Applications
The oval cross-section of flat glass fiber prevents molded products from warping or twisting, when used as reinforcement in composites. Nittobo flat fibers find several applications in the automobile industry. The industry is in transition towards electronic vehicles (EV) and is also facing increasingly stringent legislation regulating fuel economy. These factors are driving car manufacturers to replace heavy metal parts with lighter FRPs. Metal parts that are subjected to extreme conditions during operation, such as the engine head cover, can be successfully produced using Nittobo’s flat fiber technology. Flat fibers are also ideal for use in the production of casings for small electronic devices, such as smartphones. These casings must be strong, light-weight and need to be produced without even the slightest distortion.
Fig. 16 The table below summarizes the suitability of Nittobo flat fibers for various applications.
Sample Application: Cylinder Head Cover
In high-performance engines, aluminum cylinder head covers are being replaced with those made from glass fiber reinforced polyamide, to reduce the weight of the vehicle. FRP head covers have a tendency to show high warpage; the resulting distortion can cause oil leakage and may lead to residual stress in the molded part. A simulation study was conducted to investigate if warpage can be reduced by replacing conventional glass fibers with Nittobo flat fibers in the production of a cylinder head cover. The figure below shows the simulation model of the head cover and the locations that are most affected by warpage.
Fig. 17 Suitability of present and future Nittobo flat fibers for various applications
Fig. 18 Simulation model of the head cover identifying the
locations that are most affected by warpage
The simulation analysis was carried out using AUTODESK Moldflow®, a simulation software used to troubleshoot problems with plastic injection molding. The figure below shows the comparative warpage analysis results of the head cover, injected from the side gate of the mold. The dark blue regions indicate no warpage whereas the yellow region indicates warpage of around 7mm. The results for conventional fiber glass showed the greatest warpage. The warpage was maximum at the corners of the molded part. Nittobo glass fiber with a flat ratio of 2 showed significantly less warpage. The warpage was minimized in the part molded with Nittobo flat glass fiber with a flat ratio of 4.
Fig 19. Replacing conventional glass fiber with Nittobo flat fiber
reduces warpage in molded products
The graph below shows that warpage is reduced with increasing flat ratio of Nittobo flat fiber. The reduction of warpage is consistent whether the mold is injected from the center single or double gates, or from the single side gate.
Fig 20. The magnitude of warpage decreases with increasing flat ratio
Greater Tensile Strength
In addition to reducing warpage, the smaller anisotropy, resulting from the use of flat glass fiber, also enhances the
physical properties of the composite material. Moldflow® software was also used to simulate and visualize the
tensile modulus distribution in the molded cylinder head cover. Figure 9 shows that the flat fiber composite material,
with a flat ratio of 4, exhibited the highest overall modulus. The modulus for the composite with flat glass fiber ratio
of 2 was also higher than for the conventional glass fiber part. This result is important because it offers engineers
greater flexibility in product design. It means that flat glass fiber composites can match the tensile modulus of
conventional glass fiber components with a thinner layer or reduced glass fiber content. Thinner components can
help engineers achieve further weight reduction leading to increased fuel efficiency of vehicles.
Fig 21. Simulation results of tensile modulus distribution in the molded part; flat fiber with a flat ratio of 4 shows the highest overall modulus
Test results show that the tensile strength of Nittobo flat fibers is greater than the tensile strength of conventional
fibers with a circular cross section. Figure shows that replacing round glass fibers with Nittobo flat fibers increases
the tensile strength of FRP products. Nittobo fibers produce consistently greater tensile strength across a range of
glass fiber weight percentages.
The tensile strength of polymer reinforced with Nittobo flat fibers was found to be greater than the tensile strength of FRP reinforced with conventional fibers having a circular cross section. The graph below shows that replacing round glass fibers with Nittobo flat fibers increases the tensile strength of FRP products. Nittobo fibers produce consistently greater tensile strength across a range of glass fiber weight percentages.
Fig 22. Nittobo fibers increase the tensile strength across
a range of glass fiber weight percentages
The study shows that Nittobo flat glass fibers can help reduce warpage in molded composite products. Nittobo flat fibers help achieve low shrinkage and reduced anisotropy which makes them suitable for a wide range of applications that require good dimensional stability. Nittobo's flat glass fiber technology offers new opportunities to automobile manufacturers as they evolve their products towards electrification and high fuel efficiency.