Reducing excessive metal after oxy-fuel penetration

[Soulu]

Hello !

Does anyone have any tips or trick how reduce the excessive metal, that stays on the sheet after oxy-fuel flame penetrates the steel.

I'm using Rhona torches and acetylene as fuel gas. My settings for a 15mm (about 0,59 inch) steel sheet are:
acetylene 0,25 bar (about 3.63 PSI),
heating oxygen 2,6 bar (about 37.71 PSI),
cutting oxygen 4,8 (about 69,62 PSI),
7-8 seconds heating time.
speed 550-600 mm/min (21,65-23,62 inch/min)

I think the gas setting are ok, but i wrote them down just in case anyone is curious.

So anyone has any ides, can redusing the heating temperature help or does it need longer heating time.

All ideas are welcome. I also added some picture so you could understand what i'm talking about.

[packrat]

That looks normal for O/A torch cutting. When first piercing the metal, there is no where for the slag to go except on the top surface like that. After it cuts through then it blows out the bottom.

[Soulu]

Yes, I understand, that all the metal can't be blown through the plate, but the thickness of the plate in the picture is only a bit over 1/2 inch and that much slag should usually be on the top surface of a 1 1/2 inch plate. So i'm looking for some possibilities to reduce the amount of slag on the top surface.

[WSS]

It looks like you are starting motion before the pierce is complete (ramp pierce). This usually puts the slag behind the cut but I see the torch needs to get around that slag later in the cut. Two things you could try to help would be LP (propane) and hi-speed tips that run higher cut oxy pressure. The thinner stream/kerf of a hi-speed tip makes less slag and the LP sheds easier. An ease on pierce (were the cut oxy pressure ramps to the top psi) can help too.

A longer pre-heat cycle may help too. If the stream cannot get through the plate quickly, then it will start to spread which creates excessive slag topside slag and a wider pierce hole, creating the need for a longer lead-in. It is hard to tell exactly what is happening. Is this a new problem or one that only happens on this part and thickness.

http://www.cnczone.com/forums/cnc_pl...iscussion.html

Some good info here

WSS

edit: I should add that LP has (at least) one downside and that is an increased pre-heat cycle. It may take 50 to 100% longer pre-heat times if you do not have a hi/lo system.