Hi,
I am investigating an issue on our brand new IRB 4600 20-2.50. When the arm is extended out forward ("leaning horizontally") we are observing very low rigidity around the axis 1, we can push with 1 finger more than 1 cm in the direction tangent to the axis 1, when pushing multiple times we can make it oscillate back and forth 1-2cm and with an audible clicking noise. Happens with servos ON and also with brakes. We had an ABB service tech coming, tried to adjust the servo on axis 1 by loosening the bolts and the backlash was still there, dismounted the servo 1 and we could see that the gearbox input gear could be moved loosely forward/backward a couple millimeters around the shaft. The robot is gone to ABB for repair but they are now saying that this is "in tolerances".
I honestly have a hard time believing it, the gear felt almost loose. The stated backlash on these gearboxes is approx 1 arc.min on the output shaft, can it really translate to looking like a loose input gear? The service tech said it was clearly abnormal but after 2 weeks of testing at ABB they are considering it "normal". The robot is brand new, 20 hours
If anybody with experience of "normal" backlash on axis 1 of the 4600 serie robot can chime in I'd be very happy to hear!
Thbault
