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简体中文 A CNC machine outil relies on five matched core systems to complete automatic machining. Have you ever wondered what happens after pressing Cycle Start?
When you press the green CYCLE START button on the operation panel, the machine runs according to preset programs.
This automatic movement relies on coordinated work of internal components. Some parts read machining programs, some convert commands into electric signals, some drive motor operation, some detect position data, and some control coolant and tool change actions.
These components form five core systems of a CNC machine tool.
Understanding the five systems helps operators judge common machine faults quickly, and build clear learning logic for advanced machining skills.
System 1: CNC Controller
The CNC controller is the core control unit of a CNC machine tool.
Its working steps are as follows:
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Program Reading: Read NC programs from memory, CF card or network port
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Code Decoding: Convert G code, M code into identifiable internal system data
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Interpolation Calculation: Calculate tiny moving distance of each axis per unit time, and split one whole movement into countless small steps
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Command Output: Send axis movement electric signals to servo system
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Auxiliary Control: Control spindle speed, tool change, coolant switch and other M-code functions
The CNC controller receives real-time position feedback, and corrects movement deviation during operation.
The machine operation panel and display screen are human-computer interaction ports for program input, parameter modification and coordinate checking.
System 2: Servo System
The CNC controller sends displacement commands, and the servo system turns electric commands into real mechanical movement.
A complete servo system includes two parts:
Servo Drive
It amplifies control signals from CNC controller, and converts signals into electric power to drive motors. It acts as a precision power amplifier.
Servo Motor
It converts electric energy into mechanical rotation. Different from common motors, a servo motor is equipped with built-in encoder. It controls rotation angle accurately, and starts or stops within milliseconds.
One CNC machine tool is equipped with multiple servo sets:
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X/Y/Z axis feed servo: Control displacement of cutter and worktable
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Spindle servo: Control rotation speed of machining cutter
Feed servo focuses on position accuracy, while spindle servo keeps stable rotating speed under cutting force. A 5-axis CNC machine tool is equipped with 5 to 6 servo sets to control A/B/C rotary axes.
System 3: Machine Mechanical Body
Servo motors generate rotation force, and the mechanical body converts rotation into accurate linear and positioning movement for machining.
Key components of mechanical body:
Machine Bed
It is the base frame made of cast iron or welded steel plate. High-rigidity machine bed guarantees basic machining accuracy and vibration resistance.
Linear Guideway
It guides linear movement of worktable and spindle head. Rolling linear guideway is widely used for low friction and fast response. Hydrostatic guideway is adopted on high-precision machine tools for nearly zero friction.
Ball Screw
It converts motor rotation into worktable linear movement. Internal steel balls reduce friction, and support micron-level positioning accuracy.
Spindle
It clamps cutters and runs at high speed. Spindle runout value decides machining accuracy, and maximum spindle speed decides cutting efficiency. High-speed spindle can reach 40000rpm or above.
System 4: Detection Feedback System
This system is essential for closed-loop precision control.
It measures real-time moving position, and feeds back data to CNC controller to correct movement error automatically.
The closed-loop control logic runs as follows: send command → execute movement → detect actual position → compare error → adjust command.
Two common detection parts are applied on CNC machine tools:
Rotary Encoder
It is installed on servo motor shaft to test motor rotation angle. It belongs to semi-closed loop control with small transmission error, and positioning accuracy reaches ±0.005~0.01mm for common machining centers.
Linear Scale
It is mounted beside guideway to test direct worktable displacement. It eliminates screw transmission error, belongs to full closed-loop control, and reaches accuracy up to ±0.001mm for high-precision 5-axis machine tools.
System 5: Auxiliary Function System
The above four systems ensure accurate cutter movement, and the auxiliary system supports complete machining work.
Automatic Tool Changer (ATC)
It is a core feature of machining centers. Tool magazine stores multiple cutters, and manipulator finishes tool change within several seconds. Tool magazine capacity ranges from 8 cutters to more than 100 cutters.
Cooling System
It reduces cutting heat, lubricates cutter surface and removes metal chips. Common types include external cooling and spindle internal cooling.
Pneumatic & Hydraulic System
It provides clamping force for workpiece fixing, tool change and spindle cutter release.
Programmable Logic Controller (PLC)
CNC controller controls axis movement, while built-in PLC manages switch actions including tool change, coolant switch and door interlock. PLC cooperates with CNC controller to form complete machine control logic.
Signal Flow of Five Core Systems
The whole machining logic forms a complete signal chain:
This is the whole closed-loop working process after pressing Cycle Start, which runs thousands of times per second.
Sommaire
The five core systems of a CNC machine tool work cooperatively. CNC controller sends machining commands, servo system provides power drive, mechanical body finishes cutting positioning, detection feedback system calibrates machining accuracy, and auxiliary system supports matched operation. Joint operation of the five systems realizes full-automatic machining of CNC machine tools.
