Embedded Bubbles

[The Rookie]

Hello,

We are seeing what our team calls embedded bubbles and were wondering if anyone has any insight or experience.

Cavities: 64
Material: PET
Delivery: Direct Valve Gates


If you cannot view the images attached I will try to explain what we are seeing.

Essentially there is a bubble with an opaque tail following it. Many of our quality associates refer to this defect as an icecream cone or a flaming comet.

Normally we see these defects when we initially start up the machines, but occasionally we will find one in a process that has been running for hours. If there are stoppages (mold protections) the press might be down for 10-15 minutes and the operators will immediately start saving parts without allowing the process to settle back in. We will find them here quite often.

So my question is - what is causing this and is it possible to prevent it?

Thanks,

Rook