CNC (Computer Numerical Control) is a manufacturing technology where machines are controlled by a computer program. The program (G-code) tells the machine exactly how to move, how fast to cut, and when to stop, allowing high precision, repeatability, and automation.
Milling is a machining process in which a rotating cutting tool removes material from a stationary workpiece to create shapes such as flat surfaces, slots, pockets, and complex contours.
CNC Milling combines both concepts: a computer-controlled milling machine that uses rotating tools to accurately shape metal, plastic, or other materials with minimal human intervention.
What is CNC and Milling?
1. What is CNC?
CNC (Computer Numerical Control)
CNC is a manufacturing technology in which machines are controlled by computers using a programmed set of instructions called G-code and M-code.
Instead of manual operation, the machine performs machining operations automatically, accurately, and repeatedly.
How CNC Works
- A part is designed using CAD software
- The design is converted into a machining program using CAM software
- The CNC machine reads the program
- Motors move the machine axes according to the code
- The cutting tool removes material automatically
Main Components of a CNC System
1. Input Device
- Keyboard
- USB
- Network connection
2. Machine Control Unit (MCU)
- Brain of the CNC machine
- Interprets G-code and M-code
3. Drive System
- Servo motors / stepper motors
- Ball screws
4. Feedback System
- Encoders
- Scales for position accuracy
5. Machine Tool
- CNC lathe
- CNC milling machine
- CNC machining center
Types of CNC Machines
- CNC Lathe
- CNC Milling Machine
- CNC Machining Center (VMC / HMC)
- CNC Router
- CNC EDM
Advantages of CNC
✔ High accuracy and repeatability
✔ Mass production capability
✔ Complex shapes possible
✔ Reduced human error
✔ High productivity
Limitations of CNC
❌ High initial cost
❌ Skilled programming required
❌ Maintenance cost
2. What is Milling?
Milling
Milling is a machining process where material is removed from a workpiece using a rotating multi-point cutting tool.
Unlike turning:
- Tool rotates
- Workpiece is usually stationary
Principle of Milling
- Cutter rotates at high speed
- Workpiece is fed against the cutter
- Material is removed in the form of chips
Main Motions in Milling
- Cutting motion – rotation of cutter
- Feed motion – movement of workpiece/tool
- Depth of cut – thickness removed
Types of Milling Machines
Manual Milling Machines
- Horizontal milling machine
- Vertical milling machine
- Universal milling machine
CNC Milling Machines
- 3-axis milling machine
- 4-axis milling machine
- 5-axis milling machine
Types of Milling Operations
- Plain milling
- Face milling
- End milling
- Slot milling
- Angular milling
- Form milling
- Gang milling
Milling Cutters
- End mill
- Face mill
- Slab cutter
- Side & face cutter
- T-slot cutter
- Angle cutter
Milling Parameters
- Cutting speed
- Feed rate
- Depth of cut
Applications of Milling
- Flat surfaces
- Slots and keyways
- Gears
- Pockets
- Complex contours
3. CNC Milling
What is CNC Milling?
CNC milling combines CNC technology with the milling process, allowing fully automated, precise, and complex machining.
CNC Milling Features
- Computer-controlled movement
- Multi-axis machining
- High surface finish
- CAD/CAM integration
CNC Milling vs Conventional Milling
| Feature | Conventional Milling | CNC Milling |
|---|---|---|
| Control | Manual | Computer-controlled |
| Accuracy | Medium | Very high |
| Productivity | Low | High |
| Skill dependence | High | Programming-based |
Real-Life Applications of CNC Milling
- Aerospace components
- Automotive parts
- Mold & die manufacturing
- Medical implants
- Precision machine parts
In Simple Words:
- CNC → Computer controls the machine
- Milling → Material removal using rotating cutter
- CNC Milling → Computer-controlled milling for high precision
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