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Thread: Optimal CO2 laser temperature?

  1. #1
    Join Date
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    Default Optimal CO2 laser temperature?

    So, now that my laser cutter is up and running, I've started to notice the effect of water temperature on laser output. More specifically, at one stage the water loop developed a leak, and the laser was running very warm, and the power drop was quite significant.

    I haven't really been able to find what the optimal operating temp range for a sealed CO2 laser is?

    I have a 240mm radiator in the cooling loop, however if it prefers running at lower temps (Say, below 30C ish), I do have a water chiller I could adapt. My question is, would using the chiller be worth it in terms of either lifetime, beam specs or output power?

    Cheers,
    Dan

  2. #2
    Join Date
    Apr 2012
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    Chinese tube?

    We had a 80 watt chinese machine and I think the chiller was set to somewhere around 15c.

  3. #3
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    I've herd That around 15 to 20 , maybe to 25 C is ok , one thing with co2 tubes is as the temprature goes up power can drop rather steeply .

  4. #4
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    I think anything at room temp or lower is fine. My guess temp rise increases tube pressure enough to change the discharge characteristics.

  5. #5
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    Problem is, where I live, room temp is basically always over 30C, sometimes probably more like 40C then add the laser temp rise. I think I'm going to have to use my little chiller, or find another one to put in series with it for more cooling capacity. I found the other day my laser was being way overdriven, so my little chiller might have a hope of keeping up with it yet.

  6. #6
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    It is pretty easy to overdrive the chinese tubes. The software is never set so that the max power setting is the tube limit. They just run the PWM 100% which is usually too much for the tube.

  7. #7
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    Yeah, I've built this entire unit myself, but only bothered getting a current meter the other day. Was shocked to find out it was being driven at around 29ma, which is insane!

    Dropped it to a much more reasonable max of around 14mA. I'm assuming I didn't actually get any performance increase from the huge overdriving, just increased heat output and a few hours off my tube life.

  8. #8
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    Dec 2008
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    Good to see its going ok again , Wow that is abit over the normal current .

    One reason temprature rise affets power so much is , as the tube heats up less energy is removed from the helium atoms , thus the nitrogen carnt give the left over energy they have from giving it to the co2 atoms , to the helium . So the nitrogen carnt drop to normal energy state and start over by getting exscited by the HV discharge . the hotter the tube the less the process happens thus power drops right off :P .

  9. #9
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    Just tried again with the tube current limited to 18mA, and I seem to have gained a little more power. Before I needed 2mm/s at 100% power to cut through 5mm acrylic reliably, now at 2mm/s and 100% power it cuts thru fast enough to roast the MDF bed I have underneath. Still, not a huge increase, but I'm probably expecting too much from a 40W laser.

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