length guide exponents

[Geppetto82]

Good evening,
in a plastic injection mold, how long should it be along the driving hole of an expeller? is it related to its length and diameter?

Thank you.
greetings
geppetto82

 

[meccanicamg]

Good evening,
in a plastic injection mold, how long should it be along the driving hole of an expeller? is it related to its length and diameter?

Thank you.
greetings
geppetto82

I answer you as a generic mechanic:
- an expeller pushes an object by meeting a reaction to win
- normally should not generate wear on the guide bushing or excessive effort
- must resist the tip load
- possibly not to flench
- Usually for applications it is good that there is a length/diameter ratio at least equal to 2
- depending on how the mold is, steps, forces, size of the piece and extractor you could also make different relationships, make the extractor fold even a little without big problems and in other applications it must be all rigid

 

[Geppetto82]

Hello mechanicalmg,
Thanks for the answer.
what you write is all correct apart from the 5 point according to me

Usually for applications it is good that there is a length/diameter ratio at least equal to 2

the relationship is always much higher.
I have a 90mm long ø5 expeller in my case, I have to leave him 15mm driving I hope they will stick!
I'll let you know!

 

[Geppetto82]

an expert die designer recommended a guide length/diameter ratio of at least 2.5/3.
processing and mold type allowing it would be advisable 5/6 times.
Mechanicalmg rereading your answer well I realized what you were saying, my response is wrong I apologize
Hi.