TPE, TPR injection molding process skills

2021-03-25 09:23:01 admin

TPE, TPR injection molding process skills




1. If the product surface has strict requirements, it must be dried before injection. Generally, it is hopper drying at 70~80℃/2h or tray drying at 80~100℃/1h. For tray drying, it should be noted that the thickness of the material layer generally does not exceed 50mm. Tray drying is recommended. If there is blistering on the surface of the injection molded strip, or if the strip is cut and there are cavities inside, or the surface of the product is found to be scattered like silver wires, it can be determined that the TPE/TPR raw material contains too much moisture.




2. Use low-temperature injection molding as much as possible. On the premise of ensuring the quality of plasticization, try to reduce the extrusion temperature, and increase the injection pressure and screw speed to reduce the melt viscosity to achieve the purpose of improving fluidity. When the surface of the material strip injected from the nozzle is smooth and has a bright light, it can be determined that the plasticization quality is good. If the strip injected from the nozzle is very bright, it can be determined that the temperature of the barrel can be lowered. Try to use low-temperature injection molding as much as possible to reduce cooling time and improve customer production efficiency.




3. Upper parabola temperature setting. The temperature in the middle area of the screw is the highest, the feeding section is lower, and the nozzle is lower. Typical temperature settings are 150~170°C (feeding), 170~180°C (middle), 190~200°C (front), and 180°C (nozzle). This temperature setting is only used as reference data, and the specific temperature can be adjusted appropriately according to the specific physical properties of different TPE and TPR materials. If it is found that the content of the product is bulging (the gas is inside), the gate is easy to break during demolding, please refer to the second trick to make adjustments.




Fourth, the holding pressure should be as small as possible. Generally, the holding pressure is smaller than the injection pressure. The holding time can be determined by weighing the product, and the product weight will no longer increase, or the shrinkage mark accepted by the customer. If it is found that the gate is easy to break during demolding, and the second trick is not effective, then reducing the holding pressure should be feasible.




5. If it is a few-level injection, the speed is from slow to fast. Because of this, the gas inside the mold is easily discharged. If there is gas inside the product (internal bulge), or there are dents, the second trick is invalid, and this method can be used to adjust.