Originally Posted by solosman  need help in sourcing the cause, mazak 3l running on fanuc 5t, will occasionally go into machine lock, causing the axis to stop moving, but control still thinks it is moving and therefore when cycle finishes it indexes in wrong position causing it to crash. Any feedback greatly appreciated |
I would think that this issue is more likely to be caused by a machine lock switch shorting rather than a logic error. In my opinion, this is potentially the most dangerous switch on the control, and should there be an overwhelming need to have such a switch, it should be protected by it being in the form of a key lock, rather than a toggle switch that is the norm. As you have correctly identified, machine lock does not stop the program from running, but locks the mechanical aspects of the machine. If this switch is inadvertently toggled on and off, even after a brief moment, the machine will be out of position and potentially a crash waiting to happen.
To trouble shoot your problem, I would start by disconnecting the switch.
Test in the following sequence:
1. Write a test program that operates well away from the chuck and repeatedly run the program to see if the problem can be reproduced.
2. If yes to 1, use this program with the switch disconnected. Disconnect the wires where they connect to the switch. Run the program created for step one repeatedly to see if the problem still exists.
3. If yes to 2, trace the wires from the disconnected switch down to where they terminate at the control and disconnect them there. This step is required in case the wires are shorted at some point. Run the test program repeatedly again to see if the problem still exists.
4. If yes to 3, then at least the most obvious has been eliminated. If you have the manuals of the machine, there should be a schematic of the control logic in Ladder form. From this you should be able to trace where the problem may be.
Regards,
Bill
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09-07-2011, 07:46 PM
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