PET bottle is more and more useful in nowadays, so a good preform blowing a good bottle is very important. However, how to identify a good preform, that is a big question. Sino Mould is a professional mould manufacturer in the Southeast of China with nearly 25 years experiences. We can offer you the good preform solution.
Here we have summarized some key points to help you to identify what is a good preform.
a. Optimum Preform
PET Preform observed in parallel polarized light shows birefringence color pattern caused by the polymer. When you put the preform in the 45°angel, you will see the equilateral color streak. When you put the preform under the sunshine, a good preform is transparency, has inerratic parallel line and there is a black isoclinal stripe.
b. Yellow Tint
If the preform becomes yellow, it means the polymer drying time is too long or the temperature of the charging barrel is too high.
c. Condensation Marks
If the preform has the condensation, you must increase the temperature of the cooling water and decrease the air humidity around the mould.
d. Splash Marks
If there is the splash inside of the preform or on the surface, the temperature of the cooling water may too low,
If there is a flash, it may the dirt in the mould, and the mould can’t completely closed. Or the injection pressure is too high. Or the clamping pressure is too low.
1. the material filler shortage. 2. The cooling temperature is not enough. 3. The cooling time is not enough. 4. Cooling nonuniform. 5. When the preform cooling, the pressure is not enough.
g. Short shot
1. Injection speed or the injection pressure is not enough before filled. 2. The screw shot length is not enough when injection.
h. Side-wall haze
Dry time is not enough. Dry about 4 hours under the temperature 175
Anyway, if you have any preform question, just feel free to contact us. Sino Holdings Group can offer you a good preform solution.