Here We Go Again...

[Dana Johnson]

Adrian,

It may be due to the alloy makeup. Like nickel silver, brass has a lot of copper in it and copper is extremely good at ducting heat. For that reason laser cutting places here would not cut anything with copper in it 10 years ago. Now they do and I imagine it is because they have greater power available. Perhaps that greater power/heat leaves more puddling around the cut? Only conjecture, let us know if you get a defiinitive explanation.

It is not so much a question of the rate of heat conduction, though they may have explained it that way, but the ability of the alloy to absorb the laser frequencies used, which for most high power cutting lasers ( generally CO2 lasers ) is in the infrared. Copper is the best reflector of infrared ( close to 100%) of the practically available elements. ( Used for infrared mirrors in telescopes ). It isn't that it can't be laser cut, it just takes a different frequency of light the metal is happy to absorb rather than reflect to be effective. Solid state lasers like YAG lasers cut copper alloys nicely as well as cutting silver which is an even better conductor. These lasers are generally more expensive and are only now becoming common in your average laser cutting establishment. The great advantage of lasers in cutting is that the energy density at the cut can be incredibly high, melting or even vaporizing material ( laser engraving ) at the cut before the heat has been able to affect the surrounding metal. Just about every cutting method has it's limitations, but where they work, lasers are hard to beat.

[adrian brown]

 

Adrian,

It may be due to the alloy makeup. Like nickel silver, brass has a lot of copper in it and copper is extremely good at ducting heat. For that reason laser cutting places here would not cut anything with copper in it 10 years ago. Now they do and I imagine it is because they have greater power available. Perhaps that greater power/heat leaves more puddling around the cut? Only conjecture, let us know if you get a defiinitive explanation.

It is not so much a question of the rate of heat conduction, though they may have explained it that way, but the ability of the alloy to absorb the laser frequencies used, which for most high power cutting lasers ( generally CO2 lasers ) is in the infrared. Copper is the best reflector of infrared ( close to 100%) of the practically available elements. ( Used for infrared mirrors in telescopes ). It isn't that it can't be laser cut, it just takes a different frequency of light the metal is happy to absorb rather than reflect to be effective. Solid state lasers like YAG lasers cut copper alloys nicely as well as cutting silver which is an even better conductor. These lasers are generally more expensive and are only now becoming common in your average laser cutting establishment. The great advantage of lasers in cutting is that the energy density at the cut can be incredibly high, melting or even vaporizing material ( laser engraving ) at the cut before the heat has been able to affect the surrounding metal. Just about every cutting method has it's limitations, but where they work, lasers are hard to beat.

 

I guessed there must be more to it than I'd realised, so thanks for the explanations. I've just ordered a couple of further pieces from a company here in the Netherlands and it'll be interesting to compare the surface finish (They're a bit more expensive than the Swedish company)

 

Adrian

[Dana Johnson]

I looked into water jet cutting back when I was looking into lasers. For metal, they use a water / abrasive mix the only drawback I could see was the .040 inch minimum kerf. I wanted sharper corners than that. One nice feature is that the upper edge of the cut ( the one the water reaches first ) is slightly rounded which is very helpful when polishing, giving a nice broken edge. I have seen a set of water jet cut brass reed shoes that came out quite nice. May be cheaper than laser cutting. It was when I first enquired, but that was when the laser guys told me the price was so high ($75/end) because of the power they'd need to cut the Nickel Silver with their CO2 lasers 20 years ago.

Dana