Total Part Weight: XY Plot - No Help File

[kedenSHFQD]

Hey All,

I'm looking at some results for "Total Part Weight: XY Plot" for a F+P+W injection study.

I want to be able to interpret different scenarios when running multiple studies or projects.

For example, part weight stabilizes before gate freeze; part weight doesn't stabilize before gate freeze, peaks and valleys, etc...

I understand the scenarios on an IMM, but Moldflow does not always correlate, and I want to verify my understanding for each.

My issue is that Moldflow doesn't seem to have any help pages for this result (using 2023).

The only thing close is "Total Design Weight: XY Plot: in the Gas Assist help section.

The Theory & Concepts manual does provide some info, but I'm looking to add more.

Thanks.

[mason.myers]

Hello @kedenSHFQD ,

It looks like the help files from gas-assist Total Part Weight XY plot would also apply to a traditional injection molding process within Moldflow.

Ideally, the part weight should not decrease during the cycle.  This would mean the packing pressure was released too soon.

If you are seeing variability with Total Part weight, you could also evaluate Frozen Layer Fraction or the Temperature plot (set to a single contour of the material's transition temp, assuming you are in 3D).  I would think these 3 plots should produce a gate seal time within 1-2 sec of each other.

Mason

[bernor_mf]

@kedenSHFQD 

Hi,

right, no on-line help information about result plot "Total part weight:XY Plot".
Agree with @mason.myers mason that Gas-assisted Fill+Pack analysis results "Total design weight:XY Plot result" applies for explanation.

"The part weight is calculated by multiplying the filled volume at a time step by the polymer density. The analysis provides the weight of the polymer being injected into the cavity as a function of time."

I am not sure of what the concerns are, as I find the plot pretty straight forward: Show the part weight by time.
Changes of process making melt going in then out in cavity (Peaks and valleys?) should affect the curve.
But this scenario sounds a bit strange to me, so please elaborate how this appears.

Further, you might need increase the number of result interval to better capture the curve (Solver parameters - intermediate output.).
This will give more data points in curve, and if your scenario is between two data points it might not be captured with default set intervals (20).

Agree on comments from @mason.myers regarding additional results to review.
Further, reviewing a velocity plot could help to understand flow direction in gate region.

Hope this helps.

Regards,

Berndt

[kedenSHFQD]

@mason.myers 

@bernor_mf 

Hey Gents,

Thank you for your replies.

I'm just trying to gain a high level understanding of the different Part Weight XY Plots I may run into during simulations (and similar thinking for any XY plot really).

I was hoping to gain a deeper knowledge of how the software calculates part weight so I can countermeasure different scenarios effectively.

Here is an example of a recent project.

I do like the idea of the Velocity Plot so I included that info as well.

Fill = 7.7s

Pack = 45s

Cool = 250s

@52s = Total Part Weight: XY Plot shows part weight stabilize
@89s = Temperature Plot shows sprue freeze
@89s = Frozen Layer Fraction Plot shows sprue freeze
@103s = Velocity Plot shows vectors change direction towards sprue orifice
@139s = Velocity Plot shows vectors change direction back towards part

Two things stood out to me.

1. The large difference between Part Weight plot and the Temp and Frozen Layer plots.

2. The Part Weight plot shows it stabilizing at the exact moment hold-time ends

The second item is what made me start wondering how this plot was being calculated.

Did the part weight actually stabilize, or was something happening in the background?

Typically I would change some values and re-run more studies, but these runs are taking 2+ hours each time.

One last comment about the Total Part Weight help file.

When a user presses F1, it takes them to the main Help page.

It would be helpful if it took the user either to the Gas-Assist page, or a page that said "See Total Design Weight in Gas-Assist".

Maybe this last part is more for the Ideas forum :).

Thanks again.