[TheForge] Re: Burning Metal

Thu Nov 6 14:03:01 2003

Hey Jerry,
What I have observed during cutting operations, is that after setting up the
torch properly, it is critical to use the right preheat flame to heat the
steel enough to start the cutting action; but not over heat the area so that
the kerf gets sloppy. Once the cut gets sloppy, the slag diverts the cutting
action to the sides of the kerf. And the cut is kaput. The higher the O2
pressure and thicker the metal, the more slag is formed. Once the slag
oxides have clogged the cut. its a real pain to restart the cut at that
point. It's like the slag is forming an insulating barrier.
I've heard that the allstate is a really good torch, but havent tried one
yet.
Chuck
----- Original Message -----
From: "Jerry Frost" <[email protected]>
To: <[email protected]>
Sent: Thursday, November 06, 2003 3:19 AM
Subject: Re: [TheForge] Re: Burning Metal


> Hi Chuck:
>
> I'm not sure how my muddled ramblings lead to your question except perhaps
I
> didn't say the iron/steel is burning under the oxy jet. Once the steel is
> hot enough to initiate burning under the oxy it is self supporting.
Properly
> set and guided by a steady hand you can certainly shut down the acet after
> cutting starts and continue just with the oxy.
>
> Oxides and slag inclusions that shield the iron/steel from the oxy jet
stop
> the combustion. Iron and steel within the cutable range of alloys produces
> an oxide with a much lower melting temp than the unoxidized metal and is
> literally blown out of the cut by the "pressure" of it's own combustion.
>
> Ayup, improper regulator settings and tip selection is the #1 reason for
> poor torch cutting. (Oh okay, dirty tips are right up there too.) I use an
> Allstates oxy/prop rig at home and the regulators are self metering but at
> work I'm always resetting the regulators. Everybody seems to want to run
> 5lbs acet and 40lbs oxy.  What really kills me is somebody will compliment
> me on a torch cut, then rag on me for not having the regs set "right".
> <sigh>
>
> Frosty
> ------------------------
> If it ain't forged
> it ain't real.
> Wrought iron is.
> The FrostWorks
>
> Meadow Lakes, AK.
>
>
> ----- Original Message -----
> From: "Chuck Robinson" <[email protected]>
> To: <[email protected]>
> Sent: Monday, November 03, 2003 7:37 PM
> Subject: Re: [TheForge] Re: Burning Metal
>
>
> > 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
>
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