.CNC mills generally start with a block (blank) of material and removes that material until only the desired part is left. A CAD file gets translated into G-code (or similar code). This code is then uploaded to the CNC mill, where it uses a program to control its spindle in a three-axis system (X, Y and Z). The code contains the coordinates for the part and the speed at which the spindle should spin. The CNC mill follows code in order and, once finished, the part has been cut out from the blank.