Injection Molding process of Nylon material

Injection Molding process of Nylon material.
Conditions for the use of injection molding machines.
Barrel temperature.
Because nylon is a crystalline polymer, the melting point is obvious. the barrel temperature selected by nylon resin during injection molding is related to the properties of the resin itself, equipment and the shape of the products.
Too high material temperature is easy to make rubber parts appear color change, brittleness and silver wire, while too low material temperature makes the material very hard and may damage the mold and screw. Generally, the lowest melt temperature of nylon 6 is 220 ℃ and that of nylon 66 is 260 ℃. Because of the poor thermal stability of nylon, it is not suitable to stay in the barrel at high temperature for a long time to avoid discoloration and yellowing of the material. at the same time, because of the good fluidity of nylon, the nylon flows quickly after the temperature exceeds its melting point.
Injection pressure.
Nylon solution has low viscosity and good fluidity, but the condensation rate is fast, and it is easy to appear deficiency problems in the products with complex shape and thin wall thickness, so higher injection pressure is still needed, especially glass fiber.
Usually the pressure is too high, the product will have overflow problem; the pressure is too low, the product will produce ripples, bubbles, obvious fusion marks or insufficient products and other defects, most nylon varieties of injection pressure does not exceed 120MPA, generally selected in the range of 60-100MPA is to meet the requirements of most products, as long as the product does not appear bubbles, dents and other defects, generally do not want to use higher holding pressure, so as not to cause an increase in internal stress of the product.
Injection speed.
For nylon, the injection speed is good, which can prevent the ripple caused by the slow cooling rate and the problem of insufficient filling. The effect of fast injection speed on the performance of the product is not prominent.
Nylon resin should first turn on the nozzle temperature when starting, and then heat up the feed barrel. When the nozzle is blocked, do not face the spray hole, so as to prevent the melt in the cylinder from suddenly released due to pressure accumulation, which is dangerous. Empty the screw during the shutdown to prevent the screw from breaking in the next production.
The wall thickness of products, the flow length ratio of nylon is between 150,200. the wall thickness of nylon products is not lower than that of 0.8mm. Generally, the wall thickness of nylon products is 1-3.2mm, and the shrinkage of products is related to the wall thickness of products. The thicker the wall thickness, the greater the shrinkage.
For exhaust, the overflow edge value of nylon material is about 0.03mm, so the exhaust hole slot should be controlled at 0.025.