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selection of servo motors against stepper motor. Is it user defined or suitable as per requirement?

Former Member

For a printing screen machine with high speed of 400mm per sec.supported by high precision Linear guidance system and Ball screw. With an over hang load of 20 Kg. approx. working period 20 hours per day. Expected life cycle of 4 years minimum.

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    It would be unusual to choose stepper motors for this application in that true servo motors can have much better performance and the cost of the servo motor will probably not be very great compared with that of the ball screws and guides.

    You don't mention the kind of position sensor you plan to use.

    Of course you haven't told us nearly enough to make a definite recommendation but from what you have said I would be thinking servos.

    You need to specify operating load, moving mass, required acceleration, positioning accuracy, holding forces and  awhole lot more before the system can be considered to be fully specified.

     

    MK

  • 0 in reply to michaelkellett

    Thanks and nice to be introduced. Operating Load- 20 Kg. approximately. Moving mass same 20 Kg.; Positioning accuracy - 0.5mm/500 micro ; Holding forces - please define what you mean to ask? It will be helpful for me to provide further info you need.

    Table system 2 Rails + 4 blocks. Table size - 250X 500 mm . From the side 250 mm there is an overhang load of 20 Kg. rom table load is hanging downward 150mm. on aplatform of size 300X300 mm.  It is 75 mm away from the table i.e. distance between table and hanging platform is 75mm, rigidly secured/supported. Max. stroke is 1200mm. Load moves to and fro continuously without any delay. Cycle - 3sec forward-3 sec revese-3 sec fwd-3sec reverse.......... minimum 20 hous a day.

  • 0 in reply to Former Member

    I'm not sure that I've completely understood the mechanical arrangement but on the basis that you need 1.2m stroke in 3 seconds the next step is that you must define the acceleration and the force you will need to move the load. This means you need to know the acceptable velocity profile during the cycle - you need the least actuator force if the velocity is continuously changing but this may not be acceptable.

    The holding force is the maximum force that the load might apply to the motion control system when the control system is trying to keep the load in a fixed position - this may not be an issue for you.

    0.5mm isn't very precise so you might be able to use a lower cost linear actuator than the ball screws, eg toothed belt or flexible steel belt.

     

    MK

  • 0 in reply to michaelkellett

    Whole arrangement with LMG of 25 mm size and Ball screw dia 25mm  pitch 10 mm & C7 accuracy is installed . Ball Screw is fixed support on both the ends. and as per your first reply we will be using servo motor. Can you suggest Servo motor with it' suitable drive?

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    imagechetan lad printing mc..docx
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