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Thread: Spindle fail

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  1. #1
    Member
    Join Date
    Feb 2020
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    10

    Spindle fail

    Hello.

    I have a 3.7 KW 220V 1 phase input VFD and a 3Kw Spindle. Both are from China and are very cheap.
    They were running fine even if sometimes I had to unplug and plug again the energy to make the spindle start for some reason. I usually turn off the energy supply of my garage at the end of the day. While I was doing a full slot in aluminium the spindle stalled, before that it started to lose speed (RPM). With no load I was still able to run it.

    Days later I tried to make a simple operation and the spindle was cutting well for the first few minutes but then it stalled again with current draw that was no over 6A; max current draw should be 12A. After that it started to run alone at around 25Hz (maybe is related to the fact that is the home line frequency/number of poles of the motor) form the VFD and with a 5A current draw even with no load. Even if I switch the control mode to potentiometer instead of 0 10v nothing change and regardless of the potentiometer command the frequency remains 25Hz.

    Also, the spindle usually make a strange buzzing sound when powered but not rotating. The motor cable is shielded and the shielding is grounded. I also bought an input EMI filter and I will install it soon. I was also thinking to buy a DC or AC reactor even if maybe it is useless with this kind of load.
    I checked the cable with multimeter and the wires are well connected.
    I tried to run the spindle with the motor unplugged and the VFD had the exact same output. I also tried a full reset and obtained nothing.

    I also had some random strange noise coming from the motor for few seconds.

    Is there a way to tell for sure if the spindle or the VFD are broken and which one of them?

    The chineese customer service guy was very kind in the past but for some reason now he is not answering to my question.


    Thanks.

  2. #2
    Member
    Join Date
    Jan 2005
    Posts
    11651

    Re: Spindle fail

    Quote Originally Posted by StefanoPrato View Post
    Hello.

    I have a 3.7 KW 220V 1 phase input VFD and a 3Kw Spindle. Both are from China and are very cheap.
    They were running fine even if sometimes I had to unplug and plug again the energy to make the spindle start for some reason. I usually turn off the energy supply of my garage at the end of the day. While I was doing a full slot in aluminium the spindle stalled, before that it started to lose speed (RPM). With no load I was still able to run it.

    Days later I tried to make a simple operation and the spindle was cutting well for the first few minutes but then it stalled again with current draw that was no over 6A; max current draw should be 12A. After that it started to run alone at around 25Hz (maybe is related to the fact that is the home line frequency/number of poles of the motor) form the VFD and with a 5A current draw even with no load. Even if I switch the control mode to potentiometer instead of 0 10v nothing change and regardless of the potentiometer command the frequency remains 25Hz.

    Also, the spindle usually make a strange buzzing sound when powered but not rotating. The motor cable is shielded and the shielding is grounded. I also bought an input EMI filter and I will install it soon. I was also thinking to buy a DC or AC reactor even if maybe it is useless with this kind of load.
    I checked the cable with multimeter and the wires are well connected.
    I tried to run the spindle with the motor unplugged and the VFD had the exact same output. I also tried a full reset and obtained nothing.

    I also had some random strange noise coming from the motor for few seconds.

    Is there a way to tell for sure if the spindle or the VFD are broken and which one of them?

    The chineese customer service guy was very kind in the past but for some reason now he is not answering to my question.


    Thanks.
    It sounds like you may have damaged both, your VFD Drive parameters have not been set correct if you can run at 25Hz the minimum a water cooled high speed spindle can be used at is 100Hz and 120Hz is the safest for cutting Air cooled will be higher than this, so you where in the damage zone for damaging both your spindle and VFD Drive

    With what you said that you where unplugging and plugging it back in, this is also something that you must not do, this can and will damage the VFD Drive also
    Mactec54

  3. #3
    Member
    Join Date
    Feb 2020
    Posts
    10

    Re: Spindle fail

    Hi,

    Actually I unplugged it always when the VFD was not in run mode, I never unplugged it while running even if 0Hz. Also I solved the problem with the 25Hz thing: a disconnected jumper on the board. I noticed it when I gave a punch to the chassis of the VFD for frustration and the spindle started to spin, this made me understand that there was something "mechanical" not working well.

    Now I still have to understand why in the first place the spindle stalled during operation; I don't really thing this is related to the jumper.

    The only thing that come to my mind is that once for about 20 minutes the spindle worked with the watercooling radiator off and it was pretty hot but still touchable (water was hot but flowing).

    Thanks for the reply.

  4. #4
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    Join Date
    Jan 2005
    Posts
    11651

    Re: Spindle fail

    Quote Originally Posted by StefanoPrato View Post
    Hi,

    Actually I unplugged it always when the VFD was not in run mode, I never unplugged it while running even if 0Hz. Also I solved the problem with the 25Hz thing: a disconnected jumper on the board. I noticed it when I gave a punch to the chassis of the VFD for frustration and the spindle started to spin, this made me understand that there was something "mechanical" not working well.

    Now I still have to understand why in the first place the spindle stalled during operation; I don't really thing this is related to the jumper.

    The only thing that come to my mind is that once for about 20 minutes the spindle worked with the water cooling radiator off and it was pretty hot but still touchable (water was hot but flowing).

    Thanks for the reply.
    No you never had a minimum safe speed set, if you have a minimum speed set, then the spindle will never run below that Parameter setting

    You can not Plug or unplug a VFD Drive at any time this can cause damage, VFD Drives need to be power up by a Switch / Breaker or Contactor, it should never be power up by plugging it in

    Most good manuals will have this in them
    Mactec54

  5. #5
    Member
    Join Date
    Feb 2020
    Posts
    10

    Re: Spindle fail

    The VFD came with a good manual regardless of chinese reputation, I probably failed to read that passage. Actually I just bought what I'm pretty sure is a breaker. In Italian we call them "interruttori magnetotermici" which translated in English is "magnetothermal; I think is what you call "breaker".

    Actually I have repeated this process of unplugging the VFD many times so if this is really a source of problem it may be the culprit for the fail.

    Thanks for the hint.

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