Does air poppet ejection work?

[bktutor]

I am designing a mold for a toy (doll seat) and was thinking of using an air poppet to release seat! I have min 2deg taper and no under cuts! Do poppets push the part at all, or do they just break vaccum?
Please let me know!
Brian

 

[Pud]

Hi bktutor,

Poppets are usually used just to release a part from a long core - example being say a plastic beer "glass" (yuk!). The part is then usually completely removed by automation (robot). If the part is not deep, and draft angles sufficient for type of finish etc, and pin marks not acceptable, you may get the part off with the runner and gate when combined with a valve (but even a valve will leave a witness).

Poppets are sometimes mechanically operated and will push a part but usually have limited travel.

Rgds

Harry

 

[patprimmer]

In countries where runs are very short or where semi skilled labour is very cheap, robots are less prevalent. In this case, a poppet to break the vacuum and a stripper plate can work with minimal "marking".

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[davidinindy]

As a former mold designer, My experience is that they are ussually just good for breaking the vacuum on large surface areas. We always used an additional, more positive form of ejection... ie pins, stripper ring/bars, etc.
I suppose if you were using it to break the vacuum for a robot to remove the part, no other form of ejection would be neeeded. Depends on what you're doing.

 

[deper]

BKTUTOR-
I know some time has passed since your initial question but I just recently found this site. If your part geometry is appropriate, you can use air poppets to completely eject the part. We actually manufacture air poppets but also we have built molds with only air ejection. You need a part that has a closed geometry like a box or cup to build enough head pressure to eject it.