Pressure shortage on one robot when running tip wear compensation (wr_updat)

  • Hello all. I am working on a spot welding project for my job, and we are using four Fanuc R-2000iA 210F robots. There is a problem we have been having after a tip dress when using the wr_updat(1,0) program to do the wear down compensation. We only get it on one of the four robots. We get a SVGN-020 pressure shortage when it goes to do a press_motion[98] 80% of the time. There are a few times when it will randomly make it through fine, but most of the time, we get this error.


    We have tried re-auto tuning the gun, as well as re-calibrating the pressure (We went from 5% to 45% torque when doing this). We brought in a nice pressure gauge that we know is very accurate to do this. We had to reload the robot with a backup image from one of the other robots a month ago too for other reasons, but that didn't fix the problem either. I have also tried to set up the two-step tip wear down program, but I just get an INTP-303 error when it tries to move from the first point to the second point. (This is from running tw_setup(1) after a fresh cap change).


    Before we did the pressure re-calibration, we could manually put a 1 into the 98 pressure schedule for lbf when it would get the error and resume the program. It would get through it fine then. After the re-calibrations, we get a "pressure too low" error, and have to put a 100 in there. Also, we have tried putting new tips on, manually doing a gun zero master, and running the wr_setup(1) program.


    This has been bugging us for months, and we are at a complete loss. If any of you have any ideas on how we could fix this, I would greatly appreciate it. Thanks!

  • You might want to check that your Tip Disp Ratio is correct. I've run into a lot of guns lately where the number given to the programmer is wrong.
    Slowly open the gun until it collisions out and then measure the distance between 2 new caps. This should be really close, if not identical to the position of group 2 axis 1 on the teach pendant. Close the gun about 3/4 of the way and repeat the measurement and comparison to the position on the teach pendant. If these numbers do not match each other (real space and where the robot thinks the shank is), then you will want to remaster the gun but answer that you don't know the Tip Disp Ratio when it prompts you. If these numbers are correct and do match each other, then I don't know how to help you any further.
    Good luck, and if you figure it out, please post your solution. :smiling_face:

    Primary robot language: Fanuc.

    Expertise: iRVision, PalletTool, iRPickTool, DCS.

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