Cutting tip

[owhite]

I was using my laser to cut the thickest metal that I've cut before and encountered some problems. The attached pic shows the results where there are a number of pits that form because the laser just wasnt penetrating the metal.

I tried some other test cuts. The behavior of the system was really sporadic. Sometimes it would cut the complete part, other times it wouldnt. A lot of times it would look like the laser would splash out some metal, but just not make it all the way through.

I was musing over the situation and first wondered "hm, I wonder if the laser just isnt warmed up?" But that didnt make sense, at least I hadnt seen that happening ever before. And there were the cases where it would cut the thick stuff fine, but then it would fail again. Then I said to myself:

"hm, I wonder if the _part_ isnt warmed up?"

The laser has a tough job getting through the metal, its gotta a short period of time to heat up a little microspot, poke on through, and then participate in a continuous cut. If heat was getting transferred away from that cut point, then I could imagine the cut just wouldnt happen.

So I broke out the propane torch, warmed over the metal, and flopped it on the cutting table. It worked like a champ. No pitting, cut cleanly through at every point, and behaved flawlessly the way the laser works with thinner metal.

I think I was getting sporadic results before because in some cases the laser was warming the general area but didnt make a good cut, but when I'd cut another part nearby it was warmed enough to get a good cut.

I'll try some more tests but I think its the temperature of the metal. It doesnt have to get heated up much, but it makes me wonder if I could get even thicker with more heating.

owen

[CNCadmin]

How many watts is your laser?

[owhite]

The total delivery of power integrated over time is 100 watts. According to the manual, they claim that by peaking the delivery over short bursts that it actually develops intermittant delivery of 250 watts. I dont claim to know if its really doing that -- I do know that other lasers (e.g., YAG) also work on the principle of quick bursts that deliver much higher power.

[Romos V.]

What kind of metal and what thickness ?

Romos

[owhite]

16ga carbon steel which is 0.0673 inch or 1.71 mm. I know that you have reported cutting thicker metal, but this is the thickest I've done so far. I have some 16ga stainless steel that I am looking forward to trying.

Romos, what do you think? Have you ever noticed a relationship between cut quality, and the temperature of the steel that you are cutting?

owen

[owhite]

The other observation I want to report is that if I am starting to try setting the g-codes so the laser starts but does not move and does not turn on the oxygen. This results in it heating the area a little bit first. Then when the oxygen goes on, it seems like it results in a smaller splash area of molten metal when the laser first pierces the metal.

owen

[Romos V.]

I don't know if cut quality is better when the metal have some temperature, because usually I cut stainless steel letters 1mm thickness for sign makers.

Romos