Key points of injection molding in plastic bottle blank factory
1. Injection speed
Generally, the injection speed should be fast, which can prevent premature solidification during injection. But too fast, high shear rate makes the material fragile. Firing is usually done in 4 seconds.
2. Retention time
Do not use too long residence time to prevent the decrease of molecular weight. Try to avoid the temperature above 300 ℃. If the shutdown time is less than 15 minutes. If it is more than 15 minutes, clean it with viscosity PE and lower the barrel temperature to PE temperature until it is started again.
3. Selection of injection molding machine
Due to the short stabilization time after the melting point of pet and the high melting point, it is necessary to select an injection system with more temperature control sections and less self friction heat generation during plasticization, and the actual weight of the product (water containing material) should not be less than 2 / 3 of the injection volume of the machine.
4. Back pressure
The lower the better, to avoid wear. Generally not more than 100bar. It is usually unnecessary to use.
Introduction of blow molding process in plastic bottle blank production plant
1. The parison is installed in the nozzle of the machine and then put into the mold, which is divided into two parts.
2. The hot air passes through the blowing head to form a blank and expands to the shape of the die.
3. Cooling in mold for a few seconds, cooling before demoulding.
4. Remove the extra material at both ends and finish the product.