The CNC wiring diagram shown in this page is created using Mechanical Desktop Version 6 and the wiring digram is showing you the very basic CNC wiring circuit diagram. Basically this CNC machine controlled by the CNC machine controller which consists of a CNC servo drive to control all the electrical parts such as axes servo motors, coolant motor, hydraulic motor, spindle motor, lubrication motor, inverter, working light, DC contactors and DC reversing contactor. The CNC controller panel is located in front of the CNC machine and not shown on this CNC circuit diagram.
The type of CNC servo drive shown on the diagram is 2 in 1 CNC servo drive which consists of servo drive and programming logic control section (PLC). The PLC section has some input and output (I/O). The electrical parts which will generate the signal such as limit switches, sensors, button, emergency switch and etc will be connected to the PLC input to be processed and the PLC will turn on some of the related PLC output. Those electrical parts that will receive the instruction from PLC such as motor, light, solenoid valve, contactors and etc will be connected to the PLC output. The output itself can be act as an input or signal to the PLC but the input never be act as an output.
Each axis servo motor and its encoder are connected directly to the CNC servo drive to ensure the CNC servo drive gain fully control on each servo motor in order to synchronize the movement of the mechanical parts especially the movement of machine tool on the raw material when machining the part. The coolant motor, hydraulic motor, lubrication motor and working light will be connected to DC contactors and each contactor will be connected to the servo drive PLC output.
The rotation of the spindle motor whether clock-wise (CW) or counter-clock-wise (CCW) is controlled by the DC reverse contactor when instructed by the servo drive. The encoder of the spindle motor is connected to inverter and servo drive to ensure to machine tool can do rigid tapping. In fact, you can connect the output spindle CW and the output spindle CCW on the servo drive directly to the inverter CW and CCW respectively to control the spindle rotation direction without using DC reversing contactor.
The limit switches are used to determine the homing position and the maximum travel distance of each axis. All the limit switches must be always in close position or normally close (N/C) as shown on the circuit diagram.