Cavity damages

[Waqas Yousaf]

PET Mold. Cooling insert of 4 cavities damage. There is a crack. And all was damage one by one. I decrease the clamping force and speed also check the alignment but after all this the cavity was damage again.
Any suggestion guys what to do

[chrisprocess]

If the mold is stacked out well, check machine platen parallelism. Or better yet get some feeler gauges and verify clearance around the mold parting line under high pressure clamp

[rickbatey]

Also verify the wall thickness of the cores. They could be too thin and the flex induced by the injection pressure is causing the failure.
Rick.

[Waqas Yousaf]

I verify the clearance around mold with feeler gauge that is ok. Again i start production yesterday and after 9 hours there was same problem. Thickness of core is also ok

[Waqas Yousaf]

I'm using two molds on this machine. Before some days i change the mold and start production with other mold. There was no problem in that mold. But only this mold is creating problems like this. Now i have a doubt on manufacturing process of this mold

[chrisprocess]

Sounds like the issue is specific to the mold in question.

Have you verified the waterline(s) to print? Maybe waterlines were built incorrect, or they're clogged from dirty water and the excessive heat/pressure causing them to crack.. Or you're not getting enough flow in general. This may be in-line with why they crack one at a time.

Can you verify sufficient water flow? You should note the pressure drop from IN and OUT in a closed looped system (hooked up to thermolator if you use one) and also in an open loop system (into a bucket). What flow/pressure drop do you get for both systems? This may help you decide if you need to increase pressure to the waterlines, or open up cross-sectional area in cooling inserts to allow more flow.

[elmer]

PET Mold. Cooling insert of 4 cavities damage. There is a crack. And all was damage one by one. I decrease the clamping force and speed also check the alignment but after all this the cavity was damage again.
Any suggestion guys what to do

2 Thoughts: 1) Some overseas molds are improperly hardened and will crack. I've lost several gate inserts and a few cavities due to this. 2) I've had a few domestic built molds with SS cavities crack after about 1 million cycles.