Re: [CAD_CAM_EDM_DRO] Spindle power VS Motor power

----- Original Message -----
From: "Jon Elson" <elson@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Thursday, May 22, 2003 1:21 PM
Subject: Re: [CAD_CAM_EDM_DRO] Spindle power VS Motor power


>
>
> fortino wrote:
>
> >Jon,
> >
> >Ok. I see your points. But it still doesn't answer the question. The
reason
> >I ask this question is
> >that there is a friend of mine who has a big CNC milling with a dead
> >controller. The spindle is 20 kW.
> >So, If I put like 200 watts motor for each axis. Would the spindle be
> >considered too much?
> >
> >I suspect there are general rules that would give me estimate that the
> >spindle should be A times of motor
> >axis.
> >
> >
> No, this is what I was trying to tell you, there is no simple spindle
> power x constant = axis power.
>
> The weight of the machine table and the acceleration and max velocity
> are very major
> components of the calculation. The size of cutting tools and the speed
> range are also
> very important. For instance, if this is a high-speed machining center,
> that could be
> 20 KW at 25,000 RPM, in which case the tool forces on the work will be
> small, but the
> need for very rapid feedrates of the table will be needed. Here, a very
> high peak
> acceleration is needed, but the average force will be small. If this is
> a huge, geared-down
> machine, designed to use 8" cutters at 100 RPM, 20 KW translates into
> huge cutting forces
> that need to be counteracted by the axes. Here, the feedrates will be
> low, but the
> average torque from the motor may be quite high.
>
> Anyway, just to throw out random numbers, with a 20 KW spindle, I would
> thing a large
> CNC mill would use servo motors with at least a 1-2 KW continuous
> rating, and probably
> a 5-10 KW peak rating. Most modern machines use rapid feedrates of at
> least 400 IPM,
> and many exceed 1000 IPM. This takes some pretty strong motors, just
> for acceleration,
> regardless of spindle power.
>
> Jon
>
>
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