Re: Small Injection molding unit?

--- In CAD_CAM_EDM_DRO@y..., "Smoke" <gordonr@r...> wrote:

> What kind of charcoal did you use in the furnace?
> I tried melting some aluminum using charcoal briquets and had small

aluminum

> ingots (poured into cast iron cupcake pans in an earlier pour)

piled in a

> coffee can. Ran the damn thing for an hour and the aluminum never

diod

> melt.

I used some generic store brand charcoal from the local grocery
store. Nothing special about it. It took about twenty minutes to get
the aluminum I stuffed into the pot melted. After I had a small pool
of molten aluminum in the cruciable I removed the lid from the
furnace and operated it that way for the remainder of the session.
I'd make a snowball sized ball of swarf, pop it into the cruciable,
and push it down into the moltent stuff. It went real quick. I had a
chunk of aluminum about 4 inches in diameter and 3/4 inch thick that
I had to push down into the moltent stuff before I could get it to
melt. Might have melted ok if I had had the lid on the furnace.

> I fire up my ceramic wool lined furnace, put the ingots in a

silicon carbide

> pot or a welded steel pot and get melted aluminum in about ten

minutes!

> BTW...a ceramic wool lined furnace will get up to operating

temperature much

> faster than a fireclay lined furnace. It alos cools down faster

for storage

> when your done using it.

That will be the next furnace I build, probably with a propane burner
to go with it. For now though, the little charcoal furnace works and
its paid for. 8^)

>
> I use my shop shop vac for the blower on all my furnaces. All you

need to

> do to regulate the air flow is connect a house light dimmer switch

between

> the vac and the power source.
>

I started out trying to use the shop vac. Melted things ok but tended
to eat my cruciables. The house light dimmer switch is a great idea
because I'm sure the problem was I was getting too much air into the
furnace. The Wagner heat gun seems to put out just the right amount
of air.

> Thanks for the tips on the injection machine. I'll have to get a

set of

> plans and see what I can do to improve the design and get it to

work well

> for wax injection. There's an anti-stick spray you can buy to use

on the

> inside of the molds before injecting the wax. The foundry in

Montana uses

> the stuff.
>
> There's a better way of melting aluminum cans...but I wouldn't

recommend it

> for your area...the smoke would drive the neighbors...and probably

the fire

> department...crazy! You need a big trunnion mouonted furnace for

melting

> those cans.
>

Yep, them cans made lots of smoke for not much aluminum. I'll stick
with the shop swarf and big scrap pieces.


Dan Eaton (Saint Louis)