Fanuc OM Cycle Start Button Not Working

[J_Christiano]

Hello there.

We have a 1997 TVM-760D mill that runs on a Fanuc OM control. Currently its cycle start button is not working and we can't for the life of us figure out as to why.

Right now, in MDI mode, it can do a tool change, move to position, and start and stop the spindle using the output start button instead. There are no alarms currently active and no messages either. It can home all axes and their respective indicator lights are on meaning that it's in its home position. We have made sure that it has enough way oil, spindle oil, and that there is enough air coming to it. I have swapped the physical button on the pendant with a new one and still no dice. Even its bit address in the ladder logic changes states. Any sort of help or guidance will be greatly appreciated.

Thank you!

 

[dandrummerman21]

Check the ladder for G120.2

That needs to be on in order for the program to start.

the cycle start switch itself should set x8.3 to 1.

Should also make sure feed hold (g121.5) is not on for some reason. the feed hold button should be x8.5


Edit: 8.3 and 8.5 might not be correct, i was basing it on a 0m ladder in front of me but a 0m manual suggests those are interlock signals, not the cycle start button.

With that said, take a look at the following manual, starting on page 200 (or 216 if you look at the page number in adobe): https://servicetex.ru/wp-content/uploads/lib/cnc/FANUC/0-MC/Руководство по техобслуживанию.PDF

section 6.6 has a troubleshooting list for you to do if hitting cycle start doesn'tt work.

 

[Vancbiker]

Since X and Y address functions are ultimately determined by the machine builder it is only reliable to determine their function by referring to the builder’s electrical or ladder diagrams. F and G address functions are Fanuc determined.

@OP, if you 0M is a C or later model you can view the ladder on the display. You need to examine the logic that must be made true in the rung that has G120.2 at the right side of the ladder (logical coil).

 

[J_Christiano]

Check the ladder for G120.2

That needs to be on in order for the program to start.

the cycle start switch itself should set x8.3 to 1.

Should also make sure feed hold (g121.5) is not on for some reason. the feed hold button should be x8.5


Edit: 8.3 and 8.5 might not be correct, i was basing it on a 0m ladder in front of me but a 0m manual suggests those are interlock signals, not the cycle start button.

With that said, take a look at the following manual, starting on page 200 (or 216 if you look at the page number in adobe): https://servicetex.ru/wp-content/uploads/lib/cnc/FANUC/0-MC/Руководство по техобслуживанию.PDF

section 6.6 has a troubleshooting list for you to do if hitting cycle start doesn'tt work.

Thank you. Based on the ladder logic, X12.3 isn't function correctly. After looking through the manuals it seems to be the oil coolant motor, however, it is running without any issues. Could be the pressure switch?

 

[J_Christiano]

Since X and Y address functions are ultimately determined by the machine builder it is only reliable to determine their function by referring to the builder’s electrical or ladder diagrams. F and G address functions are Fanuc determined.

@OP, if you 0M is a C or later model you can view the ladder on the display. You need to examine the logic that must be made true in the rung that has G120.2 at the right side of the ladder (logical coil).

Thank you. It seems like X12.3 is the one causing this issue. According to the manuals, this is the oil coolant motor for the spindle. It says it has a fault even though it is currently running.

 

[dandrummerman21]

oil coolant? Like a spindle chiller? not the actual M8 coolant?

if there's a spindle chiller, I can imagine it giving a fault if it isn't functioning properly. Poor ladder design if it doesn't give you an alarm to accompany it.

 

[J_Christiano]

oil coolant? Like a spindle chiller? not the actual M8 coolant?

if there's a spindle chiller, I can imagine it giving a fault if it isn't functioning properly. Poor ladder design if it doesn't give you an alarm to accompany it.

yeah like a spindle chiller. The odd thing is that there doesn't seem to be any pressure or temperature switches that land onto any of the pcbs from what I've seen. I've also noticed that if the spindle chiller is on the correct address and is stopping the cycle start from working, why wouldn't they do the same thing for the output start?

 

[dandrummerman21]

What the output start button does is on a different rung in the ladder.

When some of my machines are low on waylube, I can't change tools in MDI with the cycle start button, but I can change tools in MDI with the output button.

 

[J_Christiano]

What the output start button does is on a different rung in the ladder.

When some of my machines are low on waylube, I can't change tools in MDI with the cycle start button, but I can change tools in MDI with the output button.

Makes sense.

The problem ended up being whatever switch is inside the spindle. Whoever owned it before us decided to bypass the switch and have the motor run the second the machine starts up. They did this to the same machine we have right accross from the one having the issue. The only difference is that they left on of the wire leads disconnected.

Thank you a ton for the help!