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What makes some electric motors loud?

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  • What makes some electric motors loud?

    I have a cheap electric chain saw grinder. The small 220volt motor is very loud. I recently bought a diamond blade ceramic tile cutting tabletop saw. The motor is very loud.

    Three phase motors are quiet as are some 220 volt motors. So what type of electic motors are these that are so loud?
    How to become a millionaire: Start out with 10 million and take up machining as a hobby!

  • #2
    brushed motor tend to be V loud due to the speed the run at to get the hp

    induction motor run slower ( unless on vfd or high frequ ) thus less noise but are bigger for the same hp

    same with cars small highly tuned( as in racing motor bike ) very noisy big low stressed quite as in Rolls Royce

    my 2 cents



    • #3
      I've wondered about the same, it's bound to be multiple sources. The ones I can think of:
      • Brushes running on the commutator
      • Sparking of the brushes
      • Bearings not preloaded enough
      • Torque ripple vibrating everything
      • Cooling air forced through the motor
      • Rotor not smooth and whipping at the air

      The interesting question is, what products use silent motors so you can steal them for your projects.....



      • #4
        I can answer that question during my life I worked in large HVAC systems

        and we had silent motors mad by the Bull company its ver easy to make a motor silent do not use ball and roller bearing these had babitt sleeve bearings with oil rings to pick up the oil

        as they floated on oil they were silent ( as far as we are discussing )

        as to the noise its because they are poorly made universal motors just junk motors but they are small and powerful

        BTW I was a stator and armature winder up to 1000hp for a time in my apprenticeship years ( it was 5 years then for a sparks )



        • #5
          I think most is commutator noise mixed with fan noise. Then there is a little more noise from vibration if it is a crummy motor.


          • #6
            This is a very interesting good question!!

            I just stripped and "BINNED" a 1/2hp motor i had bought at a garage sale a few years ago , (i buy numerous motors there if they run,) this thing looked very clean, was a USA made motor, (Prestolite-Leeson,) but was a very noisy, vibrating motor that was just not worth messing with.