Re: [CAD_CAM_EDM_DRO] Servo Question

mmurray701 wrote:

>I'm considering converting from steppers to servos (DC). After
>looking at some specs it seems that continious stall torque is far
>lower than peak torque. One motor I was looking at has a continious
>stall torque of 3.313 lb-in, and peak torque is 300 lb-in! Why is
>there such a huge difference? Can somebody give me a defenition of
>each?
>
>
>

Are you sure about those numbers? a 100:1 difference is a bit unusual.
The numbers
I am more accustomed to are in the range of 4:1 up to 10:1. The
continuous stall torque
is the torque the motor can exert indefinitely, and it causes gradual
heating. The peak
torque is the maximum torque the motor can produce for a short interval,
often only
a fraction of a second. This is generally limited by the resistance of
the permanent
magnets to demagnetization from armature reaction.

>I know approximatly how much torque I want on the leadscrew, which
>motor torque value do I use to figure out pulley ratios? Please help
>me out. Thanks.
>
>

If your torque requirement is for the steady-state cutting forces needed
to drive the
work into the cutting tool, then the continuous number would apply. If
the torque
requirement is for the peak load during acceleration to rapid feed
rates, then the peak
torque value would be the spec.

By the way, 300 In-Lb is a HUGE amount of torque. You will likely need
massive
belts or couplings to carry this torque without breaking.

Jon