The other night on the Discovery channel they had a show about building a destroyer. One scene showed them cutting a 2 or 2 1/2" plate on a CNC machine. What puzzled me was that the operator used a striker/sparker to start the "torch". I would have assumed that they'd be using a plasma cutter but I couldn't tell by looking at it. So, what was the torch? What do they typically use on plate that thick? Does plasma ever have to be started with a spark?
TIA, Bob
I don't know what is typical, but the local shop with a CNC cutter uses oxy/acet. They cut plate about 1 inch thick. And the steel mill that I toured used oxy-acet to cut slabs. As I remember they were about 8 inches thick.
Dan
Bob Engelhardt wrote:
building
striker/sparker
Most CNC cutting of heavy plate is done with oxygen and fuel gas. Propane is popular however some shops use natural gas. Acetylene is a problems in getting enough volume for the multiple tips so it is not practical. Plasma units are rare much over one inch capacity. Plasma cutting creates a flare to the kerf. A good flame cut on two inch plate will have less than 1/32 inch difference on the edge when a square is placed on it. A good operator who knows his tips and his CNC can flame machine to plus or minus 1/64. ( steel) With CNC the ease of fitting over the last thirty years has been changed. I can now fuss and complain around over a 1 mm discrepancy on a
100 mm wide piece. We regularly order large holes burned. They are just as accurate as drilling with a large drill bit. Boring would give greater accuracy. With CNC flamecutting one can make cuts that are not straight line. Cambers on long plates can be programmed. The ultimate in accuracy of course is laser cut stuff. I haven't worked with anything over quarter inch thick. I understand the largest plate now cut with laser is one inch. No doubt as I say this someone has an even larger capacity laser table. RandyThe old photo tracing units have been around for 40+ years. Cut a pattern out of black paper, set it up and go. These got replaced by the CNC units over the years. Set up as many torch heads as you like to do multiple pieces (I've seen 8 torches going at once). I've done 4" plate with a machine burner, 6" to 8" is quite doable. It's fairly impressive to see a chunk of 4" plate get cut up like a lace doily.
Take a look at most any backhoe or excavator. Most of the ma> I don't know what is typical, but the local shop with a CNC cutter uses > oxy/acet.
Might have been any type - even diesel oil ?oxygen? - I think that is the match - use a wood fire to get the oil hot and starting to burn not just flow - then add the o2 and blast.
Magnesium torch ? Hot fire for the length of the stick... :-)
Martin
Most likely it was old fashion Oxygen/Acetylene.
Typically 1" [25mm] is the cost effective limit for plasma cutting. Anything thicker can be cut faster and more quickly with Oxy/Fuel.
Ernie has some good stories about these "lance" type torches (i think that's what you saw).
a steel tube packed with various rods, capped at one end with oxygen input. turn on the "O" and strike the other end. the thing burns the end off almost in a plasma state, very vey hot material with mass-flow energy.
Yes, but there's no reason to use that kind of torch for 2" steel plate. Even my lightweight oxy-acetylene cutting torch will handle that just fine, and it would be child's play for any industrial CNC oxy-acetylene torch.
K> Ernie has some good stories about these "lance" type torches (i think that's K> what you saw).
K> a steel tube packed with various rods, capped at one end with oxygen input. K> turn on the "O" and strike the other end. the thing burns the end off almost K> in a plasma state, very vey hot material with mass-flow energy.
Thanks for all the replies. I learned something new. Ain't SEJW great? Bob
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