塑料成型缺陷以及形成原因（Plastic forming defects and forming reasons）.docVIP

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塑料成型缺陷以及形成原因（Plastic forming defects and forming reasons）.doc

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塑料成型缺陷以及形成原因（Plastic forming defects and forming reasons）

塑料成型缺陷以及形成原因（Plastic forming defects and forming reasons） Plastic forming defects and forming reasons There is a dark area near the head 1. The surface of the material has a discernible ring around the head. If the center type is used for the center circle, the side gate is the concentric circle, which is because the ring size is small and it looks like a dark halo. This is mainly due to the processing of high viscosity (low fluidity) materials such as PC, PMMA and ABS. If the injection speed is too high, the material flow velocity is too fast and the viscosity is high. The surface material near the head is easily misaligned and infiltrated. These dislocations will appear in the outer layer of the dark halo. Near the head of the material, the flow rate is particularly high, then gradually decreases, and as the injection rate becomes constant, the front end of the flow extends into a gradually widening circle. At the same time, a multi-stage injection must be used in order to obtain the low flow velocity near the head of the material. For example: slow - fast - fast. The aim is to obtain the velocity of the flow velocity of the melt in the entire charge cycle. It is usually assumed that the dark halo is caused by the displacement of the material in the pressure. In fact, the effect of the precurrent effect is to transfer the material inside the product during the pressure-preserving phase. The reasons for the processing parameters and the improvement measures are shown in the table below: 1. High flow rate: slow - fast and fast The molten material temperature is too low to increase the cylinder temperature and increase the backpressure of the screw 3. Mold wall temperature is too low to increase mold wall temperature The reasons for the design and the improvement measures are shown below: 1. The gate and the product become an acute Angle between the sprue and the products The gate diameter is too small to increase the diameter of the gate 3. Reposition the gate posi