Difference between time to reach ejection temperature

[Anonymous]

hi, im new working with moldflow, i have a question, which is the difference between the time to reach ejection temperature that is in the flow result and with the time to reach ejection tempeature that is in the cool results?, i searched it in moldflow help, but the aswer there didnt resolve my doubts.

i appreciate your help.

thanks

[madhukeshwart · Accepted solution]

The Time to reach ejection temperature, part result shows the amount of time required to reach the ejection temperature, {color:#ff0000}measured from the start of the cycle{color}. The part is initially assumed to be filled with material at the melt temperature at time zero, when the analysis sequence is cool.

The Time to reach ejection temperature result shows the amount of time required to reach the ejection temperature,
{color:#ff0000}measured from the end of fill.{color} when the analysis is done in flow analysis.

[Anonymous]

Thank you very much for answer me, was very helpfull for me.

[Anonymous]

I'm having a similar problem and even after reading this thread, I still don't understand the difference between these two ejection times (sorry ).  So, let me explain what I am trying to do. 

I'd like to use Moldflow to estimate the total cooling time for a part, where "total cooling time" is defined as the interval between when the injection nozzle shuts off (and no more material flows into the cavity), and when the part is ready for ejection.  I am assuming completely passive cooling, without any cooling channels.

I've tried running the "fill" analysis sequence, which gives me a "time to reach ejection temperature".  But what I don't understand is how Moldflow is getting this number.  The fill analysis only steps through to about 0.8 seconds, but it gives me an ejection time of something like 3.4 seconds.  It doesn't seem to be getting this ejection time from simulation; is it maybe computing this from some formula?

I've also tried running the "cool" sequence, but there are two problems.  First, it forces me to add cooling channels (I don't want any).  Second, it assumes that the cavity is initially filled with polymer at the melt temperature.  This is not a realistic model of what is actually going on (polymer actually begins cooling even as the mold is still being filled).

My question is, what analysis sequence will most realistically reflect the actual molding process, and how do I extract the cooling time from that sequence?

Thank you to whomever can help,

Alex

[nordhb]

Hi,
The Time to reach ejection temperature result is using a material data called  "Ejection Temperature" from Material data, tab Recommended Processing.
When this temperaure is reached in analysis, time is recorded.
You can customize this data, if you want to affect the result of Time to reach ejection temperature.

Basically, at what temperature do you want to eject the part?
If assumption is the same temperature in the whole mold you can set this mold temperature and run Fill + Pack.
Set a long enough cooling time.
Write intermediate results and track temperature in center and at wall to see at which time a certain temperature is reached.
( or change Cooling Time to Automatic and wished Part Ejection Criteria: Ejection temperature and Frozen percentage at ejection)

Does this answer your questions?

Further:
The starting point of Cool solver is a cavity filled with melt at set melt temperature.
This to get an initial heat load of melt volume and be able to run analysis.
It will then iterate to a heat balance to converge (One can run a Cool analysis only).

Regards,
Berndt