CNC stands for Computer Numerical Control. It refers to the automation of machine tools using precisely programmed commands encoded on a storage medium. The instructions control the movement of tools and machinery, replacing manual operation.
Definition
Computer Numerical Control (CNC) is a system where the functions and motions of a machine tool are controlled by a program containing coded alphanumeric data.
CNC controls:
- Motion of tool/workpiece
- Input parameters like speed, feed, depth of cut
- Machine functions like spindle ON/OFF, coolant ON/OFF, etc.
Basic Components of CNC System
1️⃣ Input Device
Used to input the part program into the CNC machine.
Common devices:
- USB drive
- Ethernet connection
- Punched tape (older systems)
- DNC (Direct Numerical Control) interface
2️⃣ Machine Control Unit (MCU)
Acts as the brain of the CNC system.
Consists of:
- DPU (Data Processing Unit): Processes part program
- CLU (Control Loop Unit): Controls drive motors, processes feedback
- Controls tool position, speed, acceleration, and error correction.
3️⃣ Machine Tool
- Performs the actual cutting or machining.
- Can be a CNC lathe, milling machine, laser cutter, etc.
- Receives motion via motors and drive systems.
4️⃣ Driving System
Composed of:
- Drive motors (Servo, Stepper, Linear)
- Amplifiers and ball lead screws
- Converts control signals to precise mechanical motion.
5️⃣ Feedback Devices
Ensure accuracy and precision by sending real-time data to the MCU.
- Position feedback devices – track position of tool/table
- Velocity feedback devices – monitor speed of spindle/tool
6️⃣ Display Unit
Interface between machine and operator.
- Shows spindle speed, feed rate, tool path
- Displays errors or warnings
- Used for simulation, diagnostics, and part verification