CO2 Laser Marking

[outlawjj]

Company is looking at purchasing a laser marking machine. We deal with stainless steel parts (304,316, etc.). I am getting conflicting information from some laser manufacturers where most state that a metal marking compound is needed and others do not state that. Do I need to really use a metal marking compound with CO2 lasers? Or is that mainly for lower powered ones (say less than 50W) and when getting to the higher powers (100W) it is not needed?

Or would looking at Fiber laser systems be better?

 

[RPosty]

Personally, I would get an ND/Yag or fiber laser if all you are going to do is mark metals. CO2 are better at Plastics, Wood, etc. You will not need a marking compound with The Yag or Fiber. Beam is Much smaller too, so it can do much more detailed work. Only Problem with Yags is they like to run everyday, if you are only using it once or twice a month it will give you problems because the water that cools the flash lamps lose resistance and shorts the lamps life considerably. If used weekly, the water is being cycled through the deionizer resin keeping it nice and healthy.

"I am stuck on Band-Aid brand, 'cause they are stuck on me"

 

[tstc]

A CO2 laser with abit of power, <100watts, will mark stainless steel provided Oxygen assist gas is used.
Laser marking onto stainless, without a marking compound, is oxidizing the surface. <= a process called annealing. (As opposed to engraving, which is removal of the material)
You are basically drawing the carbon in the stainless to the surface, creating contrast. Therefore the resultant mark is prone to rusting if left bare.
Always consider the end use your products before making the decision. It may be that a marking compound will be the better choice.

And although RPosty is on the right track, a 'good' Nd:YAG laser marker will have a closed loop water circuit (not allowing air entry) and will have a deionizing filter with conductivity measuring circuit to prevent flash lamp from firing until the water conductivity falls within preset levels. It will take longer the more the machine has sat idle.
But you should be flushing at least yearly. (same for anything with a flush button. )

Go fiber, galvo system if mark size is small enough, xy if not. (or a combo system)
Small, no chiller, low power requirement, plug into wall, usb or ethernet/wifi to pc, and away you go.

 

[RPosty]

I have worked on a lot of ND:Yags, JK 700 series, Luxtars, AB Baasals, Rofin, Raytheons, etc. I know for a fact if they are not used regularly that they will give you trouble. I have always assumed it was the water sitting, but it could be other things I suppose. CO2 Lasers on the other hand do not seem to care, I had one that was in a warehouse for 10 years, fired right up after a good cleaning and optics change. We had a wire marker in my ANG unit I worked at. It was a spectrum. We only need to use it like once a month, thing never worked right.

Worked with one Fiber (IPG), it was very nice. If your company can afford it, I would go with tstc's suggestion.

"I am stuck on Band-Aid brand, 'cause they are stuck on me"

 

[outlawjj]

I was leaning towards a fiber laser mainly for process ease, but CO2 is a little cheaper and was wondering if there was a way past the marking compound. Looking at the couple thousand delta, seems like the fiber would be the way to go. Thanks for the information.

 

[MacGyverS2000]

tstc has it already. You can mark bare steel with a CO2, but you have to go incredibly slow (think a couple of percent max speed for a typical western machine, e.g., Epilog, ULS, Trotec, etc.) and you'll really want a high-density focal lens (1 mil focal point). It's passable for prototyping when you have time to kill, but it would never fly (no pun intended) in a production environment.

Fiber bypasses all of the issues mentioned earlier about YAG, and for marking you don't need much power (10-20W should be fine for most applications)... if you need to get a deep etch, you'll want to bump the power up. For small marks (e.g., a few inches in diameter), a galvo will be the best ROI timewise. For large marks, a flatbed is usually the best bet.

Dan - Owner

http://www.Hi-TecDesigns.com