Melt polymer volume in Manifold system

[Anonymous]

Hi everyone,

We are trying to use same parameters in both moldflow and injection machine, so we have modeled IMM properties in Moldflow.

I took succesful IMM process parameters, in moldflow it has resulted with short shot.

Should i thought that moldflow used volume for manifold and we got short shot, is it possible?

Best Regards

Levent

[madhukeshwart]

If part is in production use absolute ram speed profile and exact machine details for injection molding machine, derive exact v/p switch over time,

and cushion details . Try to replicate as much as possible. Surely you will have similar results as production

[Anonymous]

@Anonymous try to get the flow rate they are using in the machine along with the ram speed profile. with the flow rate & standard molding parameters they have used in the machine will get the closer results might not be 100% but 85-90% closer results you will get. because Moldflow is a pure injection molding machine without any machine loss. but the normal Injection wont be same, need to consider the energy loss in the machine with the give parameters.

[PascalGosset]

Hello,

By my side, when I apply the IMM settings in Moldflow, the simulation fills the part clearly before what I notice in reality.

I think it is because the compressibility of the material is underestimate in the cavity and in the runners.

Sometimes the volume really injected is the double than the calculation predicts.

I guess the contrary is possible.

In the material data, look at the tab "Rheological Properties"/ "Viscosity Model Coefficients".

In it, there is the dependence Pressure/Viscosity coefficient D3.

It is practically always not filled (equal to 0).

Edit this value (around 1.5e-7), it can change all (I'm not sure that's a good idea 😞

Bye.

[Anonymous]

My main question is if moldflow fills manifold on first shot or not.

When i set moldflow according to second shot, i get short shot in real process

On the contrary when i set moldflow according to first shot, i got succesfull injection in real process.

Trials has been made with 5 drop mold.

[Anonymous]

@madhukeshwart 

Thanks, i used absolute ram speed profile.

[bernor_mf]

Hi,

in Moldflow hot runners are initially filled with melt, so it hold melt from start of injection for simulation.

No first shot needed in simulation to fill modeled hot runner.

When using real process, make sure you set machine screw diameter in Moldflow.

Regards,

Berndt

[madhukeshwart · Accepted solution]

@Anonymous

1. 1st shot, which fills manifold will not come in to picture at all..in moldlfow 

2. same in actual process, ,may 1st  2-5 components are being scraped till mold temperature stabilizes.

3. refer the following link, which surely help to match the process..

https://forums.autodesk.com/autodesk/attachments/autodesk/366/3554/2/MPI_match_mold_process_Aug07rev2.pdf