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With laptops and mobile phones, and other 3C products gradually moving \research focus. As the technology has only just begun, there is no formation of the basic theoretical system and domestic research in this area is very small, so this study will be carried out to study the thin-walled injection molding characteristics accumulate experience, and carry out the thin-walled controlled injection molding parts manufacturing and lay a good foundation. The design of this project set a mold four-cavity mold, forming four different wall thickness (0.3mm, 0.5mm, 0.8mm, 1.0mm) parts. Using Moldflow MPI5.0 software Flow/3D simulation and experimental study of different parameters (melt temperature, injection speed, part wall thickness) of thin-walled injection molding characteristics. Using Moldflow MPI / Flow 3D simulation of the melt temperature, injection speed, product thickness and other parameters on the shear rate distribution in the thin-wall molding, results show that: in the the products flow direction, near the gate of the shear rate ambitious at the other around the shear rate, and decreases rapidly with increasing distance. Sandy the 1.5mm gate of the vicinity to the end of the article, the variation of the shear rate is not clear, stable between 2000 ~ 4000S -1 . Minimum shear rate in the thickness direction of the core layer, the subsurface direction gradually increases, and reaches a maximum at 0.1mm from the surface, and then go down to the surface layer is gradually reduced, until the surface, but the surface of the shear rate is still greater than core. Thin wall is thinner, the greater the shear rate at the gate, but in the end is almost the same. Synchronous thermal analyzer, Experimental study of the distribution of crystallinity of the thin-walled products in the flow direction and the thickness direction, the results showed that: the products flow direction from the point of view, at the gate of the melting enthalpy is significantly higher than other locations. ; along the flowing direction of the melt, the melt enthalpy with increasing distance and the gate is reduced, 5mm to the end of the article, the change is not obvious; product thickness direction from the point of view, from the center to the surface, crystallization enthalpy increases as the distance increases, reaches the maximum until the vicinity of the surface of 0.08mm, then the surface of the heat of crystallization enthalpy lower, but still higher than the central portion is much larger. According to the different requirements of thin-walled plastic parts performance level of crystallinity, by adjusting the parameters of the thin-walled plastic parts injection molding, melt temperature and injection rate to control the degree of crystallinity of molding thin-walled plastic parts, in order to achieve the thin-walled controlled manufacturing plastic parts.
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