We have a dual robot cell with two Fanuc LR Mate 200iD 7L's in it that pick up small plastic molded parts and apply a bead of silicon to them. One of the robots will randomly change position in the Y by 4 millimeters, from it's taught position. This started about a year ago and it did it a few times thru ought the year, but has recently gotten worse. The positions can be touched up back to where they should be and in a few hours will shift in the Y again. I did notice that it shifts the exact distance every time. There are no offsets programmed into these positions so I am scratching my head as to what it may be. Any suggestions would be appreciated. Thanks!!!
Fanuc LR Mate 200iD 7L randomly offsetting its taught position only in the Y
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S-Ouzts -
September 3, 2020 at 3:30 AM -
Thread is Unresolved
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Will ALL positions of this robot move by the 4 mm you stated?
My guess is a failing axis/reducer/harmonic drive.
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Have you checked to make sure that the bolts that mount the robot base and tool are properly torqued?
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Agree with pdl, loosening of fasteners is number one reason. Worn tooling and lack of locating pins that allow movement in bolt holes are other issue often found.
Is the direction always in one direction or back and forth?
What coordinates is the Y direction offset?
Can it be corrected by moving a single axis in joint?
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I believe we have found the issue and wanted to let you know what it was. We saved some specific points to go back to and verify the direction it was moving in. It had changed again this morning and we found that the tip that the silicon is being dispensed out of had moved, not the robot. The part is picked up by the robot and traces the tip of the stationary silicon applicator. The tip is held by two bolts but doesn't have alignment pins and can move in the Y direction only approximately 4mm + or - if it is contacted. I checked this the other day and it didn't seem to have any movement, but I was able to move it this morning. We are going to add a support to keep this from moving. Thanks for your input.
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Thanks for providing the solution found and with good detail. Glad you were able to find it.