The relation btw X-Axis;ShotVolume% in Ram speed recommended & M/C Screw stroke

[FLUENT_Injection.Molding]

Ram speed recommended ; XY-Plot result.
Y - Axis = % (%Flow Rate)
X - Axis = Shot Volume% , show Shot Volume 0 to 100% from Left to Right.
In practice, the injection machine screw prepare 100% shot volume for each shot, and screw move forward from Right to left push the melt into the mold.
I'm trying to understand and apply recommended speed profile to real injection machine screw stroke speed profile.(reference : to maintain the FFV; Flow front Velocity and manage shear stress).

Does the %flow rate (Y-Axis) from 0 % to 20% Short Volume% (X-Axis)  is the screw speed from 100% to 80% shot stroke in the injection machine barrel  ? 
(same principle : from 20% to 50% Shot Volume%  is the same as  80% to 50% barrel stroke , etc.)
Please clarify, how both are relating.

Fluent Co.,Ltd.

[adam.james · Accepted solution]

Hi @FLUENT_Injection.Molding ,

Thanks for using the Moldflow Forums!

From 0-20% flow rate, this correlates to 80-100% of the shot volume, but not necessarily 80-100% of the stroke length. This is due to the fact that on the x axis, this is a relative ram speed profile (The x axis is referencing Shot volume percentage and not stroke length (mm))

If you have further questions or concerns, feel free to reply to this response and I would be more than happy to help. 

Please select the Accept as Solution button if a post solves your issue or answers your question.

Cheers,

Adam

[FLUENT_Injection.Molding]

Thanks for your answer.
May I have a question about Velocity/Pressure switch - over.
How 's Moldflow tells the V/P (see picture) ?

Fluent Co.,Ltd.

[bernor_mf]

Hi,

the setting is to use 80% of injection pressure.

Hence in a short response time, about 0.025 s the pressure goes from 84.64 MPa to 67.71 MPa.

The negative flow rate indicates a back flow.

The flow reverses a short while, about 0.025 s

When V/P, velocity switch over to pressure phase, the pressure in cavity is high

enough to cause this back flow in gate during transition phase until the packing pressure

moves melt forward. This happens in the time of 0.025 s.

You could review velocity result plot.

Hope this helps.

Regards,

Berndt

[FLUENT_Injection.Molding · Accepted solution]

Hi;

Thank you for your answer.
Moldflow Automatic v/p switch-over by limit the pressure rise at 80% of (Max. machine)  injection pressure.

Fluent Co.,Ltd.

[bernor_mf]

Hi,

the default setting in Moldflow Insight is to use 80% of injection pressure as packing pressure level,

and to hold for 10 s.

I first interpret your question to be about the negative flow rate.

Happy simulation. 😊

Regards,

Berndt

[FLUENT_Injection.Molding]

So, both of us have a different understanding.
My question is about the ways to get the optimum vp switch-over.
Ex.
a) Switch over by %shot volume
By default, filling phase is 99%volume.
How/Why moldflow consider 99%
And how to use Moldflow in specify the optimum vp switchover volume?

b) Switch over by position (mm)
Can Moldflow give a most optimum vp switch point?
.and...... ...etc.

Thanks.

[bernor_mf · Accepted solution]

Hi @FLUENT_Injection.Molding 

a) Switch over from velocity phase to pressure phase has some flexibility.
And often debates about the best way to switch over from fill to pack
Generally:
Avoid late switch over, as this will create a pressure spike, that possibly could damage the mold and/or create flash.
Avoid early switch over, as this could cause short shot, slow flow at end of will causing cosmetic problems, poor weld lines.

The default setting of switch over at 99%, is simply the default.
You need to review result plots to decide if move it. (pressure at injection location : is there a pressure spike?)
During filling the melt is compressed, and after switch over it will fill cavity by decompression and packing pressure.

If you set switch over at 95%, and you get short shot, then switch over is too early.

Velocity/pressure switch-over point

b)
To transfer from relative to absolute injection molding machine settings, you have to do manually.
You need information on injection molding machine to use, and set up in Moldflow.

I asked for some automation of this some years ago.
Transfer from relative processing conditions to absolute IMM setup
Kudos if you agree. 🙂
So far, not many has...

Hope this helps.

Regards,
Berndt