This document provides an introduction to CNC turning. It discusses the parts of a CNC machine, including the programming unit, machine control unit, and machine tool. It also covers fundamental CNC turning concepts like G-codes for linear and circular movements, M-codes for machine functions, and modal and non-modal G-codes. An example CNC turning program is included to demonstrate how G-codes are written to machine different shapes and features on a workpiece.
4. Ways of Turning
Conventional or Traditional
Numerical Control (NC)
Computer Numerical Control (CNC)
5. Difficulties with Conventional System
Complex shapes are difficult to machine
Depends on the human skill
Frequent & repeated measurements are required
Difficult to achieve consistency in product quality
High Changeover Time
Less productive hours
More scrap is generated
6. Parts of NC/CNC Machine
ProgrammingUnit
Machine ControlUnit
NC
Machine ToolUnit
CNC
8. Machine Control Unit
Tape Reader
Data Buffer
Signal Output Channels to Machine Tool
Feedback channels from the Machine Tool
9. Machine Tool
Structure
Extra Rigid
Easy chip disposal System, eg: Use of Slant Bed
Thermal Resistant
Drives
AC Induction motors
DC motors
13. M-Codes
M00: Program Stop, starts again when cycle start is pressed
M01: Optional Stop
M02: Program Reset
M30: Program Reset & Rewind
M03: Spindle Start in Clockwise Direction
M04: Spindle Start in Anti Clockwise Direction
M05: Spindle Stop
M06: Command Tool Change
M07/M08: Coolant ON
M09: Coolant OFF
M10: Chuck Open
M11: Chuck Close
M13: Spindle ON (CW) & Coolant on
M14: Spindle ON (CCW) & Coolant on
M25: Tailstock Quill Extend
M26: Tailstock Quill Retract
M98: Subprogram Call
M99: Return to Main Program
14. Modal & Non Modal G-Codes
The G-Codes whose effect continue in the
program once specified until it is cancelled or
overridden by another code are known as
“MODAL”. Eg: G00, G01, G02, G03 etc.
The G-Codes whose effect only in the block where
it is defined are known as Non-Modal Codes. Eg:
G04