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Nylon modification solves the shortcomings in the injection molding process
2020/7/15 9:05:57   252

PA modified material

Due to the strong polarity of PA, it has strong hygroscopicity and poor dimensional stability, but it can be improved by modification.


Glass fiber reinforced PA

When 30% glass fiber is added to PA, the mechanical properties, dimensional stability, heat resistance, and aging resistance of PA have been significantly improved, and the fatigue strength is 2.5 times that of unreinforced. The molding process of glass fiber reinforced PA is roughly the same as that of unreinforced PA, but because the activity is worse than before reinforcement, the injection pressure and injection speed should be appropriately improved, and the barrel temperature should be increased by 10-40℃.

Since the glass fiber will be oriented in the direction of movement during the injection molding process, the mechanical properties and shrinkage rate will increase in the orientation direction, resulting in deformation and warpage of the product. Therefore, when designing the mold, the position and shape of the gate must be fair, and the process can be improved. The temperature of the mold, put the product in hot water after taking it out, and let it cool down slowly. In addition, the greater the proportion of glass fiber added, the greater the wear on the plasticizing components of the injection molding machine. It is better to use bimetallic screws and barrels.


Flame retardant PA

Because flame retardants are added to PA, most flame retardants are easy to decompose at high temperatures, release acidic substances, and have corrosive effects on metals. Therefore, plasticizing components (screw, rubber head, rubber ring, rubber Rubber gaskets, flanges, etc.) need to be hard chrome plated. In terms of technology, try to control the temperature of the barrel not to be too high, and the injection speed not to be too fast, so as to avoid discoloration of the product and degradation of mechanical properties due to the decomposition of the rubber material due to the high temperature.


Transparent PA

It has good tensile strength, impact resistance, rigidity, abrasion resistance, chemical resistance, surface hardness and other properties, high light transmittance, similar to optical glass, processing temperature is 300-315 ℃, when molding processing, it needs Strictly control the temperature of the barrel. Too high melt temperature will cause discoloration of the product due to degradation, and too low temperature will affect the transparency of the product due to poor plasticization. The mold temperature should be as low as possible. High mold temperature will reduce the transparency of the product due to crystallization.

Weather-resistant PA adds carbon black and other ultraviolet absorbing additives to PA, which greatly enhances the self-lubricity of PA and wears against metal, and affects blanking and wear of parts during forming. Therefore, it is necessary to use a combination of screw, barrel, rubber head, rubber ring, and rubber gasket with strong feeding capacity and high wear resistance.