Development of a hierarchical computer numerical control milling machine control unit using low-end PIC microcontrollers

The acquisition of automated manufacturing equipment in developing nations can be expensive. Hence, this article presents the development of a computer numerical control milling machine’s control unit using low-end PIC microcontrollers. The design employs a hierarchy of five low-end PIC microcontrollers connected to a PC. A single master PIC acts as a link between a PC and four slave microcontrollers via a RS232 serial port. One slave PIC is interfaced with the electronics of the spindle drive. The three remaining slave PICs are interfaced with the electronics of the x-, y- and z-axis drives. The low-cost milling machine’s control unit has been constructed and tested. A circle–diamond–square test confirms the functionality of the machine and demonstrates that it does not accumulate error along a milled profile path.