Re: Re: DC versus 3 Phase

One advantage of DC motors in spindle type applications is that you get
full torque at zero speed. The equivalent feature in AC drives is rather
expensive. If you want low speed tapping and high speed routing from the
same drive, (without gearing or variable belts) a brush type DC motor is
much less costly.

Hope this helps the discussion.

Ray


From: Greg Jackson <jackson@...>

The acceleration is also important. AC tends to have lighter weight
rotors and can speed up faster.

Typical considerations between AC and DC are not important to machine
tools. Machine tools cannot be sized closely. You need to have
considerable reserve power and will most often be using less than 10% of
what the motor can offer. Motor maintenance is not much of an issue, since
machine tools rarely run 24 hours a day. I would recommend you buy what is
cheap. These days, AC is cheaper than DC.