[TheForge] Re: Burning Metal

Mon Nov 3 23:49:01 2003

Jerry,
If this is true, how can I shut the Acetylene valve off when the cut starts
and complete a cut in metal 1/2" thick  with out the fuel supply?
When I first started cutting  my 5+" thick steel anvil billets, I had major
problems with slag build up and sloppy wide kerfs or incomplete cuts.
After reviewing my O/A cutting text books. I lowered the O2 pressure and the
cutting action improved dramatically. The higher the O2 pressure the more
slag formed in the kerf
The cutting action is exothermic.
I believe poor O/A torch performance is mostly due to not adhering to proper
gas pressure for the tip size recommended for the steel thickness.
Chuck
----- Original Message -----
From: "Jerry Frost" <[email protected]>
To: <[email protected]>
Sent: Monday, November 03, 2003 9:21 PM
Subject: Re: [TheForge] Re: Burning Metal


> The short answer is: The oxides produced must have a lower melting point
> than the base metal.
>
> I don't know at what % C the oxides make cast iron "uncuttable" with a
torch
> nor exactly why, the graphite hypothesis sounds reasonable though.
>
> Regardless, you can see the action: preheat melts the base metal, the oxy
> jet hits it and a layer of hard slag/oxides form and the oxy jet has to
> physically push the oxides and molten material from the cut. This isn't
> cutting, it's more like excvation, soften it up and push it out of the
way.
>
> Pure iron cuts just fine and any problems cutting wrought would be the
> result of silica inclusions. Silica and or glass may have a lower melting
> point but their oxides are very refractory also even in a molten state
> silicas ave very viscous so they don't even push out of the way very well.
>
> Frosty
> ------------------------
> If it ain't forged
> it ain't real.
> Wrought iron is.
> The FrostWorks
>
> Meadow Lakes, AK.
>
>
> ----- Original Message -----
> From: "Andy Gladish" <[email protected]>
> To: <[email protected]>
> Sent: Monday, November 03, 2003 10:00 AM
> Subject: [TheForge] Re: Burning Metal
>
>
> > > I think if the carbon content was the accelerating factor, cast
> > > iron should
> > > cut easily.
> > > The  best I can do on cast iron with an O/A torch is a very sloppy
cut.
> > > My plasma torch however cuts it easily.
> > > chuck-
> >
> > I think that what is happening when I use an O/A torch to cut cast iron
is
> > that the preheat is melting the metal and the oxygen jet is blowing it
> > aside. Way different from the sharp, clean cut (burn) I get with steel
> when
> > things are set up correctly.
> > So, a torch will 'cut' things that it can't 'burn'.
> > Andy G.
> >
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