gate seal study.

[sublime1]

What is the best way to determine gate seal a hot runner mold? I'm just starting out and need all the assistance i can get.

Thanks in advance.

[Suhas]

Hi Sublime,
I am writing a paper on this to be published at a conference and so can't give out the results yet. It is a little complicated but the procedure I have come up with works GREAT !! Quick answer - there is no easy way. For now simply 'play' with the time and pressure and you will get your answer. I will put up my paper and let you all know.
Suhas

[manimaste]

after setting up speed ,pressure ,maje the hold pressure 80% of inj.pressure and make the hold.time 0, and 2nd stage h.pressure lesser than 1st stage to avoid banging,now set h.time 0 take two shots note the weight,now set h.time 1 note the weight,continue this steps till,the weight will become unchangable in particular time ,that is gate seal time.now this is your hold time

[sublime1]

Thank for the help, guys.

[brentb]

With a direct hot tip gate, you never really freeze or seal the gate do you? I mean, wouldn't something very bad happen, on the subsequent shot, if the drops were frozen? I think you do your study to the "plateau", of weight gain.
This inability to truly seal a gate, may be a reason for hot runner molds, especially multi-cavity, not running truly tight tolerance parts.
Now if the HR is feeding cold mini sub runners, that may be a different proposition.

Suhas, you are late, the definitive paper on this subject has already been written. It is short though, as the guy writing it had a terrible accident while testing his hypothesis!

Keep on Molding ( but watch the freeze)!

brent

[AWJ.services]

Now let's do it with a valve gate. Valve gate shuts at end of hold time. If the pin shuts on a slug...

[Michael76]

I also need help in gate freeze study. I'm confuse with hot tip with valve pin gate (shut off automatically). Does it really need gate freeze? I will start to get gate vestige at around 4 or 5 sec hold time. Is there a valid statement that I can use to skip this study? Sorry for reviving this thread. I can't post a new thread.