3/4" Plate - Torch Drags on Top Slag at Pierce Point

[JoeyD]

Hello everybody,
I'm having trouble cutiing 1.25" circles into a 3/4" steel plate. I am using a Hypertherm 1250 with Plasmacam software. The problem is, is that when I pierce the material, it creates a lot of slag on the metal and screws me up when it comes back around. I've started the pierce in the center but it still has a problem with the slag. The material is 3/4" steel, using 80 amps and compressed air at 80psi.. Any help will be greatly appreciated!

[Scratch]

I don't have a HT, I have a TD, but is 80 amps what the book calls for? My TD book tells me to run at 100 amps for that and thicker.
On 1" and thicker steel, I have to start the torch, wait until it blows through, then start the head moving. I've also heard people predrilling a hole in thick stuff also....

[mdwalker]

I use a flat chisel or a flat piece of metal to knock the slag off after the pierce. It is easy to knock loose. Cutting thick metal is usually slow enough that I can knock off the slag without stopping the cut.

[leatherhands]

Whats the distance between the material and the torch tip during the pierce? Depending on what your pierce height is now you may solve this with a higher pierce height. Continue to lead in from the center of your circle when you start your cut. Once the torch begins to move your height control should take over and position the torch for proper cutting height until the cut is complete.

[JoeyD]

Thanks for the replies everybody. Pierce height is .200 and cutting height is .063.. The problem is, I can't chisel the slag away because of the small circle diameter. I've tried piercing, stopping and removing slag, then start over with the cut. Then I get a "no signal" alarm because of the pierce hole.

[leatherhands]

OK, try raising your pierce height to .250-.300. This should help reduce the accumulation of slag below tip and offer you added clearance when you begin to move. Make sure that your height control still maintains proper cut height during the cut, we only want the added clearance during the pierce. Also if your tip is in bad shape and/or your air pressure is not properly set (set with air flowing) this will need to be addressed first.

[JoeyD]

Thanks Leatherhands! I got it to work right. Raised the pierce to .250 and sprayed mig welding splatter spray on all of the pierce points. Works perfect!

[hinesigns]

Leatherhands
Now I know why I visit here for all the tips.Anti-splatter can be used on any thickness of metal at the pierce point. Much cleaner all the time.
Thanks this site.
Bob http://www.hinesigns.ca