Laser Cutting in A Vacuum


#1

I will start with I have never owned a laser printer (the GF will be the first) and don’t have a degree in physics  but was trying to determine if there is a way to get around the difficulties of cutting materials that are highly reflective and have a high heat transfer coefficient. Instead of increasing the amount of power why not just put the material in a vacuum when cutting it. If in a vacuum wouldn’t the material have no way to dissipate heat making the laser that much more efficient at cutting?


#2

I cant answer exactly, as Im not 100% sure on some of these things, but heres what came to mind:

  • The material will still transfer heat within itself, as well as to the grating it sits on
  • The laser tube may be negatively affected by the pressure difference
  • Reflective materials will still be reflective in a vacuum
  • Its gonna be expensive to put this in a vacuum

If you want to try it out and let us know however, Im definitely interested in finding out what kind of results you get!


#3

Pretty much what @takitus said.


#4

You can take care of heat transfer between touching objects by setting them on something with a very low heat transfer like graphite. I did think about the tube in that I don’t know what is inside of it. If the inside of the glass tube is at sea level pressure than putting it in a vacuum will cause roughly 13 pounds per square inch of weight which may rupture it.


#5

Having something in a “vacuum” is a very relative term. To remove enough atmosphere to make convection irrelevant would require a major redesign. My guess, which is completely baseless with no literature or calculations to back it up, is you would need to get into the millitorr range (1 millitorr = 0.000019psi or 0.00000013 MPa). On top of that, you will still be transferring heat via conduction and radiation, which still happens in a vacuum. The other thing you would have to consider is that when you are cutting the material, you are releasing gasses, which would then effectively negate your effects of having the vacuum.

Well, now that I’ve been a Negative Nancy, I have to say I’m not exactly sure what would happen. It might still allow for a better cut. I’ve also been curious about laser cutting in an inert gas, such as SF6. The plus side to SF6 is its heavier than air and seems like it would be super fun to play with (Youtube Videos). The down side to SF6 is it can degrade to Hydrofluoric Acid, which is really really nasty!


#6

Let’s send a Glowforge to the International Space Station! Not mine though. :smile:


#7

I wish! I have some connections to folks who are working on ISS experiments, but I think laser cutters are a bit too ‘dirty’ (in the fumes they generate) and bulky for work in space.


#8

The primary issue you would have with metals is the heat conduction.

  1. Radiative heat transfer in metals is pretty hearty. You could treat the surface to minimize this effect.
  2. You need some kind of physical contact with something, and so will have conductive heat transfer away. You can make sure the thing you are sitting on is an insanely amazing thermal insulator and minimize this.
  3. You need to fork out the incredible energy required to hit ultra-high vacuum to completely kill convection, as stated.

But these are all overshadowed by the fact that metals themselves are great thermal conductors, which means that any energy input will distribute rather equally through the material. So if you get one part so warm it evaporates, the rest is at least warm enough to melt.

The issue of the tube itself rupturing if placed in vacuum is an interesting thing worth noting. But since you can make windows for CO2 lasers to pass through, you could contain the vacuum only around your cut target, and not the tube at all.

I have got someone working on laser pyrolysis here in my lab. He noticed that the char on the side of cut wood is a very useful byproduct when making bio-fuels, and so is trying to use a laser to evaporate wood (in oxygen deprivation, which for us is going to be a nitrogen blanket, as that is cheaper than UHV) straight to natural gas and bio oil (with minimal char and ash as well)

So… vacuum does change how lasers effect materials. But not quite as you are hoping.


#9

Well, to test the vacuum theory you would have to tether it outside the door anyway! Do they have power outlets out there?


#10

I wonder about using Argon. I used to work in the window business and that is what they use to insulate glass layers. I have also used it SCUBA diving. You pump it into a dry suit to provided a non-conductive layer between you and the water.


#11

I asked a friend of mine who’s chief scientist at a remarkable cleantech company about her advice. First thing she said was, “You should put the whole thing in a vacuum!”

So I can’t say it’s a practical suggestion, but it’s not a bad one. : )


#12

So what I am getting from this is we need to crowdsource some money to send a few units over to a company with a huge vacuum camber. All in the name of science of course. Might not be a bad way to get rid of a few of the defective beta units…


#13

so… not Laser-Powered Vacuum-Cleaners which vaporize dust?
:stuck_out_tongue_closed_eyes:


#14

It’s funny she mentioned that; it is the first thing I thought of. Figured why not make a Lexam enclosure, hook up the vacuum pump I have and see what happens…lol. More of a pipe dream as I won’t be sticking my Glowforge in a vacuum but I like talking hypotheticals. Good for exercising the mind.


#15

Okay, so we go to these guys, put the glowforge with button aligned under the bowling ball… and we are good! :stuck_out_tongue:


#16

That’s so freaking cool @jacobturner !!! :+1:


#17

I had no idea there was a vaccuum chamber that large anywhere! Great find!


#18

Unfortunately cooling in a vacuum is challenging.


#19

Hence why it needs to be tethered outside the space station. It’s cold already and vacuum.


#20

Being cold, and cooling. Two very different things :smile:

To cool something that is hot, you need physical contact with something else. Convection is what you lose in a vacuum, which requires that the particles of air (or liquid) contact the surface and move away.

So yes… space is cold. But it isn’t a freezer.