Payload over spec

    I am setting up a new robot, it is an M10 hung upside down in a cage made of aluminum extrusion. I was putting in the payload values for the EOA I got from our design group and got a warning saying "load is OVER spec! Accept?". When they designed the EOA and ran Fanuc's Payload Checker the EOA passed, it did say it was at 96% of the max allowed inertia and also said WARN under the summary results for Inertias, but technically it passed. Only issue is the weight they use in lighter than actual, they don't have all fasteners, breakout board for the prox switches, air lines, prox switches, etc in their design. Actual weight ended up .6 kg higher than what they used when they ran the payload numbers. I always just put in their values for everything but weight, for that I use the actual value I get after weighing it fully dressed. When I put the initial values in everything goes fine, but as soon as I put the actual weight in I get the over spec warning. Has anyone ran into this before? I looked through the payload section in the HandlingTool eDoc and it mentions the over spec warning popping up, but makes no mention of what, if anything, this will affect. Because of the size of the robot and the way it is mounted I planned on having no moves over 25% speed anyways, but just wondered if the over spec will have any effect on the robot moves or how it runs.

    <unpopular opinion>
    To be honest, I do not care that much for the payload definition, especially as the welding robots that we use (ArcMates 100iC and 120iC) NEVER accept the Payload ID results - we always get the "Load is over spec!" errors, even thoigh it is not true. Doesn't matter if the robot is configured as 6kg or 20kg version, Payload ID never works for us. Therefore we just manually input the approxmate weigh of the torch and other equipment, set the center point a bit off the faceplate and that's it.
    </unpopular opinion>

    Auto payload ID is only accurate if the load is off center from the faceplate signicantly. Which is not ideal as I try to design EOAT to have min inertia. So I get much more accurate results from calculating mass, CG, and inertia in the cad software.

    If I was at 96% capacity I would be looking at a larger payload robot. What if you ever need to add something? No room for futures changes, which will end up costing more.

    In your situation, the biggest concern would be an overheat or overcurrent condition, which can be simulated and checked in RoboGuide. Overheat can occur even if you are below the load spec. If you have an issue, then it could go away by slowing movements down. Since you say you're not over 25%, then it might be ok.

    Sent from my VS985 4G using Tapatalk

    Edited once, last by HawkME (January 20, 2017 at 1:14 PM).

    Thanks for the input guys. I was hoping as long as keep the moves at no more than 25% I should be OK.

    As far as Auto Payload ID I have had mixed results using it as well. I would say the majority of our EOAs are "balanced", normally we are utilizing a symmetrical setup with 2 grippers mounted opposite each other. Just like what HawkME mentioned, I had read in the manual about Auto Payload ID working most accurately when using an off-center EOA, and ours are rarely much off-center at all. Lately I have been running the Auto Payload and then comparing the values from the design guys and I would say the majority of the time they don't match very closely at all, I have had maybe a couple that were close in value. I need to start keeping better track of the values of both the calculated vs. Auto Payload. The values always vary, but not usually wildly, by I would guess at most +/-25%, but like I mentioned the design guys often aren't using the correct weight when calculating the values which Im sure plays a part in the values not matching.

    Quote from HawkME


    Auto payload ID is only accurate if the load is off center from the faceplate signicantly. Which is not ideal as I try to design EOAT to have min inertia. So I get much more accurate results from calculating mass, CG, and inertia in the cad software.

    If I was at 96% capacity I would be looking at a larger payload robot. What if you ever need to add something? No room for futures changes, which will end up costing more.

    In your situation, the biggest concern would be an overheat or overcurrent condition, which can be simulated and checked in RoboGuide. Overheat can occur even if you are below the load spec. If you have an issue, then it could go away by slowing movements down. Since you say you're not over 25%, then it might be ok.

    Sent from my VS985 4G using Tapatalk


    I am having this issue Over Currents at low speeds and any machine faults that stop/abort programing. The payload is manually setup just running at max capacity 125kg.

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