Autodesk Simulation Moldflow Insight

[#1]

Hi All,
Hope you are doing well in moldflow (A new one) world.

I have small query regarding Packing profile as below:
One of my friend was facing a warpage for a automotive part (700mmX160mmX15mmX major thickness 3mm) with ASA material. It comes around 1.5 -2 and he wants to reduce further. Warpage values near gate are 1.5 and in the end are coming as 2 mm, which is not acceptable.
- Packing pressure he used was as per calculation and within limit of clamping tonnage by using avg cavity pressure for material.

He tried different comibination but but all were in vain, with little changes (+/-). We discussed a lot and now though to share that with you to find any answer.

Please throw a light on packing profile seting ( I mean if gate are is warping then how to give packing profile and if end of fill area is warping then how to control it with packing profiles).

Nitin

[#2]

Dear Nitin,

Check frozen layer fraction of end of fill,till that time
pack with higher pressure( 80% of maximum pressure of specified machine).

Then reduce the packing pressure till gate freezing time.

With regards

Madhukeshwar.T

[#3]

Thanks for this info Madhu...

[#4]

did u check the gate dimensions and type of gate used.Not every warpage problem be solved with packing profile.
maybe there is not enough packing pressure reaching out to the ends of the part, how far is the end of fill area from the gate location, how many gates are used.

[#5]

Compare the part freeze time and gate freeze time using frozen layer fraction. If the gate freeze time is less than the part freeze time then increase the dimension of gate to increase the packing time for the part which will help to reduce the warpage of the part. But if the warping area is freezing very fast then it is meaningless to increase the packing time & then you have to thing to change the product design.

[#6]

Good Day,

One thing I may have missed was the verification that the warpage is primarily caused by Differential Shrinkage (I like to call it area shrinkage) Run the isolate warpage analysis to ensure that this is the primary cause of the warpage. It probably is differential shrinkage, but just make sure. Look carefully at the isotropic shrinkage and compare it to volumetric shrinkage. The trends should be very similar. Modify the appropriate deflection plot and use Volumetric shrinkage as the data set. This should help you easily see the correlation between the shrinkages and warpage. It is difficult to know if the shrinkage around the gate is a problem from what I read, but comparing the results as mentioned should help. Generally I ensure the gate is freezing under pressure, i.e. the gate freezes before pressure is released. I have a feeling your biggest problem is packing at a high enough pressure to keep the shrinkage down but maintaining the clamp tonnage withing limit.

As mentioned in other messages, reduce pressure over time to make the shrinkage more uniform through the part. This only works well if the shrinkage at the end of fill is acceptable, and the wall thickness variation in the part is not significant.

Good luck,

Jay Shoemaker

[#7]

I think that the first thing to find the right packing profile is search when the gate freeze (time).
When gate freeze, no more material/pressure goes inside part and this is the important thing.


So when you know that part fill in 1.5s and gate freeze at 12s, you have only 10,5s for pack the part.
If you analyze time to reach ejection temperature, you know what time gate freeze, and this time is counted after filling time.

So:

fill time=1.5s gate freeze=12s

1.5-12 = 10.5s

Packing time = 10.5s

Relative to packing pressure, i usually use maximum injection pressure (constant profile), or more or less 80% of packing pressure.
It depends of the parts.

Regards,
João Esteves

[#8]

First of all,
I thank you all for sharing your valuable time and views and sorry for my late reply.

It will be really helpul to me..

Nitin Hadpe

[#9]

Steps are as follows

1. V/p switch over time (use text screen output i.e log) - T1
2. Gate freezing time (use frozen layer fraction plot )- T2
3. Take a plot of pressure at node (at end of fill node) -note down time at peak pressure and when pressure becomes zero( T3 & T4)
4. Then take average of T3 & T4 = T5
5. Constant pressure time T6= T5-T1
6. Decay time - T7 = T2-T5

Set packing profile - 0 80%,T6 80%,T7 0%. RUN ANALYSIS.

THEN ADJUST PROFILES AS REQUIRED ON BASIS OF REQUIRED LEVEL OF UNIFORMITY IN
VOLUMETRIC SHRIANKGE PLOT

At gate area: If volumetric shrinkage is high? If volumetric shrinkage is low?

If volumetric shrinkage is high at gate, increase decay time (T7).
If volumetric shrinkage is low at gate, decrease decay time (T7).



At mid region:If volumetric shrinkage is high? If volumetric shrinkage is low?

If volumetric shrinkage is high at mid, make one more stepped profile after constant time and change time and rate of decay and do trails


At End region:If volumetric shrinkage is high? If volumetric shrinkage is low

If volumetric shrinkage is high at end of fill , increase packing pressure , i.e set packing pressure > 80% , 90%, 100%, 110%, 120%.
and also increase constant pressure time (T6).

If volumetric shrinkage is low at end of fill ,decrease packing pressure , i.e set packing pressure <80 %, 60%,40%
and also decrease constant pressure time (T6).

[#10]

Hello,

I don't know to many about parametrization of a mould injection, but i would like to know how can i choose the value of (depending of what) packing pressure?
I am making analisys with a packing vs time profile for a bib flat part with 2.5 mm wall thickness.

Thank you,