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 is generally not more than 50mm. Pallet drying is recommended.
If there are bubbles on the surface of the injection-molded strip, or if the strip is cut, and voids are found in it, or if there are scattered silver threads on the surface of the product, it can be determined that the TPE/TPR raw material contains too much water.
On the premise of ensuring the quality of plasticization, the extrusion temperature should be reduced as much as possible, and the melt viscosity should be reduced by increasing the injection pressure and screw speed to achieve the purpose of improving fluidity.
When the surface of the strip injected from the nozzle is smooth and shiny, it can be determined that the plasticization quality is good. If the sliver injected from the nozzle is very bright, you can be sure that the barrel temperature can still be lowered. Use low-temperature injection molding as much as possible to reduce cooling time and improve customer production efficiency.
The temperature in the middle area of the screw is the highest, the feeding section is slightly lower, and the nozzle is slightly lower. Typical temperature settings are 150~170°C (feed), 170~180°C (middle), 190~200°C (front), 180°C (nozzle).
This temperature setting is only for reference data, and the specific temperature can be appropriately adjusted 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 contained in it), and the gate is easy to break during demolding, you can refer to the second item above to make adjustments.
Generally, the holding pressure is smaller than the injection pressure. The holding time can be determined by weighing the product, and the weight of the product will no longer increase, or the shrink mark accepted by the customer shall prevail. If it is found that the gate is easy to break during demolding, and the second trick does not work, it should be feasible to reduce the holding pressure.
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 ineffective, and this method can be used to adjust.
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