Re: [hobbicast] Degassing
- I have a customer that buys cast grey iron
thermocouple protection tubes (TCPT) to degas
their aluminum. They drill holes into the bottom of the tube,
similar to Charles Logan's description. They then attach
the nitrogen the 3/4" female thread of the tube.
It's an inexpensive alternative to pourous graphite
and stainless steel. An 18" cast iron TCPT will cost
you around $18-20 and if protected with a good ladle wash
will last many, many melts.
If you're not familiar with a cast iron TCPTs
let me know and I'll e-mail you a picture.
16100 Garfield Avenue
Paramount, CA 90723-4847
----- Original Message -----
From: "brian whatcott" <inet@...>
Sent: Tuesday, October 31, 2000 6:13 PM
Subject: Re: [hobbicast] Degassing
> At 19:21 10/31/00 EST, you wrote:
> >Several aluminum foundry's around me (including myself) use a piece of
> >stainless pipe welded shut on the end with 1/8 holes drilled in it to
> >with argon. Use a low flow regulator and bubble your melt for 1minute.
> >the flow before inserting the pipe and turn it off after removing from
> >molten aluminum, otherwise the holes will stop up. We degass at 5 to 8
> >minutes per 100 pounds of aluminum. Black iron pipe will last a long time
> >considering your crucible sizes and how often you melt. Only degass when
> >porosity is a problem, that way a small cylinder of argon will last a
> >long time. What you pour and how it is used determines if you need to
> >Charles Logan
> This seems like a smart idea to me. Admitted, the first cost is higher
> (unless you use an argon bottle with MIG) but it has to be safer than
> solid chemicals that may be damp - you know the gas in the bottle is dry.
> Though I have never ever used this approach - I can say on general
> that the smaller the holes the more efficient the de gassing.
> There is more surface area in smaller bubbles of gas.
> brian whatcott <inet@...> Altus OK
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