Brief introduction of nylon molding process
he forming process of nylon:
1. barrel temperature: because the nylon is a crystalline polymer, so the melting point is obvious, the shape factor of barrel temperature of nylon resin selected in injection molding performance, equipment, products with the resin itself. The material temperature is too high and easy to make plastic parts appear discoloration, crisp and silver, while the temperature is too low to make hard materials may damage the mold and screw. General nylon 6 melt temperature for a minimum of 210 C, 66 nylon 260 DEG C. Due to the poor thermal stability of nylon, so it should not stay for long time at high temperature in the cylinder, so as not to cause material yellow discoloration due to liquidity nylon better temperature above its melting point after rapid flow.
2.Injection pressure: nylon solution with low viscosity, good fluidity, but the condensation speed, prone to problems in complex shape and thin wall of the product, so it still need higher injection pressure, especially with glass fiber. Usually the pressure is too high, there will be flash products; pressure is too low, products will produce bubbles, ripples, obvious melting marks or product defects, most varieties of nylon injection pressure is less than 120MPA, generally in the range of 60-100MPA is selected to meet most of the requirements of products, as long as there are no defects such as bubbles, dent products, generally do not want to use high pressure, so as to avoid product stress increase.
3. injection speed of nylon, injection speed to fast for the benefit, can prevent the ripple caused by slow cooling rate, the problem of filling defects. Influence of injection speed on the performance of products is not prominent.
4. mold temperature: die temperature has certain effect on the crystallinity and molding shrinkage, high mold temperature high crystallinity, wear resistance, hardness and elastic modulus increased, the water absorption reduced, the product shrinkage rate increase, suitable for thick products; low temperature and low crystallinity, good toughness, elongation, high shrinkage, suitable for thin products good transparency. If the wall thickness is greater than 3mm, recommend the use of low temperature mold 20 - 40C. The glass reinforced materials of mould temperature should be greater than 80C.