Motors with oil contamination IRB7600-340/2.8

  • Hello,


    We have about 38 robot in our factory, recently (1 year ago), some robots started to present a problem, the oil from the gear box leak and contaminate the motor brake, the axis slips and generate an insecure condition to our process.


    Most of the models (6 in total) are IRB7600-340/2.8 except one that is a 6640-185/2.8. The axis 2 and 3 had this problems (not in the same robot, some in the axis 2, some in the axis 3).


    The robots have about 15000 hours of operation, and had the first oil change with 6000 hours by ABB.


    We don't have a heavy duty process, I simulated the routine with Gearbox Heat Prediction in RobotStudio (thanks ABB to release the trial version this year) and none of them presented any consideration to install a fan. We measured the axis temperature during the normal process and the hottest temperature we found was about 50ºC (I do not think it's too much).


    My question is, does anyone else have this problem? Did you found any reason for this to happen? If not, any tip will be very appreciated.


    Thank you very much.

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  • S4C, S4C+, IRC5 are examples of controller version, would give me indication of age. I asked about the motors because there was a widespread problem years ago with Elmo motors having leaky seals. As best I can remember being told. Elmo had changed the seal without OK from ABB and ABB had to go out and replace many motors because of that. They later ceased using Elmo motors.

  • Thanks Skooter, we called a company that inspects and analyses the oil, they will come next week.


    Does anyone know the normal operating temperature of the servomotors? We measured in one robot 57,8°C in the axis 2 motor, is it normal? I was unable to find any information about the operating temperature of the motors in the manuals.


    Thank you

  • While it generally depends on the load and programmed motion, I would expect temps in the 35-50°C range if the ambient temp is in the 25-30°C range.

    Besides mechanical/lubrication issues and external heat transferred to the motor, less than optimal programming techniques can also be a large contributor.

  • The problem you have with the oil getting in to the motor and finally the brakes is a very common issue on the IRC5 robots.

    One of our shops had about 800 robots and over the period of 7 years we changed about 3,000 motors and roughly 600-700 Axis 2 and axis 3 gearbox's due to this issue. Early on ABB would not give us any help with this issue and kept telling us we were the only customer having trouble. At around the 2 year mark we discovered our sister plants in Germany had also been having a lot of the same issues but they just hadn't shared that information with us. In fact, many of ABB's top customers were having this trouble.

    We kept trying to tell them all of this was due to pressure build up in the gear box's, but ABB refused to believe any of this. We even experimented with putting vents on the first 3 axis like the previous generation ABB's had. (S4C robots).

    You would have thought that their R&D department would have discovered this early on in testing.

    We have actually taken the fill plugs, "not the drain plugs" out of axis 3 on several robots and have had a 10 to 15 foot stream of hot oil to come shooting out of the fill plug hole. However, ABB engineers still said, " WE DON'T HAVE A PRESSURE PROBLEM!"

    They even hired an engineer just to be over the project of fixing this problem.

    Their so called fix was actually cutting the shaft end plate cover out to hold 2 seals back to back.

    Just in case you don't know, servo seals aren't designed to handle pressure of any kind, they are just mainly dust shield.

    However, since the gearbox's were actually building pressure they were requiring the seals to keep the oil out.


    Basically this cost ABB millions of dollars and who knows how many customers. I know for a fact that this reason alone cost them the contract with the US BMW plant for the last 5 body shops. In fact, you can read that many customers that had the older S4C and S4C+ robots started refurbishing their manipulators and upgrading their controllers and cables with the newer IRC5 controllers.

  • I empathize with dblbeard on many of his points. I've seen robots where the axis 2 vent hole plug is replaced with actual venting plugs. ABB was to have fixed this by changing the the oil from Tivela S150 to Kyodo Yushi TMO150 (which is S150 with additional additives to address friction). The millions they lost are being made up by what they charge for the now proprietary TMO150.

    A good motor rebuild facility will be able to upgrade the seal. Seen this done with Fanuc motors which are notorious for oil/grease contamination caused brake issues.

  • S4C, S4C+, IRC5 are examples of controller version, would give me indication of age. I asked about the motors because there was a widespread problem years ago with Elmo motors having leaky seals. As best I can remember being told. Elmo had changed the seal without OK from ABB and ABB had to go out and replace many motors because of that. They later ceased using Elmo motors.

    I remember ABB came in and changed wrists at no charge due to leakage into the axis 6 motor on M98/99 IRB6400 of a certain serial # range. The seal issue was coupled with their poor decision to briefly use the thinner Molywhite Re.00 recommended by Nabtesco.

  • Hello again,


    Thanks guys, the information you provided is very useful for me and colleagues. We were testing many hypothesis, but knowing that this is not an isolated case settles down everything.


    I'm frustrated that I can't thank you all personally, but in case of anyone come to Brazil I'll be happy to pay a beer.


    dblbeard, If you think they consider you dumb, I'm unable to imagine what they think of us Brazilians, eheheehhe. thank you very much, your information is enlightening about this problem.


    I work with robots for just over two years.


    In this case:

    We took an thermal image of the motors, the highest temperature we found was 57.8°C, in some manual I found the information that the limit in the motor frame is 100°C, this information is for the MU100 to MU400 external axis motors, but in the lack of information about the manipulator I considered this number.

    The oil analysis from ABB came to nothing, everything was ok.

    In simulation of the work cycle with RobotStudio and Gearbox Heat Prediction tool, the result is ok for every robot/axis.

    The seals, motors and robots were originals.

    The preventive maintenance (oil change) was executed by ABB itself.


    The conclusion is that there is some problem with the equipment. I'm sad that ABB isn't helping us with this.


    Once again, thank you all.

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