Injection Compression Molding Process parameters selection

[riad.ashraf]

Dear Altrusit,

I am working on my project in Injection Compression Molding. I have been using Moldflow to simulate two different materials with three different press compression speed in the compression settings to determine various qualities between these two materials. I have been facing some problems. Please help me out.

1. At first, I set the Fill+Pack setting as the automatic. Then I tried to change the parameters. For three different compression speed I got three different filling time in the automatic section. For the highest velocity profile the filling time is the least and the lowest velocity profile the filling time is the highest. Now I wanted to change the filling paramaters so that I want to get exactly same filling time for each profile. I took the highest filling time as reference and put the value in the Highest velocity profile as Injection time. Then I got the problem Short shot. What is the problem! Is not the filling time means the injection time in filling settings? Or do I assume it wrong or do I put the highest value which will not work here where i got the elast filling time as automatic one.

I want same filling time for all velocity profile. What should I do?

2. I found out that the percentage vollume filled during velocity pressure switch over is 125 percentage from the automatic parameters set. How can this be possible? Is it alright ? I put this value manually and it worked fine. Can you explain how this things happen?

3. There is no packing in Injection compression molding. In that regard, what should I do regarding the packing parametes?

4. In the compression setting switch to press force controll options, should I put from the start of compression? or any other option?

5. I have set all the parameters automatic and it worked fine. Now facing problems while changing the parameters manually. Specially in the filling and packing phase. Please help me out in this filling and packing phase problem. If I want same parameters specially same filling time and other aspects like 100 percent frozen layer fraction, what should I do in the filling and packing phase? How could I get the manual values from the preset data. Which values I need to consider.

These problems need to be solved. Please help me out. Specially @bernor_mf , I am really looking for your help as you helped me earlier. I am sending some screenshots for your consideration.

Best regards.

Riad

[bernor_mf]

Hi @riad.ashraf ,
you are welcome. Happy to help. 😊

Comments from the information you provided:

From process settings:
Press open distance is 0.75 mm.
According to displacement graph it comes to about 0.65 mm.
This means mold halves does not close.

Reasons could be:
Too much volume initially filled.
Press speed too slow, and cavity not filled - short shot?
The press speed too slow at end of press time.
Switching to press force control, but cannot close: force too low
Part freeze off and the compression stroke is stopped.

Compression element (3D), property you could unchecked option "Frozen check for compression control".

Review the Analysis Log of simulation progress.
It holds a lot and good information.
(You could save the information to text-file by right-click in text area and Save as...)

Hope this helps.
Regards,
Berndt

[riad.ashraf]

Dear @bernor_mf ,

Thanks a lot. I tried unchecking the option. It still did not work for me. I am sending you a powerpoint presentation. In which I am showing you that I want the Press Displacement curve like this. That is my goal. For this I need to change the parameteres in the Press Compression. But Iam getting something strange XY plot curve. Can you please tell me the reasons of it?

It will be really hepful if you tell me how to make the XY plot curve like this. I really want the curve like this. Is there any way around?

[riad.ashraf]

Dear,

I am facing problems with the compression stage regarding Speed control and Force control. As you can see I have set three determinded compression velocities. I want to use that. I want them to be used by the software during compression. But the software does not take my Compression velocities. If it takes the velocities then I will get a profile like that which I have given to you. Now, please tell me how can I get the velocity profile like this?

What do I need to do regarding speed and force control in the compression stage?

Best regards.

[bernor_mf]

Hi @riad.ashraf  ,

you could maybe use a press profile with 0 mm movement, but a change in speed.

( I refer to a setting from a previous post in thread.)

row 1) 0 mm 36.02 mm/s                     aim for speed directly

row 2) 2.8 mm 36.02 mm/s               this means 36.02 mm/s for about 0.08 s

row 3) 0 mm 6.56 mm/s                       aim for speed directly

row 4) 2.8 mm 6.56 mm/s                 this means 6.56 mm/s  for about 0.43 s

row 5) 0 mm 1.71 mm/s                        aim for speed directly
row 6) 2.9 mm 1.71 mm/s                   this means 1.71 mm/s for about 1.70 s

It will not agree with plateaus as on hand sketch.
As first plateau is very short time, and more a peak in press speed.

Think of how you really want the "corner points" of speed profile and how long time each speed should be maintained.

How long time should 36.02 mm/s be used?

How long time should 6.56 mm/s be used?

How long time should 1.71 mm/s be used?

This will give press displacement.

There will be a response time in system.

If you have short times, the machine hydraulic response time will affect this too.

By default it is set to 0.2 s.

You could edit this in Process settings : Advanced options...
Injection molding machine. Edit...

Tab Hydraulic Unit.

Change "Machine hydraulic response time" from 0.2 s to 0.01 s.

Rerun simulation to understand the effect and difference.

Still some system reaction times, but shorter response time.

Even if you set this profile on injection molding machine, there will be response times too, and not sharp plateaus as drawn in sketch.

I think you should review what the machine really did in terms of speed, the true press speed profile.

Hope this helps.

Regards,

Berndt

Attach picture which shows the effect.

[riad.ashraf]

Dear @bernor_mf ,

I do not have any word to express my joys. Without you I could not be able to do the simulation. Thanks is not enough for you. I have changed all the parameters accordingly and give it a run. I will get the results within tomorrow and let you know.

I just have one query. Why do you change the forche speed cap to 40 mm/s? What is the reason behind it? Is there any refernce value? Like how to change the values or can I change it randomely? Please give me an insight.

Best regards.

[bernor_mf · Accepted solution]

Hi @riad.ashraf ,

thank you for the kind and warm words. 😊

Happy to help. 😊

Now, regarding Press speed cap.

Default: 1000 mm/s  

You had a value of Press compression speed of approx. 36 mm/s.

I just rounded Press speed cap off to 40 mm/s, roughly +10%.

You could probably stay with default if you wish.

Regards,

Berndt