Hi there, i am working on a problem with a robot used for milling applications. In short - there is a difference when it is milling with different degrees lets say +30 and -30 around X (
Base). The difference is about 2 mm horisontaly and verticaly.
I noticed that there is a bit of play on 4 and 5 axis - is it possible this to cause the problem? The robot is freshly mastered and is working fine when milling vertically.
Any ideas? I am starting to think tthat it may need fixing of these two axis. Tje robot is not hardly used - about 13000 hours.
kr210 l150 krc2 issues when milling with different angles
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vvelikov -
July 2, 2014 at 12:40 PM -
Thread is marked as Resolved.
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Are you changing orientation during the milling path? Because that will exacerbate any minor errors in your TCP. It will also cause errors due to the change in how the robot flexes under load. A fixed vertical orientation minimizes these effects.
If you're running a fixed orientation during a cutting path, look for spots where one of the axes has to reverse direction in order to maintain the linear path. That's where you're most likely to have path errors show up.
Unfortunately, depending on your KR model, some play in the wrist may be inevitable. Getting the wrist maintained couldn't hurt, but without further testing there's no guarantee that it will help.Also... 13000 hours ?!? That's the equivalent of running 540 days, 24hrs/day. And the hour meter only measures motors-on time, not idle time. So most of that is time in motion. That's not a lightly used robot, that's well used!
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I have encountered similar problems in our milling applications. i am working with a kr150 witch has spend 10 years welding cars, so i consider it a very used robot. When a robot is this used you can expect problems like this. Luckily for me i found out that the fault is constant with a certain angle. so i run the program once and then adjust where it is needed. If in your case the fault is the same every time you can easily adjust this in your program.
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Hi guys, thank you for the fast replies!
I am using 3+2 strategy for the milling - it is not simultaneous milling, just approaching the detail from different angles - with fixed angle(orientation).
There is a lot of rotation of 4 axis as part of the path is getting close to singularities.
I am sorry if a get wrong about the usage of the robot but i was under impression that it is counting as not hardly used under 20 000 hours - the first maintenance of the robot? May be the robot needs oil changing and check of all gears?Leon - i just found this fault - didn't checked with different angles. Will do detailed checks with 5 axis milling to see if that happens when robot moves continuously.
Thanks again! -
Maintenance cannot only be counted in hours, for example a robot that has been used for 2000 hours over 3-4 years still need oil change and stuff. Cannot really remember how often they recommend to change the oil,if it is every 2nd year or every 5th... Also isnt the oil change on the wrist axis's (A4,A5,A6) 5000 or 10000 hours?
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Also, some robots spend all their time moving very fast and violently and top accelerations, especially in Automotive. Robots from Aerospace or Medical applications might have spent the same amount of time moving, but much more slowly and gently. So the number of hours is only part of the question as to how worn-out the robot is.
Also, as Xerces said, it matters how well the regular preventative maintenance was carried out. Sadly, many Automotive companies simply work the robots to death, never do maintenance, and then sell the robots to the secondhand market. -
Xerces, depending on robots but not more than
10 000 Hours Lubricate O-ring (A4,A5)
20 000 Hours Oil change for gear train (A4, A5, A6)Or 5 years because of oil ageing
that's what the manual says