PET is a kind of moisture absorption plastics, usually its
water content is
about 0.05%. To get perfect PET preform (transparency and
physical performance), also to enhance moulding efficiency,
the water content of PET resin should be <=0.005%. Therefore
necessary drying of PET is required.
The common drying method is drying by hopper
dryer or dehumidifier.
of Preform mould
Cooling of preform mould is also very important. It affects
preform's quality directly. The temperature of cooling water
should be 15~20oc, and the pressure of cooling
water should be around 5Bar. Water chiller is suggested.
For injection machine, temperature of nozzle and front zone
should be about 280oc, and middle zone around 282oc,
rear zone around 275oc. The temperature of hot
runner in preform mould should be around 270oc.
These temperature vary a little bit with IMM, preform's design
and weight, mould's structure and cooling, etc.