Views: 6 Author: Site Editor Publish Time: 2023-02-27 Origin: Site
30% glass fiber reinforced PA6 modification
30% glass fiber reinforced PA6 modified chips are ideal materials for processing power tool shells, power tool parts, construction machinery parts and auto parts. Its mechanical properties, dimensional stability, heat resistance and aging resistance have been significantly improved, and the fatigue strength is 2.5 times that of the unenhanced, and the modification effect is the most obvious.
The injection molding process of 30% glass fiber reinforced PA6 slice is roughly the same as when it is not enhanced, but because the flow is worse than before reinforcement, the injection pressure and injection speed should be appropriately increased, and the processing points are as follows:
1. The temperature of 30% glass fiber reinforced PA6 barrel is easy to increase by 10-40 °C. The barrel temperature selected during injection molding of PA6 modified chips is related to the performance of the slice itself, the shape factor of the equipment and the product. Too high material temperature is easy to make the parts color change, brittle, resulting in silver filament and other defects, too low barrel temperature is easy to harden the material, damage the mold and screw. The melt temperature of PA6 is as low as 220 °C, and due to the good fluidity of nylon, the temperature exceeds its melting point and flows rapidly. The fluidity of 30% glass fiber reinforced PA6 modified sections is significantly lower than that of pure material chips and injection grade PA6 chips, and the barrel temperature is easy to increase by 10-20 °C.
2. The temperature of 30% glass fiber reinforced PA6 processing mold is controlled at 80-120°C. The mold temperature has a certain influence on the crystallinity and molding shrinkage, and the mold temperature range is 80-120 °C. Products with high wall thickness should choose high mold temperature, its crystallinity is high, wear resistance is good, hardness, elastic modulus increases, water absorption decreases, and the molding shrinkage rate of products also increases. Thin-walled products should be selected with low mold temperature, which has low crystallinity, good toughness, high elongation and reduced shrinkage. The wall thickness is greater than 3mm, it is recommended to use a low-temperature mold of 20~40 °C. The mold temperature of 30% glass reinforced material should be greater than 80 °C.
3. The wall thickness of 30% glass fiber reinforced PA6 products should not be less than 0.8mm. The flow length ratio of PA6 is between 150-200, and the wall thickness of the product should not be less than 0.8mm, generally selected between 1~3.2mm. The shrinkage of 30% glass fiber reinforced PA6 products is related to its wall thickness, and the thicker the wall thickness, the greater the shrinkage rate.
4. The exhaust hole groove should be controlled below 0.025mm. The overflow value of 30% glass fiber reinforced PA6 resin is about 0.03mm, so the exhaust hole groove should be controlled below 0.025mm.
5. The gate aperture should not be less than 0.5*t (t is the thickness of the plastic part). With submersible gates, the minimum diameter of the gate should be 0.75mm.
6. The shrinkage rate of 30% glass fiber reinforced PA6 products can be reduced to 0.3%. The shrinkage rate of PA6 pure material is between 1%~1.5%, and the shrinkage rate can be reduced to about 0.3% after adding 30% glass fiber reinforcement. Practical experience shows that the more glass fiber is added, the smaller the molding shrinkage of PA6 resin. However, with the increase of fiber added, it will also cause consequences such as surface floating fiber and poor compatibility, and the 30% glass fiber reinforcement effect is relatively good.
7. 30% glass fiber reinforced PA6 recycled material should not be used more than 3 times. 30% glass fiber reinforced PA6 does not contain any recycled material, but if the customer uses too much recycled material, it is easy to cause discoloration of the product or a sharp decline in mechanical and physical properties, and the application amount should be controlled below 25%, otherwise it will cause fluctuations in process conditions, and the recycled material must be dried before mixing with new material.
8. The amount of release agent used is small and uniform. The release agent of 30% glass fiber reinforced PA6 products can be selected with zinc stearate and white oil, etc., which can also be mixed into a paste, and a small amount of release agent has the effect of improving and eliminating defects such as bubbles. When used, the amount must be small and uniform, so as not to cause surface defects of the product.
9. After the product is molded, put it in hot water and cool it slowly. Because glass fiber will be oriented along the flow direction during the injection molding process, causing mechanical properties and shrinkage to enhance 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 temperature of the mold can be increased in the process, and the product should be put into hot water to cool it slowly after taking it out.
10. 30% glass fiber reinforced PA6 parts used in high temperature environment should be treated with humidity control. Boiling water humidity control method can also be used, potassium diacetate aqueous solution humidity control method can also be used. Boiling water humidity control method to place the product in a humidity of 65% of the environment, so that it can reach a balanced moisture absorption capacity, potassium acetate aqueous solution (potassium acetate to water ratio of 1.25:1, boiling point 121 °C) humidity control method treatment temperature of 80-100 potassium acetate aqueous solution humidity control method, the treatment time mainly depends on the wall thickness of the product, when the wall thickness is: about 2 hours when 1.5mm, about 8 hours when 3mm, about 16-18 hours when 6mm.
Nanjing Haisi Extrusion supply twin screw extruder for 30% glass fiber reinforced PA6 modification.
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