Cutting Hast X on Mitsi LZP

[2lmaker]

Hello All,

I'm new to the laser end of things, but I was just put in charge of our laser dept. and I hope you may be able to help. My immediate problem is that we have a machine that will not behave. We are cutting 3/16 Hast X on an older Mitsi LZP and have it running full power with the focus .350 below the surface of the matl to get a dross free cut, and the same cutting conditions will not get the same quality of cut in the same sheet 2 days later. We are trying for .001/side taper or less and some days I just beat my head against a wall trying to hold tight tolerences.
Also can you suggest a good reference book?
Thank You
Mark

 

[msandoval]

No matter what you do you are going to get taper in lasercutting. The only thing to minimize would be to use the proper focus lens (7.5" Focus Lens in this case) and try to put the focus at least 1/2 to 2/3 material thickness.

Lasercutting has a lot of variables which have been minimized with newer machine and laser technology. Has anybody changed the cutting conditions in the machine?

I would suggest

a) to look at the cutting lens and see if it has any damages. Get a set of circular polarizing mirrors. Put one in front and one in back of the cutting, check it against light and see if the lens has stress fractures (it will look like a cross).

b) Check your external optics for alignment and also cleaning/replacement if needed

c) Check for leaks inside the resonator although this would be a task for a capable maintenance guy or a service technician from the OEM itself. The mode of the laser may be changing due to contamination.

d) Maybe internal optics relacement? How many hours in the current set of internal optics?

Advise

 

[2lmaker]

hi msandoval,

Thanks for the response. I will do my best to answer you questions.
First, the 7.5" lens is new, hopefully not bad.
Second, our maint. guys check alignment and do a calorimeter check monthly at a minimum
As far as internal optics or leaks inside the resonator, are there any indicators that might be obvious to me externally if there is a problem. I do not fully trust the maintenance department to do everything necessary to keep me up and running.
The last time they did PM on our 5-axis YAG it took 3 days and we still had problems. I realize that these will never be "put on the part and push the green button" machines as my boss would like, but every time they do maint. they cause a new set of problems.

Thanks Again, Mark

 

[msandoval]

Mark,

There should be a procedure to check for leaks in the resonator. Almost every single OEM today has a "Leak Test" function to check vacuum and leaks.

Some do an acrylic mode burn or mode shot using an acrylic block, warming up the optics for a specific amount of time and then shooting the beam and analyzing it for its roundness and elongation. If the mode shot is too sharp, then the beam is pre-focusing before it even gets to the cutting lens and killing lenses quickly.

You can also put a "power puck or power meter" at the cutting head without the lens and see how much output you are actually getting.

I would certainly contact the Service Department for tips and pointers with your problem. After all, this is why you bought the machine and therefore you are entitled to service and technical support.

Good luck in your search