Introduction to CNC Programming
Introduction to CNC Programming
Introduction to CNC Programming
CNC stands for Computer Numerical Control.
It is the method of controlling a machine tool (like a lathe, milling
machine, router, grinder) using a computer program written in a
special language called G-code.
🔧 What is CNC
Programming?
CNC programming is the process of writing instructions
(codes) that tell the CNC machine:
- Where
to move
- How
fast to move
- What
path to follow
- What
operation to perform (cutting, drilling, turning, milling, etc.)
These instructions are typed as a sequence of blocks (lines)
and executed by the machine.
📜 Structure of a CNC
Program
A CNC program is made of many blocks/lines, each
starting with an N-number.
Example:
N10 G21
N20 G90
N30 G00 X0 Z2
N40 G01 X-20 Z-50 F0.2
N50 M30
🔤 Two Main Types of Codes
1. G-Codes (Preparatory Codes)
Tell the machine what motion or cycle to perform.
Examples:
- G00
– Rapid movement
- G01
– Linear cutting
- G02/G03
– Circular cutting
- G71
– Rough turning cycle
- G76
– Threading cycle
2. M-Codes (Miscellaneous Codes)
Control machine functions.
Examples:
- M03
– Spindle ON (clockwise)
- M05
– Spindle OFF
- M08
– Coolant ON
- M09
– Coolant OFF
- M30
– Program end and reset
🗂 Types of CNC Machines
Where Programming is Used
- CNC
Turning Centre (Lathe)
- CNC
Machining Centre (Milling)
- CNC
Router
- CNC
Plasma/Laser Cutting Machine
- CNC
Grinding Machine
📐 Coordinate System
CNC machines work with X, Y, Z axes.
- Turning
– X and Z axis mainly
- Milling
– X, Y, Z axes
- X
= Diameter control (in lathes)
- Z
= Length direction
🧮 Absolute vs Incremental
Programming
- G90
– Absolute mode
All positions measured from zero point. - G91
– Incremental mode
Positions measured from previous point.
🪛 Basic CNC Program
Example (Turning)
N10 G21 (Metric
mode)
N20 G90
(Absolute)
N30 G00 X50 Z5 (Rapid to start position)
N40 G01 X20 F0.25
(Cutting)
N50 G01 Z-60
N60 G00 X100 Z100
(Return)
N70 M30 (End)
✔ Advantages of CNC
- High
accuracy
- Repeatability
- Faster
production
- Complex
shapes easily made
- Reduces
human error
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