Common problems and solutions for PET preforms injection molding machine, Part 5.

11, Dented and sunken surface on the preforms.

A, Causes:

   1, Granules temperature is too high

   2, Injection time is too short

   3, Pressure holding time is too short

   4, Injection shot time is too short

   5, Cooling time is not enough

B, Solutions:

   1, Reduce the raw granules temperature

   2, Reduce the injection speed

   3, Increase the pressure-holding time

   4, Increase the injection shot time

   5, Increase the cooling water

12, Plastic thread on the preform injection inlet hole place.

A, Causes:

   1, Hot isolation is not working well

   2, Cooling is not enough

   3, Pressure exist inside the hot runners

   4, Check-valve function on the injection screw is not working well

   5, Holding pressure is too low

B, Solutions:

   1, Fix the injection holes hot-isolation function

   2, Increase the cooling

   3, Extract the pressure inside the hot runners

   4, Clean the injection screw nozzles

   5, Increase the holding pressure