simulation of release of warapage of PA 66 GF30 parts after heating up

[Brucipes_123]

Here and there, specialists would say that "if you want to release / reveal / show hiden warpage", heat it up.

So for example, old "precticioners" are sometimes saying: "When you have problem with warpage, make cooling time longer

and for sure that you will, here and there limit warpage".... But... if part is functional at higher temperature, heat it up (say some PA 66 GF30

part to 120 oC) and you will see that warpage that was artificially "frozen" by longer cooling time will be released -> meaning will be bigger compared to

room temperature".

Does anyone have some experience (in general) with PA 30% fibre glass parts - that when you heat them up, that (in general) measured warpage

(like roundness, flatness, etc.) is practically always getting "worse"? Or is it just more or less theoretical thing?

And...moreover, can somebody give opinion if that is possible to (at least approximatelly) simulate actually in Moldflow? Any "heating" up in the sence of annealing of injected plastic part?

Thank you

Brucipes

[mayur_dhumal]

Hi Brucipes,

First thing first! You need to understand the cause of warpage, this can be simulated from a DD warp analysis (Check the box 'Isolate cause of Warpage' in warp process settings).

When you talk about heating the part that means you are releasing the internal built up stresses.

When considering the contributors to warpage, it is convenient to identify shrinkage due to:

1. Variation in shrinkage from region to region (differential shrinkage).
2. Temperature differences from one side of the mold to the other (differential cooling).
3. Variations in the magnitude of shrinkage in directions parallel and perpendicular to the material orientation direction (orientation effects).

Each of these types of shrinkage will contribute to the total warpage of the product.

So if you know the cause of warpage, no need to heat the part & do any trial-error.

With PA 30% fibre glass, i don't think you will need such dissertation to perform. PA will have moisture absorbing properties, so you will need to dry the material before supplying to feeder.
As you are saying the product application area is at high temperatures, so add heat stabilizers as well with fillers (Which is recommended).


Regards,
Mayur