Reactive molding - venting

[petr_AL]

Hi,

Our company produce reflectors from Thermoset materials. All our molds use venting with underpressure. Underpressure is connect to spew groove on the end of flowpath. Here is valve, which close underpressure short time before full cavity filling.

This help easily and more quickly fill the cavities.

My question is, when the Vent exit pressure is set to minus value - underpressure, are the Moldflow results computed using whole cavity underpressure?
When is not possible to set time for venting, how Moldflow compute, when the cavity is fully filled and underpressure is teoretically keeping connect to cavity?

Thank you

Petr

[raalteh]

Hi Petr,

When yous setup a venting location, with a specific vengin geometry, and you specify a negative pressure at the vent, you specify the venitng pressure at the end of the vent (NOT at the location you specify in the cavity). The pressure frop over the vent itself should hopefully not be large, and if so, the venting pressure in the cavity should be close to the value you specified.

(in other words, the the solver accounts for the pressure drop in the cavity as well as over vent.)

Hope this helps.

[petr_AL]

Hi Raalteh,

thank you for your answer.
When I'm looking now at Venting result, on the start of filling is in cavity underpressure almost same as I set to venting properties - see image. Venting locations on the top of reflector.
If the cavity is fully filled, the venting under pressure is stopped?

Thanks

Petr