The differences between CNC and PLC can be seen as a competition for the “strongest brain” in the automation era.
On the assembly line of smart factories, CNC machines are carving metal parts with a precision of 0.001mm, while the PLC system coordinates the operation of robotic arms, conveyor belts, and inspection instruments in real-time. How do these “golden partners” in industrial control fulfill their respective roles? Let’s first look at the definitions of CNC and PLC.
CNC (Computer Numerical Control System) is the core technology that drives machinery to perform high-precision, automated processing through pre-programmed digital instructions (such as G-code/M-code).
PLC(Programmable Logic Controller) is a programmable control device designed specifically for industrial environments, achieving automated management of machinery or production processes by executing logical operations, sequential control, and other instructions.
Next, let’s explore the differences between CNC and PLC.
01Essential Positioning Differences
The essential positioning differences between CNC and PLC
02Core Function Comparison
1. Control Capability
·CNC：
·Precision Motion Control：Achieves 5-axis linkage interpolation calculations with a positioning accuracy of 0.001mm
·Dynamic Compensation：Real-time calibration of tool wear and thermal deformation errors
·PLC：
·Logical Sequential Control：Processes discrete signals (such as starting/stopping conveyor belts, opening/closing valves)
·Scalable Expansion：Supports thousands of I/O modules, coordinating clusters of production line equipment
2. Real-time Requirements
The real-time requirements of CNC and PLC
03Programming and System Architecture
The programming and system architecture of CNC and PLC
04Typical Application Scenarios
The typical application scenarios of CNC and PLC
05Trends in Technology Integration
1.Hardware Integration：
·Modern CNC integrates PLC modules for auxiliary control of machine tools
·High-end PLCs support soft CNC functions
2.Collaboration with Industry 4.0：
·CNC generates processing simulation data streams
·PLC constructs virtual production line logical models
06CNC and PLC Selection Guide
1.Select Based on Core Requirements
·Precision Trajectory Control→ Choose CNC ·Need to achieveMulti-axis Linkage Processing(≥3 axes) ·RequirePositioning Accuracy≤0.01mm(e.g., aerospace impeller processing) ·Typical cases: five-axis milling of complex surfaces, turning-milling composite processing
·Device Logic Coordination→ Choose PLC ·ControlI/O Points ≥ 200in production lines ·ProcessSensor Interlocks, Sequential Processes(e.g., filling line start-stop logic) ·Typical cases: synchronous automotive welding lines, warehouse logistics sorting
2.Refine Based on Industry Scenarios
The CNC and PLC selection guide
In the field of smart manufacturing, CNC and PLC are like the “precision brain” and “coordinating hub”: CNC focuses on μm-level motion control (such as five-axis processing), while PLC excels in coordinating thousands of logical points (such as production line scheduling). The differences are significant—CNC pursues trajectory accuracy at the 0.1ms level, while PLC emphasizes timing control in the range of 1-100ms; the former uses G-code to plan tool paths, while the latter manages device interlocks with ladder diagrams. In modern smart factories, 60% of production lines adopt a CNC + PLC integrated solution, achieving a win-win of “precision processing + intelligent management”.