maximum injection pressure

[kulandaivel_palanisamy]

Dear all,

I am running fill analysis for a part which is 5 cc and short of thin part.

So I gave injection time of 1 sec and V/P 99% with default packing.

The result shown that the maximum pressure required for the part is around 184 MPa.

So I explained my customer that the maximum injection pressure deliverable by any Inj. molding m/c is 180 MPa. And 140 MPa (80% of Max. inj. Pressure) should be on the safer side.

When I limit the maximum injection pressure of the machine to 140MPa (advanced settings) and if I give the same process parameters, then the part is also filled with 140 MPa with fill time of little more time than the previous option.

So when the maximum injection pressure of the machine is only 140 MPa, the part should shown as unfilled (short shot) ? Why is the part which needs the maximum pressure of 184 MPa is filled with just 140 MPa in moldflow? How can I make the part is short shot due to insufficient pressure?

Please share your views

Regards, JK.

[nishit78]

Basically, when you are limiting the MAX pressure to 140 MPa you are running the mold pressure limited. It is not necessary that the part will be short if the pressure (140 MPa) is sufficient to keep the melt flowing and fill the part before it freezes enough to stop flowing.

In pressure limited molding, it will just fill differently and the post molded part quality will be affected. Check your fill time animations. You should see more hesitation in the pressure limited simulation. Also check out the temperature plots. The flow front temperature would drop more in the pressure limited simulation.

I have never experimented with a pressure limited simulation intentionally but this is what first comes to my mind.

Nish

[mtrujil1]

basically when you limit the pressure the flow pattern will change, like Hesitation, due to the velocity of the flow front is decreasing and you might have some cold spots at the flow front.

isn't mandatory that limiting the Pressure , you obtain short shot.

regards