Laser tube discharges in a spark

[buc]

Hello,

we are cutting with some cheap china lasers of 100 and 80W in an 8 h shift. Recently, there was aproblem, when one of the lasers started to discharge sparks (like a light arch) at the backend of the tube very strong and continously between the wire and the machine housing.
After changing the tube the problem disappeared, but the cutting power seems not to be the same anymore.
Today it happened also to another machine, where the tube is about 3,5 months old (aprox. 500h working hours).
Here is the question:
Is it the tube that wears off and starts to discharge in that way?
Is the laser power supply damaged?
Anyone out there who experienced a similar problem and resolved it?

Thanks a lot and keep up the good cutting.

buc

[zax15uk]

This is usually caused when the HV insulation around the terminal breaks down.

In most cases the tube is ok, and providing you do not continue to run the machine like this the PSU should be undamaged too.

Zax.

[buc]

Thanks for replying Zax,

it started to burn after replacing the insulation, first there was quite a sharp sound of discharging, after it appeared a flame.

What do you think? Should we use a even bigger insulation or can something else be the cause?

Thanks and regards,

buc

[zax15uk]

It sounds like your insulation may not have been rated for the HV of laser tube. You should only use the thick HV electrical tape or HV caulk, commonly used in neon signs.

Zax.

[buc]

Hello Zax,

we did use this time insulation tape for high voltage. For a second, the laser emitted regularely, now there appears just a violet light at the backend inside, combined with a sizzling noise and the laser does not emit at all...

Sounds very weird, anyone any further experiences with those issues?

Thanks at all,

buc

[shane@lazer-me]

we had a discarge problem with ower 3040 all we did was cut 2" of the water pipe split it down its lenth an slid it oner the wire whare it sparking
shane

[avetek]

When I first bought my machine it did exactly this - we traced the problem to a cracked tube (some thoughtful chinese individual thought he could fix it with some epoxy before it was sent) - we replaced the tube and away it went - I can only assume the tube leaked the CO2 gas it had in it and therefore it would no longer excite the appropriate bits causing the discharge I saw.

[buc]

Thanks for your replies..

Indeed, the tube cracked inside. As the cooling water level was suddenly too low, it overheated somehow at the anode, cracking the tube and building up overtension.

At least, this sounds like a reasonable explanation

And after having the tubes changed, everything works just fine ( one tube was broken already by transport.. seems to happen quite often)

buc