Flow Lines?

[chrisprocess]

would look into machine down time and throughput of your dryer. PET can degrade easily if dried too long

[cheeseyone1]

I would say looking at the image that this is more of a heat check issue than a true flow line this happen when the surface of the tool gets to hot . Are the core steel ? how hot does the surface of the core run when in cycle ? I could imagine that water does not run up to the tip of the core . Look at the pictures are the lines only on the inside of part ? Do you see them on first shots ? I would try to lengthen the open cycle time to allow the tip of the core to cool before mold closes and see if that helps .

Also when valve gating if you have your hold time to long and the plastic starts to freeze at the surface when your valve gate closes is like a second inject when valve gate closes . So maybe try to slow the valve gate closing speed and see if the flow lines change .