People are paying more attention to the issue of lightweight and trend, to satisfy the more secure, energy-saving, environmentally-friendly and comfortable demands. Carbon fiber is the material having the advantages of high strength and lightweight. At present, the use of carbon fiber cloth has become gradually mature and marketable, but its molding is difficult, and the labor cost for process is high. Therefore, the process of long fiber injection molding has become the mainstream and it can produce the complicated components and improve the structural strength.
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Photo 1- Diagram for the relationship between fiber length and stiffness, strength and toughness |
At present, the process of fiber application injection molding includes the combination of short fiber and resin SFT, combination of long fiber and resin aggregate LFT-G as well as the combination of continuous long fiber and resin LFT-D, FCS and LFT-D (Long Fiber Thermoplastic Direct) application injection molding. The finished product of fiber with the fiber length of more than 12 mm is tested in the target test. It is observed from photo 1 that short fiber (0.1~1 mm) can only sustain the structure stiffness of the finished product; when the fiber length is increased (10 mm~50 mm), it can not only sustain the structure stiffness but also improve the strength of materials; the continuous fiber (more than 50 mm) can improve the toughness of finished product and FCS target can improve the structure stiffness of the finished product as well as the strength of materials.
The unit equipment (see photo 2) required by long fiber application injection molding has the special barrel, so it is necessary to match the following equipment to realize long fiber injection molding:
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Photo 2- Diagram for the framework of long fiber molding injection units |
(1) VENT barrel: VENT barrel is the free-drying molding barrel and characteristic of this barrel is that it can mold the undried plastic raw material; the special design of barrel can exhaust the steam and gas in the plastic raw material and meanwhile the continuous fiber is input through the exhaust vent.
(2) HUNGRY FEEDER: the exhaust vent is designed in the middle of the VENT barrel. If a large amount of plastics enters through the feeding hole, it will cause the plastics to discharge from the exhaust vent, so it is necessary to install HUNGRY FEEDER to control the feeding.
(3) FIBER ROVING: different from the short fiber molding, the long fiber application injection molding needs to use the input of the continuous fiber.
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Photo 3- Flow chart for the test of long fiber application injection molding |
According to the test result, the fiber length has reached the target length of 12 mm set by FCS. The carbon fiber injection molding mainly focuses on energy and lightweight industry, thus, this technology will be introduced to the clients related to carbonfiber application industry, to help them solve the difficulty in long fiber injection process, so as to improve the product value of long fiber injection molding.
