Focal lens and gas pressure

[JeanFreli]

I am using a fiberlaser and I often cut stainless steel.From what I read the focal lens can take hight pressure gas. Nitrogene is used for that. The guys who sold that machine told me always used high pressure with fiberlaser. Example: 11ga at 18bar, 12ga he put 20bar, .250 at 22bar. I have great result with lower pressure. Actually my cut are much better then his. he had a slice or dross mine is like the top of the cut. I cut the gas consumption a lot. My question is; do I dammage my focal lens faster if i use less pressure? I change the focal lens every 2 or 3 months.How long usually the focal lens last?
Thanks

 

[tstc]

From what i understand, the fiber lasers produce a small kerf so higher gas pressures are needed.
And probably due to the high absorptivity, too much heat means boiling the material rather than melting...
Does your fiber laser have a lens protection window? If so, i cant see using a lower pressure causing any damage to the lens.
Unless the cut is lost and back reflection occurs... but i would assume the fiber modules detect this and shut down.

 

[JeanFreli]

Yes I have a protection lens before the focal lens ( which is sealed). I test the piece just after the cut and it is not hot like abnormal. I am very happy with your answer. Now do you have an average about the life of the focal lens? I mean not been destroy by the back reflexion but just ready to send cleaning.
Thanks

 

[lasermate]

Lens life is very hard to judge. There are to many variables to say for sure how long a lens will last. Material, operator, environment, maintenance, time and such.

 

[LaserSpyder]

2-3 months before you switch but how often do you use your laser? we switch out ours about every 2 monthe but we run 3 shifts so the laser runs for 5 days straight and the operator has ALOT!! to do with it

 

[JeanFreli]

I understand that a lens life is hard to gage due to too many factors.I took note of the date we change them since 9 months. Of course I did so many mistakes when I start that I have to erase some of the stats.It is the third weeks we put a new one and still doing good. Except today adventure I tell you later. The lens before was about two months and I was working almost seven days a week. Between 10 to 16 hours a day. As I go I learn more and the experience is coming so I expect a little bit more time for the lens. At least (like laserspider say) I have an average of experienced peoples.
Today I tought I lost the lens again. It wasn't that. The guy in charge of ordering stuff gave me a couple of protective lens and new nozzles to try. I imagine for saving more and more money for the company. So we are friday and since monday afternoon I install the new protective lens. Well this morning giant burrs suddenly appeared on a thickness I usually have no problems. After different checks everywhere from nozzle to parameters I decide to clean the protective lens. As I undo it I saw the lens yellow. I compare with a new one (which are the real lens I'm suppose to use) and it was clear. I install the new protective lens and bang....perfect cut. I don't know why it become yellow but for sure it masked the power of the focal lens.
Well thanks a lot to all of you people who read and answer. It is the best site I found for learning more and more on laser. You help a lot.
Happy thanksgiving