Lost of power on our Reci W6 tube?

Community Laser Talk
1

Hi,

We have two laser tube one our machine:

  • one 150W Reci W6 (called laser 2)
  • one 50/60W no-name chinese laser brand (called laser 1).

Recently we saw a lost of power on our 150W Reci tube… we were not able to cut as much as before. We though it was alignment / bad lens / old mirrors so we replace everything:

  • new GaAs mirror
  • we did try a GaAs lens
  • we did do a perfect alignment of all three mirrors.

However results are quite poor still. For instance with our 50W/60W laser we are able to cut plywood 4mm at 20mm/s at 80% power.

Today we did make some test we used to do before to compare with the 150W laser and we got strange results:

image
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For example on the left it was test made 2 or 3 years ago when we got the machine. Today it was some tests made … the strange thing is that it seems to cut well between 30% and 75%/80% but nearly nothing at 90%. I checked the amperemeter at the same time and it appears taht it seems correct. We have approx 17mA at 50% while 35mA at 90%.

We did reproduce this strange phénomena with various lens and various thickness… for example on 10 mm plywood:

image
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  1. We are wondering if our 150W tube is dying and if should aim at replacing it or if we can fix this issue.

  2. How can we explain this phenomena ?

  3. Does somebody has a link to do advancerd checking on laser tube ?

  4. What are reasonable setting for 4mm , 6mm, 10mm plywood for a 150W laser tube. Which speed should we aim at ?

Best regards

2

If you have

  1. properly working tube
  2. aligned and clean optics
  3. proper focus

It will work, so one of these is having a problem.

A proper alignment should start at m1 (mirror 1) examining the beam quality from the source (tube). This should resonate in TEM00 mode or it never will align properly.

I cut targets out of watercolor paper so I can press fit them into the mirror holders.

target-sheet-crop-tube
target-sheet-crop-tube1920×997 121 KB

The burn mark needs to be light enough to see the Gaussian power distribution curve across the beam. A picture of a hole is of little use. Generally lighter is more informative than darker.

Here is the curve … it should have more power in the center… you should be able to get a good cross section on your target.

The-distribution-Gaussian-of-laser-beam-profile-nb

We might not think of this as machining, but it is in the sense we are removing material by some type of tool… Both additive and substantive machining can do the job at a great variety of values, known as speed/feeds, however there is a small area of these values that works best with that tool and material. Meaning less energy, tool/machine wear and better results of the end product. I’m sure you’ve seen this.

For metal or man made materials cutting with spindles and bits you can compute the speeds/feeds for that item… When using naturally made materials and lasers it’s not so simple because we don’t have sufficient data on either the tool or the material. We can only control with accuracy the feed rate.

Speed usually relates to the tool spindle, with lasers it more like percent power and feed is how fast the material/head move by each other.

What I try to do is run at the maximum comfortable power at the fastest speed that will do the job.

This seems to give the best results for me and it what I commonly do.

I’d love to just be able to tell you the sweet spot, but alas I cannot. :cry:

Does any of this make sense?

The Reci is a good tube, a grade A Reci, if that’s what you have … I’d expect 5 years (10K hours) of commercial use before a failure… There are lots of variable here, but your symptoms look like the tube is going south.

Good luck

:smiley_cat:

1 Like
3

Hi
Thank you for your reply.
I did not really understand your explanation about TEM0. We should see a dot or a cross ? At which pulse power do you do the test ? Because results in our case depends on the power we ask from the tube.
Unfortunately watercolor paper will not result the 150W power of the tube.

" What I try to do is run at the maximum comfortable power at the fastest speed that will do the job." What do you call the maximum " comfortable" power ? In my case I consider running the tube at 80% and then I go as fast as I can to cut … but what is strange in our case since recently is that it behaves / cuts better at 50% than 80% … like if their was too much loss of power at high power.

In the case of our Reci tube, we have it since more or less 3 years , and it is hard to tell because there is another laser tube on the machine but it seems the machine did not run more than 1000 hours.

4

For the lasing to occur the tube has to be at resonance to properly lase. If these fields change, the beam is no longer powerful in the center with the power getting less to the outer edge.

This is my tube going south… you can see the power is mostly on the right and there is no power in the lower center.

tem-failure-crop-target
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I had cut some thick acrylic and I always run through an alignment before the job. That was a Friday and it was aligned in < 5 minutes. The m1 target was dead center and looked perfect.

Tuesday morning, it acted up, the target is as you see, it went from great to bad in three days of no use…? Even moving the beam off center that close to the tube.

I had to keep aligning it until the new tube arrived. It was so far off it started hitting the nozzle on the way out… at the best alignment point…

It probably would if you find the lowest consistent lase percentage and set the Ruida to pulse for a very short duration. You can always stick a 2X4 in there … You will have to figure out how to do this, one way or the other…

Let us know how you make out…

:smiley_cat:

5

Ok so we replaced tube with a GSI HLC130B and it seems fine after.

6

Thanks for posting you had success…

Which one of the posts would you say solved your issue?

Thanks

:smile_cat:

7

Your first post with your 1 / 2 / 3 rule !