DC motor means direct motor and which has two kinds of winding, the armature and field winding. And this kind of  motor is used in almost all the cnc milling machine, cnc lathe.

In 1900 a turning operation on a bar of steel mainly to cutting tool improvements, the time taken to machine a bar of the same dimensions was down to 1.2min. Today, a time of half the 1970 value is possible, with the added bonus that if a facing-off operation is required on a bar, a constant surface speed could be used. With DC motors, the trend at present is to use Thyristorflriac controls to be fitted to machine tools. Asynchronous motors with variac controls which were fitted to the older machine tools could only achieve a speed range of 1:4.

By using gearboxes the range could be enlarged to over 10 speed ranges in a geometric progression. The problem with the older system was that even with the highest speed selected, the range was not great enough to optimise the new speeds required by the latest cutting tools and to obtain a constant surface speed requirement. DC motors allow the advantages of higher speeds available with a better ratio between the lowest and highest speeds and this simplifies the gearbox requirements, whilst their high torque characteristics enable them to turn large diameter bars at low surface speeds.

And in almost all the cnc machining center, cnc gantry, this DC motor is applied. And any one can have a look of the DC motor applied in Datan machine :http://www.cncdatan.com/Products/3.html