Light Gauge Cutting

[jhowie]

Hello All! I am new to this site and plasma cutting as well. This is a great wealth of help and information! As a complete newbie, I appreciate how freely everyone here is willing to help each other. My question relates to cutting lighter gauge material. My company uses a lot of 26 ga galvanized. While the machine will cut it, it tends to get a lot of warpage and a lot of burn marks. The warpage I am afraid may be the nature of the beast but does anyone know how to mininmize the burn marks on the metal? I have played with the settings a little, but as this is the bread and butter stuff for the company, I cant afford to mess stuff up. Besides, if I can make this more profitable for the boss, I am hoping to talk him into trying more of the fun custom stuff that a lot of you are doing! Thanks for any help.
Howie

[jhowie]

Sorry, here is my machine info: Multicam 1000 Plasma table, Hypertherm 1250 running 40 amp consumables on 30 amps at 510 fpm.
thanks!

[jhowie]

It shows some on the pierce and lead out but more so on the length of the cut. It starts and stops on long straight cuts as well as on circles and curves. It usually is not on the whole length of the cut. It almost seems to happen in random spots on the cut but quite consistently. It doesn't appear to be more or less often in corners. Hope that makes sense.

[jhowie]

After rereading what I wrote, let me try to clarify my question. Say I cut a series of 12" circles. With new consumables, I get the first 5 or 6 to cut nicely. #7 has a spot about 1-2" that is ragged or doesn't completely cut through and leaves scorch type marks. That may happen on 1 or 2 parts but then it will clear up for the next 5 or 6 or 15. It seems to happen on all my light ga projects just not in a predictable way.
The same will occur on straight cuts. 24" cut may be fine first 12" then an inch or 2 will be ragged or not cut through then its fine again. The corners seem to cut alright. Our machine does not have the auto THC instead we have the wheeled hold down plate.
Sometimes it will cut through fine but will leave the burn marks in random spots on the cut.
Thanks,
Howie

[Metal Troll]

I also run a Multicam 1000 5' x 20' table with the roller head but with a Hypertherm 1000 and 40amp consumables set at just under 30amps cutting 26ga G90 galvanized. I have run into this problem also. There are a couple of things that have helped me. Every Monday when we come into the shop we drain the aircompressor which has a dryer built into it and inline dryers to the machine but still huge amounts of liquid come streaming out. Also when choosing are material types in the hand controller I select 26ga under the unshielded menu. When adjusting my nozzle I drop the head down and use the head of a Nickle to set my height. I am not sure if any of this is the correct way to do it but these things have helped my cut quality on my lighter gauges.

Metal Troll

[srp]

I also use the nickle approach - works good for me.
the best thing I did to monitor my height was to wire an analog dc volt meter on the pin out in my plasma machine. I'm on the divided voltage but that gives me a good reference. When the voltage varies from the reference I know it is time to check height.

[jhowie]

I have been using a dime as my height reference per our multicam dealer. I will check the moisture content in the lines. We have a dryer and a couple line filters. I have been concerned about that but the boss seemed to think it would be enough. Thanks for you tips. I will be implementing them as soon as I can and see what happens.

[jimcolt]

A nickle is about .080".....and is good enough for setting height when using a rollerball head. For better cut quality with your Hypertherm on 24 gauge galvanized...use the FineCut consumables....and turn thr amperage down to about 35 to 40 amps max...cut speed should be in the 300 to 350ipm range. The FineCut parts are designed specifically for cutting thin gauge materials at slightly slower speeds (as compared to the 40 Amp parts) with superior quality.

If you need part numbers, etc...let me know...or you can find them on the Hypertherm website under torch and consumables, then consumables by system.

Jim Colt Hypertherm

[jhowie]

Thank you for the advise. This is a fantastic forum. Wish I had found it before we got the plasma so I could have been more informed. I appreciate the way you all give advise so freely. Can't wait til the day I learn enough to help someone else! Howie

[Plasman256]

I agree. This sounds like a moisture or just an air problem. Does the Air compressor kick on just after the problem shows? Your air pressure may be fluctuating too much to stay in the operating pressure range of the plasma and you also may be getting too much moisture in the line. Any moisture is bad for a plasma system and will cause misfires, shortened life of consumables and cut quality issues. The PowerMAX 1250 unit needs a constant pressure of 70 to 80 PSI. I hope this helps! Plasman

[jhowie]

Thanks for the advise. I raised the torch to "nickel" height as suggested and that has made a lot of difference. The air pressure remains constant and so far is dry. Going to make sure that we keep a better eye on the compressor from now on. What I did notice when I put the roller head down and moved it across the metal was the tip was actually contacting the material in different location as the wheels would occasionally all be between slats. The 26 ga "flexes" with the down pressure from the head making it actually roll up and down as it moves around the table. I am not sure what the down pressure is on the head yet or if it is something that can be adjusted easily or not. The cut is a lot cleaner and smoother now thanks to the advise you all have given. I am gonna keep trying to get it "perfect".