Vertical machining centers are the most common type of machine tool sold. They are also referred to as CNC mills, VMCs and milling machines. Machining centers are a staple in any machine shop or tool room. With VMCs, the spindle is located in the vertical position. Most machines are 3-axis type (X,Y,Z). Other types of machining centers include, horizontal with the spindle in the horizontal position, 5 axis used to cut complex parts, and high speed mills with spindle speeds as high as 40,000 rpm.