heaters on the barrel and nozzle, and calibrate the thermocouple.减少料筒、喷嘴的加热器是否损坏，校准热电偶Delamination What is delamination? 层脱Delamination (sometimes called lamination or layering) is a defect in which the surface of a molded part can be peeled off layer by layer. 层脱（有时叫做层裂或分层）是成型制品表面一层一层剥落。Causes of delamination 层脱原因Delamination can be caused by several factors, including: · Incompatible materials blended together 不兼容的材料混合在一起· Too much mold release agent being used during the molding process 注射成型过程使用过多的脱模剂。· Low melt temperature in the cavity 型腔内的熔体温度过低· Excessive moisture 水分过多· Sharp corners at the gate and runner 浇口或流道拐角处有尖角Change the material preparation 做好材料的成型前准备Avoid using foreign material or contaminated regrind material in the molding process.避免使用外来料或受污染的再生料。Alter the mold design更改模具设计Smooth all of the corners at the gate and runner.在浇口和流道拐角处倒圆角Sharp corners can tear apart melt flow and cause lamination.尖角会将熔体流动分离引起分层Adjust the molding conditions改善成型条件Avoid using excessive mold release agent to fix the de-molding problem.避免使用过量脱模剂来解决脱模问题Delamination can be caused by excessive use of mold release agent. You should repair the ejection system or other problems to eliminate the difficulty of de-molding instead of over-using the mold release agent.使用过量脱模剂可以导致层脱。可以通过修整脱模机构或其他可以消除脱模困难问题的方法来代替使用过多脱模剂Follow the pre-dry instructions for the specific material and pre-dry the material properly before molding.根据材料的干燥说明，在成型前对材料进行充分的预干燥。Excessive moisture heats up and forms steam, which results in lamination on the surface.大量水分蒸发并形成蒸汽，会导致表面分层。Increase the barrel temperature and mold temperature.增大料筒和模具温度If the melt temperature is too low, layers of material are formed because they can't bond to each other. When ejected or subjected to stress, they separate from each other.如果熔体温度过低，材料因不能结合而分层，当顶出或承受应力时，材料就会脱离。Dimensional variation What is dimensional variation? Dimensional variation is a defect characterized by the molded