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IndustryArena Forum > CNC Electronics > Spindles / VFD > How low can I drop my rpms on my spindle?
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  1. #1
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    How low can I drop my rpms on my spindle?

    Hi guys
    I have a 2.2kw water cooled spindle and my vfd is the askpower 131. I attach the manual of my vfd.
    I have been dropping it as low as 100hz which means 6000rpm. I would like to know if I can drop it lower without hurting the spindle. Say 50hz or even lower if possible?

  2. #2
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    Re: How low can I drop my rpms on my spindle?

    Anyone has any info?

  3. #3
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    Re: How low can I drop my rpms on my spindle?

    Hi,
    yes you can drop it lower but you won't get any increase in torque.

    Many spindles are air cooled and because the fan the fan slows as the spindle running such spindles at low speed is to risk a bad overheat situation.
    Your spindle being water cooled is less prone to overheat, but if you notice it getting hot stop immediately.

    A 2.2kW spindle has a rated torque of:

    T= (24000 / 60)*2*PI /2200
    =1.14Nm

    So don't expect to drive a 10mm tool in steel, in fact without taking light cuts a 6mm tool will stall a 1.14Nm spindle.

    Craig

  4. #4
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    Re: How low can I drop my rpms on my spindle?

    Quote Originally Posted by jimskeet View Post
    Hi guys
    I have a 2.2kw water cooled spindle and my vfd is the askpower 131. I attach the manual of my vfd.
    I have been dropping it as low as 100hz which means 6000rpm. I would like to know if I can drop it lower without hurting the spindle. Say 50hz or even lower if possible?
    Only if the Spindle you have has a 3000 RPM rating which some do, it won't have any useful torque below 6,000 RPM and most don't go below 7,200=120Hz as they mostly cut at this speed, at 6,000 RPM they barely make it and have a high possibility of stalling, once you stall your spindle damage is quite possible
    Mactec54

  5. #5
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    Re: How low can I drop my rpms on my spindle?

    I want to drive 3mm tool to take light cuts on stainless. Like 0.3mm stepdown passes.
    I have run it at 6000 rpm very often.

  6. #6
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    Re: How low can I drop my rpms on my spindle?

    Hi,
    you can run 24000 rpm asynchronuos spindles slowly but they are far from their optimum.

    I was so dissapointed that my 24000 rpm spindle could not be run slowly and that it has so little torque to render it almost
    useless in steel and stainless that I made a second spindle using a direct coupled 1.8kW AC servo, 3500rpm, 6.2Nm comt, 18Nm
    overload. Works a treat in steel and stainless.

    Craig

  7. #7
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    Re: How low can I drop my rpms on my spindle?

    Thanks for the info

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