When 30% glass fiber is added to PA, the mechanical properties, dimensional stability, heat resistance and aging resistance of PA are obviously improved, and the fatigue strength is 2.5 times that of unreinforced. The molding process of glass fiber reinforced PA is almost the same as that of unreinforced, but the injection pressure and injection speed should be appropriately increased due to the increased flow front, and the barrel temperature is increased by 10-40 °C. Since the glass fiber is oriented in the flow direction during the injection molding process, the mechanical properties and shrinkage rate are enhanced in the orientation direction, resulting in deformation and warpage of the product. Therefore, when the mold is designed, the position and shape of the gate should be reasonable, and the process can be improved. The temperature of the mold, the product is taken out and placed in hot water to allow it to cool slowly. In addition, the greater the proportion of glass fiber added, the greater the wear on the plasticizing components of the injection molding machine, preferably using a bimetallic screw and barrel.
2. Flame retardant PA
Due to the addition of flame retardant in PA, most of the flame retardants are easily decomposed at high temperatures, releasing acidic substances and corrosive to metals. Therefore, plasticizing components (screws, rubber heads, aprons, glues) Washers, flanges, etc.) need to be hardened. In terms of process, try to control the temperature of the barrel not to be too high, and the injection speed should not be too fast to avoid discoloration and mechanical properties degradation caused by decomposition of the rubber temperature. 3. Transparent PA
Has good tensile strength, impact strength, rigidity, wear resistance, chemical resistance, surface hardness and other properties, high light transmittance, similar to optical glass, processing temperature is 300--315 ° C, when molding processing, need Strict control of the barrel temperature, too high melt temperature will cause discoloration of the product due to degradation, too low temperature will affect the transparency of the product due to poor plasticization. The mold temperature should be as low as possible, and the high mold temperature will reduce the transparency of the product due to crystallization. 4. Weather resistant PA
Ultraviolet absorbing agents such as carbon black are added to the PA, which greatly enhances the self-lubricating property of the PA and the wear of the metal, and affects the blanking and wear parts during the molding process. Therefore, it is necessary to use a combination of a screw, a barrel, a rubber head, an apron, and a rubber gasket with high feeding ability and high wear resistance.
