Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


Parameter Changing

Parameter Changing

Parameter Changing

Hello all,

I have been running a Bystronic Bystar 3015 for a couple of years now and it has been a great machine, however. Since we have had the machine every now and again the cut quality will just go right out the window. I could be cutting a 4 sheet nest, I can have cut 2 sheets then after transfering the third sheet hit start and the parts will be stuck together like the focal length is wrong or it will plasma the top of the sheet. To rectify this problem I have had to do some major changes of parameters to get back to a quality cut. This could entail changing laser power, gas cutting pressure, focal and feed rate, or sometimes all 4. Then after a day or to it will just go south again still using the same params that were working fine. I would change the params back to what they were originally and it's back to normall for a month or 2. This could also just happen halfway through cutting a sheet as well not neccesarily after starting a new sheet. It has everyone here scratching there head when it happens. Service Tech puts it down to beam alignment but I can't see that being the problem as it can change back to old params.

To give you an idea of the changes I sometimes have to make

Normal params for 3mm SS After issue depending on how bad it is
LASER POWER 3600 Between 3000 - 4200
FEED RATE 4400 Between 3900 - 4800
GAS PRESSURE 12 Always up never down 15bar
FOCAL LENGTH 3.8 Between 2.9 - 6

It's so random

Anyone experienced anything like this before ???.
It's not a major issue if I catch it early and I have enough knowledge to fix this issue when it arises quite fast, but if I can stop it from happening in the first place that is more ideal.

Bystronic Bystar 3015
Year of Manufactor 2005
The machine orginally came from Germany and now is in Perth Western Australia. I'm wondering if that has something to do with it. I remember one Tech who came to service it said it was missing something or had something on it that was unusual until I told him it came from Germany. That will be why he said because of the extreme cold during there winter.

Cheers in advance for any advice.


RE: Parameter Changing

Could very possibly be a height regulation issue just a thought or an autofocus issue

RE: Parameter Changing

I was thinking that. I had to replaced the detect circut board in our 7.5 inch head which had an intermitent fault causing the head to rise about 30mm above the sheet. Might be a similar but different issue regaurding the same board. Might swap them over and see if it happens when it's in the 7.5 inch head. I don't use it as often as the 5 inch so would be a worth while change.

Cheers drossfree

RE: Parameter Changing

i dont know this machine myself. But could there be any problems with any connections cables to the head ?

As i said dont know the machine but. i have seen similar things and then it has been faulty wire to head or the connector on the head which could be faulty.

RE: Parameter Changing

Sorry I don't know your machine either I run amada fo3015 and previously ran Trumpf machines but was trying to point you in the right direction

RE: Parameter Changing

i work 10 years on lasers...

do you cut with or without folie,thats very important ...do you cut 304 or 316

for 3mm ss with pvc folie ;

nozzle height 0.7 mm
lens 5"
focus -2.5 to -3.0 or on bystronic 2.5 to 3.0
speed never over 4000 mm/min
power on ss always on 99% of the machine
nitrogen pressure from 10 to 13 bars....not more(you get counter effect)

without pvc little less pressure and more speed,lower focus

with 7,5" lens i dont recommend if you need top quality



RE: Parameter Changing

We had the same problem

1. Check if there is a rubber spacers next to your head. See photo below.
2. Check if your laser head clamps, clamp head firmly. We have changed those.
3. Ceramics in laser head can be broken or with cracks. I suggest to change it to new.
4. Check if O2/N2 filters are clean.(Next to intake gauges)
5. Couple of mirrors in resonator or along the path could be weared off, dues to age or bad cooling.

RE: Parameter Changing

What adjustments are you chasing the most? Does it have an adaptive optic? How are the filters that clean the air for the beam purge? Is the power stable?

Chris Krug http://krugtech.com/
Maximum Up-time, Minimum BS

RE: Parameter Changing

I've seen stressed output couplers on fanuc resonators do that as well as stressed lens. The symptom on the output coupler is at high demand like 3800-4000 watts power can't keep up and you see actual power drop a couple hundred watts over time. We will then set demand low enough that it won't drop like 3500 watts (lowering federate to compensate for less power). Then change output coupler at earliest convenience.

Not sure how bystronics work, but I imagine very similar.

"I am stuck on Band-Aid brand, 'cause they are stuck on me"

RE: Parameter Changing

Thanks for all the replies guys.

@ Maito
1. Check if there is a rubber spacers next to your head. See photo below. Yes
2. Check if your laser head clamps, clamp head firmly. We have changed those. Yes but havent changed them since we've had the machine. But head is tight and secure
3. Ceramics in laser head can be broken or with cracks. I suggest to change it to new. I'm vigilent with checking the ceramics when issues arise
4. Check if O2/N2 filters are clean.(Next to intake gauges) Service was done in Jan this year and all filters replaced
5. Couple of mirrors in resonator or along the path could be weared off, dues to age or bad cooling. All mirrors have been replaced within the last year including the $10.000 Bypos mirror

I have long suspected the head clamps may be an issue so thats my next change out. It only takes a fraction of movement at the head to throw the beam alignment out. Did you guys buy in new Bystronic parts or did you cut them in house ???. It's the intermitant nature of the problem that has me scratching my head.


All the filters are newish and replaced reguarly. The adjusting of params can range from just changing the focal length of the beam to having to change feed rate, focal, laser power and gas pressure in one go. The power is stable, I can watch it in realtime through the diagnostics tab while laser is cutting. No change in power when issue is there. What it always seems like is the beam alignment is out but when checking it, it is perfectly centered.

@ RPosty

Most of the working components have already been changed out. The output coupler and the Thermoplie both were changed only 3 months ago. The Thermopile was actually not working at all and we all thought yay that's been the issue all along as thats what sets and maintains the power output. But saddly no the problem still remains. The only working components yet to be changed are 3 of the 4 Exitation modules. We had one die which according to Bystronic is very rare. They say there good for 80,000 hours before problems may happen. Ours are only at 38,000 hours.

Thanks heaps for your input. The knowledge base on this site is invaluable.

If I finally nut this problem out and find the cause I will certainly be sharing it on here.

RE: Parameter Changing

When you change all these parameters, are you ever changing them back? What materials do you see this happen on the most? Where are you located?

Chris Krug http://krugtech.com/
Maximum Up-time, Minimum BS

RE: Parameter Changing

I always go back to close to the default setting when what I've changed the params to starts to cut badly. The machine seems to settle over time and get over what ever is causing it to
change in the first place. I have in the past just left it cutting badly as we have a 1500mm wide Linisher to knock the molten steel off and its gone back to cutting perfectly all on it's own without changing anything. Mostly cut Mild steel 316, 304 Stainless. I may go months without it happening, it could happen twice a day.
I am locacted in Perth Western Australia. Dry hot climate most of the time. The Machine origanally came from Germany which has a similar summer but much colder winter.

RE: Parameter Changing

To give you a visual on whats happening.
The first pic is the underside of 3mm Carbon steel as you can see it's a clean cut. No dross, no small beads. The type of cut quality we all want. The other pic is the other end of the same sheet with the same settings and look at it. In need of a hammer to get those parts apart then a clean up. Now the funny thing about this time is it is only happening at about 3/4 of the sheet. It has done this on the last 3 sheets cut but not the 4th. ( Insert, Bangs head against wall smiley here ). To look at that I would say it needs a nozzle alignment but the sheet before that point and after that point are as good as the fisrt pic.

It's got a new lence, new ceramics and the nozzle is centered. Can't see how it changes so dramaticly and only in that spot.

I tried adjusting the focal length as the cuts get to that part of the sheet and it cuts perfectly again but then returns to crap as the focal is out when it moves further over to the last quarter. So a quick change back and it's fine. So it looks like the focal length is changing with the moving of the bridge. But as I said above it's not doing it now. Might need to get our tech guy back out. Problem is it never does this when he's here. And we all know how hard it is to find an intermitent fault.

Thanks for the advice and help on this. I will keep it updated if I finally knock this Gremlin on the head.

RE: Parameter Changing

How many hours on machine?
Just thinking out loud. Is it possible that linear guides are wearied off at certain place? Maybe there is some other equipment or machinery running nearby which cause vibration? When you did beam alignment was it checked in all 4 corners? and beam circle is the same everywhere?

RE: Parameter Changing

Beam alignment was done about 2 months ago and yes all same. Although in saying that it will always be out in the furtherest corner from the reference point. Longest travel for the beam. The machine is a 2005 model but for it's age it's reletivly low on hours. Exitation modules are at 34,000 hours. According to Bystronic there good for 80,000 hours. So not even at half life yet.
No idea on the linear guides on the bridge though. The head guides where done recently as the bearings started to fall out. We will contact our Tech and see whats involved. Boss always likes to save money if we can do it ourselves.
I don't think vibration is an issue but I have long thought about an excessive power draw in the area from another business in the area at certain times. Hence the fact it happens intermitantly. Perhaps putting a strain on the power.

RE: Parameter Changing

if its only on a certain part of the sheet.
i would say mirrors should be checked, if they are not fasten properly. (or bad mirror)

RE: Parameter Changing

I use an amada FO3015 with a 160 controller and see the same problem very rarely now. I have also noticed that the AO mirror on my laser bounces from being flat to flexed over and over when it is happening. I was told that the regulator controlling the mirror is faulty. I was also told that, this would give me the intermittent problem. Mainly i notice this when I am also cutting with higher wattage. 3000-4000. My problems generally have only lasted a day or two at a time. I usually switch down to a thin material using far less power and a different lens for the remainder of the day. When i come back in the AM i try whatever wasn't cutting the night before and it usually cuts perfect again.

I know this isn't much help in solving your problem. But maybe we are experiencing similar issues and it seems everyone knows the FO3015 on here. Any further input would be greatly appreciated.

RE: Parameter Changing

When is cutting good check the chiller temp.
Also do a nozzle tape shot when you know the cut is good.
When it starts cutting bad check the chiller temp again (is it the same temp)
When it starts cutting bad quickly check the check the nozzle shot again with tape (compare the good & bad nozzle shot, diameter & position in the nozzle)
Do you always cut from one end of the bed & work to the other end? try starting from the opposite end of the sheet (where is the poor cutting now, which end of the sheet)
have you done both cold & hot mode burns, if not you should, might be blocked water way feeding the OC.
Im guessing OC temp related, you mention you changed the focus part way through the sheet & then it comes good again, there might be a chance that in the time it takes you to change the focus the OC has cooled down again & the mode is back to normal?
You should get you hands on a laser thermometer & check all optic temps when it cutting good then check then all again when cutting bad & compare.
how much are you changing the focus by to get it cutting again?

RE: Parameter Changing

I operate an Amada FO 3015 laser and we also experienced similar issues ever since I got on this laser five years ago. we recently had our routine service and after the new tech was done the machine wouldn't cut like it should after a mirror cleaning anyways long story short after a bunch of back and forth talk between tech and his boss they decided to change the "GAS REGULATOR" and oh my oh my has that changed are cut quality for the better! our aluminum is cutting the best it ever has we are really amazed at what a difference it made!! I know ur machine is different but it might be something to look into. hourglass

RE: Parameter Changing


what "GAS REGULATOR" are you talking about?

RE: Parameter Changing

Fabprohelp the "NC programmable assist gas regulator" p/n 71359715 NC regulator .........

RE: Parameter Changing

Looking at those pictures I think you loosing power somewhere. I had similar problem on my Trumpf. It could be lens, it could be RF Tube or driver stage.

RE: Parameter Changing

Thanks guys for all the helpful advice. Thats why I read these forums.

Anyway Problem solved. Seems my ARC mirror decided to increase the beam diameter to twice it's factory recomended size, 40mm instead of 20mm.
So now it's smooth cutting from here on in.
Thanks again guys

If you ask me to do something, I will do it. There's no need to nag me every 6 months

RE: Parameter Changing

How did you find out this problem?

RE: Parameter Changing

@ Maito We had our bi-annual service done last week. Just found it while doing a full power test shot into a plaster target. As I said it's normally suppose to be 20mm and it was bigger then the plaster target. Wouldn't ever have been anything I would have checked. Plus even if I had removed it to check it, it didn't show any sign that it was damaged, all looked clean and not spotted.

I can now cut using Bystronic default settings with only minor tweaks rather than major changes.

If you ask me to do something, I will do it. There's no need to nag me every 6 months

RE: Parameter Changing

I was thinking about doing shot on plastic cube, but I don't know how to do it. Could you please explain it to me. Is it pulse shot on 100% power? How many milliseconds? Where do I place the cube?

RE: Parameter Changing

Maito_Cosmos start a new thread on mode shot 3eyes

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close