How accurate are Mold Flows?

[Joel JS]

Hello gang,

Wanna poll all you guys here, because I am not the expert with mold flows:

I am being asked to approve a gate design based upon a mold flow analysis, and I don't know how accurate these are typically.

For instance, if the mold flow ( Autodesk Moldflow Insight 2019 was used) the max plastic pressure stated was 15,000 psi.... Is this good plus/minus 10%?

And if it states max deformation is 0.4mm, is this good to plus/minus 10% as well?

Last question, (not as important to understand), it shows a fill time of 3 seconds, would this be an input by the guy doing the mold flow?

Thank You!
Joel

[nikom]

I haven't had any training but have been using moldflow for awhile and have been trying to find time to compare results to the real world.

The most important aspect of getting reliable results is having good material data. Moldflow helpfully provides ratings on all materials in its database with bronze, silver, or gold. Any simulation is only as good as the inputs.

I've found the pressure to be accurate if the mold is run at the same settings as simulated. Often processing must be adjusted due to cosmetic issues that are not captured by simulation. I use moldflow advisor which does not simulate the machine at all so I usually add 5000 psi to the moldflow pressure for machine loses. It's my understanding moldflow insight can simulate the machine also and you might not need to do this.

Deformation can be accurate also, with a well characterized material and identical process settings.

For the fill time, this can be input by the user or optimized using moldflow.

[Joel JS]

Much Appreciated Nikom, thx!

Joel

[Suhas]

Agreed with Nikom.

I use it fr more of a qualitative analysis that quantitative. So to see where the end of fill is? Which way will a part warp? (not how much) Does this need high pressures to fill the part? (not how much).

My customers have not had great luck with actuals. But it is a great tool

Suhas