Hi all,
Could anyone explain why there is short shot with hot runner system while the same fills 100% with Cold runner? (pressure 13665 psi) (Please check the attachment)
Material is PC. I have set Mold temp 180 F, Injection time 0.2 sec V/P Switchover at 98% for both studies. I have tried with maximum machine injection pressure (i.e 70000 psi), still i observed short shot.
Do I need to change any setting for hot runner system?
Thanks in advance,
Moses
Solved! Go to Solution.
Solved by efoltz. Go to Solution.
Moses,
How are you controlling your fill time? Check your flow rates for the two different scenarios. My guess is that the model with the cold runner has a much higher flow rate than the hot runner. This is because in the simulation the hot runner is assumed to be filled at the beginning of the filling. However, with the cold runner system the melt has to pass through both the runner and the part in the specified time.
Typically it is best to determine the fill time for the part before you add the runner system to the model. This will allow you to determine how fast you should be filling the cavity, and will help you size the gates appropriately.
Hope this helps,
Erik
Dear Erik,
Thanks for your kind reply. Yes. I checked the flow rates of the two studies.
i.e., 1.330in^3/s with cold runner and .075in^3/s with hot runner system.
I understand the flow rate is very less and now I set 0.05 sec injection time which raised the flow rate to 0.301in^3/s ; and I observed 100% filling with 15914 psi pressure and .1672 sec fill time.
Thanks for your kind help.. This is very help full. Actually I was running many trials by changing many parameters. But I didnt reduce the filltime beyond 0.2 sec, since i thought it was very small enough.
Thanks and regards,
Moses