[peloflex]

Dear Fanuc experts,

I have been trying to solve a problem found on a mill machine controlled with a 18-MC control (FS16/18) and basically the mayor symptom is that all of sudden the control unit loses its operational parameters and goes out of wack. completely.

Someone here suggested that it could be an issue with the MEMORY CARD, so I went ahead trying to, at least, navigate through the screen options related to memory card, but there would be a blinking yellow message that reads MEMORY CARD NOT EXISTS... PRESS SELECT KEY. But to the best of my knowledge, the machine has not only one card but 3 or 4 which I am attaching pictures of. I wonder is the card is there but it had gone bad and thus is not being recognized. Any helpful thoughts or hints?

[spark-el]

When you get a "memory card not exist" message it is referring to the PCMCIA card, not the memory cards on the control. If you have one (it is an option) then you will get that fault every time you try to connect to it if that slot is empty (usually located upper left in cabinet). It is used for up/downloading data and doesn't have anything to do with the problem you're having of losing parameters. What is the fault you're getting when the machine loses it's "operational parameters", and how many times has it happened & how did you recover from it?

[peloflex]

When you get a "memory card not exist" message it is referring to the PCMCIA card, not the memory cards on the control. If you have one (it is an option) then you will get that fault every time you try to connect to it if that slot is empty (usually located upper left in cabinet). It is used for up/downloading data and doesn't have anything to do with the problem you're having of losing parameters. What is the fault you're getting when the machine loses it's "operational parameters", and how many times has it happened & how did you recover from it?

Hello Spark, thank you for clarifying that about the PCMCIA card. Regarding your question about the fault; the most noticeable fault shows up with the spindle control, and also de Z axis drive. the immediate symptom shows at the spindle load gauge/indicator (%) where this red needle jumps all the way to full load as soon as software finishes booting up. so, from there, the machine won´t go any further. The way I have been recovering from this fault is by reentering the parameters I have copied from a similar machine we have here, But is being several times already. Sometimes the machine will run for an entire week without showing this error.
Greetings.
peloflex

[mbservice]

Silly question but have you changed the back up batteries recently ?

[peloflex]

Silly question but have you changed the back up batteries recently ?

Hello rk. this machine is relatively new to our place, to be honest, I would not know for sure when did the back up batteries were replaced. According to operations, this battery had never being changed since they received the machine.

[spark-el]

I'm still not understanding what you mean by "lost parameters". If you lose parameters the cnc will display faults. If you check the parameters and there is data there (not all zeros), then you have not lost your parameters, and I wouldn't be uploading anything. It sounds like you might have a spindle problem, but again you should be getting alarms on the control. The next time it happens, hit the reset button and see if it resolves the problem, if not cycle the power and re-boot the control, try again. You mentioned something about the Z axis. If this is a vertical machining center the Z is held up by a brake and sometimes when you power up it will release that brake momentarily and cause the Z to slip down, then you must re-home in order to run programs. Just some ideas, but I'm really thinking your problem is not parameter-related.

[peloflex]

I'm still not understanding what you mean by "lost parameters". If you lose parameters the cnc will display faults. If you check the parameters and there is data there (not all zeros), then you have not lost your parameters, and I wouldn't be uploading anything. It sounds like you might have a spindle problem, but again you should be getting alarms on the control. The next time it happens, hit the reset button and see if it resolves the problem, if not cycle the power and re-boot the control, try again. You mentioned something about the Z axis. If this is a vertical machining center the Z is held up by a brake and sometimes when you power up it will release that brake momentarily and cause the Z to slip down, then you must re-home in order to run programs. Just some ideas, but I'm really thinking your problem is not parameter-related.

spark-el, What is happening is that all of a sudden without reason or notice, the machine loses its parameters and goes into an error (s) state. So when we go into the parameters pages, we find DIFFERENT VALUES in there, Most pages show different values or settings other than the ones we had there before when the machine was running. So weird! the operators is tired of having to reload manually the parameters from this other machine, like I said. so he ended up throwing the towel and this machine is now just sitting there.

[peloflex]

You mentioned something about the Z axis. If this is a vertical machining center the Z is held up by a brake and sometimes when you power up it will release that brake momentarily and cause the Z to slip down, then you must re-home in order to run programs. Just some ideas, but I'm really thinking your problem is not parameter-related.

Yes, it is a Vertical machine, and the problem with the Z axis kinda goes away whenever we reload the right parameters, although I must say that this axis has been giving us some "8" errors every now and then. But we clear it by shutting down the main power completely and the restarting. Sometime it takes more than just once, for this fault to clear.

[spark-el]

Here are a few questions: 1) What is the error you are getting? 2) What page are you reloading parameters on (are they CNC or PMC parameters), and are you doing it manually? 3) What make & model is the machine? 4) I'm assuming the "8" is on the spindle drive? If so, try swapping the drives with the other machine and see if the problem follows the drive, if not it may be the motor. 8 is a high current alarm so it can be either.
I have seen the Z fall on power up because the brake releases (as it should) but before the amp has initiated, therefore it is applying voltage to a moving axis, so driving a high current alarm, this could be why it is intermittent. The time frame is very short, can be a worn brake that is causing the problem. I still don't think it's parameters.

[spark-el]

I should mention it could also be a sticking brake, or not releasing as the control initiates. If you are drifted slightly below home position the control may try to move it while the brake is still engaged, thereby drawing excess current. In any event I still think it is the Z axis causing your problems, not parameters, but let us know what you find - I would check out the brake first, and any associated mechanical or pneumatic buffer that may be involved on the vertical Z.

[peloflex]

Here are a few questions: 1) What is the error you are getting? 2) What page are you reloading parameters on (are they CNC or PMC parameters), and are you doing it manually? 3) What make & model is the machine? 4) I'm assuming the "8" is on the spindle drive? If so, try swapping the drives with the other machine and see if the problem follows the drive, if not it may be the motor. 8 is a high current alarm so it can be either.
I have seen the Z fall on power up because the brake releases (as it should) but before the amp has initiated, therefore it is applying voltage to a moving axis, so driving a high current alarm, this could be why it is intermittent. The time frame is very short, can be a worn brake that is causing the problem. I still don't think it's parameters.

Here is a shot of the screen that shows what it looks like whenever this problems appears.

[peloflex]

Here are a few questions: 1) What is the error you are getting? 2) What page are you reloading parameters on (are they CNC or PMC parameters), and are you doing it manually? 3) What make & model is the machine? 4) I'm assuming the "8" is on the spindle drive? If so, try swapping the drives with the other machine and see if the problem follows the drive, if not it may be the motor. 8 is a high current alarm so it can be either.
I have seen the Z fall on power up because the brake releases (as it should) but before the amp has initiated, therefore it is applying voltage to a moving axis, so driving a high current alarm, this could be why it is intermittent. The time frame is very short, can be a worn brake that is causing the problem. I still don't think it's parameters.

Machine make is SUPERMAX V56A with a 18MC control. Condition for this second hand machine is fairly well.
Yes, we are reloading the parameters manually every time we have to.
No, the "8" error is from the Z axis drive, which is a High Current alarm. Your diagnostics on the brake conditions are very appropriate. That is next on the list, although a technician that passed by this machine on an earlier call, had checked the mechanical side of things and found nothing wrong, but I think we have enough reasons to double check.

[peloflex]

I should mention it could also be a sticking brake, or not releasing as the control initiates. If you are drifted slightly below home position the control may try to move it while the brake is still engaged, thereby drawing excess current. In any event I still think it is the Z axis causing your problems, not parameters, but let us know what you find - I would check out the brake first, and any associated mechanical or pneumatic buffer that may be involved on the vertical Z.

I will follow your suggestions for sure, starting by replacing the back up battery, then the brake. I will for sure come back with a feedback. I appreciate your help greatly. Many Thanks!

Peloflex

[peloflex]

2) What page are you reloading parameters on (are they CNC or PMC parameters),

And one last thing, The parameters that change by themselves are the 3000 and 4000 groups. Spindle control ans Serial spindle.

[spark-el]

The CNC alarms in the picture are consistent with high current alarm 8 on servo, so it's all pointing to that. Another thing you can check is coolant getting in the motor connector, but I doubt it since the Z motor is probably up above all that. You would always have to cycle power at the main disconnect to clear these alarms, especially the one on the servo itself. I would first check brake, then swap servos (not difficult), motor cables, then motor. You can swap servos first if you like, might be easier to do than the rest.

[spark-el]

PS: The 751 is position detect error, which is the pulsecoder (motor), however the scenario with the brake could also cause it too.

[spark-el]

I just noticed your comment about replacing batteries, I don't recommend it for this, BUT - if you do it make sure not to pull the main disconnect while doing it or you will lose all memory for the ones backing up the CNC.

[peloflex]

The CNC alarms in the picture are consistent with high current alarm 8 on servo, so it's all pointing to that. Another thing you can check is coolant getting in the motor connector, but I doubt it since the Z motor is probably up above all that. You would always have to cycle power at the main disconnect to clear these alarms, especially the one on the servo itself. I would first check brake, then swap servos (not difficult), motor cables, then motor. You can swap servos first if you like, might be easier to do than the rest.

At some point I got all suspicious about the Z axis motor encoder so I went up and removed the cover (red cap) but everything looked almost brand new. like many other parts on this machine. And for the High current motor, I saw in one of the Fanuc docs they offer some sort of measuring device or electronic card that is specially designed for this particular purpose, "Fanuc servo check board" you plug it in to the test pins located towards the bottom of the servo drives, I wonder how beneficial could be to have one of this cards, it seems difficult to run this with a different method. Have you tried using one of these before? Is it worth buying based on your experience? Thank you!
Peloflex

[spark-el]

Yes, if it identifies whether it's motor, encoder, or amplifier, then it would be nice to have if it is affordable. I've never used one so I can't say. Fanuc parts used to be expensive, don't know how it is now as I've been retired for almost a decade. Problems like these are sometimes an easy fix, other times it can be real frustrating. It can even be a ballscrew that is going bad, or chips built up behind a guard that inhibit the axis movement. Anything that works against the drive can cause a overcurrent alarm, even the drive itself can be bad and give you one. I've seen instances of each of the things I told you about, with the exact same faults.

[peloflex]

spark, are you Fanuc specialist or do you also see other brands? The reason why I am asking is because here in my country we are struggling big time by the lack of knowledgeable techs in all CNC control brands, and at some point I think I am going to be sponsoring a CNC (maintenance and repair) training seminar, since besides me being a bit knowledgeable about CNC repair (HAAS factory trained in 2009) I am also currently in the technical educational field. Perhaps in the near future, considering that you are retired, we could be extending an invitation to participate. I would like to get your initial thoughts on this.
Regards,
Peloflex