Plasma cutting question

[Threadkiller]

Morning all. I have a Primeweld 50amp plasma cutter. Its been a great machine especially for the price.

I was having an issue the other day while cutting 1/4" plate. I'm sure it's something I'm doing wrong. As I was cutting, the molten slag from the cut was sticking to the bottom of the plate an as it cooled it would basically reform the plate under the cut and I would have to break out the angle grinder with the cutoff disk which kinda defeats the purpose. The only saving grace is that the cut was already made and was pin straight so the cutoff wheel didn't wander.

I had the machine pinned at 50amps but afterwards I started lowering the amps of the machine which didn't seem to make a difference. The machine still cut 1/4" plate at 30amps which I thought was pretty good. Does anyone have any advice on what I'm doing wrong? I also tried messing with the air pressure which didn't seem to make a difference either. Should I just run the air at 125 PSI to try and clear the slag better? I don't know.

 

[Threadkiller]

Also another question. This machine is a touch arc machine. After I strike an arc can I lift the torch up? I go through a lot of consumables because I drag the torch on every cut.

 

[gpiggaz]

My guess is you are going too slow on the cut- but that's just a guess- based upon what my manual shows.

What does the manual say for optimum cutting of a 1/4" plate? I have the PrimeWeld Cut 60 and it says 45Amps, 60PSI for mild steel - which is probably similar for yours- Also, cut height matters- as well as speed- Mine calls for 0.06 cut height and 47in/min speed- As for cut height, you should be able to place a foot on the head to maintain close to that cut height which will help with consumables. Finally, what does the flame look like? that can help you judge your drag rate- too fast and it will be slanted quite a bit, too slow it will be pushing almost straight down. Just right, you want it slightly angled away from the direction of drag. It takes practice- of course I am still sort of new at plasma cutting, so I'm still learning too.

 

[Threadkiller]

Hey thanks for the reply. Honestly I never looked at the manual but I just found it online and it shows for 1/4" should be 30 amps with 40-50psi. It doesn't specify a height though. I am definitely going slow. It's hard to maintain a constant speed especially dragging the torch on the work piece. I don't know if it's because it's a base model machine but mine doesn't have speed or cut height specifications like yours does in the manual. Just reading the manual though it does say there will be an unnecessary buildup of slag if travel speed is too slow though. I guess I'm going way too slow. I will have to look into getting an attachment for the torch head to keep it off the work

 

[rsanter]

Too slow
Too fast
Tip is worn
Poor ground

 

[tarmy]

Too slow
Too fast
Tip is worn
Poor ground

This pretty much covers it OP. That and DRY air.

 

[slowtwitch73]

Start pretty fast...nothing blowing back (up) is good.. means it's all shooting out the bottom.

If you get it coming up means you're too fast.. the uncut portion has shot the molten part back up towards you.