Selecting Analysis Sequence for accurate Clamp Tonnage results:

[Anonymous]

I am experiencing variations in clamp force results, when selecting three different analysis sequences for the same model (3D part & 3D hot runner, and 4-cavities) : Fill Only, Fill + Pack and C + F + P + W.  Please note that the last option includes cooling channels.  Has any one also experience this type of results?  If you have found a way to set up a correct Analysis Sequence in order to obtain accurate clamp force predictions, please let me know.

[beth.mollica]

hi @Anonymous 

Please have a look at the following - Modeling for accurate clamp force prediction

Specifically - Clamp force during filling and packing:

Typically, both the pressure and the clamp force increase progressively during filling. Once into the packing phase, the cavity pressure becomes more uniform and, if the filling pressure is maintained, the clamp force will increase significantly. Under normal molding conditions, the packing pressure is lower than the filling pressure and so the clamp force required during packing may be higher than or lower than the clamp force required during filling.

Additionally, please also reference Clamp Force.  For the clamp force calculations to be correct, the model must be positioned so that the clamp force is applied along the Z axis direction as shown in the following diagram.

Thank you!

[Anonymous]

Hi Beth,

Appreciate for your feedback.  I agree about what you mentioned in your reply.  My concern is that when I ran an analysis with the cooling channels (C + F + P +W Sequence), the clamp force almost doubled compared to the clamp force predicted without cooling channels (F + P Sequence).  This high clamp force does not make sense.  I was therefore asking whether there is a way to select an analysis sequence, so the clamp force can be accurately predicted. 

Waiting for your response.

Thank you so much,

Jaykant

[bernor_mf]

Hi @Anonymous ,
beside the information from @beth.mollica I think you need to review results and process settings in detail.

As the clamp force increase in CFPW sequence, the Cooling seems to have an effect on the pressure to fill.
FP sequence uses the same mold temperature around cavity.
CFPW calculates the mold temperature. So maybe an area cools too fast?

Do you use packing pressure percent (%) of injection pressure (% Filling pressure)?
Adding Cool to your sequence, and you might get an early freeze off somewhere in part and maybe an unbalanced fill, which will increase injection pressure, and pressure spikes?
Hence it increase packing pressure, and affect clamp force needed if using packing pressure as an % Filling pressure.

So review and compare result Pressure at V/P Switchover for FP and CFPW sequence first.
Is there a big difference? If, analyze why.

Review process settings pack/holding control.
Maybe use absolute packing pressure for the FP and CFPW sequence to get comparable results?

Hope this helps.
Regards,
Berndt