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## Simulation Moldflow Insight

Contributor
Posts: 20
Registered: ‎10-31-2009

# Time to reach ejection temperature, Part (3D) vs. Temperature (3D)

1190 Views, 18 Replies
03-16-2011 03:59 AM

Good day,

I am perplexed a bit by the results I have right here. I've run a Cool+Fill+Pack+Warp analysis with a full mold. I want to check the time when the whole part can be ejected (Whole part is under Teject.).

-At first I've checked Time to reach..., Part result under Cool. It shows me ~40 secs. I add ~4 secs for filling getting a ~44 secs total measured from the start of the filling phase.

-Then I've checked Temperature result under Fill. Set the Scaling of this result to show only a temperature range above ejection temperature (And've removed the tick from "Extend color".). So this shows a closed volume of polymer above the ejection temperature at a given time. I've animated the result until there was only the "empty", translucent model and assumed that that is the time when the whole volume of the part is under the ejection temp I'd set. And got 28 secs.

So ~44 s =<> ~28 s. ???

Balázs

Valued Contributor
Posts: 82
Registered: ‎08-05-2009

# Re: Time to reach ejection temperature, Part (3D) vs. Temperature (3D)

03-18-2011 03:43 AM in reply to: solymossy

The result in cooling analysis is a little different from the one in the flow analysis. In that, the cooling analysis assumes that the entire part is at the melt temp and it cools down to the ej. temp. However, in the flow analysis it takes into account the dynamics of fill and packing phases giving a more realistic result in my opinion.

All that being said, i dont know why you are getting such a high differential. I usually see differences but not of such magnitude.

One thing i'd suggest (and it is the same as what you are doing right now) but go to the flow analysis temperature result, set the scale back to "all frames" and then go to the methods tab and change to contour-->single contour-->enter the ej temp. This will show you part volume above the ej temp through the entire cycle. This pretty much does the same as what you have done with scaling but is just something different to confirm the times.

Let me know if this makes sense and if you find out what the problem is

Ni****

Contributor
Posts: 20
Registered: ‎10-31-2009

# Re: Time to reach ejection temperature, Part (3D) vs. Temperature (3D)

03-18-2011 08:06 AM in reply to: nishit78

Hi Ni****,

"The result in cooling analysis is a little different from the one in the flow analysis. In that, the cooling analysis assumes that the entire part is at the melt temp and it cools down to the ej. temp. However, in the flow analysis it takes into account the dynamics of fill and packing phases giving a more realistic result in my opinion."

I know that Cool - as an initial condition - starts with the cavity filled with melt at Tmelt. And after Cool is done, Flow uses the average temperatures at the cavity-mold interface from Cool's calculations AND takes shear heating (etc.) into consideration.

"One thing i'd suggest (and it is the same as what you are doing right now) but go to the flow analysis temperature result, set the scale back to "all frames" and then go to the methods tab and change to contour-->single contour-->enter the ej temp. This will show you part volume above the ej temp through the entire cycle. This pretty much does the same as what you have done with scaling but is just something different to confirm the times."

I've tried that and got exactly the same results!

Thanks,

Balázs

Product Support
Posts: 453
Registered: ‎03-23-2009

# Re: Time to reach ejection temperature, Part (3D) vs. Temperature (3D)

03-23-2011 06:26 AM in reply to: solymossy

Hi,
could you give this plot setup at try:

Cool: Time to reach ejection temperature, part
right-click and Properties
tab Methods : Countour - Single contour
tab Animation : Animate result over : Single dataset
and Show lower values
and Animate result at: last time step
tab Scaling: All Frames

Above shows areas at ejection temperature by time.

The result from an analysis similar to yours gives reasonable results for
Cool: Time to reach ejection temperature, part
comparing Fill+Pack : Temperature.
See attached plot. (Ejection temp 101C)
(The temperature at flow front is close to melt temperature.)

Regards,
Berndt

Berndt Nordh
Contributor
Posts: 20
Registered: ‎10-31-2009

# Re: Time to reach ejection temperature, Part (3D) vs. Temperature (3D)

03-23-2011 07:38 AM in reply to: nordhb

Hi Bernd!

I've done what You have adviced and this is what I have right now (See attachements!)

Each results needs one timestep (~1 s) to cool the part under the ejection temperature but even with adding the filling time (~4,7 s) to the Time to reach results (~28,6 s) we won't get the Flow's Temperature (~37,5). But they are close and the difference might come from Flow's additional shear heating calculation.

What do You think?

Cheers, Balázs

Valued Contributor
Posts: 82
Registered: ‎08-05-2009

# Re: Time to reach ejection temperature, Part (3D) vs. Temperature (3D)

03-23-2011 07:45 AM in reply to: solymossy

After reading your post again i realized that i did not understand why you need to add fill time to your "Time to reach ej temp, part" result. This result is at the end of I+P+C time which you specify in the cooling analysis.

Am i missing something here

Contributor
Posts: 20
Registered: ‎10-31-2009

# Re: Time to reach ejection temperature, Part (3D) vs. Temperature (3D)

03-23-2011 07:54 AM in reply to: nishit78

Hi Ni****!

If You start to examine Cool's Time to reach result, You'll see that at 0 s the cavity is full! That's because Cool assumes that the cavity is filled with molten polymer at melt temperature. So to compare my results (Flow's Temp and Cool's Time to), You have to add the filling time to the Time to reach result to get the a real Time to reach ejection result.

And no, this result is not at IPC. Time to reach can be animated through time (Check Bernd's previous comment!).

Thank You,

Balázs

Valued Contributor
Posts: 82
Registered: ‎08-05-2009

# Re: Time to reach ejection temperature, Part (3D) vs. Temperature (3D)

03-23-2011 08:01 AM in reply to: solymossy

Yes I understand the result can be animated. What i meant was that the result is created over the I+P+C time.

If what you say is correct then why is the cooling process setting input called "inject+pack+cool time"

If you run a flow anlaysis afterwards it subtracts the fill + pack time from the I+P+C time to get the cooling time for the subsequent result.

This was my understanding.

Valued Contributor
Posts: 82
Registered: ‎08-05-2009

# Re: Time to reach ejection temperature, Part (3D) vs. Temperature (3D)

03-23-2011 08:10 AM in reply to: nishit78

I just checked the help info. This is what it states

The Time to reach ejection temperature, part result is produced by a Cool analysis and shows the time required to reach the ejection temperature, measured from the start of the cycle.

I hope we can clarify this.

Contributor
Posts: 20
Registered: ‎10-31-2009

# Re: Time to reach ejection temperature, Part (3D) vs. Temperature (3D)

03-23-2011 08:12 AM in reply to: nishit78

And right after that it states:

"At the start of the measurement, the part is assumed to be filled with material at its melt temperature (Tmelt)."