Basic of cnc programming | G codes and M codes

This is the basic of CNC Programming .Here you will get a complete idea about the programming for CNC machine.Here you will learn about the codes,defining part of the program,Operation part of the program and closing part of the program.You will learn about some simple example of programming.

Basic of CNC programming is to learn about G codes ,M codes and all the steps.It is to learn about all steps of a program to complete a machining process.

Basic of cnc programming codes

Language of CNC machines

G code
M code

What is G code..?

CNC machine language which control the movement of axis /Tools.

What is m code..?

CNC machine language which control the machine function.

Here we are going to learn about Basic programming of FANUC (Oi-TB)and SIEMENS(802d/802dSL/828d).

Siemens G code list-802d

Codes	Function
G00	Linear interpolation at rapid traverse rate
G01	Linear interpolation at feed rate
G02	Circular interpolation clockwise
G03	Circular interpolation counter clockwise
G04	Dwell time
G18	Z,X-Plane(Standard turning)
G33	Thread cutting with constant lead
G40	Tool radius compensation off
G41	Tool radius compensation left of contour
G42	Tool radius compensation right of contour
G53	Settable work- offset–Non- modal skipping
G54	1st settable work offset
G55	2nd settable work offset
G56	3rd settable work offset
G57	4th settable work offset
G58	5th settable work offset
G59	6th settable work offset
G71	Metric dimension data input
G90	Absolute dimension data input
G91	Incremental dimension data input
G95	Feed rate F in mm/Spindle revolutions

G codes

Siemens M code list-802d

Codes	Functions
M00	Programmed stop
M01	Optional stop
M02	End of the program with return to program start
M03	Clockwise rotation of spindle
M04	Counter clockwise rotation of spindle
M05	Spindle stop
M08	Coolant ON
M09	Coolant OFF
M30	End of program(as M02)

M codes

Fanuc G codes-Series Oi-TB

Codes	Function
G00	Rapid traverse
G01	Linear interpolation
G02	Circular interpolation-CW
G03	Circular interpolation-CCW
G04	Dwell command
G10	Programming data input offset
G20	Outer/inner dia cutting cycle
G21	Thread cutting cycle
G24	End face turning cycle
G27	Reference point return check
G28	Reference point return
G33	Threading
G40	Tool nose radius comp. Cancel
G41	Tool nose radius comp.Left
G42	Tool nose radius comp.right
G53	Cancel work offset
G54	Work coordinate system 1 (optional)
G55	Work coordinate system 2 (optional)
G56	Work coordinate system 3 (optional)
G57	Work coordinate system 4 (optional)
G58	Work coordinate system 5 (optional)
G59	Work coordinate system 6 (optional)
G65	Macro calling
G70	Inch programming(Optional)
G71	Metric programming (optional)
G72	Finishing cycle( optional)
G73	Stock removal in turning(Optional)
G74	Stock removal n facing(Optional)
G75	Pattern repeating(Optional)
G76	Peck drilling in z axis (Optional)
G77	Grooving in X axis (Optional)
G78	multiple thread cutting cycle(Optional)
G90	Absolute programming
G91	Incremental programming
G92	Position preset & spindle speed clamp in css mode during S word.
G94	Per minute feed
G95	Per revolution feed
G96	Constant surface speed
G97	Direct RPM programming

Fanuc M codes-Oi-TB

Codes	Function
M00	Program stop
M01	Optional stop
M02	End program
M03	Spindle ccw
M04	Spindle cw
M05	spindle stop
M08	Coolant ON
M09	Coolant OFF
M10	Chuck /Collet Close
M11	Chuck / Collet Open
M12	Low chucking pressure(Optional)
M13	High chucking pressure(Optional)
M18	Tailstock swing IN(Optional)
M19	Tailstock swing OUT(Optional)
M20	Quill LEFT(Optional)
M21	Quill RIGHT(Optiional)
M22	Turret Index reverse
M23	Turret index Forward
M24	Steady rest-1 Open(Optional)
M25	Steady rest-1 Close(Optional)
M26	Steady rest-2 Open(Optional)
M27	Steady rest-2 Close(Optional)
M28	parts catcher open(Optional)
M29	Parts catcher Closr(Optional)
M30	Program reset and rewind
M36	Cancel M37
M37	Ignore upto speed feedhold signal
M40	Dry run spindle OFF
M41	Dry run spindle ON
M42	Dry run cancel
M48	Cancel M49
M49	Feed rate and Spindle speed overrides inactive
M62	Spindle Hold OFF
M63	Spindle Hold ON
M76	Low quill pressure ON(Optional)
M77	Low quill pressure OFF(Optional)
M78	Select quill zero pressure(Optional)
M90	In position check ON
M91	In position check OFF
M92	Soft jaw boring
M98	Sub program call
M99	Sub program end

Programming systems

There are two types of programming mode used in CNC.

Absolute
Incremental

Incremental progamming mode(G91)

This is the programming mode where the movement (tool/bed/spindle) based on its last(Current) position.

Absolute progamming mode(G90)

This is the programming mode where all the movement measures from Origin point.

Difference between absolute and incremental programming in CNC

Incremental Dimension

Absolute dimension

CNC Positioning System

Point To point
Continuous path(contouring)

Point to point Positioning

Positioning(tool/spindle/Bed) from one coordinate(X,Y) to another to perform operation like drilling,Boring,reaming,taping..etc.

Continuous path(contouring)

The cutting tool travel from one point to another in Contact with work piece .Example- Turning .Milling

Zero Point Setting

Zero point can be set by any one method.

Operator
Manually by program
Work coordinate

What is work offset in CNC?

This is also called work coordinate.This method is used to set zero point of the machine.Example- G54 X_ Z_.This is for master tool only.For other tool we need to set the tool geometry.

How to set work offset in CNC?

Practical of Work offset setting.-Touch the tool tip on face of raw material/workpiece and go to work offset G54 and set the Z value 0.0.Again touch the tool tip on OD of the work piece and set the X value .That is OD value.

What is Tool geometry offset in CNC?

This is the work offset for individual tool.Work offset required for other tool to perform the different operation.

What is Tool wear offset in CNC?

This offset is used to compensate tool wear.For example if there is 0.1mm of material remain after finishing cut.Then we need to input -0.1 in tool wear section and again to run the finishing cut program to remove remain material.

Interpolation

This method is the movement of Cutting tool from one point to another.

Linear
Circular
Helical
Parabolic
Cubic

Linear Interpolation(G00/G01)

In this method the cutting tool move in a straight line.

Circular Interpolation(G02/G03)

In this method the cutting tool moves as circle or arc.This is of two types.Clockwise and counter clockwise

Block(CNC information)

Its consists of 5 word written in Horizontal line.This is recognized by MCU((Machine control Unit).

How to cnc programming

Basic of cnc programming-Its contain all the steps of a CNC program

Step-1 : `DATUM SETTING`

Example:-

G00 G54 G90 G95 X_ Z_;

Step-2 : ^{TOOL CALL}

Example;-

T1 D1;

Step-3 : Spindle/Chuck-RPM & Direction

Example:-

M03 S90 ;

Step-4 : Safety Distance

Bring the Tool to a Safety Distance

Step-5 : Main operation

Example:-Turning/Facing/Grooving/Chamfer/Radius

G01 X_ Y_;

Step-6 : Safety Distance

Return the tool to a safety distance.

Step-7 : Spindle /Program Stop

Example:- M05 M30;

CNC programming example-fanuc(Lathe)

O0001(PLAIN TURNING)-Fanuc
N1; Sequence number
T0; Tool wear cancel
G40; Cancelling G41 & G42
G28 U0 W0; Home position
G54; Work coordinate
G92 S1000 ; Limiting speed
G95 F0.2 T0101; Feed & Tool
G96 S250 M04; Cutting speed & Spindle Rotation
G00 Z 3.0; Safety distance for Z axis.-Rapid
G00 X 56.0; Safety distance for X axis-Rapid
G1 X 50.0 M08; Turning operation & Coolant ON
G01 Z -40; Turning Operation.
G1 X 56.0; After turning operation tool will return to safety distance in feed.
G00 X 200 M09; Return to safety distance in Rapid & coolant OFF
T0;
G28 U0 W0; Return to home position
M01; Optional stop
M30; Program reset

Basic of CNC programming example-Siemens(Lathe)

G0 G54 G90 G94 X120 Z2; Datum setting & rapid movement of a tool to a safety distance X120 and Z2
T1 D1 ; Tool Selection
M03 S90 ; Speed and direction
G0 X60 Z2 ; Safety distance
G1 X50 Z0 F0.3; Starting point & feed
G1 X50 Z-220; Turning
G1 X80 Z-220; Turning
G1 X80 Z-565; Turning & end point
G1 X100 F0.4 ; Tool safety
G0 X120; safety distance
G0 Z2; Safety distance
M05 M30; Spindle stop & Program end

Basic of CNC programming lathe

Before learning about cnc programming for lathe machine we should know about the Cartesian Coordinate system.From which we can find out the coordinate point for any work piece.We should also learn about WORK CO-ORDINATE,TOOL GEOMETRY,TOOL WEAR.

Cnc Facing programming

Raw material size – Diamter-20,Lenght- Any. If we want facing for 2 mm.

Basic of CNC programming-Facing program example

G0 X21.0 Z0.5 ; – Safety distance(Tool will move to 21.0 point in X axis and 0.5 in z axis rapidly ).20.0 is the diameter of raw material and face of work piece is the Z0.0.Tool will stop at Z 0.5 which is the distance from face.This is the suitable safety distance for raw material.After this it will start facing.

G01 Z-1.0 F0.3; – Tool will move to Z -1.0 in feed (Feed you can change)

G01 X 0.0; – Tool will move to X0.0 in feed .This is the facing operation of tool.As the tool start removing material from Z-1.0 to X0.0.That means 1.0 mm of material remove from face of the work piece.

G01 Z0.5; Now tool will move to Z 0.5 in feed.

G00 X21.0; Tool will move rapidly move to X21.0. Next to perform another facing operation.

G01 Z-2.0; Tool will move to Z-2.0 so that it can remove another 1.0 mm material

G01 X0.0; Tool will remove 1.0 mm of material from face of the work piece in this movement.

Now we can again move the tool to Z 0.5 in feed and then X21.0 in rapid.We can use the facing cycle to perform the facing operation.There we have to set the dimension to face and feed.The facing cycle will remove the material as per your requirement.

Basic of CNC Programming-Turning.

If the Raw material having diameter 20 and lenght 30. and we want to make it of diameter 18 upto lenght 15mm.

G00 Z3.0; – This is the safety distance for Z axis i.e tool will move rapidly and stop at Z3.0.Which is the distance from face.(As face of workpiece is taken Z0.0)

G00 X22.0; – This is the safety distance for X axis.

G01 X19.0; – The tool will move to 19 diameter in X axis in feed. .(This movement is for turning of 1mm i.e upto 19 diameter)

G01 Z-15; – This is the Turning operation.Tool will move from X19.0 to Z-15 with removing material.(Here you can turn ON the coolant)

G01 X22.0; – Tool will move to safety distance of x axis.

In this way you can turn another 1mm.This is the way for turning operation.

Simple programming example.

Learn Hydraulics-Click here.
Learn about Solenoid valve-Visit here.

CNC Operation & Maintenance-Visit here

*Facing program*	*Turning program*	*Taper turning program*
*Grooving Program*	*Radius program*	*Turning cycle & Facing cycle*

Basic of CNC programming | Basic program writing

Published by Rajib on December 6, 2020December 6, 2020