Hi all, (Jim Colt in particularly :-) )
We have recently bought a used plasma, 6x2m table with HD3070 - manual gas and upgraded torch. We are now installing the machine.
At this point I need to find out:
1. what is the consumption of O2 and N2? Meaning of flow rate (ipm/scfh) and test flowrates from manual gas console cut chart for upgraded torch?
The gas flow specs are in the upper right corner of the cut charts for the upgrade torch.
2. Is it possible to use air/air or or O2/air, and what would be the parameters for mild steel, 70A and 100A?
The only recommendations are to use the gasses suggested in the cut charts. The use of air as either plasma or shield gas will affect cut quality and consumable life. Since this is an older product and other gas testing has not been done.....I cannot speculate on the exact outcome. It is possible that air may work satisfactorily as a shield gas, assuming it was clean and dry and at the same inlet pressure as the suggestion for nitrogen. I definitely do not recommend air as the plasma gas...this system was designed for cutting steel with oxygen.
We would mostly cut mild steel S235, S275 and S355; 5mm thick and 10mm thick.
We have an industrial compressor 45kW with suitable dryer. Plenty of air, 5400m2/h, 10bar.
From manual, worst case conditions, delivery of O2 should be 77,8 scfh with 120psi. I estimated that bottle of 8,4kg under 150bar would last 4min of arc time under this conditions. Is it correct? I expect that consumption in operation is 50% of worst case, giving me 8min, which is still rather unusable...
A standard high pressure cylinder of Oxygen holds about 240 cubic feet. When I do the math I would expect over 200 minutes of arc on time. This system, when used as suggested will cut steel with far better quality and at a lower operating cost as compared to an air plasma system. So, for test during installation and maybe even later for production, it would be most convenient to use air for shield, and maybe even for plasma or O2 for plasma and air for shield. From Jim's quote this sounds viable. Is it?
In manuals for HD3070, even for upgraded torch, and Operating Instructions from plasma cutter manufacturer, there are no parameters for air/air for mild steel. How do I choose suitable Amps, travel speed, Torch to work distance...