Bubble free steel epoxy dies in hydraulic metal forming
I have found it difficult to get consistent results using “Devcon
Steel Epoxy”. I also found the product to be too expensive along
with the bubbles created.
I have started to use iron powder mixed with "Devcon Two Ton Epoxy"
and find that the bubbles persist. I’ve tried using a vibrator
(vibratory polisher), on the epoxy separately and mixed with the
iron powder. I’ve also tried adding 5% acetone as advised by Devcon
with poor results. The opportunity to do anything is severly limited
by the fast cure rate of the mix. Because of the extremely thick
consistincy and the fast cure rate I cannot imagine the vacum
machine being effective.
I would apprectiate any suggestions on bubble elimination.
I seem to recall there being a retarder to slow curing for some
epoxies, but can’t be sure as it’s been a real long time since I last
did much with high end epoxies.
I would still give vacuum a go, but go easy as you don’t want to
vacuum boil the stuff!
A vacuum is only going to make it worse, what you need is pressure,
this is what the people who make garage models do.
Make sure you get a pressure vessel that is certified to over that
pressure, I use a paint pressure pot, with the stirrer removed. There
is a company that sells them, Alumilite? Google pressure pot resin
casting
Make sure you get a pressure vessel that is certified to over that
pressure, I use a paint pressure pot, with the stirrer removed.
There is a company that sells them, Alumilite? Google pressure pot
resin casting
Vacuum works as well but you do need to be careful to not pull too
high a vacuum or you will cause problems with evaporating the resin.
Pressure pots are a excellent tool but as you say make sure not to
over pressurize or it will be a bomb.
Use a slower cure epoxy something with a pot life of 1 hr will do the
trick, then mix the resin and the iron filings and vacuum to remove
entrained air from the filings. Once the resin has fully wetted the
fillings and has been degassed then you add the hardener and you will
only have the bubbles that are mixed in rather than all the air that
is brought in when adding the filings. Mix then degas in the vacuum
chamber than pour slowly in a very thin stream over the model, brush
the epoxy over the model to work the epoxy onto the surface and
eliminate any bubbles that adhere to the model via surface tension
then continue to fill the mold in a thin stream.
Vacuum chambers are also potential bombs, although a pressure pot
can be made into a much larger bomb.
Oh yes, they can but you can only get 14 psi pressure on a vacuum
chamber. In a pressure pot you can get a lot more, even garden
variety air compressors will produce 100 psi. As you say a much
bigger bomb. Any pressure vessel is a potential bomb but it is very
easy to unintentionally over pressurize a pressure pot not so with a
vacuum vessel.