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Clamp Tonnage calculation

thenagu
Participant

Clamp Tonnage calculation

thenagu
Participant
Participant

My Moldflow Results Shows : The Total Projected Area for the 4 cavity mold is 94.8292 sq.cm. The Maximum Injection Pressure during filling is 48.75 MPa. And also Maximum Clamp force required during molding is 22.89 ton.

 

Can somebody put some light on how the Clamp tonnage is calculated here by Moldflow.

 

Also the customer is telling we need more than 100 tonnage machine to run this as the small tonnage machine like 30-40 tonnage machines can't accommodate the big mold (which is already running). Currently the production is running in 120 tonnage machine.

 

Clear me pls.

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mason.myers
Autodesk
Autodesk

Hello @thenagu ,

 

Is your model orientated correctly for Moldflow?  Did you include runners in your model?  I would also suggest running at least a Fill+Pack.  Orientation, runners (pressure to fill), and the analysis sequence will all impact clamp force calculations:

https://help.autodesk.com/view/MFIA/2024/ENU/?guid=MoldflowInsight_CLC_Modelprep_Molds_for_injection...

 

It sounds like while the clamp tonnage might be low (less than 100 tons), the larger mold size might require a larger press that also has more tonnage?  

 

Mason

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PascalGosset
Collaborator
Collaborator

Hi simulators,

 

Clamp force (kg) = pressure (Bars = 10 x MPa) x surface (cm²)

 

But generally the maximum clamp force occurs at start of packing.

In fact, at swithchover, the pressure is maximum at gate but zero at the end of the flow.

 

Look at my sample below: 

switchover       at 2.2 s      Pressure :  760 bars          Clamp force : 26 tons

packing start   at 2.4 s      Pressure : 500 bars          Clamp force : 41 tons

(Don't forget to take into account a margin of error).

 

To choose the injection machine, you have also to estimate the size of the mold.

This depends on the parts size, the number of cavities, their layout...

 

Good luck  😉

 

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