How strong laser do I need for engraving and cutting?

[Eriksen]

How strong laser do I need to engrave and cut knife blades? Can it be sufficient with a 45 w laser? I want to engrave deep enough to fill with brass.

 

[F. Allin Kahrl]

A commercial 1.5kW (that's 1500 watts) laser is not really powerful enough to cut 1/8" brass. You have to understand that copper-based alloys (like brass) and aluminum conduct heat away from the cut so fast that the laser can't build up enough energy to burn the material away.

I did the research for my company recently on getting a CNC laser to cut parts out of tool steel. What I basically found out was that a 1.5kW machine would cost $350,000, would barely handle 1/8" tool steel and would never cut brass satisfactorily.

If I were you, I'd look into a small milling machine like this:

http://www.sherline.com/mills.htm

I have one and it's great.

-Allin

 

[adammichael]

A commercial 1.5kW (that's 1500 watts) laser is not really powerful enough to cut 1/8" brass. You have to understand that copper-based alloys (like brass) and aluminum conduct heat away from the cut so fast that the laser can't build up enough energy to burn the material away.

I did the research for my company recently on getting a CNC laser to cut parts out of tool steel. What I basically found out was that a 1.5kW machine would cost $350,000, would barely handle 1/8" tool steel and would never cut brass satisfactorily.

If I were you, I'd look into a small milling machine like this:

http://www.sherline.com/mills.htm

I have one and it's great.

-Allin

Huh?

1500 wat lasers will cut 3/4" mild-tool steel, 1/4" aluminum 10 gage brass/bronze and I have personally cut 1/8" titanium with it. The problem with cutting copper is that it is very reflective and the laser bounces off the surface of the copper instead of cutting into it. The bend mirrors inside the laser that bounce the beam from the resonator through the lens to the tip is copper clad. The problems cutting copper can be overcome by edge cutting or putting some masking tape on the area where you will be piercing so the beam goes in instead of reflecting off.

I etch with 50 watts at 60% duty and 500Hz.

 

[Eriksen]

Is it possible to cover steel and brass with etching resistant coat and burn away areas that I want to etch with a laser? Are there any etching fluid that I can use for deep etching on damascus steel?

 

[F. Allin Kahrl]

1500 wat lasers will cut 3/4" mild-tool steel, 1/4" aluminum 10 gage brass/bronze and I have personally cut 1/8" titanium with it.

Oops. Guess I spoke out of turn. IIRC, Mazak only claims that their 1500W machines will cut 1/2" mild steel. We found mostly 1000W machines on the used market and nobody wanted to commit to saying that one of them would cleanly cut 1/4" A-2 at anything approaching production speeds.

I guess that doesn't really answer Eriksen's question, though. Sorry for creating confusion.

-Allin