Serious problem in new Fanuc 0iMC.

[motordude]

Hello all,
I bought a new Doosan DNM400 last year. It has now run 340 hours. At 140 hours this thing happened: I was running from a PMCIA card, milling waterline, hence the z value is constant, at that time it was, say 35 (can't remember exact value). The feedrate was 250mm/min. Suddenly the z value started to fluctuate between 34.xxx and 36.xxx. The values on the screen was 35. The feeding started to slow down and speed up from 120-600. I can't say if the X & Y moved wrongly, or if it was only the Z axis.
In other words, the program on the screen didn't take palce in the machine.
The part was damaged. When shutting the machine down and restarting the same program all was fine, no problems

I contacted my sales rep and the contacted Fanuc. They said that running from a non Fanuc memorycard may cause this problem. I got a Fanuc card and have been using it since. Now at 340 hours the same problem occurs, and is remedied by shutting down and restarting.

Has anybody experienced similar problems and found a cure for it?

Thanks!

[ALEXCOMO]

I usually use non fanuc cf memory card with pcima adapter, and i run 1250h with no problem, fanuc oimc on johnford vmc.
Try to use DNC ,if it's work well memory card it's fault.
Check parameter acc/dec ,gain.
Do you use g8 ,g5 or nothing ???try to change between this g05 sometime cause problem.
Check arc programming tollerance in parameter and cam system arc programming.
Which cam?

Best Regards
Alex

[motordude]

Hello Alex, thanks for your reply. I can't use DNC as I have no ethernet option and no adapter for RS232/USB. I don't think it's the memory card, the first time this fault occured I used a non Fanuc card, and the second time a Fanuc card.

I never use G8 or G05.

The tolerance of the the arc in my CAM (SprutCAM) is x.xxx. Should this value be equal to the parameters in the machine? I remember the machine did some arcs when the error happened last time, I don't recall if it was using arcs the first time.

I have looked through my Fanuc parameter manual, but don't know where to look for acc/dec, gain and arc programming tolerance. Could you point me in the right direction?

Thanks for your help, Alex!

John

[ALEXCOMO]

The error occour also in in the CNC graphic???
I think is a program problem....
For touch parameter setting it's better try all the way....
Try to postprocess the program only in segment (only g1 g0) it's a common cam option .
If you have the program sent it to me I can try it on my vmc or my graphic simulator( better you send me only the part who generate error)

p.s.:I'm Italian i work in mm.

Hi

[motordude]

Hello Alex, I just sent you a PM. No, the code shown in the graphics (CNC display) are the same as the program. The machine performs movements that are different from what is shown on the display. I don't think it's the program, when I turn the machine off and restart, the error is gone. But I'll send you the program and you can test it! Great! Thanks a lot!

John

[angelw]

Originally Posted by motordude The tolerance of the the arc in my CAM (SprutCAM) is x.xxx. Should this value be equal to the parameters in the machine? I remember the machine did some arcs when the error happened last time, I don't recall if it was using arcs the first time. John

1. If you mean that the CAM package output the G code file to x.xxx, but internally is working to a greater accuracy, and your machine is, say,x.xxxx, then you should have it output to the same accuracy as the machine control is set.

2. I you are referring to the internal accuracy setting of the CAM package, then this should be set to at least one more decimal point than the machine control setting. Lets say that the machine is set to x.xxx then the CAM package should use at least x.xxxx for internal calculations and output to the same accuracy as the machine control setting.

Regards,

Bill

[motordude]

Hello Bill, thanks for your response, how do I find out the accuracy of the machine control? I'm looking in the manuals, but can't find anything.

Best regards
John

[angelw]

Originally Posted by motordude Hello Bill, thanks for your response, how do I find out the accuracy of the machine control? I'm looking in the manuals, but can't find anything. Best regards John

`I think its parameter #1004 for the Oi control, but you can check in your manual. If bit 0 and 1 are both set to 0 then the least input and output increment will be 0.001mm and 0.0001inches. If bit 0 is set to 1 then the least input and output increment will be 0.01mm and 0.001inches. Unless these values have been altered, the control will generally be set to the smaller incremental input/output.

Regards,

Bill

[motordude]

Hello Bill,
I just checked the parameters in 1004, and they were all 0. The output from the CAM postprocessor is x.xxx, so that should be fine. There is a box called "machine state parameters" within the CAM program, and axis X (Y & Z, too) has value: Increment 0.0001, I suppose that is correct too(?).

Thanks again for your help!

John

[angelw]

Originally Posted by motordude Hello Bill, I just checked the parameters in 1004, and they were all 0. The output from the CAM postprocessor is x.xxx, so that should be fine. There is a box called "machine state parameters" within the CAM program, and axis X (Y & Z, too) has value: Increment 0.0001, I suppose that is correct too(?). Thanks again for your help! John

If that setting is for the system accuracy of the CAM package, then that's OK, but I'm not familiar with your software. However, I doubt that arc accuracy has anything to do with the problem you describe in your original post.

I take it that the program you're running is quite large and hence the reason for running it from a card. Will the program down to where you experience the error fit in the memory of the machine? If so, I would run the program from memory to see if you get a similar error.

Regards,

Bill

[motordude]

Hello Bill,
the program is quite large, but the problem is not consistent. I ran the program from the card, and there was a problem. I turned off the machine and ran the same program again 2 minutes later, from the card and everything else the same, and the problem was gone. This error has come up twice in 340 hours, so I doubt running the program from the machine memory will tell me if the problem lies with the card.

Best regards
John

[angelw]

Originally Posted by motordude Hello Bill, the program is quite large, but the problem is not consistent. I ran the program from the card, and there was a problem. I turned off the machine and ran the same program again 2 minutes later, from the card and everything else the same, and the problem was gone. This error has come up twice in 340 hours, so I doubt running the program from the machine memory will tell me if the problem lies with the card. Best regards John

Hi John,
Intermittent problems can be hard to pin down. However, unless you change something in an attempt to rule out possible causes, you may never find the cause of the problem.

If you ran the program from memory and after a good amount of time, perhaps your previously mentioned 340 hours, you had no problems, then change back to running from the card for an extended amount of time to see if the problem occurred again. If the problem appears running from memory, then you could probably dismiss the card as the cause of the problem and focus elsewhere.

No matter what is causing the problem, and what steps you take to remedy the issue, its going to take you some time to know if the problem has been resolved.

Regards,

Bill