Cnc Codes and Letters

7/28/2019 Cnc Codes and Letters

1/48

CNC Codes and Letters

NOTE: The following will be a listing and description of

Computer Numerical Control (CNC) Codes and Letter

designations. We will try to stick with only generic

codes that will work on most machines. Someexamples may be specifically for the machines we

have at South Adams / Area 18 Machine Trades.

Please contact the instructor if you find any errors,

missing items, or anything you would like to see

added. [email protected]


2/48

You should already have alist of G&M Codes and

CNC Letters as shown. If

you do not have one, see

your instructor, ordownload one off of the

South Adams / Area 18

Machine Trades

Code Meaning Letter Meaning

G00 Positioning (Rapid Traverse) A Rotary indexing axis around the "X" axis

G01 Linear Interpolation (Feed) B Rotary indexing axis around the "Y" axis

G02 Circular Interpolation CW C Rotary indexing axis around the "Z" axis

G03 Circular Interpolation CCW D Cutter Radius / Diameter offset number

G04 Dwell E Feedrate in inches per revolution (Lathe)

G17 X,Y Plane of Interpolation F Feedrate in inches per minute (can be used on lathes)

G18 X,Z Plane of Interpolation G Preparatory commands

G19 Y,Z Plane of Interpolation H Offset Number (Mill - tool length)(Lathe - Position offset)

G20 Input in Inch I Arc center location in the "X" axis

G21 Input in MM J Arc center location in the "Y" axis

G28 Return to Machine zero (reference point) K Arc center location in the "Z" axis

G40 Cutter Compensation cancel L Fixed Cycle repetion count / subprogram repetition count

G41 Cutter Compensation left M Miscellaneous function

G42 Cutter Compensation right N Block / Sequence number

G43 Tool length compensation + O Program Number

G44 Tool length compensation - P Subprogram / Macro Number call

G54-G59 Set Local Coordinate Systems (Datum Shifts) P Dwell time in milliseconds

G80 Canned Cycle cancel P Block number in main program when used with M99

G81 Spot Drilling Cycle (no dwell) Q Depth of peck in fixed cycles (G73and G83)

G82 Drill/Counterbore (with dwell) Q Shift amount in fixed cycle (G76 and G87)

G83 Peck Drilling Cycle R Retract point in fixed cycles

G85 Bore R Arc Radius designation

G90 Absolute Programming S Spindle speed in RPMs

G91 Incremental Programming T Tool function

G92 Set Program Zero U Incremental move in "X" axis

G94 IPM Programming V Incremental move in "Y" axis

G95 IPR Programming W Incremental move in "Z" axis

M00 Program stop X "X" axis coordinate value designation

M01 Optional stop Y "Y" axis coordinate value designation

M02 End of Program Z "Z" axis coordinate value designation

M03 Start Spindle (Clockwise)

M04 Start Spindle (Counterclockwise)

M05 Spindle off

M06 Tool change

M08 Coolant on

M09 Coolant off

M30 Program reset/tape rewind

M98 Sub-Program call

M99 Return to previous program


3/48

G Codes- G Codes are known as Preparatory Commands

which means they are preparing the CNC machine

to do something.

- Normally there should only be one G code per

line, one exception is in the Safety Line at the

beginning of the program.

- G Codes are to be at the start of the Block ofProgram.

Safety Line Example: G17 G20 G40 G80 G90


4/48

G00 Positioning Rapid Traverse

-First of all notice that it is G Zero Zero all of

the G&M Codes use Zero and not the letter O.-G00 means the tool is going to move fromwhere ever it currently is to the next position in a

straight line as fast as the machine will go.- Think of G00 as a dragster, something that willgo from point A to point B in a straight line as fastas possible

Example: G00 X2.00 Y3.00


5/48

G01 Linear Interpolation- G01 means the tool is going to move from where ever it currently

is to the next position in a straight line but this time with a givenfeedrate.

- Think of G01 as a truck driving on highway 218 or 124 through

Adams County, Indiana, these highways are straight AND they have a

speed limit.- On Milling Machines, the feedrate will typically be in IPM (inches

per minute) and labeled with an F.

-On Turning Machines, the feedrate will typically be in IPR (inches

per revolution) and labeled with an E or F

Example: G01 X2.00 Y3.00 F6.00


6/48

G02 Circular Interpolation (CW)

-G02 Used anytime you need an arc in the Clockwise

direction.

- As with any Interpolation (machine movement), the

machine already knows where it is, you only need to

tell it where you want to go next.-For example: if you are setting at X0,Y0 and you want

to put a 1.00 radius to X1.00, Y1.00 the Block

would look like one of the following:G02 X1.00 Y1.00 R1.00 F12.0

G02 X1.00 Y1.00 I1.00 J0 F12.0


7/48

G03 Circular Interpolation (CCW)

-Just like with the G02 preparatory command, the

G03 will move from point A to Point B only this time

in a Counter Clockwise direction.

- The Block of code will look identical to the code for

G02 only the code will change.G03 X1.00 Y1.00 R1.00 F12.0

G03 X1.00 Y1.00 I1.00 J0 F12.0

- Always keep an eye on the details, the difference between G02

and G03 would be devastating if you wanted one and entered the

other into a program!


8/48

CNC Vocab pit stop

- Modal [mohd-l]

- A Command that is to remain in acertain mode until canceled byanother mode

- In other words: it keeps going andgoing and going and going.. Untilit is told to stop later in the program

- Antonym = Non-modal


9/48

G04 Dwell-G04 is used anytime you want to pause or dwell

at a position- A common Block when Dwell is required

would beG04 P500

-The G04 of course specifies Dwell-The P500 states that it will be for 500 milliseconds

- Note: 1 Second equals 1000 milliseconds

- Therefore if you need to pause for 4.5 seconds you

would program the Block as: G04 P4500

Example: G04 P1000


10/48

G17 X,Y Plane of Interpolation

-G17 is the most common plane to choose for a

vertical machining center.

-G17 will normally be one of if not THE first G

code in a program.

- The reason the G17 is so popular is that it could

also refer to the table in front of you, the X axis

is right and left movements while the Y axis

would be towards and away from you


11/48

G18 X,Z Plane of Interpolation

-G18 could best be described as a normal engine

lathe because the Z axis is the longitudinal travel

of the lathe and the X axis would be your cross

slide.

- On a vertical machining center, this plane wouldbe like looking at the screen of the controller since

the X axis is right and left and the Z axis is up

and down.


12/48

G19 Y,Z Plane of Interpolation

-On a Vertical milling machine, this would be the

plane parallel to the side of the machine.

- Once again, just think it through, the Y axis is

towards and away from you and the Z axis is up

and down.


13/48

G20 Inch Input-G20 will typically be at the beginning of the

program, that way the CNC knows right away that

every dimension entered will be Inch and not

metric.

- G20 is very important to enter into eachprogram you want to be inch, imagine if the

program that ran prior to yours was a metric

program and you do not switch it to inch, everydimension you enter will be read by the CNC as

metric. OPPS!


14/48

G21 Metric Input-Many shops have switched over to total metric, so

G21 is becoming more popular in this area.

- How you program using G21 is identical to

G20 the only difference is you are entering

Metric dimensions instead of Inch.


15/48

G28 Return to Machine Zero-AKA: Return to Reference Point

- G28 can be very handy, On a Vertical Machining

Center anytime you want the tool as far away from

the part vertically as possible you would enter

G28 G91 Z0. If you want the part to come asclose to you as possible for easy part changing you

would enter G28 Y0

-Example: G28 G91 X0 Y0 Z0 Would bring the

machine as fast as it can to its home position


16/48

G40 Cutter Compensation Cancel

-Typically found in the Safety Line of the program

- Just like the description implies, G40 is used to

cancel any cutter compensations whether it is for

length (or height) compensation or Diameter

Compensation.- Keep in mind that the person operating the

machine prior to you could have done something

with cutter compensation totally legal BUT differentthan what you need, cutter compensation cancel will

clear everything out and be ready for you to add.


17/48

G41 Cutter Compensation Left-Cutter compensation is used to program a part

exactly to size using the dimensions provided on

the print. THEN at the machine, offset that

geometry to compensate for the tool you are using

- Imagine climb milling around the outside of thispicture the cutter would be rotating clockwise and

moving around the picture clockwise, now guess

which side of the part the cutter is. Your right,the LEFT side!


18/48

G42 Cutter Compensation Right- Just like the G41 compensation only the

opposite. Imagine conventional milling the same

outside of this picture, the cutter is still spinning

clockwise but this time the cutter is traveling

counterclockwise around the outside of the part.NOW which side of the part is the cutter traveling

on? You are right the Right side!


19/48

G43 Tool Length Compensation +- Tool length compensation allows a machine to

adjust for the different lengths of the tools.

- Basically it is telling the machine how far it is

from its Z home position to the position when

the part touches the Z origin of the part.

- The H value will be Added (+) to programmed

Z position

Example: G43 Z1.0 H01


20/48

G44 Tool Length Compensation -- Tool length compensation allows a machine to

adjust for the different lengths of the tools.

- Basically it is telling the machine how far it is

from its Z home position to the position when

the part touches the Z origin of the part.

- The H value will be Subtracted (-) from the

programmed Z position

Example: G44 Z1.0 H01


21/48

G54-G59 Work Offsets- AKA: Datum Shifts

- AKA: Set Local Coordinate Systems

- Specifies the distance the machine would need

to move from its home position to the origin of

the part or fixture.

- Used mostly when multiple parts / fixtures /

Set-ups are on the same table

Example: G55 G90 G00 X0.000 Y0.000


22/48

G80 Canned Cycle Cancel- AKA: Fixed Cycle Cancel

- Clears out any Modal Canned or Fixed cycles

used earlier in a program

- Used in the Safety Line to insure that what

someone else did before does not affect what

you will be doing in your program

Example: G82 X2.00 Y3.00 R.100 Z-.500 F6.0

G80


23/48

G81 Spot Drill Cycle (no dwell)- Specifies that you want to drill to a given depth

- Along with the G81 you will also need to specify

the following:

- Hole Position

- R-Plane

- Z Depth

- Feedrate

Example: G81 X2.00 Y3.00 R.100 Z-.250 F6.0


24/48

G82 Spot Drill Cycle (dwell)- Specifies that you want to drill to a given depth


the following:

- Hole Position

- R-Plane

- Z Depth

- Feedrate

- Dwell time

Example: G82 X2.00 Y3.00 R.100 Z-.250 F6.0 P500


25/48

G83 Peck Drill Cycle- Specifies that you want to drill to a given depth


the following:

- Hole Position

- R-Plane

- Z Depth

- Feedrate

- Peck Increment

Example:

G83 X2.00 Y3.00 Z-1.500 R.100 Q.250 F6.0


26/48

G83 Peck Drill Cycle ComparisonG83 X2.00 Y3.00 Z-1.500 R.100 Q.250 F6.0

- OR -

N0110 G00 X2.00 Y3.00

N0120 G00 Z.100

N0130 G01 Z-.150 F6.0

N0140 G00 Z.1

N0150 G00 Z-.150N0160 G01 Z-.400

N0170 G00 Z.1


27/48

WE ARE NOT DONE YETN0180 G00 Z-.400

N0190 G01 Z-.650

N0200 G00 Z.100

N0210 G00 Z-.650

N0220 G01 Z-.900

N0230 G00 Z.100

N0240 G00 Z-.900N0250 G01 Z-1.150

N0260 G00 Z.100


28/48

STILL A COUPLE MORE LINESN0270 G00 Z-1.150

N0280 G01 Z-1.250

N0290 G00 Z.100

That is just for one hole! Now imagine doing that

for EVERY deep hole!

One line per hole versus 19 Lines you decide!


29/48

G73 Peck Drill Cycle (High Speed)- Specifies that you want to drill to a given depth

- Does NOT fully retract after each peck depth


the following:

- Hole Position

- R-Plane

- Z Depth

- Feedrate- Peck Increment

Example:

G73 X2.00 Y3.00 Z-1.500 R.100 Q.250 F6.0


30/48

G84 Tapping Cycle (RH)- Specifies that you want to Tap a previously

drilled hole


the following:

- Hole Position

- R-Plane

- Z Depth

- Feedrate = RPM X Lead of the thread- 1/4-20 Thread at 800RPM = F40.0

Example: G84 X2.00 Y3.00 R.100 Z-.250 F40.0


31/48

G85 Boring Cycle- Specifies that you want to Bore to a given depth


the following:

- Hole Position

- R-Plane

- Z Depth

- Feedrate

Example: G85 X2.00 Y3.00 R.100 Z-.250 F6.0


32/48

CNC Vocab pit stop- Cartesian Coordinate System(krt'zhn)

A system in which the location of a point is givenby coordinates that represent its distances fromperpendicular lines that intersect at a point calledthe origin.


33/48

G90 Absolute Programming- The Origin or Datum location of your part does

not move.

- ALL coordinates are in relationship to one

location in space

Example: G90 G00 X2.00 Y3.00 Z1.00


34/48

G91 Incremental Programming- The Origin or Datum location of your part does

moves as your tool moves

- ALL coordinates are in relationship to the point

the tool is located at

Example: G91 G00 X2.00 Y3.00 Z1.00


35/48

M Codes- M Codes are known as Miscellaneous

Functions.

- Normally there should only be one M code per

line. Most machines are really picky about this,more so than with G codes.

- M Codes are to be at the start of the Block of

Program.

Example: M03 S1500


36/48

M00 Program Stop- REMINDER: notice that it is M Zero Zero

all of the G&M Codes use Zero and not theletter O.

- M00 will stop the program without pressing

Feed Hold

- Insert M00 whenever you want to stop the

program no matter what the conditions are.

- Note: on some machines this will also turn offthe spindle and not restart it without a M03

Example: M00


37/48

M01 Optional Stop- M01 is a conditional stop, it is determined by an

operator activated switch on the control panel

- If the switch is on, it will stop the program

identical to a M00

- If the switch is off, it will ignore the M01

- Best uses:

- Before or After Tool Changes

- Anytime you want to inspect, oil or manipulate the

part or tool

Example: M01


38/48

M02 End of Program- M02 is used only at the end of the program

- Some machines will not start a program unless

it knows there is an end

- M02 does not rewind the program

Example: M02%


39/48

M03 Spindle Rotation Normal- M03 Mill Clockwise rotation If you were on

top of a vertical milling machine looking down

- M03 Lathe Normal Rotation the direction

the chuck would need to spin if you had a

normal right hand helix drill bit

Example: M03 S1200


40/48

M04 Spindle Rotation Reverse- M04 Mill Counter-Clockwise rotation If you

were on top of a vertical milling machinelooking down

- M03 Lathe Reverse Rotation the opposite

direction the chuck would need to spin if youhad a normal right hand helix drill bit

Example: M04 S1200

dl ff


41/48

M05 Spindle Off- Turns spindle off

Example: M05

i l h


42/48

M06 Automatic Tool Changer- AKA: ATC

- Will put away the tool that is in the spindle and

replace it with the tool that is identified on the

same line as the M06

Example: M06 T01

or

T01 M06

0 i C l O


43/48

M07 Mist Coolant On- Turns on Mist Coolant

Example: M07

M08 Fl d C l O


44/48

M08 Flood Coolant On- Turns on Flood Coolant

Example: M08

M08 C l Off


45/48

M08 Coolant Off- Turns Off All Coolant pumps / Soleniods

Example: M09

M30 E d f P & R i d


46/48

M30 End of Program & Rewind- M30 is used only at the end of the program

- Some machines will not start a program unless

it knows there is an end

- M30 does rewind the program

- All you have to do is change the part and press cycle

start

- More common than M02

- Especially if more than one part is to be made

Example: M30

%

M98 S b P C ll


47/48

M98 Sub-Program Call- Used in a main program when you want to call

up another program while still in the mainprogram.

Example: M98 P1001

M99 S b P E d


48/48

M99 Sub-Program End- Used in place of an M30 when a program is

used as a sub-program

Example: M99

%

Documents

Cnc Codes and Letters