Re:How I Got My Laser Eye Injury
by convolvatron on Thursday August 01, 2024 @11:42AM
(#41130375)
I tig. wear a helmet and have to buy argon every year. this seems like a huge hassle in comparison. is there that big a difference in quality and or range of processes that make it worth it?
its the operator skill part when dealing with thin sheet metal. It just works better / easier / faster for thin stuff, where in TIG, that's the high-skill work that everyone pays big bucks for.
Agree with the post above, though. The safety setup for lasers is basically full isolation.
Re:How I Got My Laser Eye Injury
by convolvatron on Thursday August 01, 2024 @01:01PM
(#41131199)
seems like its more cost effective to just stay on or above 20ga unless you're really high volume or you really need the weight savings
I know one of the reasons we wanted pico-second and shorter pulsed lasers is that they can cut material with little to no damage of the neighboring material. There was a demo that I read about when this was all brand spanking new research, where they claimed that a laser scalpel causes no heat damage to tissue outside of a cell’s breadth from the contact point.
That's how LASIC and PRK work, after all!
Re:How I Got My Laser Eye Injury
by justinclift on Thursday August 01, 2024 @09:53PM
(#41135469)
Re:How I Got My Laser Eye Injury
by eaglefield on Friday August 02, 2024 @07:23AM
(#41137894)
It's related, but as i recall the reason that short pulses cut better has to do with heat transfer. Most heat transfer in metal is due to the vibration in the electrons, being much lighter than the atomic lattice they move in. Very short pulses, means that the heating in the beam path happens faster, than the electrons can transfer it out to the rest of the metal. In long pulses once the metal is vaporised, a lot of the surrounding material has melted. This molten metal cools into jagged structures and that leaves the edge weird. All this doesn't happen if the pulse is short enough. It vaporises metal before the surrounding structure has a chance to heat up.
Here's a figure showing the quite stark difference. https://www.researchgate.net/figure/SEM-image-of-the-substra...
Re:How I Got My Laser Eye Injury
by justinclift on Friday August 02, 2024 @07:42AM
(#41138001)
Awesome, those photos do illustrate the difference really well.
Thanks heaps. :)
Re:How I Got My Laser Eye Injury
by eaglefield on Friday August 02, 2024 @07:09AM
(#41137828)
Here's a figure comparing the hole left in a metal surface with normal and femto-second pulses. The difference is quite stark.
https://www.researchgate.net/figure/SEM-image-of-the-substra...
If you can't do this, you do need to panel or curtain the ceiling or use laser absorption coating or other things.
There are places that also just use reflection sensors that detect reflection on the ceiling and trigger (again, machines already support handling this). I have heard this works very well but have no direct experience with it.
All that said, reflection off ceiling is more uncommon for practical reasons (The angle at which you hold the gun to the piece, the fact that ceiling directed angles often become back reflection into the gun which it already detects, etc).
They already detect very high reflection as well.
For a makerspace, one of the issues you will have is that people will likely want to try to weld copper and aluminum a lot, both of which are highly IR reflective.
If you said "You can only weld steel and iron" you would eliminate a very high percent of reflection in the first place.
Here's a basic chart that looks right: https://www.researchgate.net/profile/Tomasz-Kurzynowski/publ...
For a 1064nm laser, you can see Al or Cu is going to reflect a lot of the energy, while steel/iron are still off the graph high in absorption