gas assists

[wiitard]

hello all, i am new to these forums but i thought i would give it a shot, i have only been setting for about 2 years, and recently trying to get into external gassing of moldings,

the tools we use run a external over flow type of gas assist, now my question here is pressure wise what should i be looking at,

i would like to see what the lowest of gas pressure i could possibly use as im getting really bad shine marks on the core but then gas burns at the other end of the overflow,

any tips here would be helpful please,

the material im using is glass filled pbt/pet, the tool temp is around 45 degrees, total cycle time is down to 2 mins

[rickbatey]

I've done very little gas assist but I think the sink may mean your gas PSI is too low and the burn makes me think the gas flow is too fast/high.
Rick.

[Jendalf]

Hi

This is hard to say exactly but be prepare to use preassure up to 250 bars. (long channel, low MFR)

It depends on the volume of the material You need to press out by GIT.

Can You share us some pictures of the part, inlet of gass and channel that You have for rest of the materiál (all scaled).

j.

[Rendy]

Hello i did gas assists for a few years you need to hit it hard then back it off near the end of fill think of gas as injection molding. you should use three stage of gas i'd say 1500 psi then 1000 psi then 500 or lower watch your over flow if to much lower you shot size..

[Rendy]

45 f on mold heats really... email me rendynoble@yahoo.com