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Plastic sticks to Mold. How to release it easily?


This topic contains 5 replies, has 3 voices, and was last updated by  POLYMEER 1 week ago.

POLYMEER polymeergermany

Plastic sticks to Mold. How to release it easily?

08/01/2019 at 16:36


we are working with LDPE and HDPE and our mold is made of steel. Unfortunately the plastic always sticks at the mold even with Mold Release Wax Paste (MIKON MIRROR WAX). What can we use to make it not stick at the mold or what can we do to release it in a easy way?

Thank you!



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08/01/2019 at 23:07

Hey @polymeergermany , If you can share some pictures then it might be more helpfull to identify.
If by sticking you mean sticking like glue then then may be your mold temperature is too high or the plastic has not fully cooled yet. Try putting the tool in water for a while and then remove the part. If nothign works then try this Mold release spray : https://www.profishop.de/industriebedarf-und-technischer-handel/spray/reparatur-und-trenn-spray/462771/weicon-formentrennmittel-400-ml-12-stueck-11450400?number=WE0-147&utm_campaign=camp_gshopping&utm_source=source_gs&utm_medium=medium_gs&gclid=Cj0KCQiAsdHhBRCwARIsAAhRhskOcugXE1xE3REcUdIRHgROhYp-V_fcPw2eKccjm22lUnJ4Ned9pJMaArX_EALw_wcB.

10/01/2019 at 15:58

OR, put your melted plastic into COLD mould, EASY release & 0 chemicals needed !

i had a lot of problem with that kind of stickiness, and we just stopped putting the plastic to melt in the mould; 2 seperate steps : put to melt in teflon coated dish or similar nonsticky product,  take out & put in mould & press
(that’s if you are using compression moulding)

Also, another trick that helped for the stickiness is only using the top coils from the oven (using the bottom ones tend to overheat plastic and make it stick a lot)

11/01/2019 at 15:46

Hey @tajdark an @imuh,
thanks for your fast answers 🙂

@tajdark: The plastic does not stick like glue, I think. And we also put the mold in water to cool it down. Here are some photos, maybe you can identify better? Thanks! 🙂

@imuh: If nothing else works, we will try it. Thanks 🙂

13/01/2019 at 11:02

@polymeergermany , What I can imagine is that the part is sticking on the Male /Core side of the mold. There could be a few things you can check.
1. Do you have a draft angle on the core to help part ejection. Minimum 2° ~ 3° would help.
2. Your part may be shrinking too much on the core , making it hold on tight to the core. May be you are cooling the part too much. Try taking it out while its warm (~40°C i.e. warm to touch). The reason may be because HDPE shrinks 2 to 3 % .

14/01/2019 at 15:48

@tajdark we will try and check this, thank you 🙂

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