KUKA KR-120 R2700 Extra HA

  • Hi Everyone,

    New here and thank you for having me!

    Does anybody have and tips and tricks with this robot for milling?

    I have a Yaskawa driver coupled with this robot and a VEM 20hp spindle and PLC control of water and compressed air.

    Material is stone (sandstone/granite)


    I can post pictures of my rig later this week.


  • Don't expect it to be easy or quick. Robots are far less accurate, or rigid, than CNC machines. That's the price you pay for device that costs far less than a CNC machine with the same working envelope and degrees of freedom.

    Alignment is everything. Whatever software you use to generate your CAM paths, you need to have it and the robot very well aligned to each other. An accurate TCP setup is also vital.

    Avoid end effector orientation changes as much as possible. Those are the moves that wreck accuracy faster than anything else. Likewise, avoid reversing an axis mid-move if possible (lots of Linear moves reverse an axis mid-move). Robots have bad backlash effects, compared to CNCs.

    This is an HA robot, which means it has Absolute Accuracy calibration. This attempts to make the robot more accurate by trying to compensate for the "sag" caused by the payload as the robot changes poses. This only works if you perform your payload calibration and Mastering correctly, and use accurate payload data. Not just weight, but also CoG.

    Be prepared to make a number of "spring passes." Given the robot's lack of rigidity, even a mathematically perfect pass may need to be run 2-3 times to remove all the material. For the same reason, be prepared to program for lightweight cuts with low engagement forces.

  • Thank you so much SkyeFire! Amazing encouragement from you on this subject. I also program 5 axis stone center from GMM made in Italy. You are absolutely correct in terms of the CNC rigidity. The gantry for the CNC machine itself is made of cast iron and weighs about 10000 lbs and driven by HA servos.

    Thank you again for the wise words. I will keep you posted on my progress.


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