Laser Tube Failure

I have a Chinese Red and Black 80W machine and I have had it since May of this year, so here is my issue. I have already had to put a new tube in the machine due to the one the machine came with going bad. So the second tube that I purchased was a Yongli 80W tube. We installed the tube and had nothing but issues from the beginning. The tube maybe lasted 20 hours, it is hooked up to a Zye 80W power supply. It was tuned to 21 MA which is what Yongli recommends. I was having issues with the cut through and we started to look further into the machine to see what was going on. The tube started making arcing noises and come to find out that the lense in the tube was all of a sudden cracked and burned. I am just wondering what could cause this? The machine is hooked up to a 5200 industrial chiller which is working just fine and filled with distilled water.

The lens on the laser tube is susceptible to failure from contamination of the surface from the lack of or inadequate fume extraction.

Similar to the reflecting mirrors and focus lens, when these surfaces collect residue, the film Of this contamination absorbs the energy eventually causing failure.

Other possibilities:

  • unintentional overdriven tube (understanding you have made adjustments to limit the mA output to 21). There are many questions to understand if the tube could still be accidentally over driven e.g., do you have an in line ammeter, have you calibrated the laser PSU’s trim pot, are you using an analog or PWM signal to the laser PSU, have you made changes to the PWM frequency, etc.

  • new old stock laser tubes are being used. See if you can find a date of manufacture on the laser tube. (Never mind, I see the date on the picture).

  • counterfeit laser tube. (Not entirely impossible).

Also, you had a premature failed laser tube and, by your description, had nothing but problems from the moment you put a new replacement in. This indicates a very high possibility of a faulty Laser PSU or some other component rather than the actual tube itself. You may have a problem, for example, with the laser PSU that is killing the tubes.

Hello Jeff

We have had no real fume extraction issue in the past. we have a 450CFM turbine fan that pulls from the machine. Are mirror and lens seem to be very clean even when we do are weekly cleaning to them.

I had adjusted the trim pot to 21ma at 100% power just as Yongli recommends. it is run by a Topwisdom controller so I dont know what the signal it receives would be. I am not very familiar with the electronics side yet. I have not made any adjustments to the PWM frequency.

We do have a digital ammeter installed but I am starting to not trust it. I have ordered a analog to replace it.

We ordered the tube from Cloudray so I would assume it is not counterfeit. I have contacted them about the premature failure as well.

I have ordered a new power supply along with another 80w tube from Cloudray. Is there anything I could have missed when I installed it the first time that could have caused this failure.

Are second machine will be delivered tomorrow it has a 100w Reci tube and is run by a Ruidi controller. I am hoping we have less trouble with that machine. I have learned a lot over the past few months and did a lot more research this time before buying.

Only other thing I could throw in would be what you are working on or the surface under being too reflective. I would think it would take out the lens, but I’m not a laser expert by any means. It’s just a WAG.

So far all we have cut is 3mm plywood on a honeycomb bed

Ah well, like I said, it was a WAG.

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