Pet Preform are typically manufactured from hot runner molds. It is preferred to have a thermal insulator between the mold and the injection molding machine. The thickness of the preform is approximately 12 mm and the insulator must withstand high pressure. Ventilation must be sufficient to avoid local overheating or air traps, but the depth of the ventilation slots should not exceed 0.03 mm, otherwise flashing can easily occur.
It can be measured by air jet method and the temperature can be set between 270 and 295 °C.
Enhanced green fluorescent PET can be set to 290-315 ° C
Usually, the injection speed is fast, which prevents early coagulation during the injection process. But the speed is too fast and the high shear rate makes the material brittle. Shooting is usually done in 4 seconds.
The lower the back pressure, the better the injection effect to avoid wear. Generally no more than 100 bar.
Do not use excessive residence time to prevent molecular degradation. Try to avoid temperatures above 300 ° C if the downtime is less than 15 minutes. Only air jets are required; if it is more than 15 minutes, clean with viscous polyethylene and bring the temperature of the tub down to the temperature of the polyethylene until it is turned back on.
(1) Recycled materials should not be excessive, otherwise it will easily cause “bridge” and affect plasticization.
(2) If the mold temperature is not well controlled or the material temperature is not properly controlled, it is easy to produce “frost” and opacity.
Jilian Plastic Mould is an experienced China Pet Bottle manufacturer. Our product range is rich and complete, and we can also provide you with tailor-made solutions. What are you still hesitating? If you have any needs in this regard, come and contact us!