Abstract: This paper introduces the structure, features, and key technologies of a special CNC system used for key machining. The system uses several numerically represented key codes to describe its trajectory parameters. This method embodies a programming technique with key-machined characteristics. Practice has proven that the system has high machining accuracy, efficiency, and automation. Keywords : key machining; numerical coding; CNC; special milling machine; open system architecture 0 Introduction The development of the automobile and motorcycle industries has promoted the improvement of related machining equipment and its process design level. Although keys are an accessory of automobiles and motorcycles, their market demand is large and directly affects the security of use. Currently, it's common for the same key to open other vehicles, and its processing precision affects the quality of unlocking. Currently, key processing relies mainly on manual adjustment to match machined keys, resulting in low precision and poor system flexibility. Since there are thousands of different types of keys, relying solely on manual adjustment and memorization often leads to errors and makes it difficult to avoid repetitive issues. Therefore, developing such specialized CNC milling machines is practical. The key processing CNC milling machine introduced here uses a 3-axis stepper motor drive and an industrial PC as the control system. Two milling cutters can process keys from both sides, allowing for the processing of several keys at once to ensure uniformity and improve processing efficiency. [b][align=center]For more details, please click: Research on Specialized Milling Machine CNC Systems[/align][/b]