30% glass fiber reinforced PA6 modification
30% glass fiber reinforced PA6 modified chip is an ideal material for processing power tool shell, power tool parts, construction machinery parts and automobile 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 chips is roughly the same as that without reinforcement, but because the flow is worse than that before reinforcement, the injection pressure and injection speed should be appropriately increased. The processing points are as follows:
1. The barrel temperature of 30% glass fiber reinforced PA6 is easy to increase by 10-40 ℃. The barrel temperature selected for injection molding of PA6 modified chips is related to the properties of the chips themselves, equipment and shape factors of the products. Too high material temperature is easy to make parts color change, brittle, silver wire and other defects, too low barrel temperature is easy to harden the material and damage the mold and screw. The lowest melt temperature of PA6 is 220C. Because of its good fluidity, nylon flows rapidly when the temperature exceeds its melting point. The fluidity of 30% glass fiber reinforced PA6 modified chips 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 ℃.
2. 30% glass fiber reinforced PA6 processing mold temperature is controlled at 80-120C. The mold temperature has a certain influence on the crystallinity and molding shrinkage, and the range of mold temperature is 80-120 ℃. The products with high wall thickness should choose high mold temperature, which has high crystallinity, good wear resistance, increased hardness and elastic modulus, decreased water absorption and increased molding shrinkage. Thin-walled products should choose low mold temperature, which has low crystallinity, good toughness, high elongation and decreased shrinkage. If the wall thickness is greater than 3mm, it is recommended to use a low temperature mold at 20 ℃ to 40 ℃. The mold temperature of 30% glass reinforced material should be higher than 80 ℃.
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. the wall thickness of the product should not be lower than that of 0.8mm. Generally, the choice is between 1~3.2mm. The shrinkage of 30% glass fiber reinforced PA6 products is related to its wall thickness. The thicker the wall thickness, the greater the shrinkage.
4. The exhaust orifice groove should be controlled below 0.025mm. The overflow edge value of 30% glass fiber reinforced PA6 resin is about 0.03mm, so the exhaust slot should be controlled below 0.025mm.
5. The gate diameter should not be less than 0.5 kilott (t is the thickness of the plastic part). With a submerged gate, the minimum diameter of the gate should be 0.75mm.
6. The shrinkage of 30% glass fiber reinforced PA6 products can be reduced to 0.3%.
The shrinkage of PA6 pure material is between 1% and 1.5%, and the shrinkage 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 is. However, with the increase of the amount of fiber, it will also cause surface floating fiber, poor compatibility and other consequences, 30% glass fiber reinforcement effect is relatively good.
7. 30% glass fiber reinforced PA6 recycled materials should not be used more than 3 times. 30% glass fiber reinforced PA6 does not contain any recycled materials, but if customers use too much recycled materials, it is easy to cause discoloration of products or sharp decline in mechanical and physical properties, the application amount should be controlled below 25%, otherwise it will cause fluctuations in process conditions, and drying treatment must be carried out before recycled materials and new materials are mixed.
8. The amount of mold release agent is small and uniform. The release agent of 30% glass fiber reinforced PA6 products can choose zinc stearate and white oil, or it can be mixed into paste, and a small amount of release agent can improve and eliminate defects such as bubbles. Use must be small and uniform, so as not to cause surface defects of the products.
9. After the product is out of the mold, put it into hot water to cool slowly. Because the glass fiber will orient along the flow direction in the injection molding process, the mechanical properties and shrinkage will be enhanced in the orientation direction, resulting in the deformation and warping of the products. Therefore, in the mold design, the position and shape of the gate should be reasonable. The temperature of the mold can be raised in the process, and the product should be put into hot water to cool slowly.
10. 30% glass fiber reinforced PA6 parts used in high temperature environment should be moisturized. The humidity control method of boiling water or potassium diacetate solution can be used. The humidity control method of boiling water puts the product at a humidity of 65% to achieve equilibrium moisture absorption. The treatment temperature of potassium acetate aqueous solution (the ratio of potassium acetate to water is 1.2515, boiling point 121C) is 80-100potassium acetate solution. The treatment time mainly depends on the product wall thickness, when the wall thickness is about 2 hours for 1.5mm, about 8 hours for 3mm, and about 16-18 hours for 6mm.
Post time: 08-12-22