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Problem with Amada FO4020NT U Axis (CBL)

Problem with Amada FO4020NT U Axis (CBL)

Problem with Amada FO4020NT U Axis (CBL)


I am new to laser cutting so please use words of one syllable or less. :)
I have recently joined a company to run their Amada FO4020NT here in Perth, West Australia.
It has an ongoing problem with the CBL unit (U axis) every so often getting out of calibration.
This necessitates a long list of codes etc to be typed into the Amada operating system to recalibrate it.
This is quite dangerous as prior to my arrival something was done wrong that resulted in the X axis bellows being damaged ($25,000 au).
I had calibrated it several times in the past but one morning I must have done something wrong and ALL axes would not calibrate, resulting in a technician being flown out from Sydney on a special trip and a lot of very unhappy people.
This has been an ongoing problem for many months and no-one seems to have an answer.
I have noticed that the CBL always stops in contact with the lower of 2 micro switches on the U Axis track. I have mentioned this to the Amada technician who seems to think it is just a coincidence. To me I would have thought it is maybe the switch, connectors, cable or something in the line from the switch.
The tech has contacted Japan who has recommended replacing all the cables in the tracks which is obviously an expensive and time consuming option. As well as this has been done recently anyway.
My questions are firstly has anyone else experienced the same problem and if so, can you let me know what the eventual fix was so I can pass it on.
Kind Regards
Ian Wood

PS. This internet is a small world; I notice one of the contributors is Chris Krug that I have spoken to on a totally unrelated subject in a totally unrelated forum in relation to a RR Nimbus going into my Salt Lake Racer here in Australia.
Anyway hello Chris......small world ....

RE: Problem with Amada FO4020NT U Axis (CBL)

Can you elaborate? In the stats we have ZXY and B axis runs the focus lens. What does the U Axis do?

Also, if you can give any alarm numbers and descriptions that would help. I do not know what CBL means, sorry. I am sure its just a difference in terminology but I need clarification.

RE: Problem with Amada FO4020NT U Axis (CBL)

Hello Laserninja, thanks for the reply.
The U axis runs the Constant Beam Length unit (CBL).
It a set of 2 mirrors that move at half the speed of the X axis (+ or - the Y&Z axis) so that (theoretically) the beam from the laser generating oscillator to the work remains the same length regardless of where on the sheet it is cutting.
I will have to look up the codes tomorrow and repost but its description is "laser alarm".
I know the codes are not in the alarm list in the manuals for the machine as I have looked for them before but must be in a more comprehensive manual that I do not have.
Thanks again for your help.

RE: Problem with Amada FO4020NT U Axis (CBL)

Please forgive me. I have been working on these machines for many years now. I haven't worked for Amada since 2007 so I may have missed something.

Is it possible you have a "Mitsubishi" Amada? I have a few friends that work for Mits and they maybe able to help us out.

All the machines that come to the states are Fanuc controls, and almost all Fanuc drives, except the linear machines.

It sounds to be like the there is a loss in communication with the encoder and or the machine has lost its reference position.

Does this happen only when you turn on the machine in the morning? Or do you have this pop up anytime throughout the day? Can you tell me what type of control the machine has on it? Motors?

The reason I ask is, you can have either an absolute pulse coder with remembers its position after you turn the machine off, or you have a retract slow down limit switch that origins the axis and establishes home position.

I know, seems like a lot of random questions. But I just trying to figure out a work around for ya. Also, I'm thinking that maybe Amada isn't being much help because they didn't build the machine. It may be necessary to circumvent them.

Main things

Motor type?

Post a picture of the machine. Please.

RE: Problem with Amada FO4020NT U Axis (CBL)

    Firstly apologies for not posting earlier, but I now have my camera and computer up and running again.
    Luckily (?) we also had another CBL crash this morning so I am able to post pictures of the machine, codes and the crash position.
    Looking at previous crashes it looks as though the most common time for a crash is Monday morning. The machine runs 2 shifts Monday to Friday and 1 shift on Saturday so the problem arises (most commonly) when the machine has been shut down for 36 hours or so.
    I have had a look at the build plate and all labels etc on the machine and can't see any reference to anyone but Amada and Fanuc. If Mitsubishi did make controllers I cannot see reference to it.
    I hope these pics will shed more light for someone on the problem, please let me know if you need clarification on any of the pictures.

Kind Regards

RE: Problem with Amada FO4020NT U Axis (CBL)


I have a bit more information and a few more questions. I did not know this until I started asking around. The 6kw full-on Amada has a U axis as you described. The first one in this area is being installed this week.

As you said, U axis has to do with beam length compensation. I was amazed at how this axis is suppose to work. As it was described to me this is a machine with linear drives on XYZ and obviously a FANUC servo on the U. My understanding is that X and Y go like hell for the home to the first pierce point in a program and this poor little U axis servo is suppose to keep up with two linear drives... Even at half the distance, as you stated, amazing...

So, on a typical Monday morning, the operator would come in an reference all the axis by pressing the buttons corresponding + buttons. I have been told that the U axis referenced automatically when you hit the button to origin X and Y.

Is this the point where it alarms out or later on?

Also, Your pictures are helpful. You mentioned two switches where it alarms out on. This was in your first post. Can you post a picture of this.

A friend of my thinks this problem may have to do with the drive belt tension. This belt comes off the servo motor and moves this axis around. Take a picture of that too if you can.

Granted I don't know what I'm talking about here. But I know a few people that do know. If I ask them the right questions, we may be able to get some answers.

RE: Problem with Amada FO4020NT U Axis (CBL)

Hello Laserninja,
Thanks for the reply drive belt tension sounds like a very reasonable place to look.
You are correct it does happen soon after setting the origin.
I thought I had posted all the pictures on the page but it appears that the site will allow only one attachment per posting so what I have done is pasted all the separate links below and will give a brief description of the image.
Please let me know if you need more information.
Image 1.
Is the CBL in the full back (crashed position) viewed from the rear. In the centre are the 2 micro switches mentioned the one closest to the camera in on the cam ramp. Now I think about it, it is probably a last resort switch to stop the CBL physically hitting the back of the machine it usually stops on the other switch when it goes back to the G50 position. Could it be that switch that is the problem??????
Image 2.
Record of alarm codes for the morning 4079 is the alarm for the crash.
Image 3.
Outside of machine
Image 4.
Larger view of CBL.
Image 5.
CBL Motor
Image 6.
Laser oscillator.
Image 7.
View from inside the bed down the CBL bellows & track
Image 8.
Crash position for cutting head etc

Image 9.
Bed in crash position
Image 10.
Model designation on door
Image 11
Alarm details.
Image 12.
Lower view of CBL & Track
Kind Regards

RE: Problem with Amada FO4020NT U Axis (CBL)

Fantastic pictures. Thanks. It helps a lot.

I don't have much time so I have to be brief. I wonder what happens if you press one of those limit switches. I believe one of them is a retract slow down limit switch. The other, is an emergency over travel switch.

I am wondering this. On all other axis (XYZ) when you move the axis too far, you make contact with an hard over travel limit switch. To get out of this condition the operator has to press the over travel release and jog the axis away from the switch.

By manually pressing the limit switches i want to see if you get the same CBL alarm or an EMG alarm comes up on the screen.

I think that the reference position is too close to this EMG limit switch and occasionally, on Mondays it over shoots and makes the switch causing the alarm.

If this is the case, it could be an easy fix.

It would be helpful if you can describe the steps required to get out of this alarm. Are you manually jogging the axis, pushing it, or is it just a shut down and re-start.  In one of your posts you mentioned a long list of parameters you have to change. Do you have an electronic copy of this procedure? I hate to ask, but can you post it too? If you don't have an electronic version, can you take a picture of it an post it that way. Is it every time you get this alarm you have to change a bunch of parameters?

I know I ask a lot of questions but I think we are making progress.

Thanks for being patient.

RE: Problem with Amada FO4020NT U Axis (CBL)

    I have scanned the procedure for calibrating the CBL and attached it here.
    With regards to pressing the micro switch to see if we get the problem I am a little concerned as if it does give the error I will have to go through the whole process to re-set it and the machine will be down for the 30 minutes of so it takes to be done. Next time the technician is in I will get him to press the switch and will report on the outcome.
    I have been thinking about the speed that the CBL has to move heading for home and thought that may be the problem with the inertia of the unit coming to a stop. I can adjust the speed of the return to home from 100% to 75%, 50% or 25%. Running the speed at 75% seems to produce what appears to be slightly less crashes that running at 100%.
    The more I think about it the belt seems a very likely place to look. The belt is about 20mm(3/4 inch) wide and about 4 metres (13 feet) in length each way so a total or 8 metres (26 feet) around the loop. If we are talking about a say 40 kg (90#) unit running back and forth pulled by the belt, it would not take much for it to stretch a little and throw things out of wack?      
    I will check on Monday if there is some type of automatic tensioner on it and ask if the belt has been replaced.
    Kind Regards


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