The Solutions to Air Patterns in Polycarbonate (PC) Injection Molding
In polycarbonate injection molding production, if there are air patterns or shot lines near the injection port of the plastic parts, you can refer to the analysis in this article to improve it. Among them, reducing the injection speed is our primary means to improve the problem of injection lines and air patterns. The second thing to do is to check whether the size of the injection nozzle is too small or too thin.
There are some differences in the appearance of injection molding parts due to different reasons for the air pattern and shot pattern of the glue inlet. Paying more attention to observation and recording during the plastic injection molding process can speed up the analysis and problem-solving speed.
Baking the raw materials is the basic action to ensure polycarbonate injection molding production. This major precondition must be fulfilled. If the polycarbonate(PC) plastic material has been fully baked, but there will still be air lines or jet lines at the water inlet during production, the following factors must be considered.
Solutions to the 8 factors causing air patterns
- 1. The speed of the first-level injection is too fast, which is the main reason for the air pattern at the water inlet. It makes the melted glue produce serious eddy current when it enters the cavity, resulting in eddy current air pattern. Therefore, this is the first consideration for the adjuster, and it is necessary to reduce the speed and try.
- 2. The glue inlet is too thin or too thin, which is also an important factor causing the air pattern and shot pattern of the water inlet. Because the glue inlet is too small or too thin, the injection speed of the molten glue into the cavity is bound to be too fast. Thereby producing ray and gas lines. This is also the reason for the serpentine pattern. Therefore, when the problem cannot be eliminated even if the injection speed is reduced enough, the adjuster needs to consider whether the water inlet is too thin or too thin, such as less than 0.5 mm or less.
- 3. The thicker the wall thickness of the injection molded parts at the glue inlet and the nozzle position, the easier it is to produce air lines, such as more than 4 mm. Because the thicker the wall thickness, the easier it is to generate eddy current when the melted glue enters the nozzle, resulting in the generation of air streaks. When this happens, it is sometimes difficult to eliminate the air pattern by increasing the water inlet and reducing the speed. At this time, it is best to change the glue inlet to a place with a thinner wall, such as below 3 mm.
- 4. The higher the polishing level of the surface of the mold cavity, the brighter the surface of the injection molded part, the easier it is to generate air lines. If the surface of the injection molded part is too bright, slight air lines will appear.
- 5. If the mold temperature is too low, the injection molded parts will also have shot lines caused by the jelly, accompanied by matte air lines.
- 6. For raw materials that are easy to burn glue, if the melting temperature is too high, air lines will be generated due to excessive decomposition of gas.
- 7. The quality of the melted glue should be confirmed. The back pressure of the PC material should be set at 10bar~25bar. The speed of the melted glue should be set to a medium speed. Flowers, the glue pumping stroke should be set according to the back, the greater the back pressure, the longer the glue pumping stroke setting, generally 2mm~10mm is better.
- 8. If the temperature of the nozzle is too high or too low, if it is too high, the rubber material at the nozzle will decompose, resulting in air lines; if it is too low, the injection will not be smooth, forming jet lines or cold offset printing.
Application of PC (polycarbonate) injection molding parts
PC plastics are widely used in the automotive industry, electronic and electrical parts, optical lighting, electrical instrument housings, and medical equipment structural parts. PC modified materials are widely used in commercial products. Usually, people custom plastic with glass fibers, mineral fillers, chemical flame retardants, and other plastics can be added.
- Automotive industry: PC has good impact resistance, thermal distortion resistance, good weather resistance, high hardness and good mechanical properties. Therefore, PC is suitable for the production of various parts of automobiles, mainly the processing and manufacturing of lighting systems, instrument panels, heating panels, defrosters and bumpers made of PC alloys.
- Medical devices: PC products are less prone to yellowing and physical performance degradation when subjected to steam, cleaning agent cleaning, heating and large doses of radiation. Therefore, PCs are widely used in medical devices that need to operate under transparent and intuitive conditions. Such as injection molding production of high pressure syringes, surgical masks, dental appliances, blood separators, etc.
- Aviation aerospace: The application of PC in aircraft and spacecraft is increasing day by day. Excellent PC modified materials are made into hundreds of polycarbonate (PC) parts and protective articles of different configurations in the aerospace field.
- Electronic appliances: PC has good and constant electrical insulation in a wide temperature and humidity range, and is an excellent insulating material. At the same time, PC material has good flame retardancy and dimensional stability, making it widely used in the electrical and electronic industry. PC resin is mainly used in the production of various food processing machines, power tool housings, brackets, refrigerator freezer drawers and vacuum cleaner parts, etc. Even for important parts in computers, video recorders and televisions that require high parts accuracy, PC materials have shown extremely high use value.
- Optical lens: PC has the unique characteristics of high light transmittance, high refractive index, high impact resistance, dimensional stability and easy processing and molding. Therefore, PC occupies an extremely important position in the manufacturing field of optical lenses. While lighting manufacturers have traditionally used plexiglass (PMMA), LED designers can realize many benefits by choosing PC, including greater impact and heat resistance, improved flame retardant ratings, and enhanced design flexibility. PC materials are widely used in the manufacture of street light lenses.
Optical lenses made of optical grade PC materials can be used not only in cameras, microscopes, telescopes and optical testing instruments, but also in projector lenses, copier lenses, projector lenses, laser beam printer lenses, as well as various prisms, polygon mirrors And many other areas of office equipment and home appliances. Another important application area of PC in optical lenses is as a lens material for children’s glasses, sunglasses, safety glasses, and tinted glasses.
- Packaging: A new growth point in packaging is reusable water storage bottles. Because PC products have the advantages of being lightweight, having good impact resistance and transparency, no deformation and transparency when washed with hot water and corrosive solutions, PC bottles in some fields have completely replaced glass bottles.
Choose polycarbonate injection molding manufacturer as a partner
As a one-stop injection molding manufacturer, Sungplastic provides one-stop services from mold design and manufacturing, product injection processing, and plastic shell surface treatment (oil injection, silkscreen, etc.). Our professional capabilities are enough to support mass production in the later stage, not only to ensure the injection molding process, but also to control other processing links fully. This can eliminate or reduce the risk of customized services for customers.
The service of injection molding factory “Sungplastic” is not only pre-sale, in-sale and after-sale. Our service is not only about the delivery on time, but also about recognizing the needs of customers in advance, and being able to do preparatory work before production, so as to avoid problems. On the other hand, if you encounter a problem, you must be able to respond quickly, actively cooperate to solve the problem, seek the most suitable way and actively optimize your own process system.
High quality injection molding service is the basis for a win-win situation. Sungplastic provides reliable services for plastic projects of customers. According to the pre-set goals of the project, the production quality after injection molding is tested, and finally mass production is carried out. Sungplastic not only has rich experience in manufacturing PC parts, but also is proficient in the performance and use of PP, PE, PBT, PVC, ABS, PC, PMMA, PCTG, PPSU, PS, PA, POM and other injection molding materials. We use high-end Japanese TOSHIBA injection molding machines. It is suitable for the production of various precision plastic products, such as electronic product accessories, medical equipment, optical lenses and other products.
Of course, since every project is unique, you should work closely with your manufacturing partners to find practical solutions to help you achieve your product development goals.
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