New Machine Build Need help to calculate motor size needed.

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Thread: Need help to calculate motor size needed.

  1. #1
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    Default Need help to calculate motor size needed.

    Hi guys.
    I already have a machine on which I am using Leadshine ES M22430 motors with 3nm torque and ES D808 Drives. The machine is a CNC gantry and I use 20mm ballscrews with 5mm thread pitch.
    The whole bridge weight is ~80kg and is driven by 2 motors (X Axis).
    The Y axis motor is driving ~30kg
    And the Z axis motor is driving ~15kg
    The performance I get from the machine is ~6500 movement speed.

    I am designing the new machine because I need longer X axis travel. Current one has 1000x450x180 and the new one I design will be 1600x450x200.
    Also I plan to use again 20mm ballscrews but with 10mm thread pitch. I want to achieve bigger movement speed. My aim is 12.000-15.000.
    The weight of the new bridge will almost the same as the current one, just a little bit heavier. I calculate it to be
    85kg for the whole bridge
    33kg for the Y axis motor to drive
    15kg for the Z axis motor to drive

    My current thought is to use the Leadshine ES M23480 motors with the same drives which have 8nm torque. 2motors for X and 1 for Y axis. And the ES M23440 motor for Z axis which has 4nm torque. The Z axis will probably be limited to lower movement speed since it will have only 200mm of travel.
    Anyone that can help me decide on the motors?
    Do you think they will be ok for the performance I want to achieve?

    Here are the torque diagrams from the Leadshine website for the motors I use now and the motors I want to use on the new build.



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  2. #2
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    Default Re: Need help to calculate motor size needed.

    Guys any thoughts???



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    Default Re: Need help to calculate motor size needed.

    take care, don't expect to much from the 8nm motor, it has twice the self inductance of your 3 nm motor. If you look at the torque diagram's you will see that it drops almost twice as fast.
    So only if you stay at low RPM ( below 200 ) you have advantage. At 400 RPM they are almost the same.
    if you need stronger motors, at the same speed, you need the same self inductance or lower.



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    Default Re: Need help to calculate motor size needed.

    Thanks for the answer. I have been considering this too. That at high rpm there is not significant difference... Maybe I will need servo motors for my application? But I have no clue of how to setup a servo motor system.



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    Default Re: Need help to calculate motor size needed.

    Some servo systems also use the Step Dir input like the stepper motors. I expect that this is the easy way to replace them. Again a warning, some sellers show closed loop steppers as servo system.
    These still have the same issue with the higher self inductance but they stop and give a warning when they are missing to many steps



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    Default Re: Need help to calculate motor size needed.

    I know. These leadshine steppers I use are closed loop. They have encoders and never had any issue with loss of steps or accuracy. I just want to build the new bigger machine with much higher speeds.



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    Default Re: Need help to calculate motor size needed.

    Hi,
    modern AC servos will eat any stepper ever made, even closed loop steppers.

    The manufacturers of closed loop stepper systems claim they are as good as servos.....pure BS, they are still steppers and suffer degrading torque as the speed
    increases, EXACTLY the same as open loop steppers.

    If you want genuine speed and VERY generous overload capability then go for modern AC servos. I'd recommend Delta (Taiwanese made in China) or DMM ( Canadian made in China)
    as two quality, well supported brands at reasonable prices.

    There are even cheaper Chinese made AC servos and while I have no complaint abut quality or performance, the documentation is poor, support questionable and
    worst of all.....no set up and tuning software. You have to program the drives by pushing buttons on the drive like a microwave....avoid like the plague.

    I bought three 750W Delta B2 series (160,000 cpr encoder), one braked. They are direct coupled to 32mm diameter ballscrews of 5mm pitch and they accelerate up to 25m/min
    in half an eye blink! My axis beds are 115kg each, so they have plenty of get up and go. Using rated torque only (not the up to three times rated torque) the axes accelerate at 0.25g,
    and I could, using the overload capability get up to 0.75g acceleration. They seriously kick-arse!

    Craig



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Need help to calculate motor size needed.

Need help to calculate motor size needed.

Need help to calculate motor size needed.