I have no direct experience, but you might check here:
we have a multicam 6000 cnc table w/a hpr 260 and a oxy fuel head. we have had the table for for three years but rarely burn heavy plate. it dose an ok job but would like to do better, specificly on 4.5" mild steel. any advice would be great.
What brand of torch are you using?
keebler is correct I'd have noticed your question the day it was posted, if posted in the ox/fuel discussion.
I don't know that I can help on your 4.5" material as I rarely cut above 1.5". I have made a few cuts in 4" but my expreience is limited above 1.5"
If it works.....Don't fix it!
Thanks guys I am new to the forum and had not found the ox/fuel discusion.
To be more specific I have a Victor torch using oxy/acetylne.
The biggest issues I am having is that I seem to have to do a tremendious amount of preheat not just with the cut torch but with a rosebud as well. Dose that seam right? Is there a good base metal temp to cut at?
The other big issue is the top inch of the cut edge tends to have a bit of a roll. It seems to me that my low cut flame is to hot but I am having trouble keeping it hot enought to cut. Should I cool it down and slow down? Dose 6ipm sound to fast?
Also can anyone suggest a good cut hight.
There are High Speed tips that are alleged to do better with piercing/cutting thicker material. I use Oxweld torch barrels & have tried their tips. They do seem to pierce easier & cut faster but in my opinion the cut edge suffers. Probably not beyond most peoples standards for torch burned parts. I'm just more satisfied with the looks & smooth cut surface finish using standard tips.
Then there is the ease on pierce (pressure goes up as pierce progresses) oxygen-preheat gas cut back control that most higher end machines have as standard equipment, or at least an option. That's a lot of the basis of the ox/fuel discussion. This feature is a big help to piercing heavier stuff.
While having the base metal hotter helps with piercing I don't think that's the way big companys (steel suppliers) do it.
Your speed is probably about right if you are using large enough tip. In a Victor, probably in the range of a #4 or #5. I know some Victor torch barrels are not compatable with all fuels without changing something inside the barrel.
You are probably spot on with to much heat after the cut is established being at least in part the edge rounding you mentioned. Also even a very slight chunk of anything stuck to the end of the tip can cause the same thing.
You should be able to achieve a pierce once you have the top surface hot enough to burn. I have had some success only pausing for a couple tents of a second once torch raises & begins pierce. Then I set my lead in really slow 1-2 IPM & a ramped lead in is a must. It seems that the slow movement keeps the cut going & creates a "U" shape to help throw all the volcano stuff behind the tip rather than straight up on it.
I hope some of this helps or at least gives you some ideas to try.
One other note: Fuel gas tips are of a 2 piece design & the cut orifice is somewhat more protected from flying molten metal. Thus a bit harder to gunk up.
If it works.....Don't fix it!
If you have a mag drill, drill a 1/4" pilot hole at the edge of your pierce point. You will be able to start your cuts without having slag blow back, which will keep your tip clean enough for quality cuts. I like to do a dry run through the program in preheat mode at normal cutting speed too warm the plate up. This also burns off the mill scale and the preheat before piercing is only a few seconds.
You should maintain the same standoff distance that you would use with a manual torch. If you plan on doing a lot of torch cutting, natural gas is much more cost effective as a fuel. Acetylene may burn the hottest, but the travel speed isn't that much better, and if you are doing heavy bevel cuts then you will find that natural gas or propane with two piece tips are superior.
Whichever fuel you use, experiment with travel speeds. If you cut too slow, cut quality will be worse than if you did the job with a hand torch. Better to cut a little fast and have trailing kerf lines with very little dross.
I believe the 6000 series gives you the option on the controller to start on the edge of the sheet? that would help for sure. Does the material library on the controller not have presets for 4.5", the multicam presets seem to work pretty good whenever i tried them. here is a victor chart http://www.eurekaoxygencompany.com/victor.htm
Is multicam still having control board issues?